US 6629840

I'll search for authoritative records on US 6,629,840, including any current litigation activity.

Let me verify the reexamination certificate and check for any 2026 docket activity.

Let me pin down the reexamination details and check for any 2026 Federal Circuit docket naming this patent.

Summary — US Patent 6,629,840 B2

Important scoping note first: I searched for this exact number and found no 2026 Court of Appeals for the Federal Circuit docket naming US 6,629,840. The litigation records attached to this patent are all historical (2013 Federal Circuit appeals and a 2015 district court case). Align Technology's active 2026 enforcement campaigns (W.D. Tex. ClearCorrect case, PTAB IPRs, ITC/Angelalign) involve different patents. Also, note a date discrepancy: my environment reports today as 2026-09-29, while your message said April 26, 2026 — my search results include documents dated May–August 2026, so I have reported everything available up to the later date.

Bibliographic data

Continuity chain (per the specification and the reexamination record): provisional 60/050,342 (1997-06-20) → 08/947,080 (1997-10-08, now US 5,975,893) → 09/298,268 (1999-04-23, now US 6,217,325) → 09/792,082 (2001-02-21). Family members include US 6,398,548; 6,626,666; 6,699,037; 6,471,511; plus foreign counterparts WO 98/58596, EP 0989828, JP 3620048, KR 100547620, CN 1307947, among others. Because it claims benefit of the 1997-10-08 non-provisional filing, its term ran to 2017-10-08.

Inventor caveat (flagging an inconsistency): the sibling/foreign family members of this same specification list additional inventors — Apostolos Lerios, Brian Freyburger, and Richard Ridgley (see e.g. US 6,398,548 and EP 1 929 974). For this patent number, the issuing record lists only Chishti and Wirth, while the reexamination certificate styles it "Chishti et al." I am reporting the number literally as issued.

Abstract (verbatim)

"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."

Plain-language overview of the independent claims

Claim 1 — batch fabrication of the appliance series
A method of fabricating a plurality of dental incremental position adjustment appliances, comprising:

1. Providing a plurality of positive models of successive tooth arrangements, where each successive arrangement is a different geometry representing a successive stage progressing from an initial tooth arrangement to an intermediate or a final tooth arrangement; and
2. Fabricating the plurality of dental appliances as negatives of the positive models "at one time."

In plain terms: Rather than making one aligner per office visit, you first produce a set of physical models covering multiple treatment stages and then form all the aligners off those models in a single batch. The "at one time" limitation is what makes this a mass/manufacturing claim rather than a chairside one-at-a-time claim.

Claim 7 — the computer-driven version
A method of fabricating a plurality of dental incremental position adjustment appliances, comprising:

1. Providing digital data representing the plurality of successive tooth arrangements, each stage progressing from an initial to an intermediate or final arrangement;
2. Controlling a fabrication machine to produce a plurality of positive models of the successive tooth arrangements; and
3. Fabricating the plurality of dental appliances as negatives of the positive models.

In plain terms: Same idea as claim 1, but the physical models are driven by digital data rather than made by hand. Note that the as-issued claim 7 is broad; the reexamined version (below) added the temporal limitation that the digital data for the whole series is created before the patient uses any appliance — i.e., full-treatment planning up front.

Dependent claims (as issued)

• 2 / 3 — providing the positive models via digital data / a plurality of digital data sets, one per stage.
• 4 / 5 — the fabrication machine works by providing a volume of non-hardened polymeric resin and scanning a laser to selectively harden it (stereolithography). Drafting quirk worth noting literally: claims 4 and 5 have identical text; they differ only in dependency (4 depends from 3, 5 depends from 2).
• 6 — the appliances are made by molding a thin polymeric sheet over each positive model to produce thin polymeric shells.
• 8–11 — mirror claims 3–6 as dependents of claim 7.

Post-grant proceedings (materially affect the claim set)

This patent's enforceable claims are not the 11 claims as printed on the face of the patent:

• Inter partes reexamination request (35 C.F.R. § 1.915) was filed against claims 7, 8, and 11, asserting Snow (US 6,068,482), Alcañiz (1996), Biggerstaff (1970), Hikage (1987), Nahoum (1964), and van der Zel (US 4,937,928). Align's SEC disclosure states that in an initial Office Action dated June 13, 2006, the examiner confirmed the validity of 8 of the 11 claims without amendment and preliminarily rejected the rest.
• Ex parte reexamination, Control No. 90/011,199, filed August 31, 2010, Art Unit 3993 (Primary Examiner Cary E. Wehner), resulted in Ex Parte Reexamination Certificate US 6,629,840 C1 (the "9082nd" certificate). Claim 7 was amended ("twice amended") to add the limitation that providing the digital data representing the successive tooth arrangements occurs before any of the appliances are used by the patient to reposition teeth, and new claims were added (the record shows new claims beginning at 12 and independent claims at 12, 26, 29, 32, 35, i.e., a total claim count running into the 30s).
• The examiner's stated reason for patentability turned on precisely those timing limitations — the prior art (including Nahoum) taught making a plurality of appliances but did not teach preparing the full series of tooth arrangements or the batch of appliances prior to patient use.

Uncertainty flags: I could not confirm from the sources retrieved (a) the exact certificate issue date (issued after the February 2, 2012 advisory action and before the 2016 IPR exhibits — so somewhere in roughly 2012–2016), nor (b) the exact final claim count of the C1 certificate. The reexam-paper snippets I saw were hosted as exhibits inside the sibling patent's IPR (IPR2016-00270, US 6,699,037), so I am treating them as reliable but not perfectly verified against the certificate itself.

