US 5975893

I'll verify against live sources before summarizing.

Let me try to retrieve the rest of the claim set, since the fetched text truncates mid-claim 10.

Verified identification — US 5,975,893

I confirmed the number against the authoritative patent text at https://patents.google.com/patent/US5975893/en. I did not substitute any similar number; everything below is for US 5,975,893 specifically ("the '893 patent").

Bibliographic data

Note on a date discrepancy (not auto-corrected): some third-party aggregator pages (e.g., Unified Patents' page for US-5975893-A) list a priority date of 1997-06-19, whereas the patent record and Google Patents state 1997-06-20. 1997-06-19 is the PCT/US98/12861 filing date used as a priority link for the wider family. I am reporting both literally rather than reconciling them.

Abstract (verbatim from the patent)

"A system for repositioning teeth comprises a plurality of individual appliances. The appliances are configured to be placed successively on the patient's teeth and to incrementally reposition the teeth from an initial tooth arrangement, through a plurality of intermediate tooth arrangements, and to a final tooth arrangement. The system of appliances is usually configured at the outset of treatment so that the patient may progress through treatment without the need to have the treating professional perform each successive step in the procedure."

Independent claims — plain-language overview

Only two independent claims are verifiable from the text I retrieved (claim 1 and claim 6). The fetched patent text truncates in the middle of claim 10, so I cannot verify claims 11–29 — see the uncertainty section below.

Claim 1 — System claim (apparatus).
A kit/system of clear orthodontic appliances for moving teeth from an initial to a final arrangement, comprising:

• a first appliance shaped to move teeth from the initial arrangement to a first intermediate arrangement;
• one or more intermediate appliances shaped to progressively move teeth onward through successive intermediate arrangements; and
• a final appliance shaped to move teeth from the last intermediate arrangement to the final arrangement,
• where each appliance is a polymeric shell with a cavity, and the cavities of successive shells have different geometries shaped to receive and resiliently reposition the teeth from one arrangement to the next.

In short: a pre-planned sequence of differently-shaped plastic aligner trays, each representing one increment of tooth movement. This is the foundational Invisalign-style system claim.

Claim 6 — Method claim (treatment method).
The method counterpart: placing the first incremental appliance in the patient's mouth to go from the initial to a first intermediate arrangement; successively replacing it with additional appliances whose geometries progressively move the teeth through intermediate arrangements; and then placing a final appliance to reach the final arrangement — again with each appliance being a polymeric shell whose cavity geometry differs from the prior shell's, so as to resiliently reposition the teeth.

In short: the clinical method of treating a patient by stepping through the same series of trays in order.

Selected dependents (verified):

• Claims 2 and 7: successive appliance geometries differ from the prior appliance by no more than 2 mm (per tooth position).
• Claims 3–5: the system has at least two intermediate appliances (claim 3), at least ten (claim 4), at least twenty-five (claim 5).
• Claims 8–9: the method's successive-placement step involves at least two additional appliances (claim 8) / at least ten added appliances (claim 9).
• Claim 10: begins "A method as i…" — text truncated, dependency/scope unverified.

Independent claims beyond claim 6 — not verified. The specification describes additional subject matter (producing a final digital data set from a manipulated visual image; producing a plurality of successive digital data sets by interpolating positional differences; fabricating appliances via a stereolithography-style fabrication machine producing positive models, with the appliance molded as a negative). It is plausible but not confirmed from the record I retrieved that some of claims 11–29 are additional independent claims covering those method aspects. I am flagging this rather than asserting it.

USPTO / docket check for 2026

I did not find any 2026 CAFC appeal docketed for the '893 patent itself, and that is consistent with its status: the '893 patent is listed as expired – lifetime, with anticipated expiration 2017-10-08 (20 years from the 1997-10-08 filing date). A 2026 CAFC appeal of a PTAB decision on the '893 patent would be unusual for an expired patent, and none surfaced.

What the live searches did surface in the Align ecosystem (all on different patents, listed here only so you don't mistake them for '893 activity):

• PTAB IPR2025-00819 and IPR2025-00820 (ClearCorrect Operating LLC v. Align Technology, Inc.) — petitioner exhibit "Exhibit-1050 – US Patent No. 5,975,893," dated Apr. 14, 2025. Here the '893 patent appears to be cited as prior art against a later Align patent, not as the challenged patent. I cannot confirm from these search hits which patent is under review.
• Align Technology, Inc. v. ClearCorrect Operating, LLC et al., W.D. Tex. No. 6:24-cv-00187 — an order setting a May 27, 2026 motion hearing on ClearCorrect's preclusion motion, Align's partial summary judgment of validity, and ClearCorrect's § 101 invalidity motion. The patents at issue in that case are not identified in the order I retrieved; I have no evidence the '893 patent is asserted there (and given its 2017 expiration, it almost certainly is not).
• Dental Monitoring SAS v. Align Technology, Inc. — 2026 CAFC activity (Nos. 2024-2270 and 25-1879) involving Align's deep-learning dental-image patents (the '248 and '945 patents), § 101 and § 103/obviousness. Again, not the '893 patent.
• Google Patents records family litigation for the '893 family: N.D. Cal. 5:15-cv-04864 (flagged "Critical") and S.D. Tex. 4:11-cv-00695.
• A related Align patent's file history shows the examiner used claims 1–5 of the '893 patent in an obviousness-type double-patenting rejection against application 10/040,269 (which issued as the '863 patent, U.S. 7,054,611 lineage); Align responded with terminal disclaimers. That is historical (2003) and concerns other patents' terms, not the '893 patent's own term.

Uncertainty and data-quality flags

1. Claim text truncation. The authoritative source I retrieved cuts off at claim 10 of 29. Claims 11–29 (and any independent claims among them) are not verified. I will not guess at their content.
2. Apparent OCR errors in the claim text at the source — reported literally, not corrected:
   • Claim 6 reads "…wherein the cavities of successive shells have difficult geometries to receive and resiliently reposition teeth…" — almost certainly a scanning artifact for "different."
   • Elsewhere: "arid" for "and," "palette" for "palate," "stimulate the extraction" for "simulate," "ALIGN TECHNOLOGY, INC. / WITH, KELSEY" in one assignment record for "WIRTH, KELSEY," and "3D System, Valencia, Calif." for 3D Systems.
3. Live-database access. I could not log into USPTO PatentCenter, PACER, or the CAFC docket to query the '893 patent's docket directly; the litigation/PTAB items above come from web search hits. Treat the IPR petitioner-exhibit detail (IPR2025-00819/00820) as indicative but unconfirmed.
4. No 2026 CAFC docket for '893 was found — stated as a negative finding based on search, not as a certification that none exists.

I'll research litigation involving US patent 5975893. Let me start with searches on litigation databases.

Let me search for the specific cases identified in the patent record.

Let me dig into the SmileCareClub case and check which patents were asserted, plus the earlier Ormco litigation.

Based on my research, here are the litigation matters I could tie specifically to U.S. Patent No. 5,975,893 ("Method and system for incrementally moving teeth," Chishti et al., filed Oct. 8, 1997, issued Nov. 2, 1999, expired Oct. 8, 2017, assigned to Align Technology, Inc.).

Confirmed district-court cases asserting the '893 patent

1. Align Technology, Inc. v. SmileCareClub LLC, et al.

• Court/jurisdiction: U.S. District Court for the Northern District of California
• Case number: 5:15-cv-04864
• Filed: October 22, 2015
• Plaintiff: Align Technology, Inc.
• Defendants: SmileCareClub LLC; Camelot SL, LLC d/b/a SharperImage.com; Brookstone, Inc.
• Patents asserted: Fourteen Align patents, the first-listed being U.S. Patent No. 5,975,893 (the "'893 patent"). Align's complaint specifically identifies the '893 patent as issued to Align on Nov. 2, 1999, and attaches it as Exhibit A. Claim causes included patent infringement plus false advertising/unfair competition.
• Outcome/status: Docket status is Closed. I do not have a verified record of the precise termination terms (e.g., settlement vs. dismissal), so I will not guess at them.