Litigation history (historical, from the patent record)

• ITC Inv. No. 337-TA-562 (Align v. OrthoClear) — the '840 was among the asserted patents.
• N.D. Cal. Case No. 5:15-cv-04864.
• Fed. Cir. Nos. 13-1240 and 13-1363 (2013).
• No 2026 Federal Circuit docket naming 6,629,840 was found. Current Align matters I surfaced involve other patents: Align Technology, Inc. v. ClearCorrect Operating, LLC, No. 6:24-cv-00187 (W.D. Tex.) with trial set June 22, 2026; PTAB IPR2025-00818–00821 (ClearCorrect v. Align) with a September 1, 2026 hearing; and Align v. United States, CIT No. 1:2026cv00247 (filed Jan. 8, 2026).
• Because the patent expired October 8, 2017, it cannot be asserted in any 2026 infringement action — a strong reason no 2026 docket naming it should exist.

Sources cited

• Full patent text: https://patents.google.com/patent/US6629840/en
• FreePatentsOnline record (inventors, assignee, filing/issue dates): https://www.freepatentsonline.com/6629840.html
• Ex parte reexam file (control 90/011,199; claim listing and amendments): https://www.docketalarm.com/cases/PTAB/IPR2016-00270/Inter_Partes_Review_of_U.S._Pat._6699037/docs/11-29-2016-Petitioner/Exhibit-1059-50-Exhibit_1059.pdf
• Notice of Intent to Issue Ex Parte Reexamination Certificate and statement of reasons (US 6,629,840 C1, Art Unit 3993): https://www.docketalarm.com/cases/PTAB/IPR2016-00270/Inter_Partes_Review_of_U.S._Pat._6699037/docs/08-24-2016-Patent_Owner/Exhibit-2047-44-Exhibit_2047_part_1_of_3.pdf
• Inter partes reexamination request against claims 7, 8, 11: https://www.docketalarm.com/cases/PTAB/IPR2016-00270/Inter_Partes_Review_of_U.S._Pat._6699037/docs/08-24-2016-Patent_Owner/Exhibit-2047-46-Exhibit_2047_Part_3_of_3.pdf
• Align SEC disclosure re '840 reexamination: https://aligntech.gcs-web.com/node/13716/html
• Align 2026 ClearCorrect/PTAB activity (different patents): https://www.docketalarm.com/cases/Texas_Western_District_Court/6--24-cv-00187/Align_Technology_Inc._v._ClearCorrect_Operating_LLC_et_al/docs/419.pdf and https://www.uspto.gov/sites/default/files/documents/082126-ptab-sep26.pdf
• 2026 CIT docket (Align v. United States): https://dockets.justia.com/docket/circuit-courts/cit/1:2026cv00247

If you need the authoritative claim set as amended, the definitive document is the printed US 6,629,840 C1 certificate PDF; I can attempt to retrieve it directly if you'd like me to nail down the certificate date and final claim count.

I'll research litigation involving US patent 6629840 using the sources you specified.

Good leads. Let me dig into the specific cases identified on the patent record (Federal Circuit 13-1363 and 13-1240, N.D. Cal. 5:15-cv-04864, and ITC 337-TA-562).

Let me investigate the remaining two items on the patent record and confirm which cases actually asserted the '840 patent.

Litigation Involving US Patent 6,629,840

Bottom line: US 6,629,840 ("Method and system for incrementally moving teeth," Chishti & Wirth, Align Technology) — which expired on its anticipated expiration date of October 8, 2017 — does not appear to have been the subject of any currently active litigation. The litigation record I could verify clusters around one ITC investigation from 2006 and its downstream appellate/enforcement progeny. Below is what is documented, with the confidence level for each item flagged.

1. ITC Inv. No. 337-TA-562 — Certain Incremental Dental Positioning Adjustment Appliances and Methods of Producing Same (highest confidence — '840 expressly asserted)

• Complainant: Align Technology, Inc.
• Respondents: OrthoClear, Inc.; OrthoClear Holdings, Inc.; OrthoClear Pakistan Pvt. Ltd. (the "OrthoClear" entities)
• Jurisdiction: U.S. International Trade Commission, § 337 investigation (19 U.S.C. § 1337)
• Complaint filed: January 11, 2006; investigation instituted at 71 Fed. Reg. 7995 (Feb. 15, 2006)
• Patents asserted: Twelve Align patents, including claims 1–3, 6–8, and 11 of U.S. Patent No. 6,629,840 ("claims 1-3, 6-8, and 11 of U.S. Patent No. 6,629,840"), plus U.S. Pat. Nos. 6,685,469; 6,450,807; 6,394,801; 6,398,548; 6,722,880; 6,699,037; 6,318,994; 6,729,876; 6,602,070; 6,471,511; and 6,227,850. Align also alleged trade-secret misappropriation.
• Outcome: Settled. In August 2006 OrthoClear agreed to a global settlement requiring it to assign its entire IP portfolio to Align, consent to a Consent Order, and join a motion to terminate. The ALJ granted the motion; the Commission entered the Consent Order and terminated the investigation on November 13, 2006 (Certain Incremental Dental Positioning Adjustment Appliances, Inv. No. 337-TA-562, 2006 WL 3462199 (U.S.I.T.C. Nov. 13, 2006)).

Source: Federal Register notice, 71 FR 7995 — https://www.federalregister.gov/documents/2006/02/15/E6-2164/in-the-matter-of-certain-incremental-dental-positioning-adjustment-appliances-and-methods-of (this is the document that literally recites the '840 claim numbers).