Sources: Align press release (Oct. 22, 2015), https://aligntech.gcs-web.com/news-releases/news-release-details/align-technology-files-patent-infringement-and-false-advertising ; complaint excerpt (Patents-in-Suit, ¶¶8–20), https://www.docketalarm.com/cases/California_Northern_District_Court/5--15-cv-04864/Align_Technology_Inc._v._SmileCareClub_LLC_et_al/docs/1.pdf ; docket summary https://ai-lab-cl-prod.azurewebsites.net/case/dct/cand/5:15-cv-04864/align-technology-inc-v-smilecareclub-llc

2. Align Technology, Inc. v. ClearCorrect, Inc., et al.

• Court/jurisdiction: U.S. District Court for the Southern District of Texas (Houston Division)
• Case number: 4:11-cv-00695
• Filed: February 28, 2011
• Plaintiff: Align Technology, Inc.
• Defendants: ClearCorrect, Inc.; ClearCorrect Operating, LLC; ClearCorrect Holdings, LLC
• Judge: Vanessa D. Gilmore (case initially assigned to Lee H. Rosenthal)
• The '893 patent's involvement: The case asserted nine Align patents. The '893 patent was among them — Align publicly stated that after ex parte reexamination certificates confirmed the '893 and '548 patents, it "is asserting both confirmed patents in its pending patent infringement lawsuit against ClearCorrect in the Federal District Court, Southern District of Texas."
• Outcome/status: The case was stayed May 10, 2012 pending ITC proceedings, lifted January 4, 2017, and the docket shows the case closed on March 28, 2019 (case open ~2,951 days). I could not verify final disposition terms.

Sources: RPX Insight docket, https://insight.rpxcorp.com/litigation/txsdce-[868734](/patent/868734)-align-technology-v-clearcorrect ; CourtListener docket, https://www.courtlistener.com/docket/[4398500/248](https://assignmentcenter.uspto.gov/search/patent/reelFrameDetail?reelFrame=4398500-0248)/align-technology-inc-v-clearcorrect-inc/ ; reexamination/assertion summary, https://huangshandental.com/both-sides-claim-victory-in-clear-aligner-patent-case/

Related proceedings I reviewed that do NOT appear to involve the '893 patent

To be transparent about what the '893 patent was not part of:

• ITC Inv. No. 337-TA-562 (Align v. OrthoClear) — the asserted patents listed on appeal were 6,685,469; 6,450,807; 6,394,801; 6,398,548; 6,722,880; 6,629,840; 6,699,037; 6,318,994; 6,729,876; 6,602,070; 6,471,511; and 6,227,850. '893 does not appear. (Fed. Cir. 771 F.3d 1317.)
• ITC Inv. No. 337-TA-833 ("Digital Models," Align v. ClearCorrect) — asserted 6,217,325; 6,471,511; 6,626,666; 6,705,863; 6,722,880; 7,134,874; and 8,070,487. '893 does not appear.
• ITC Inv. No. 337-TA-1090 (Align v. 3Shape) — asserted 9,615,901; 8,638,447; 8,638,448; 6,845,175; and 6,334,853. '893 does not appear.

Post-issuance proceeding (not litigation, but relevant to the '893 patent)

An ex parte reexamination of the '893 patent was requested in fiscal 2005–2006 by a San Francisco law firm on behalf of an unnamed party. All claims were initially rejected (first office action Jan. 26, 2006; final rejection June 23, 2006), and after amendments, the USPTO issued a Notice of Intent to Issue a Reexamination Certificate dated Sept. 18, 2007, i.e., all challenged claims were ultimately confirmed. Source: Align SEC filing, https://aligntech.gcs-web.com/static-files/bda2e415-84be-4def-8552-01e512beecdf

Caveats / confidence

• The Google Patents litigation tab for US5975893 lists exactly two U.S. case identifiers: the N.D. Cal. case 5:15-cv-04864 and the S.D. Tex. case 4:11-cv-00695 — consistent with the two cases above. It also flags "first worldwide family litigation filed" via Darts-IP (family 21964711), but provides no case-level detail.
• I could not confirm that the '893 patent was asserted in Ormco Corp. v. Align Technology (C.D. Cal., filed Jan. 6, 2003) or in the numerous Align v. SmileDirectClub / Invisalign antitrust matters (e.g., Snow v. Align, N.D. Cal. 3:21-cv-03269) — those appear to involve different patents or non-patent claims. If you need Ormco confirmed, that would require a PACER pull of the C.D. Cal. docket.
• Case numbers, dates, and docket statuses above are drawn from the cited sources; I have not independently verified outcome terms for either case, and the '893 patent expired October 8, 2017, so it is no longer assertable.

If you need a certified litigation history, the authoritative next steps would be PACER for both dockets and a Darts-IP/Unified Patents family litigation pull for family 21964711.

I'll start by verifying whether any AIA trial proceedings exist for this patent, since the structured ODP block says none are on file.

The searches surface reexaminations, not AIA trials. Let me dig deeper on whether any IPR/PGR/CBM ever targeted the '893 patent specifically.

Important lead: IPR2025-00819 appears to involve the '893 patent. Let me investigate that proceeding and any companion filings.

US 5,975,893 — AIA Trial Proceedings Report

Patent: US 5,975,893 A ("Method and system for incrementally moving teeth") — Align Technology, Inc.
Effective filing date: 1997-10-08 (CIP of provisional 60/050,342, filed 1997-06-20) · Issued: 1999-11-02 · Legal status: Expired – Lifetime (Google Patents lists anticipated expiration 2017-10-08)
Source of record: https://patents.google.com/patent/US5975893/en

Proceedings overview

There are zero AIA trial proceedings (IPR/PGR/CBM) on US 5,975,893. The structured "PTAB proceedings on file" block from the USPTO Open Data Portal reports no AIA trials, and independent web research through docket aggregators, PTAB E2E/PTACTS document repositories, Align's litigation-related press releases, and the Federal Circuit's ITC appeal record surfaces no petition ever filed against the '893 patent — breakdown: 0 active, 0 claims invalidated, 0 claims sustained by the Board, 0 settled, 0 institution decisions (grant or denial). The defensive posture is therefore not "hardened by surviving IPRs" and not "claims canceled by the Board" — it is untested in an AIA trial, but also expired. The '893 patent was twice confirmed in ex parte reexamination (Control Nos. 90/007,477 and 90/013,581), each time with all challenged claims confirmed without amendment, and it appears in the 2025 PTAB docket only as a prior-art exhibit (Ex. 1050) in a different patent's IPR. For a defendant being asserted today, the controlling fact is not the PTAB history at all — it is that the patent term ran out on 2017-10-08.

AIA proceedings on the '893 patent

None.

No Inter Partes Review, Post-Grant Review, or Covered Business Method review has ever been instituted or even requested against US 5,975,893. I verified this rather than assuming it, because the 2025 PTAB docket contains an Align/ClearCorrect case number whose exhibits include the '893 patent — that reference is an exhibit, not a challenged patent (see adjacent-proceeding notes below).

Why the AIA lanes are structurally closed on this patent:

Adjacent proceedings (NOT AIA trials on the '893 patent — flagged to prevent docket confusion)

These are the items web search surfaced that name or touch the '893 patent. None of them is an AIA trial of the '893 patent. I include them because a defendant's counsel will see them in Align's litigation narrative and may mistake them for PTAB validity outcomes.