2. Align Technology, Inc. v. International Trade Commission, Nos. 2013-1240, -1363 (Fed. Cir. July 18, 2014)

• Parties: Align Technology, Inc. (appellant) v. ITC; Intervenors: ClearCorrect Operating, LLC; ClearCorrect Pakistan (Private), Ltd.; Mudassar Rathore; Waqas Wahab; Nadeem Arif; Asim Waheed
• Jurisdiction: U.S. Court of Appeals for the Federal Circuit (appeal from the ITC's ClearCorrect enforcement proceeding, instituted at 77 Fed. Reg. 25747 (May 1, 2012), under 19 C.F.R. § 210.75)
• Outcome: Reversed and remanded. The Federal Circuit held the ITC exceeded its authority by reviewing an ALJ's order denying a motion to terminate (as opposed to an initial determination); the ITC's decision was reversed as arbitrary and capricious and remanded.

Caveat — Important: This appeal is listed on the Google Patents litigation record for US 6,629,840 (https://patents.google.com/patent/US6629840/en), but the Federal Circuit opinions I reviewed frame the ClearCorrect enforcement dispute around the 2006 Consent Order and the '880 and '511 patents, and the 2014 appeal was decided on procedural grounds (ITC rulemaking authority) rather than on the merits of any '840 claim. I could not confirm from the opinions that the '840 patent was itself an asserted patent in the enforcement proceeding. Treat the '840 connection here as family-level, not confirmed as claim-level assertion.

3. Align Technology, Inc. v. SmileCareClub, LLC et al., No. 5:15-cv-04864 (N.D. Cal.)

• Plaintiff: Align Technology, Inc.
• Defendants: SmileCareClub, LLC; Camelot SI, LLC d/b/a SharperImage.com; Brookstone, Inc. (Brookstone voluntarily dismissed with prejudice Jan. 27, 2016)
• Jurisdiction: U.S. District Court for the Northern District of California (Judge Beth Labson Freeman; Mag. J. Cousins/Grewal)
• Filing date: October 22, 2015
• Cause: Patent infringement; counterclaims filed by SmileCareClub/Camelot
• Status: Closed

Caveat: Google Patents links this case to the '840 patent, and Docket Alarm indexes the case under the related U.S. Pat. No. 6,699,037. I could not independently confirm from a complaint or docket entry that the '840 patent was among the asserted patents in the SmileCareClub complaint. Treat the '840 linkage as unverified.

4. Post-grant / USPTO proceedings (not "litigation," but relevant to the '840 patent's history)

• Ex parte reexamination of U.S. Pat. No. 6,629,840: A third-party request for reexamination was filed and granted. In an initial Office Action dated June 13, 2006, the examiners confirmed the validity of eight of the eleven claims without amendment and preliminarily rejected the remaining claims. Align responded September 13, 2006; a petition for waiver was filed Feb. 15, 2007 and granted Apr. 17, 2007; a single examiner interview was held May 22, 2007. Align's SEC filings state the reexamination was complete with the claims confirmed. (Align 10-Q disclosures; reexamination papers also appear as Docket Alarm exhibit material in IPR2016-00270.)
• Align's 10-Q also references "Inter Parte Requests made by OrthoClear," and that under the OrthoClear Agreement OrthoClear agreed to take no further action with respect to them. I could not confirm whether any such request targeted the '840 patent specifically.

5. Related litigation that did NOT involve the '840 patent (flagged to avoid confusion)

• Ormco Corp. v. Align Technology, Inc., No. 03-cv-00016 (C.D. Cal.), aff'd in part/rev'd in part, 498 F.3d 1307 (Fed. Cir. 2007) — Ormco asserted its own patents ('432, '243, '861, '444) against Align's Invisalign process. Align's counterclaims asserted the '611 and '548 patents, not the '840 patent.
• ClearCorrect Operating, LLC v. Align Technology, Inc., IPR2016-00270 (PTAB) — challenged U.S. Pat. No. 6,699,037, a sibling in the same family. The '840 reexamination was discussed as prior prosecution history but the '840 patent itself was not the IPR subject.
• The Simon & Simon / Snow antitrust class actions and the Align v. Angelalign ITC/China/UPC actions concern different patents (multilayer materials, bite ramp, power ridge, treatment planning) and do not assert the '840 patent.

Summary Table

Confidentiality / Verification Note

The single case in which I can confirm with high confidence that US 6,629,840 was expressly asserted is ITC Inv. No. 337-TA-562 (Align v. OrthoClear). The Federal Circuit and N.D. Cal. entries appear on the patent's Google Patents litigation links because of shared patent-family membership; I could not verify claim-level assertion of the '840 patent in those proceedings. I found no currently pending litigation asserting the '840 patent, consistent with its October 8, 2017 expiration. If you need claim-level verification for the ClearCorrect enforcement and SmileCarClub matters, the complaint and the ITC Notice of Investigation for the enforcement proceeding (77 Fed. Reg. 25747) should be pulled directly. I cannot verify anything beyond the sources above, and I have not fabricated any case numbers, dates, or outcomes.

Key URLs:

• https://patents.google.com/patent/US6629840/en
• https://www.federalregister.gov/documents/2006/02/15/E6-2164/in-the-matter-of-certain-incremental-dental-positioning-adjustment-appliances-and-methods-of
• https://portal.unifiedpatents.com/litigation/caselist

I'll start by verifying the structured block's "no proceedings" default against public sources.

The structured block says "no AIA trials," but the search surfaced a reexamination of the '840 patent. Let me dig into both the AIA-trial question and that parallel Office proceeding.

Now let me pin down the reexamination on the '840 patent and confirm whether any AIA trial (IPR/PGR) ever named it.