90/013,581 — ex parte reexamination of US 5,975,893 (requester: ClearCorrect Operating LLC)

• Type: Ex parte reexamination — not an AIA trial; the PTAB never adjudicated it.
• Filed: circa 2015 (the ClearCorrect reexamination wave against Align patents was filed in mid-to-late 2015; the contemporaneous requests are reflected in the PTO Litigation Center Report of 2015-10-15, e.g., Control No. 90/013,606 for the '548 patent filed 2015-10-14: https://natlawreview.com/node/53399/printable/pdf).
• Status: Concluded — all challenged claims confirmed without amendment; reexamination certificate issued in the February–March 2017 window. Align's press release reports certificates for the '893 and '548 patents "On February 22 and March 22, 2017" without mapping each date to a patent; I cannot confirm from available sources which of the two dates is the '893 certificate: https://investor.aligntech.com/index.php/news-releases/news-release-details/align-technology-prevails-additional-us-patent-office
• Judge panel: None — ex parte prosecution before a CRU examiner, no Board panel.
• Grounds: Prior-art rejections (§ 102/§ 103) raised by the third-party requester; specific references not confirmed from the record available to me. I will not guess at the art.
• Institution decision: N/A (requester has no participation rights after filing).
• Final written decision: N/A. Outcome: certificate confirming patentability of all challenged claims, no claim amendments. (Contrast with the sibling '880 patent, Control No. 90/013,491, whose certificate of 2017-02-10 confirmed claims 1–3, 11–14, 18, 20–21, 23, 27–35, and 37–39 without amendment — source: Align's Updated Mandatory Notices in IPR2016-00270.)
• Settlement / termination: N/A.
• Appeal: None. Ex parte reexamination certificates are appealable only by the patent owner, and Align had no adverse outcome to appeal; a third-party requester who is dissatisfied has no appeal right.
• Defensive value: Double-edged. Align will cite it as proof of validity; the requester's public position (Scott McKeown, ClearCorrect's lead counsel) is that the reexamination record is "one-sided" and was decided without the adversarial rebuttal the Board had in the parallel IPR on the '037 patent. Practically, the confirmations make a district-court § 102/§ 103 attack on the '893 claims harder to pitch as a quick win — but they carry no issue-preclusive or estoppel effect, and they say nothing about the 2025-era prior art.

90/007,477 — earlier ex parte reexamination of US 5,975,893

• Type: Ex parte reexamination (not an AIA trial).
• Filed: Not determined from available sources; identified as a co-pending/prior matter on the '893 patent in Align's mandatory notices filed in IPR2016-00270 (https://www.docketalarm.com/cases/PTAB/IPR2016-00270/Inter_Partes_Review_of_U.S._Pat._6699037/docs/12-22-2015-Patent_Owner/Notice-5-Related_Matters.pdf).
• Status / outcome / panel / appeal: Not verified. I did not locate the certificate. Treat as unresolved rather than assuming a result.

IPR2016-00270 — ClearCorrect Operating, LLC v. Align Technology, Inc. (US 6,699,037 — different patent, same title)

• Type: Inter Partes Review.
• Filed: 2015 (petition filed late 2015; patent owner's mandatory notices dated 2015-12-22).
• Status: Final Written Decision issued 2017-03-24 — claims 1, 2, 9, and 10 unpatentable. Institution May 2016.
• Judge panel: The Board's decision file is captioned "IPR2016-00270 FWD Mayberry–Cocks–Tierney_RFM," which indicates a panel of Administrative Patent Judges Mayberry, Cocks, and Tierney. (Inferred from the document caption; I did not independently confirm each APJ's full name from the Board's caption page.)
• Petition grounds: § 103(a) — the sole instituted ground was that claims 1, 2, 9, and 10 were obvious over Snow, Hultgren, and Kesling. ClearCorrect challenged only claims 1, 2, 9, and 10 of the 21-claim patent.
• Institution decision: Instituted on a single ground, May 2016.
• FWD: Claims 1, 2, 9, and 10 canceled. The panel expressly rejected Align's argument "that digital modeling was in its very early stages in the relevant timeframe," holding that this "contention contradicts the '037 patent, which discloses that generating three-dimensional digital data representing the shape and position of a patient's tooth was known." Claims 3–8 and 11–21 were never challenged and were not addressed. Full text: https://www.docketalarm.com/cases/PTAB/IPR2016-00270/Inter_Partes_Review_of_U.S._Pat._6699037/docs/03-24-2017-Board/Final_Decision-43-Final_Written_Decision.pdf
• Settlement / termination: No settlement — decided on the merits.
• Appeal: Align publicly stated it "intends to appeal to the Court of Appeals for the Federal Circuit" (Align press release, 2017-03-28). I could not confirm a CAFC docket number or disposition; do not assume affirmance or reversal without pulling the CAFC docket.
• Defensive value: This is the single most useful data point a defendant has against the Align '893-era family. The Board canceled the challenged independent claims of the closely related, same-titled '037 patent on § 103(a) over Snow/Hultgren/Kesling — the same art and the same "known digital modeling" reasoning that a defendant would aim at the '893 claims. But it is not a validity ruling on '893, and it creates no estoppel or preclusion as to '893.

IPR2025-00814 through IPR2025-00821 — ClearCorrect Operating, LLC v. Align Technology, Inc. (2025 wave — none of these patents is the '893 patent)

• Type: Inter Partes Review (eight petitions).
• Filed: 2025-04-14.
• Patents challenged: US 10,456,217 (IPR2025-00814); 10,524,879 (-00815); 11,369,456 (-00816); 10,791,936 (-00817); 10,973,613 (-00818); 11,154,384 (-00819); 11,648,090 (-00820); 11,648,091 (-00821). US 5,975,893 is not among them. The '893 patent appears in the IPR2025-00819 record only as ClearCorrect Exhibit 1050 — a prior-art patent cited against the '384 patent.
• Status (as of 2026-09-29): Institution granted in at least IPR2025-00819 on 2025-11-06 ("DECISION Granting Institution of Inter Partes Review 35 U.S.C. § 314"); independent aggregators list trial instituted. Statutory FWD deadline ≈ 2026-11-06 to 2026-11-08 (the Director's decision records a "projected final written decision due date ... November 8, 2026").
• Judges: Panel assignments for the 2025 wave are not confirmed in the sources I reviewed.
• Key procedural event — Director action: On 2025-08-29, Acting Director Coke Morgan Stewart rejected Align's discretionary-denial request and referred all eight petitions to the Board, reasoning in part that "for each of the challenged patents, there is evidence in the record indicating that the Office erred in a manner material to patentability such that discretionary denial under 35 U.S.C. § 325(d) is not appropriate" and that the projected FWD date (2026-11-08) versus W.D. Tex. trial statistics "neither favor nor counsel against discretionary denial." https://www.docketalarm.com/cases/PTAB/IPR2025-00819/ClearCorrect_Operating_LLC_v._Align_Technology_Inc/docs/08-29-2025-Board/Director_Discretionary_Decision_Refer-14-Director_Discretionary_Decision_Refer.pdf
• Defensive value: Relevant to a defendant only as pattern evidence — Align's current assertion set is the newer portfolio (asserted in W.D. Tex. No. 6:24-cv-00187-ADA against ClearCorrect/Straumann: 10,973,613; 11,154,384; 11,648,090; 11,648,091; 8,038,444; 10,456,217; 10,524,879; 11,369,456; 10,791,936), and ClearCorrect is attacking that portfolio hard at the Board. The '893 patent is not in that fight.

Strategic summary

Claim status. No AIA tribunal has ever canceled a claim of US 5,975,893. The patent reissued-into-force with its 29 claims intact, was twice confirmed in ex parte reexamination without amendment (90/007,477 and 90/013,581 — the latter producing a certificate in the 2017-02-22 / 2017-03-22 window alongside the '548 patent), and expired on 2017-10-08. So the correct characterization is neither "canceled" nor "sustained by the PTAB" — it is untested by the Board and expired. Every claim is "untested" in the AIA sense. The only Board-level invalidity finding in this family is the 2017-03-24 IPR2016-00270 FWD canceling claims 1, 2, 9, and 10 of the different '037 patent over Snow/Hultgren/Kesling.

Estoppel landscape. Because there has never been an AIA trial on '893, no § 315(e)(2) estoppel attaches to this patent at all — no petitioner, and no privy of any petitioner, is barred from raising any ground against the '893 claims in district court. Conversely, ClearCorrect's ex parte reexamination requests do not create estoppel (estoppel is an AIA-trial creature), and ClearCorrect's 2025 IPRs on the newer Align patents create estoppel only as to those patents. If you are defending against '893, the full prior-art universe — Snow, Hultgren, Kesling, and anything else, including art that ClearCorrect used or could have used — remains available to you in district court, unencumbered. The practical constraint is not estoppel; it is § 286 and the expiration date.