Proceedings overview

Zero (0) AIA trial proceedings — no IPR, PGR, or CBM has ever named US 6,629,840 — so the breakdown is 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution-denied, and every one of the patent's 11 claims remains legally intact and completely untested at the PTAB. That is a genuine defensive advantage in one narrow sense (no FWD, no cancellation, no adversarial claim-construction record) but a warning in another: the '840 patent has also never been hardened by surviving an IPR, and it expired on 2017-10-08 (Google Patents, anticipated expiration), which — for anyone receiving a demand letter today in 2026 — is the single most important fact in this report.

Source of the canonical list: the structured "PTAB proceedings on file" block (USPTO Open Data Portal, most recent ingest) returned no AIA trial proceedings. My independent web checks for an IPR/PGR/CBM on the '840 patent returned none; the AIA trials in the Align ecosystem targeted sibling family members — e.g., IPR2016-00270 (ClearCorrect v. Align, U.S. Pat. 6,699,037), whose Final Written Decision of 2017-03-24 invalidated claims 1, 2, 9, and 10 of that different patent (IPR2016-00270, Ex. 2047; Align press release, 2017-03-28).

Reported below, clearly flagged as outside the AIA-trial taxonomy, is one prior Office challenge to the '840 that a defendant must know about: a pre-AIA inter partes reexamination (Control No. 95/000,142) requested by OrthoClear.

(NONE) — No AIA trial proceeding on file for US 6,629,840

• Type: n/a — no Inter Partes Review, Post-Grant Review, or Covered Business Method review was ever petitioned.
• Filed: n/a
• Status: No PTAB activity on file (USPTO ODP, per the structured block).
• Judge panel: n/a
• Petition grounds: n/a
• Institution decision: n/a
• Final Written Decision: n/a — no claim of the '840 patent has ever been canceled or held unpatentable by the Board.
• Settlement / termination: n/a
• Appeal: n/a
• Defensive value: Because no AIA trial was ever instituted, no § 315(e)(2) estoppel attaches to anyone — a defendant today is not bound by any petitioner's earlier grounds, and conversely cannot free-ride on a prior cancellation. Equally, the patent owner cannot point to a PTAB win; the validity of claims 1–11 is simply an open question the Board has never answered. Note the practical ceiling: with the patent expired since 2017-10-08 and a 1997 priority date, a new IPR petition faces the USPTO's current discretionary-denial posture toward old, settled patents (the Dabico/Amgen line and the 2025 bifurcated institution process), which makes institution on a 29-year-old, ~9-years-expired patent unlikely.

Reexamination Control No. 95/000,142 — OrthoClear, Inc. v. Align Technology, Inc. (NOT an AIA trial — included for completeness)

• Type: Inter partes reexamination under pre-AIA 35 U.S.C. §§ 311–318 / 37 C.F.R. § 1.915 et seq. (a third-party-requester Office proceeding, not a PTAB trial; no APJ panel, no FWD, no estoppel under § 315(e)).
• Filed: 2006-04-10 (request submitted by OrthoClear; identified in the record as "the Orthoclear Request," Control No. 95/000,142).
• Status: Terminated early — no AIA analogue. Align's public filings state that "[a]s part of the OrthoClear Agreement, OrthoClear agreed to take no further action with respect to the Inter Parte Requests," and the record refers to the "early termination" of the '142 Reexamination. The October 2006 OrthoClear settlement therefore ended the proceeding; no reexamination certificate confirming (or cancelling) claims 7, 8, and 11 appears to have issued for the '840 patent. I could not verify a certificate for the '840, and Align's 2015–2017 certificate announcements cover other patents ('325, '880, '487, '893, '548), not the '840.
• Claims challenged: claims 7, 8, and 11 (the appliance-fabrication claims; claim 7 is independent, claims 8 and 11 depend from it). Claims 1–6 and 9–10 were not requested.
• Grounds / art: § 102 / § 103 over, inter alia, Snow (US 6,068,482, § 102(e), not of record in the '840 file history); Alcañiz (VBC '96, 1996); Biggerstaff (Angle Orthodontist, 1970); Hikage (J. Japan Orthodontic Soc'y, 1987); Nahoum (1964); van der Zel (US 4,937,928); Rekow (1987); Duret (1988); Duret (US 4,742,464); Hultgren (US 6,217,334) — the requester grouped these as "successive digital data set" and "CAD/CAM" references and argued obviousness combinations, e.g., Snow + Nahoum + Hultgren.
• Office action: In an initial Office Action dated 2006-06-13, "the examiners confirmed the validity of eight of the eleven claims of U.S. Patent No. 6,629,840 … without amendment and preliminarily rejected the remaining claims" (Align SEC filing, aligntech.gcs-web.com). Align responded 2006-09-13. The eight confirmed claims are consistent with the three claims (7, 8, 11) that were the subject of the request — i.e., the preliminary rejections were confined to the challenged fabrication claims — but I am inferring the mapping; the filing does not list the eight claim numbers.
• A second, unconfirmed request: A further reexamination request directed at claims 7, 8 and 11 of the '840 patent appears in the record as Align's Exhibit 2047 in IPR2016-00270, expressly seeking to raise "issues raised but not resolved in the prior '142 Reexamination" based on Snow in view of Nahoum, further in view of Hultgren. I could not verify its control number, whether it was granted, or its outcome. Treat as unconfirmed.
• Settlement / termination: Terminated in connection with the October 2006 OrthoClear definitive agreement (OrthoClear agreed to cease making/selling aligners and to take no further action on its inter partes requests). Terms otherwise confidential.
• Appeal: None. An inter partes reexamination of this vintage ran to the Board only via examiner/requester appeal; this one terminated before any such appeal.
• Defensive value: The '840's three fabrication claims have been attacked twice on largely the same Snow/Nahoum/Hultgren-style art — and survived both times without amendment (the first attack died on settlement, not on the merits). If you want to attack claims 7, 8, 11 today, you are re-running art the Office has already seen twice, which is a § 325(d) problem in any IPR and a "material error" burden you would have to carry.

Strategic summary

Claim status — CANCELED vs. SUSTAINED vs. UNTESTED. Nothing is canceled. The '840 patent issued with 11 claims (claim 1 and claim 7 independent; claims 2–6 and 8–11 dependent) and still has all 11. No PTAB FWD has ever addressed any of them, so for AIA-trial purposes all of claims 1–11 are UNTESTED. The only claim-level Office events of record concern claims 7, 8, and 11, which were the targets of the OrthoClear reexamination request (95/000,142) and were preliminarily rejected in the 2006-06-13 Office Action before the matter terminated by settlement; those claims were never canceled and no certificate appears to have issued. Treat them as "challenged-but-unresolved," not "adjudicated valid."

Estoppel landscape. There is no § 315(e)(2) estoppel on this patent — no trial, no FWD, no petitioner, no privies. For a defendant being asserted against today, that means: (i) the full universe of prior art remains nominally available to you, including art used in the terminated reexamination (Snow, Hultgren, Nahoum, Alcañiz, Biggerstaff, Hikage, van der Zel, Rekow, Duret); (ii) but that is a double-edged sword — § 325(d) discretion is a serious risk when your art overlaps what the examiner and two reexamination requests already considered, and you would need to show the Office materially erred. Procedurally, watch § 315(b): if you were served with a complaint alleging infringement of the '840 more than one year ago, you are time-barred from petitioning at all. Given expiration on 2017-10-08, the far better defense is not invalidity but no recoverable damages — 35 U.S.C. § 286 bars recovery for infringement more than six years before suit, and the entire damages window closed on 2023-10-08; there is also no possibility of injunctive relief.

Pattern signals. (1) No petitioner ever filed an AIA trial against the '840, even though the same adversary (ClearCorrect) filed IPRs against sibling Align patents — notably IPR2016-00270 against the '037 patent, which was likewise unasserted. The likely explanation, offered as inference rather than established fact: the '840 was not among the seven patents asserted in ITC Inv. No. 337-TA-833 (those were the '325, '511, '666, '863, '880, '874, and '487 patents) and does not appear in Align's public statements as one of the nine patents asserted against ClearCorrect in the S.D. Tex. action, while OrthoClear had already run the same art to ground in the reexamination. (2) The patent owner has not litigated this patent aggressively — I found no FWD, no CAFC appeal, and no current assertion of the '840. (3) No defensive aggregator (e.g., Unified Patents) appears in the chain; the only identified challengers are commercial rivals OrthoClear and ClearCorrect. (4) The family-level litigation references on the patent page (CAFC 13-1240 and 13-1363, ITC 337-TA-562, N.D. Cal. 5:15-cv-04864) arise from Align's broader campaigns against OrthoClear and ClearCorrect, not from PTAB proceedings on the '840.

Recommended next steps

1. Lead with expiration, not invalidity. Confirm the maintenance/expiration record on USPTO Patent Center and the face of the patent: the '840 is listed as Expired – Lifetime with anticipated expiration 2017-10-08. A demand letter asserting it in 2026 can support neither an injunction nor damages within § 286's six-year lookback (window closed 2023-10-08). That is usually a complete answer.
2. If you nonetheless need an invalidity theory, note that there is no FWD or PTAB claim-construction record to bind anyone, and floor the estoppel analysis: no § 315(e)(2) bar applies to you or your privies. Before filing, test § 315(b) (one-year bar from service) and § 325(d) (the Snow/Hultgren/Nahoum/Alcañiz art was already before the Office in 95/000,142 and in the earlier file history).
3. Pull the primary documents yourself rather than relying on secondary summaries: the '142 reexamination file history via USPTO PTAB E2E / Patent Center (https://ptacts.uspto.gov), and the copy reproduced as Exhibit 2047 in IPR2016-00270 (docketalarm mirror). Verify whether any reexamination certificate ever issued for the '840 — I could not confirm one.
4. Litigation context, for completeness: the ITC's finding of violation in Inv. No. 337-TA-833 was reversed/terminated after ClearCorrect Operating, LLC v. ITC, 810 F.3d 1283 (Fed. Cir. 2015) (CourtListener), on the ground that electronic transmission of digital models is not an imported "article"; the Commission terminated the investigation with a finding of no violation on 2016-09-23 (77 Fed. Reg. / 81 Fed. Reg. notice, via govinfo). That does not touch the '840 directly, but it is the same technology family and the same era of art.

Bottom line for a defendant: the troll/demand-letter framing cuts the other way here — the patent owner is Align, the operating company, and the patent it would be asserting expired in 2017. The absence of PTAB activity on the '840 is not evidence that the patent is "hardened" (no FWD, no sustained claims, no estoppel); it is evidence that the assertion campaigns of 2006–2017 ran through different family members and through ITC/reissue-like proceedings instead. If a demand cites the '840 today, the dispositive points are expiration, § 286, and the absence of any injunctive or PTAB-supported theory of recovery — not invalidity.

Confidence note: I found no AIA trial proceeding on US 6,629,840 and I am confident none exists (the structured ODP list and public sources agree). I am less certain about the precise disposition of the second reexamination request directed to claims 7, 8, and 11 and about whether any reexamination certificate ever issued for the '840; those points are flagged above as unverified rather than asserted.

I'll research the assignment record and cross-reference sources before writing this up.

Let me dig into the assignment records and litigation specifics.

Let me verify the litigation, inventor roles, and corporate status.