Pattern signals. (1) No defensive aggregator appears anywhere in the '893 chain — Unified Patents is not a petitioner on this patent (the only Unified Patents references in the record are per-case litigation links in the Google Patents family data, not proceedings). (2) Same petitioner, repeat player: ClearCorrect has now attacked Align three separate ways — an ex parte reexamination wave (2015, including '893), a single IPR on the '037 patent (IPR2016-00270, 2015 filing), and an eight-petition IPR wave in 2025 (-00814 through -00821). Align's posture is to appeal adverse Board outcomes (it announced an intent to appeal the '037 FWD) and to litigate in parallel in the ITC and district court. (3) One-sided vs. adversarial record: the same prior art appears to have produced opposite outcomes in the ex parte reexaminations (patentability confirmed) and the IPR (claims canceled) on related patents — a point ClearCorrect has made aggressively and that cuts against giving the '893 reexamination confirmations strong weight.

Recommended next steps

If you are a defendant being asserted against US 5,975,893 today:

1. Lead with expiration, not the PTAB. The term expired 2017-10-08. For any suit filed now, 35 U.S.C. § 286 limits recovery to the six years preceding the complaint — a window that falls entirely after expiration, meaning there is no recoverable infringement period for a newly filed action. Confirm the term calculation on the face of the patent (no PTA evident; 20 years from the 1997-10-08 filing date) and confirm there is no later-filed continuation/member of the '893 family being silently asserted instead. Verify in PAIR/E2E at https://ptacts.uspto.gov/ptacts/.
2. Do not concede a "hardened by IPR" narrative. There is no IPR, PGR, or CBM on '893 — no institution decision, no FWD, no settlement, no appeal. If opposing counsel represents that the patent "survived PTAB challenge," that is inaccurate; what exists is two ex parte reexaminations and an unrelated IPR on the '037 patent.
3. Attack the reexamination confirmations' probative weight. They were ex parte and unopposed. Quote ClearCorrect's public framing: the reexamination decisions were "one-sided," and "the reexaminations would not have concluded in Align's favor except for the missing review briefing" (Scott A. McKeown, Oblon). Source: https://huangshandental.com/both-sides-claim-victory-in-clear-aligner-patent-case/
4. Harvest the IPR2016-00270 record as a § 103 roadmap. The Board's finding that "generating three-dimensional digital data representing the shape and position of a patient's tooth was known" and its Snow/Hultgren/Kesling combination are directly reusable, and nothing estops you from using them. Full FWD: https://www.docketalarm.com/cases/PTAB/IPR2016-00270/Inter_Partes_Review_of_U.S._Pat._6699037/docs/03-24-2017-Board/Final_Decision-43-Final_Written_Decision.pdf
5. Preserve invalidity defenses. With the patent expired, IPR is functionally unavailable (and likely § 315(b)-barred if you were served over a year ago), so your invalidity case must be made in court — draft it without relying on any Board proceeding.

If you are monitoring the family rather than this patent: the live fight is W.D. Tex. No. 6:24-cv-00187-ADA-DTG (Align v. ClearCorrect Operating LLC, ClearCorrect Holdings, Inc., and Institut Straumann AG) and the eight parallel IPRs (IPR2025-00814 through -00821), with Final Written Decisions due on or about 2026-11-06/2026-11-08 under the statutory one-year deadline from institution. Track claim-construction rulings (the parties' competing constructions on "successive," "mid-line shift pattern," and the § 112 ¶ 6 "means for" limitations in the '444/'456 patents are already teed up) and the PTAB's treatment of the § 325(d) "Office error" rationale the Director endorsed on 2025-08-29. Related ITC/Federal Circuit background for context only: ClearCorrect Operating, LLC v. ITC, 810 F.3d 1283 (Fed. Cir. 2015), and Align Tech., Inc. v. ITC, 622 F. App'x 910 (Fed. Cir. 2015) — jurisdiction over electronic transmissions, not patentability.

Confidence and gaps (stated explicitly): I am confident there is no AIA trial proceeding on US 5,975,893. I am not able to confirm from available sources (a) the exact challenge date or reference set of reexamination 90/007,477, (b) which of 2017-02-22 / 2017-03-22 is the '893 certificate date, (c) the specific claims challenged in 90/013,581, (d) the full APJ names on the IPR2016-00270 panel, or (e) whether Align perfected and how the Federal Circuit resolved the appeal of the IPR2016-00270 FWD. Those items should be pulled from PTAB E2E (https://ptacts.uspto.gov/) and the CAFC docket before being relied on in a filing.

I'll research this patent's assignment record, litigation, and ownership before writing up.

Key litigation facts confirmed. Now let me try to pin down the actual assignment records and any post-issuance transfers.

Let me verify the litigation dockets and try to pin down the assignment reel/frame data.

Ownership & Assignment Analysis — US 5,975,893 ("Method and system for incrementally moving teeth")

Scope note on sourcing (read first). I could not open assignmentcenter.uspto.gov / assignment.uspto.gov directly from this session — my tooling returned search-result snippets only, and none of the retrieved pages rendered the reel/frame or correspondent fields for this patent. The assignment facts below are taken from the legal-events block on the Google Patents record for US5975893A (https://patents.google.com/patent/US5975893/en), which mirrors the Assignment Center's event list but does not publish reel/frame or correspondent. Where a field was not retrievable I say so rather than fill it in. Verify reel/frame and correspondent at https://assignmentcenter.uspto.gov/ (search by patent number 5975893) before relying on them.

Inventors

All five were affiliated with Align Technology, Inc. at the time of filing — the patent was filed 1997-10-08 (CIP of provisional 60/050,342, filed 1997-06-20), the same year Align was founded, so the inventors are effectively the founding team rather than rank-and-file employees. All five appear as assignors on the two 1998 assignment records, which is consistent with a standard founder/employee invention-assignment package rather than a staged transfer.

Unusual-pattern check — negative. There is no evidence of the "all inventors depart within 12 months" fire-sale precursor. What is present is a different, well-documented pattern: co-founder-inventor Zia Chishti subsequently left Align and founded a direct competitor (OrthoClear, Inc.), which Align sued in February 2005 (Align 10-K/10-Q disclosures: "we filed a complaint against OrthoClear, Inc., OrthoClear Holdings, Inc., Mr. Chishti, one of our founders, and several former employees"). Kelsey Wirth likewise departed Align in the early 2000s. Departures post-date issuance by years and did not trigger any recorded transfer of the '893 patent.

Original assignee

Align Technology, Inc. (Santa Clara / San Jose, CA at various times; NASDAQ: ALGN).

• Did they ship a product embodying the claims? Yes, unambiguously. The '893 patent is a foundational Invisalign patent — it teaches the multi-appliance incremental aligner system claimed in claim 1 (a first appliance, one or more intermediate appliances, and a final appliance, each a polymeric shell with successively different cavity geometries). Align's own SEC disclosures state it "depend[s] on the sale of the Invisalign system for the vast majority of our revenues."
• Primary line of business: commercial manufacture and sale of the Invisalign clear-aligner system and associated scanners/software for orthodontic and dental practices.
• Current status: Operating, publicly traded, solvent. No bankruptcy, no Chapter 7/11, no fire sale. Google Patents lists the current assignee as Align Technology Inc — i.e. the original assignee still owns the patent.

Assignment timeline

Two records appear in the legal-events chain, both from 1998, both inventor→company. No post-issuance assignment of any kind is recorded (no LLC transfer, no security agreement, no change of name, no release).

• 1998-08-13 (executed) / recorded 1998-08-13 — Reel not retrieved / not published on the source used

  • Conveyance: Assignment of assignors' interest (see document for details)
  • Assignor: RIDGLEY, RICHARD; FREYBURGER, BRIAN; CHISHTI, MUHAMMAD; LERIOS, APOSTOLOS; WIRTH, KELSEY
  • Assignee: ALIGN TECHNOLOGY, INC.
  • Correspondent: Not retrievable from the sources available to me. I am not going to supply a name; pull the reel/frame at https://assignmentcenter.uspto.gov/ to capture it. No recurrence pattern can therefore be assessed for this chain.
  • Context: Initial capture of founder/employee invention rights by the newly formed operating company — standard startup assignment, not a reorg or monetization step.

• 1998-08-17 (executed) / recorded 1998-08-17 — Reel not retrieved

  • Conveyance: Assignment of assignors' interest (see document for details)
  • Assignor: RIDGLEY, RICHARD; WITH, KELSEY [sic — typo for WIRTH]; FREYBURGER, BRIAN; LERIOS, APOSTOLOS; CHISHTI, MUHAMMAD
  • Assignee: ALIGN TECHNOLOGY, INC.
  • Correspondent: Not retrievable from the sources available to me.
  • Context: Second, near-identical inventor→Align record four days after the first. Most plausibly the companion assignment covering the second application in the priority chain (utility app 08/947,080 vs. provisional 60/050,342) or a corrected re-execution; this is an inference, not a documented fact — the record text on the page I could reach does not identify which application each instrument covers. Note that the assignor list here is the same five names, and the instrument is signed by the inventors, so it is not a subsequent corporate transfer.

Nothing after 1998. The chain runs inventors → Align Technology, Inc. and stops there. Given 28 years of recorded events with no further entries, and Align's continued assertion of the patent in its own name in 2011, 2015 and later, the reasonable reading is that Align has held record title continuously since 1998.

Timeline diagram

timeline
    title Ownership of US 5975893
    1997 : Provisional 60 050 342 filed Jun 20
         : Utility app 08 947 080 filed Oct 8
    1998 : Inventors assign to Align Technology
         : Second assignment recorded 4 days later
    1999 : Patent 5975893 issues Nov 2
    2005 : Align sues founder-led OrthoClear
    2011 : Align sues ClearCorrect on 893 patent
    2015 : Align sues SmileCareClub and retailers
    2017 : Reexam certificate confirms 893 claims
         : Anticipated expiration Oct 8
    2019 : ClearCorrect case closed

NPE / troll-pattern signals

1. Shell-entity transfer — not present. There is no recorded assignment from Align Technology, Inc. to any "IP / Holdings / Licensing / Ventures" entity. The only two instruments of record are from the five named inventors to the operating company in 1998. This is the cleanest possible negative: the signal requires evidence of a transfer, and there is none.

2. Known asserter in the chain — not present. Neither the original nor the current assignee matches any published NPE/PAE list (Acacia, Marathon, IV, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, DGC, Spangenberg family). The only assignee in the chain is Align Technology, Inc. (NASDAQ: ALGN), a product company. In Align Technology, Inc. v. ClearCorrect, Inc., 4:11-cv-00695 (S.D. Tex., filed 2011-02-28), RPX Insight classifies the patent owner explicitly as "Operating Company (L)" — https://insight.rpxcorp.com/litigation/txsdce-[868734](/patent/868734)-align-technology-v-clearcorrect.

3. Repeat correspondent across the chain — unclear / not verifiable. This is the one signal I cannot responsibly score either way. There are only two links in the chain, and I was unable to retrieve the correspondent of record for either from the resources available in this session. I decline to name a correspondent without a reel/frame citation. If you pull the two 1998 records at the Assignment Center and the same attorney/firm appears on both, note that this would be expected (same assignee, same four-day window) and would not by itself be an NPE indicator — recurrence is only diagnostic when it spans differently named assignees.

4. Cascading transfers — not present. Two assignments, both to the same assignee, executed four days apart in August 1998, with no further links. There is no chained-LLC sequence within any 24-month window, no shared registered-agent address, and no common-principal pattern.

5. Pre-litigation transfer — not present. Last recorded assignment: 1998-08-17. First suit naming the '893 patent: 2011-02-28 (Align v. ClearCorrect, 4:11-cv-00695) — a gap of roughly 12.5 years. No assignment occurred in the six months preceding that filing, or preceding the second assertion (Align's 2015-10-22 suit against SmileCareClub / Sharper Image / Brookstone, N.D. Cal. 5:15-cv-04864, which lists the '893 patent among fourteen asserted patents). The chain was not rearranged to manufacture standing or venue.

6. Bankruptcy fire-sale — not present. Align Technology has never filed Chapter 7 or Chapter 11; it has been profitable and publicly listed throughout. There is no reorganisation proceeding in which the '893 patent was sold. (Separately, ClearCorrect later underwent a change in company ownership — noted in its 2018 correspondence in the S.D. Tex. case — but that is a fact about the defendant, not about title to this patent, and it does not appear in the assignment chain.)

7. Privateering — not present. The inverse would be more accurate: Align is the operating company asserting its own patents itself, against competitors (ClearCorrect, SmileCareClub), with no NPE intermediary anywhere in the record. Align has not transferred the '893 patent to a monetization vehicle; it has litigated it directly, including in the ITC (the related ClearCorrect v. ITC line, ITC Inv. No. 337-TA-833, and Federal Circuit appeal).

8. Defensive aggregator — not present. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN. There is no evidence of neutralization. Note the one genuinely negative commercial fact for an NPE case: Google Patents records an anticipated expiration of 1997-10-08 → 2017-10-08, and legal status "Expired - Lifetime." The patent has been off-term since 2017, so it is not a live monetization asset for anyone, Align included.

One related proceeding worth logging (not an assignment): ClearCorrect challenged the '893 patent in reexamination. Per Align's own 2017-03-28 investor release, the USPTO issued reexamination certificates on 2017-02-22 and 2017-03-22 confirming the patentability of all challenged claims of U.S. Pat. Nos. 5,975,893 and 6,398,548 without amendment or narrowing (https://investor.aligntech.com/index.php/news-releases/news-release-details/align-technology-prevails-additional-us-patent-office). This further confirms Align held and was asserting the patent in its own name, as owner, through 2017.

Verdict

Operating-company assertion.

Justification: the entire recorded chain consists of two 1998 inventor→Align Technology, Inc. assignments (recorded 1998-08-13 and 1998-08-17, reel/frame not retrievable in this session), with zero post-issuance transfers of any kind — no shell-entity hop, no chained LLCs, no pre-suit assignment, no defensive-aggregator termination. Align is a NASDAQ-listed operating company (ALGN) that ships the Invisalign product embodying claim 1, and it asserted the '893 patent itself against actual competitors in Align v. ClearCorrect, 4:11-cv-00695 (S.D. Tex., filed 2011-02-28) and the 2015-10-22 SmileCareClub/Shaper Image/Brookstone action in N.D. Cal. (5:15-cv-04864). The patent expired 2017-10-08.

Caveat on completeness: every fact above rests on the Google Patents legal-events mirror plus Align's SEC filings and press releases. The reel/frame numbers, execution-date confirmations, and the correspondent of record for the two 1998 instruments were not retrievable with the tools available in this session, and I have left those fields explicitly blank rather than infer them. Confirm at: https://assignmentcenter.uspto.gov/ (patent-number search for 5975893) and the patent's legal-events block at https://patents.google.com/patent/US5975893/en.

I'll research each cited reference systematically. Let me start with parallel searches on the key prior-art families.

I have strong material on the non-patent literature. Now let me pin down the front-page patent citations and the Ormco/positioner patents.

Prior-art analysis for US 5,975,893 ("Method and system for incrementally moving teeth")

Method and sourcing note

I worked from the authoritative full text of the '893 patent (the Google Patents fetch supplied in this thread, https://patents.google.com/patent/US5975893/en) plus live searches. Two things need to be said up front, per the operating rules:

1. I could not retrieve the literal front-page "References Cited / U.S. Patent Documents" face of the '893 patent. The text I have carries the prior-art citations in the body (the "Description of the Background Art" and "Other patents of interest" lists) and in the front-page "Other Publications" list (which is visible on the Google Patents family pages, e.g. the /zh variant). I therefore treat the following as the "patent citations for 5975893," literally as they appear in the record — and I flag where I am relying on the patent's own one-line characterization rather than an independent reading of the reference.
2. I did not auto-correct anything. Duplicated numbers in the "other patents of interest" list (e.g., 5,055,039; 4,798,534; 4,856,991; 5,035,613; 5,059,118; 5,186,623; 4,755,139 all appear twice) are reported as they appear.

Also note the earlier sections flagged that the fetched claim set truncates at claim 10 of 29. That matters here: the references fall into two clear buckets — (A) positioner/appliance art that maps to claims 1–10, and (B) digital-imaging / scanning / CAD art that maps to the unverified claims 11–29. I will not assign bucket-B references to specific unverified claim numbers; I map them to claim families by subject matter and say so.