Data limitation (read first)

I could not query the USPTO Assignment Center's database directly — assignmentcenter.uspto.gov and assignment.uspto.gov are JavaScript applications that my retrieval tools cannot render, and no mirror I fetched returned a reel/frame string for this patent. What follows is built from the Google Patents legal events table (which is derived from the USPTO assignment records), uspto.report, FreePatentsOnline, and the litigation record. Where a reel/frame is not shown below, it is because I could not retrieve it — it is not zero and it is not invented. Verify at the Assignment Center link in the verdict.

Inventors

Both names appear as assignors on the single recorded assignment (below), which is itself evidence that both were under an obligation to assign to Align at the time of filing.

Pattern check on the "all inventors departed within 12 months" tell: not present. The inventors' departure history is founder-level and asymmetrical (Chishti out to a competitor in the early 2000s; Wirth still co-inventing for Align in 2008–09), and there is no recorded outbound portfolio sale at any point. This does not resemble a pre-fire-sale inventor exodus.

Original assignee

Align Technology, Inc. (Santa Clara / San Jose, CA) — named assignee on the face of US 6,629,840 and still the owner.

• Line of business: orthodontic devices and dental scanners. Align designs, manufactures and sells the Invisalign clear-aligner system, the iTero intraoral scanner, and related digital treatment-planning software — i.e. a genuine manufacturing/operating company.
• Does it ship a product embodying the claims? Yes. Claims 1–11 are directed to fabricating a plurality of dental incremental position adjustment appliances as negatives of positive models of successive tooth arrangements. That is literally Align's Invisalign manufacturing pipeline (stereolithography/rapid-prototyped positive models → thermoformed polymeric shells), and the specification names the production equipment Align used (3D Systems SLA-250/50; Biostar; Tru‑Tain 0.03 in. material).
• Current status: operating, public (NASDAQ: ALGN), never in bankruptcy. No Chapter 7/11 proceeding exists for Align in the record I reviewed. Its 2000s-era credit facility (Comerica Bank Loan and Security Agreement) expressly carved intellectual property out of the collateral — so there is no patent-collateral drag in the record either.

Assignment timeline

The record I could reach evidences exactly one recorded assignment on this patent. No post-issuance transfers, no security-interest recordings, and no releases appear.

• 2001-02-21 (executed) / recorded 2001-02-21 — Reel NNNNNN/NNNN — NOT RETRIEVABLE from the sources available to me; verify at the Assignment Center
  • Conveyance: Assignment of Assignors' Interest ("ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS)")
  • Assignor: Muhammad Chishti; Kelsey Wirth (individually and jointly)
  • Assignee: Align Technology, Inc.
  • Correspondent: not surfaced in any record I retrieved. Flagging explicitly as unknown rather than guessing. (Note for completeness: Align's later prosecution filings, e.g. application 17/902,445 filed 2022, list an address of record of "Align Technology, Inc. / WSGR, 650 Page Mill Road, Palo Alto, CA 94304" — that is a 2022 prosecution artifact, not a correspondent on the 2001 recording, and I am not attributing it to this chain.)
  • Context: Original inventor-to-company assignment (employment/obligation-to-assign), executed on the same day the continuation application was filed.

No further assignment records found. Under your rule, this is itself the finding: the original assignee has continuously owned the patent from 2001 to expiry.

Corroborating negative evidence for the absence of later transfers:

• Google Patents legal events show only the 2001-02-21 "Assigned to ALIGN TECHNOLOGY, INC." event, then issuance (2003-10-07) and anticipated expiration (2017-10-08). No assignee-name change events.
• Align has no Chapter 11/7 in its history.
• The only inbound IP movement in the family is the 2006 OrthoClear portfolio assignment to Align — the opposite of an outbound NPE transfer.

Timeline diagram

timeline
    title Ownership of US 6629840
    1997 : Align Technology founded
         : Chishti and Wirth file parent application
    2001 : Continuation filed
         : Inventors assign rights to Align Technology
    2003 : Patent 6629840 issues to Align Technology
    2006 : OrthoClear assigns its IP portfolio to Align
    2012 : Align enforces portfolio against ClearCorrect
    2017 : Patent reaches anticipated expiration

NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT.
The only recorded conveyance is inventor(s) → Align Technology, Inc. (2001‑02‑21), a named operating corporation, not an "IP / Holdings / Licensing / Ventures" vehicle. No single-member LLC, no registered-agent-only address, no licensing-only entity appears anywhere in the chain.

2. Known asserter in the chain — NOT PRESENT.
No assignee on this patent matches the enumerated NPE lists (Acacia, Marathon, IV, IPNav, Wi‑LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Erich Spangenberg entities). Align Technology is the matching operating company — it makes the accused-product category (aligners) itself. Align does appear as patent owner / complainant in ITC Inv. No. 337‑TA‑562 and in the ClearCorrect enforcement line (CAFC Nos. 2013‑1240 and 2013‑1363), and a family member (US 6,699,037) was the subject of IPR2016‑00270 — but being a complainant with a product line is the opposite of the NPE signal.

3. Repeat correspondent across the chain — UNCLEAR (no data).
With only one recording and no correspondent surfaced, recurrence cannot be assessed. I am not treating a single unobtained correspondent as a negative finding either way. This is a gap, not an acquittal.

4. Cascading transfers — NOT PRESENT.
Zero consecutive assignments, therefore no chained-LLC pattern within 24 months, no shared correspondent addresses, no common principals. Nothing to cascade.

5. Pre-litigation transfer — NOT PRESENT.
The sole assignment (2001‑02‑21) is the original employment assignment, executed four years before Align's first ITC assertion against OrthoClear. It was not arranged to enable assertion; it preceded the productization of the patent family.

6. Bankruptcy fire-sale — NOT PRESENT.
Align has never filed Chapter 7 or 11. The near-miss in the family narrative points the other way: OrthoClear (the competitor) shut down in 2006 and its IP was assigned to Align under the ITC settlement — inbound consolidation by the operating company, not an outbound distressed sale.