Framework: what a §102 reference would have to disclose

Claim 1 (system) requires, in one reference: (a) a plurality of incremental position-adjustment appliances; (b) a first appliance geometry → initial to first intermediate; (c) one or more intermediate appliances → progressively; (d) a final appliance → last intermediate to final; (e) each appliance a polymeric shell having a cavity; and (f) cavities of successive shells having different geometries to receive and resiliently reposition teeth. Claim 6 is the method mirror. Dependents add the ≤2 mm per-step limit (claims 2, 7) and appliance counts (claims 3–5, 8–9).

Because §102 requires every element in a single reference, the decisive question for each reference is whether it supplies both (e)–(f) the elastomeric shell with a tooth-receiving cavity and (a)–(d) the ordered series of differently-shaped appliances.

A. Positioner / appliance art (maps to claims 1–10)

A1. Kesling, "The philosophy of the tooth positioning appliance," Am. J. Orthod. Oral. Surg. 31(6):297–304 (June 1945)

• Type/date: Journal article, June 1945 (pre-dates the '893 filing by 52 years).
• Description: The foundational disclosure of the elastic tooth positioner — a single molded appliance that fits over the teeth and moves them toward a predetermined ("setup") arrangement. As the '893 specification itself acknowledges, this is the origin of the finishing positioner.
• §102 relevance: Discloses element (e)/(f) (a resilient tooth-receiving appliance that repositions teeth). Does not disclose a plurality of successively different appliances. Potentially anticipates only a single-appliance claim; not claim 1 or 6 as granted.

A2. Kesling, "Coordinating the predetermined pattern and tooth positioner with conventional treatment," Am. J. Orthod. Oral. Surg. 32:285–293 (1946) — ⚠️ closest cited art

• Type/date: Journal article, 1946.
• Description: Kesling's "predetermined pattern" technique — rearranging teeth in a plaster setup model to define a target, then building a positioner to that pattern. Crucially, a secondary source in the '893 record (Warunek et al. 1989, JCO) characterizes this 1946 work as proposing "a series of positioners for graduated movement toward a corrected occlusion."
• §102 relevance: If that characterization is accurate, this single reference arguably supplies (a)–(d) (a series of appliances moving teeth in graduated steps) and (e)–(f) (elastomeric positioners with tooth-receiving cavities of differing geometry). This makes Kesling 1946 the strongest §102 candidate against independent claims 1 and 6 and, derivatively, against the series/step-count dependents (claims 3–5, 8–9) and the ≤2 mm dependent (claims 2, 7) insofar as "graduated movement" implies small increments.
• Confidence flag: I am relying on the Warunek 1989 characterization and the '893 patent's own citation, not a primary reading of Kesling 1946 (I did not retrieve its full text). Treat this as a lead requiring the primary document.

A3. Warunek et al., "Clinical use of silicone elastomer appliances," J. Clin. Orthod. (JCO) 23(10):694–700 (Oct. 1989)

• Type/date: Journal article, October 1989. (Cited in the '893 specification for "silicone positioners for the comprehensive orthodontic realignment of a patient's teeth.")
• Description: The source of the statement that Kesling "proposed a series of positioners for graduated movement." Discusses silicone-elastomer positioner appliances and their clinical use.
• §102 relevance: As a reference, it can be relied on for the series-of-positioners teaching (§102(b)) and for the elastomeric-appliance element. Same exposure profile as A2: candidate against claims 1, 6 and dependents.

A4. Warunek et al., "Physical and mechanical properties of elastomers in orthodontic positioners," Am. J. Orthod. Dentofac. Orthop. 95(5):388–400 (May 1989)

• Type/date: Journal article, May 1989.
• Description: Comparative physical/mechanical testing of HTV silicone (Orthocon), urethane, and vinyl positioner elastomers; notes newer materials "effectively move teeth over a greater range."
• §102 relevance: Supports element (e) (the polymeric/elastomeric shell) and possibly the "resiliently reposition" function. Not a series reference. Not anticipatory of claims 1/6.

A5. Nishiyama et al., "A new construction of tooth repositioner by LTV vinyl silicone rubber," J. Nihon Univ. Sch. Dent. 19(2):93–102 (1977); Kamada et al., J. Nihon Univ. Sch. Dent. 24(1):1–27 (1982) and 26(1):11–29 (1984); Yoshii, "Dynamic Positioner (D.P.)" series, Nippon Dental Review 452:61–74, 454:107–130, 457:146–164, 458:112–129 (all 1980)

• Type/date: Journal articles, 1977–1984.
• Description: A family of Japanese disclosures of LTV vinyl silicone rubber tooth positioners, including the "Dynamic Positioner" used for active (not merely finishing) tooth movement, and construction of a repositioner from a setup model.
• §102 relevance: Reinforces element (e)–(f) (an elastomeric shell with a repositioning cavity, used actively). Describes single appliances, so it does not supply the plurality. Not anticipatory of claims 1/6; useful art on the appliance structure and on "resiliently reposition."

A6. U.S. Patent 5,186,623 — "Orthodontic finishing positioner and method of construction"

• Citation/date: U.S. 5,186,623; inventors Abbatte, Breads, Warunek; application Ser. No. 07/781,076; granted February 16, 1993; assigned to Great Lakes Orthodontics, Ltd.
• Description (from the reference's own summary): An elastomer-body positioner with a recess shaped complementary to the teeth in a predetermined orientation, plus indentations to nestingly accept coupling members on the teeth; when stretched over the teeth it biases them toward that orientation. Construction method uses a repositioned "dental facsimile."
• §102 relevance: Directly discloses element (e)–(f) and the "resiliently reposition teeth" function for a single finishing appliance, and the "predetermined orientation" concept. It does not disclose a plurality of successively different appliances → not anticipatory of claims 1/6, but it is the most structurally on-point U.S. patent on the appliance itself. (I verified grant date/assignee; I did not independently verify its exact filing date.)

A7. U.S. Patents 5,059,118; 5,055,039; 5,035,613; 4,856,991; 4,798,534; 4,755,139 — "manufacture of orthodontic positioners"

• Citation/date: As listed in the '893 specification (this same group also appears in the "other patents of interest" list). I did not independently verify each filing/publication date.
• Description: Cited collectively by the '893 specification as describing manufacture of orthodontic positioners.
• §102 relevance: Provide art on the (e) "polymeric shell" manufacture and the general positioner concept. Individually they are single-appliance references → not anticipatory of claims 1/6. ⚠️ I have only the '893 patent's one-line characterization; the descriptions and dates above are not independently confirmed.

A8. "Other patents of interest": U.S. 5,549,476; 5,382,164; 5,273,429; 4,936,862; 3,860,803; 3,660,900; 5,645,421

• Citation/date: Listed in the '893 specification with no description given.
• §102 relevance: ⚠️ Cannot map to claims. The specification supplies neither titles nor a description, and I did not verify these. Note 3,660,900 and 3,860,803 are early (pre-1975) dental/orthodontic patents; if they are positioner or elastomeric-appliance art they would be cumulative to A1–A7. Flagged as unverified.

B. Digital-imaging / scanning / CAD art (maps to the unverified claims 11–29)

These are cited in the '893 background as enabling the "initial data set → manipulated visual image → successive intermediate data sets → fabrication" pipeline. They do not address the claims 1–10 subject matter (the appliance series) and cannot anticipate claims 1 or 6.

B1. Kuroda et al., "Three-dimensional dental cast analyzing system using laser scanning," Am. J. Orthod. Dentofac. Orthop. 110:365–369 (1996)

• Laser-scans a plaster dental cast to produce a digital image. Cited for exactly that. Maps to the "initial digital data set (IDDS)" method family. Not anticipatory of claims 1/6.

B2. U.S. Patent 5,605,459

• Per the '893 specification: "producing plaster casts of teeth and generating digital models using laser scanning techniques." The '893 patent expressly incorporates it by reference. Maps to the IDDS/digital-model family. Date not independently verified here.

B3. U.S. Patents 5,533,895; 5,474,448; 5,454,717; 5,447,432; 5,431,562; 5,395,238; 5,368,478; 5,139,419 (Ormco Corporation)

• Per the '893 specification: "manipulating digital images of teeth for designing orthodontic appliances." Maps to the "manipulate a visual image to reposition teeth → FDDS" family. (The '893 patent is a 1997 filing; the Ormco art is digitized-model manipulation.)
• §102 relevance: These are the most on-point patents for the digital-manipulation method claims (bucket B). They do not disclose the multi-appliance system of claims 1/6. ⚠️ Dates/descriptions taken from the '893 characterization, not independently verified.