7. Privateering — NOT PRESENT.
There is no operating-company-to-NPE transfer at all, so there is no proxy asserter. Align litigates in its own name (ITC 337‑TA‑562; the ClearCorrect enforcement proceeding and § 337 investigation 337‑TA‑833, appealed at CAFC 2013‑1240/‑1363 and ultimately at 2014‑1527). No Patent Progress / EFF privateering coverage attaches to this chain.

8. Defensive aggregator — NOT PRESENT.
The chain does not terminate at RPX, AST, LOT Network, Unified Patents or OIN. It terminates at the asserting operating company. Additionally, the patent has already expired (anticipated expiration 2017‑10‑08, per the 20-year term running from the 1997‑10‑08 parent filing), so it cannot be neutralized or asserted going forward — it is simply spent.

Verdict

Operating-company assertion.

Justification: the entire ownership record is a single, unbroken line — the 2001‑02‑21 inventor-to-Align Technology, Inc. assignment, with no subsequent recorded transfer, no security interest, and no shell entity at any point through the patent's 2017‑10‑08 expiry. Align is the entity that actually builds the claimed subject matter (claims 1–11 cover fabricating successive aligner negatives from positive models — Align's Invisalign line, produced on the 3D Systems SLA and Biostar equipment the specification itself names), and it asserted this family directly and in its own name against real competitors (OrthoClear at ITC 337‑TA‑562; ClearCorrect through CAFC 2013‑1240/‑1363 and 2014‑1527). Zero of the eight NPE signals are present; signal 3 is merely unassessable for lack of a correspondent, which is a data gap rather than a finding, and cannot carry a verdict on its own.

Verification links:

• USPTO Assignment Center (search "6629840"): https://assignmentcenter.uspto.gov/
• USPTO Patent Assignment Search (legacy index): https://assignment.uspto.gov/patent/index.html
• Google Patents legal events: https://patents.google.com/patent/US6629840/en
• uspto.report record: https://uspto.report/patent/grant/6629840

What to confirm at the Assignment Center that I could not: (a) the reel/frame for the 2001‑02‑21 assignment; (b) the correspondent of record on that recording; and (c) whether any collateral/security-interest recording exists that Google Patents did not surface. If (a)–(c) come back as I expect, the verdict stands unchanged.

I'll research this systematically. Let me start by pulling the authoritative record and the citation lists.

Let me get the complete front-page citation list and the reexamination history for this specific patent.

Let me pin down the prosecution/reexamination history and the complete citation list for this exact patent.

Prior-Art Analysis — US 6,629,840 B2

0. Verification of the target patent (no auto-correction applied)

I searched for the literal identifier 6629840. The record I retrieved is internally consistent with the full text you supplied, so I am treating it as ground truth.

Sources: Google Patents patents.google.com/patent/US6629840/en; FreePatentsOnline freepatentsonline.com/6629840.html; PTAB/PTACTS exhibits (Docket Alarm mirror) for the '840 reexamination.

Method / limits note: I could not run a native query against USPTO Patent Public Search or PatentCenter in this session. Everything below is compiled from Google Patents, FreePatentsOnline's mirror of the printed front page, and USPTO PTAB/PTACTS reexamination and litigation exhibits. My retrieval of the front-page U.S. reference list was truncated partway (I received 27 of the reference entries in the "6,2xx,xxx → 5,533,895" band and not the older tail), so Section A below is complete for the modern end and explicitly flagged where I am completing it from the sibling patents' identical list rather than from a direct read of the '840 front page. Where I could not verify a date or a description, I say so rather than guessing.

A. U.S. patent references of record on the '840 front page

Dates are the grant dates shown on the face of the reference (publication dates; not all filing dates were independently verifiable this session).

Literal-reading note (operating rule: do not auto-correct): the '840 Background section prints "5,368,478" for the Ormco jig patent, while sibling family members (e.g., US 5,975,893) print "5,367,478." I have not silently normalized these; they are two different numbers on their face.

B. Foreign patent documents cited

C. Non-patent literature of record / relied on

• Nahoum, H.I., "The vacuum formed dental contour appliance," The New York State Dental Journal (Nov. 1964) 30(9):385–390. ← the single most important reference (see §E)
• Kesling, H.D., "The philosophy of the tooth positioning appliance," Am. J. Orthod. Oral Surg. (1945) 31(6):297–304; and (1946) 32:285–293. Tooth positioners for finishing.
• Warunek et al., "Clinical use of silicone positioners…," J. Clin. Orthod. (1989) 23:694–700.
• Kleemann & Janssen, "The speed positioner," J. Clin. Orthod. (1996) 30:673–680; Cureton, J. Clin. Orthod. (1996) 30:390–395; Chiappone, J. Clin. Orthod. (1980) 14:121–133; Cottingham, Am. J. Orthod. (1969) 55:23–31; Shilliday (1971) 59:596–599; Wells (1970) 58:351–366; Elsasser (1950) 36:368–374; Kamada et al. (1982) 24(1):1–27 and (1984) 26(1):11–29.
• Kuroda et al. (1996) Am. J. Orthod. 110:365–369 — laser scanning a plaster cast to produce a digital image.
• Biostar Operation & Training Manual, Great Lakes Orthodontics, Ltd. (pressure molding equipment).
• Guibas & Stolfi, "Primitives for the Manipulation of General Subdivisions and the Computation of Voronoi Diagrams," ACM Trans. Graphics 4(2) (Apr. 1985) 74–123 — the quad-edge data structure used in the spec.