B4. U.S. Patent 5,011,405

• Per the '893 specification: "a method for digitally imaging a tooth and determining optimum bracket positioning for orthodontic treatment." Maps to the digital-imaging family.

B5. U.S. Patent 5,338,198

• Per the '893 specification: "laser scanning of a molded tooth to produce a three-dimensional model." Maps to the IDDS/scanning family.

B6. U.S. Patent 5,452,219

• Per the '893 specification: "laser scanning a tooth model and milling a tooth mold." Maps to the scanning + fabrication family.

B7. U.S. Patents 5,607,305 and 5,587,912

• Per the '893 specification: "digital computer manipulation of tooth contours." Maps to the image-manipulation family.

B8. U.S. Patents 5,342,202 and 5,340,309

• Per the '893 specification: "computerized digital imaging of the jaw." Maps to the imaging family.

B9. U.S. Patents 5,059,118; 5,055,039; 5,035,613; 4,856,991; 4,798,534; 4,755,139; 5,186,623 (repeat listing)

• These appear a second time in the "other patents of interest" list. Same references as A7/A6.

B10. Non-patent ancillary sources also cited

• Chiappone (1980) J. Clin. Orthod. 14:121–133 ("Constructing the gnathologic setup and positioner"); Cottingham (1969) Am. J. Orthod. 55(1):23–31 ("Gnathologic clear plastic positioner"); Wells (1970) Am. J. Orthodont. 58(4):351–366; Shilliday (1971) Am. J. Orthod. 59:596–599 ("mini-positioner"); Kleemann & Janssen (1996) J. Clin. Orthod. 30:673–680 ("The speed positioner"); Cureton (1996) J. Clin. Orthod. 30:390–395; Elsasser (1950) Am. J. Orthod. 36:368–374; and the Raintree Essix catalog (Aug. 13, 1997).
• §102 relevance: All are single-appliance / finishing positioner art (setup models, gnathologic wax setups, mini- and speed-positioners). They support elements (e)–(f) and the "predetermined target arrangement" concept. None discloses an ordered series of differently-shaped shells → not anticipatory of claims 1/6.

Summary judgment: what actually anticipates vs. what is merely relevant

Bottom line. Among everything cited on/against the '893 patent, the most relevant prior art is:

1. Kesling (1946), Am. J. Orthod. Oral. Surg. 32:285–293 — the only cited reference that arguably discloses a series of tooth-positioning appliances producing graduated movement, i.e., the closest thing to claim 1/claim 6. Its §102 strength hinges entirely on the "series of positioners" reading (which is documented via Warunek 1989 JCO, not yet verified against the primary 1946 text).
2. U.S. 5,186,623 (Breads et al., Great Lakes Orthodontics; granted Feb. 16, 1993) — the closest U.S. patent on the elastomeric tooth-receiving appliance with a predetermined target orientation.
3. Kuroda et al. (1996) and U.S. 5,605,459 — the closest art for the digital-model generation that underpins the method claims (bucket B).

Important caveat on the §102 posture: No single cited reference appears to disclose all elements of granted claims 1 or 6 — in particular the combination of (i) a plurality of appliances, (ii) with successively different cavity geometries, (iii) each being a polymeric shell. The cited positioner art gives the single shell; the cited imaging art gives the digital pipeline; the "series" concept appears only via Kesling 1946/Warunek 1989. That is the classic profile of a §103 obviousness challenge built from a combination, rather than a clean §102 anticipation — and it is consistent with the fact that the '893 patent granted and later survived ex parte reexamination with its claims confirmed (Notice of Intent to Issue Reexamination Certificate, Sept. 18, 2007, per the earlier litigation section).

Explicit uncertainty / next steps

• Unverified front page. I could not pull the '893 patent's literal front-page "U.S. Patent Documents" list. The patent citations above come from the specification body and the front-page "Other Publications." If the front page lists additional U.S. patents, they are not captured here.
• Unverified dates/descriptions. For U.S. 5,605,459; 5,011,405; 5,338,198; 5,452,219; 5,607,305; 5,587,912; 5,342,202; 5,340,309; the Ormco group; and all "other patents of interest," I have only the '893 patent's own one-line characterization (dates not independently confirmed). U.S. 5,186,623's grant date/assignee are verified; its exact filing date is not.
• Kesling 1946. The individual-reference §102 weight I assign to it depends on a secondary characterization (Warunek 1989 JCO: "proposed a series of positioners for graduated movement"). The primary 1946 text should be pulled before relying on this.
• Claims 11–29 remain unverified (earlier section's truncation). My bucket-B assignments are by subject matter only.
• Authoritative next step: a certified front-page "References Cited" pull (USPTO PatentCenter / Global Dossier) for US 5,975,893, plus the primary Kesling 1946 article and the full texts of the Ormco and positioner patents, to confirm dates and element-by-element mapping.

I'll research the prior-art references identified in the '893 patent's own "Description of the Background Art" section before building the § 103 analysis.

Now let me ground the digital-design and fabrication-side references, plus check whether any validity ruling addressed the '893 claims.

Obviousness Analysis — U.S. Patent No. 5,975,893 under 35 U.S.C. § 103

Note on scope before we start. The record I hold truncates in the middle of claim 10 of 29 (see my earlier patent summary). This analysis covers the verified claim set — independent claims 1 and 6 and dependents 2–5 and 7–10 — and expressly does not opine on claims 11–29, whose text I cannot read. Where the source renders claim 6's shell geometry as "difficult geometries," I read the intended limitation as different geometries for analysis purposes only; I am not correcting the identifier or text. The '893 patent is pre-AIA (filed 1997-10-08), so § 103(a) as it read then governs.

1. The legal frame and the claim actually at issue

Graham v. John Deere (scope/content of prior art; differences; PHOSITA level; secondary considerations), refined by KSR Int'l v. Teleflex (motivation may come from the problem, the references' teachings, or common sense; predictable use of known elements is obvious; design incentives and market forces count). All references below are analogous art — same field (orthodontics) or reasonably pertinent to the problem (digitizing, modeling, and molding tooth arrangements).

Claim 1 — the hard target. Read literally, claim 1 requires only:

Critically, claim 1 recites no digital design, no interpolation, no "all fabricated at the outset," no packaging, no increment size, and no minimum count. The '893 specification even concedes that the system "may be produced by non-computer-aided techniques" — cutting a plaster cast with a saw, holding teeth in soft wax, and molding multiple appliances over the successive castings. That concession strips the digital subject matter out of claim 1's scope and is a significant § 103 liability.

PHOSITA: an orthodontist or dental-lab engineer with several years of experience in removable/thermoformed appliances, optionally with access to the scanning/CAD-CAM literature.

2. The prior art of record (the page's "Background Art" section and its reference lists)

(The remaining enumerated "other patents of interest" — 5,549,476; 5,382,164; 5,273,429; 4,936,862; 3,860,803; 3,660,900; 5,645,421 — appear in the record only as a bare list. I have not verified their disclosures and do not rely on them.)

3. Combination A — the core § 103 case against claim 1

Kesling 1945/1946 + Warunek 1989 + U.S. 4,755,139 (+ clear-thermoform art), optionally + Shilliday/Kleemann/Cureton.

Element map: Kesling supplies (e) a molded resilient shell with tooth-receiving cavities that (f) resiliently repositions teeth to the geometry of its sockets, plus the "predetermined" target and the staged/sequential concept. Warunek supplies the express extension of that same structure to comprehensive realignment — the exact motivation the patent's own background section flags. U.S. 4,755,139 supplies the fabrication loop that produces a series of such shells: reposition the model to an intermediate target, mold an elastomeric appliance over it, repeat for the next target. Plurality of appliances (a), first/intermediate/final staging (b–d), and per-stage differing cavity geometry follow directly from simply iterating 4,755,139's claim-7 procedure.

Motivation, articulated on the record:

1. Physics of the single-positioner failure mode. An elastomeric shell's restoring force decays as the teeth approach the molded geometry — the '893 spec says so explicitly, and it is inherent in Warunek's force/deflection data. The art therefore had a self-evident reason to divide a large correction into smaller ones, each with a fresh model and its own force budget.
2. Kesling's own limited-indication teaching. Kesling reported positioner-alone success only where "needed tipping and rotation movements … were moderate in degree and distance" — which is a direct instruction to keep per-stage movement small, and to divide larger corrections.
3. The art was already iterating positioners. Clinical practice described in the contemporaneous literature was to remake positioners when wear exceeded a few months, each remake rebuilding the setup; each remake is, functionally, a successive appliance with a different cavity geometry.
4. Known materials and known forming. Tru-Tain/Essix/Nahoum/Ponitz supply thin, clear, vacuum-formed polymeric shells as the shell species, with the Biostar and Raintree Essix equipment named in the patent itself.
5. Predictable result. KSR: arranging known, functionally distinct elements (a resilient tooth-receiving shell; a staged treatment plan; a repositioned-model molding step) to achieve their known functions is not inventive. Nothing in the claim requires an unexpected interaction — claim 1 merely concatenates the series.

This combination is the single most dangerous attack because it does not require any computing at all, and the '893 specification concedes the manual version is within the invention.

4. Combination B — adding the digitizing/CAD-CAM layer (bolsters Combination A; targets any claim I could verify that implicates digital design and fabrication)

Combination A + Ormco/Andreiko (esp. U.S. 5,368,478 / 5,431,562 and continuations) + Kuroda/U.S. 5,605,459 + U.S. 5,338,198 + U.S. 5,452,219 + U.S. 5,607,305/5,587,912.

Andreiko's system is startlingly close to the '893's specification on the digital side: scan a model → digitize tooth contours → computer derives finish positions → interactively let the orthodontist adjust the setup (testing extractions and over-correction) → generate machine code → automatically fabricate the appliance; and it expressly contemplates building positioners by layer deposition with selectively cured resin or by wax-jet-printed patterns/molds. Kuroda and U.S. 5,605,459 supply the plaster-cast laser scan; 5,338,198 and 5,452,219 supply scanning/milling of a 3D tooth model and mold.

Motivation: the '893 background section itself frames these references as "methods for manipulating digital images of teeth for designing orthodontic appliances." A POSITA facing the known bottlenecks (per-visit impressions, hand-cutting plaster setups, lab labor, repeatability) had a strong, market-driven reason to automate the Kesling/4,755,139 workflow on the Ormco/Kuroda platform — fewer office visits, higher throughput, and precision. KSR endorses exactly this "known technique applied to a known method, yielding predictable results" reasoning. Note also Andreiko's dual low-/high-resolution scanning maps onto the '893's FIG. 3 two-resolution scheme, and its "layer deposition … materials that are selectively activated, cured or hardened, such as by exposure to light" maps onto the '893's stereolithographic SLA-250 embodiment.

The ephemeral but telling corroboration in my searches: current PTAB petition papers reproduce the '893 background-art paragraph verbatim (petition 1557671 materials), and Align's own later patents (e.g., US 10,045,835; US 9,161,823) carry the Kesling/Warunek/Kuroda/Andreiko reference list forward — i.e., the same prior-art lineage is still the operative attack surface in 2025–2026 proceedings.

5. Claim 6 (the method claim) and dependents

Claim 6 is Combination A performed clinically: place the first shell → successively replace it with further shells of progressively advancing geometry → place a final shell; same "polymeric shell / different successive cavity geometry" requirement. Every step is 4,755,139's method and Kesling's staged concept; the "successively replacing" step is the inherent practice of serial positioner use. Obvious for the same reasons.

Claims 2 and 7 (≤2 mm per stage). This is the weakest link. Warunek's force/deflection data and Kesling's "moderate … distance" guidance make small increments an obvious design choice, and one can argue "no more than 2 mm" is a result-effective variable optimized by routine experimentation (In re Boesch/In re Aller line). But I did not recover a pre-1997 reference that numerically states a ≤2 mm (let alone ≤1 or ≤0.5 mm) per-appliance limit. Absent such a reference, these dependents are materially stronger than the independents.

Claims 3–5 and 8–9 (at least 2 / 10 / 25 additional appliances). Simple arithmetic consequence of claims 2/7: fix the total correction distance and the per-stage increment and the count follows. Ten or more stages is squarely within KSR's "finite number of identified, predictable solutions." Claim 5 ("at least twenty-five") and claim 9's "at least ten" are progressively harder — if the art of record contemplated only a handful of serial appliances (Kesling's staged concept; the 8–12-per-course figures seen in later practice), Align can argue the claimed counts reflect an unobvious degree of treatment segmentation. I would expect this to be a genuine factual fight, not a foregone conclusion.

Claim 10 is truncated at the source ("A method as i…"); scope unverified, so I withhold opinion.

6. Counterarguments the patentee will (and largely did) press, and how they fare

• Teaching away. Kesling's own data — positioner-alone success in only a few of 1,000+ patients, with "very few malocclusions … warranting treatment can be corrected by positioner therapy alone" — is a genuine teaching-away/limited-independence argument for comprehensive treatment with clear shells. Response: Warunek 1989 expressly did comprehensive realignment with silicone positioners, and Cureton 1996 moved incisors with removable retainers. In re Fulton/DePuy: a teaching away argument fails where another reference in the same field steps into the gap.
• No express "series" motivation in any one reference. This is Align's best doctrinal point. Response: KSR permits motivation from the problem itself (force decay; biological limits on per-stage movement) and from the routine clinical remaking of positioners. The 2025 review and Kesling's 1946 paper support a sequential-series reading of Kesling.
• Unexpected results / secondary considerations. Invisalign's commercial success is real, and the examiner's 2005–2007 ex parte reexamination ended with all challenged claims confirmed (Notice of Intent to Issue Reexamination Certificate, Sept. 18, 2007). But (i) reexamination is not an obviousness adjudication and carries no presumption of validity by res judicata effect against a later district court; (ii) commercial-success nexus must attach to the claimed subject matter — the broadest claim covers manual plaster-and-wax workflows that were never Align's commercial product, which weakens nexus; and (iii) the orthodontic community's early skepticism about aligner force systems cuts the other way on the narrow claims (quantitative increments, high stage counts) far more than on claims 1 and 6.
• Prosecution-history signal worth mining. Per my earlier section, the examiner used claims 1–5 of the '893 in an obviousness-type double-patenting rejection against application 10/040,269 (U.S. 7,054,611 lineage), forcing terminal disclaimers. A § 103 examiner having found claims 1–5 obvious variants of another application's claims is not an obviousness holding, but it is probative of how broadly the office viewed claim 1's scope, and it should be pulled from the file wrapper before relying on it.

7. Bottom line and confidence

Confidence and limits. The combination for claims 1 and 6 rests on references the patent itself cites and that I retrieved substantially (U.S. 4,755,139 claim 7, Kesling, Warunek) — I rate that analysis high confidence. The quantitative dependents (2, 5, 7, 9) depend on references I could not fully retrieve before reaching my tool-call limit: I have no verified pre-1997 disclosure of a numeric per-stage millimeter limit or a ≥25-stage protocol, and I have not verified the contents of the bare-list patents (5,549,476; 5,382,164; 5,273,429; 4,936,862; 3,860,803; 3,660,900; 5,645,421) or of U.S. 5,186,623 / 5,059,118 / 5,055,039 / 5,035,613 / 4,856,991 / 4,798,534, which the patent cites only for "manufacture of orthodontic positioners." I also could not confirm whether any court or the PTAB has ever ruled on the '893's § 103 validity: the S.D. Tex. and N.D. Cal. cases involved the patent (see my litigation section), but I have no verified validity holding. Treat the above as a prior-art-based invalidity theory, not an adjudicated result.

Next verification steps: (1) pull the '893 file wrapper from PatentCenter for the examiner's citations and the ODP rejection; (2) obtain full texts of U.S. 4,755,139, 5,186,623, 5,059,118 and Shilliday 1971 / Kleemann 1996; (3) obtain the reexamination file (2005–2007) to see which art was actually applied and overcome; (4) retrieve claims 11–29.