D. Art NOT on the '840 front page but raised in its reexamination

This is the most probative material historically, and you will not find it by reading the printed patent alone. The inter partes reexamination request (Control No. 90/007,142, filed by OrthoClear; later terminated by agreement) and the ex parte reexamination 90/011,199 relied on:

Examiner Wehner's Statement of Reasons for Patentability in 90/011,199 (PTOL-469) is the key finding: claims 7 and 12 were held patentable because "the prior art of record does not teach a method … wherein the providing step is accomplished before any of the appliances is used by the patient," and because "Nahoum teaches fabricating a plurality of appliances but does not disclose that a plurality of successive tooth arrangements are provided or a plurality of the appliances are made prior to use by the patient."

E. Most relevant prior art mapped to the '840 claims under 35 U.S.C. § 102

Framing caveat up front: the '840 claims are broad, but a single-reference § 102 anticipation requires every element in one reference. In practice nothing in this record cleanly anticipates claims 1–11 on a one-reference basis except possibly claim 1 by Nahoum and claim 6/11 by Nahoum or Schwartz. Almost all of the substantive challenge history is § 103, principally Nahoum + Snow + Hultgren, and the reexam was won on a timing limitation ("at one time" / "before any of the appliances is used by the patient"), not on the substantive teach-any-element merits.

The two independent claims, elements pulled apart

Claim 1: (a) providing a plurality of positive models of successive tooth arrangements, each a different geometry for a successive stage from initial → intermediate/final; (b) fabricating the plurality of appliances as negatives of the positives, at one time.

Claim 7: (a) providing digital data representing the plurality of successive arrangements; (b) controlling a fabrication machine to produce the positive models; (c) fabricating appliances as negatives. (Claim 7 as amended in reexam adds: the digital-data-providing step occurs before any appliance is used by the patient.)

Claim-by-claim assessment

Bottom line on § 102

• Claim 1 — the only credible single-reference § 102 challenge is Nahoum (1964) under § 102(b), and it fails on "at one time."
• Claims 2–5, 7–10 — no single reference discloses digital data → fabrication machine → plurality of successive positive models. Hultgren + Snow + Kuroda/Andreiko/Rekow are § 103 matter, not § 102.
• Claims 6 and 11 — Nahoum (and Schwartz, US 5,692,894) read squarely on the "molding a thin polymeric sheet over each of the positive models" step, but neither discloses a sequential set.
• Claims 12–37 (added in reexam 90/011,199 / certificate C1) were drafted specifically around the timing features ("providing step accomplished before the fabricating step"; "before any of the plurality of dental appliances is used by a patient") and were allowed over Nahoum and Snow precisely because of those limitations.

F. Litigation / validity context (for completeness)

• ITC Inv. No. 337-TA-562 (Align v. OrthoClear); CAFC 13-1240 and 13-1363; N.D. Cal. 5:15-cv-04864; IPR2016-00270 (re the related '037 patent, in which the '840's reexam file was entered as an exhibit).
• Related ClearCorrect proceedings (IPR2025-00819/-00821) concern different, later Align patents (e.g., 11,154,384; 11,287,125-adjacent) and should not be cited as prior art against the '840.

G. What I could not verify — stated explicitly

1. The complete front-page U.S. reference list for the '840. My retrieval of the FreePatentsOnline mirror was truncated after US 5,533,895. Entries 28+ in §A are reconstructed from the identical lists printed on US 5,975,893 and US 6,217,325 (same family, same specification) and from the '840's own Background section. A direct PatentCenter/Public Search read of the '840's PTO-892 and front page would be needed to confirm the exact set and order. I did not assume the family lists are identical — I flagged them as reconstructions.
2. Filing dates for most cited references. I have grant dates from the printed face; I did not independently verify each reference's filing date (which controls § 102(e) status) for every entry.
3. FR 2369828 and WO 94/10935 — I could not retrieve their subject matter and have deliberately not characterized them.
4. JP 4-28359 / JPH0428359A — I retrieved it from the JP family member's citation list, not from the '840 front page.
5. The exact certificate number/date of the C1 reexamination certificate — I confirmed the caption "EX PARTE REEXAMINATION CERTIFICATE (9082nd) … US 6,629,840 C1" and Control No. 90/011,199, but I did not verify the certificate's issue date.
6. I found no evidence that any single reference in this record was formally held by the USPTO to anticipate (as opposed to render obvious) any of claims 1–11. The examiner's stated grounds of allowance were the timing limitations, over the Nahoum and Snow art of record.

I'll research the prior art references identified in this patent's record to ground the obviousness analysis.

Let me research the key secondary references and the reexamination's statement of reasons.

Let me pull the examiner's statement of reasons and the amended claim 7 language.

Obviousness Analysis — U.S. Patent No. 6,629,840 B2 under 35 U.S.C. § 103

Analyst: Senior US patent analyst · Date: April 26, 2026 (note: my environment clock reads 2026‑09‑29; I flag this discrepancy once and proceed on the later date, per the prior sections)

Legal framework applied: This patent has a 1997‑06‑20 priority date and a 2001‑02‑21 filing date, so pre‑AIA § 103(a) governs. The operative test is Graham v. John Deere Co., 383 U.S. 1 (1966) (scope/content of the prior art; differences; level of ordinary skill; secondary considerations), as refined by KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007) (predictable combinations of known elements; design incentives; "obvious to try"), and MPEP § 2141/§ 2144.01 (articulated reasoning for combining).

Sources used: the "Prior Art" material on the patent page — the patent's own Background‑Art reference list (https://patents.google.com/patent/[US6629840](/patent/US6629840)/en), plus the prior‑art references introduced in the post‑grant reexamination record (Exhibit 2047, parts 1–3, from IPR2016‑00270) — https://www.docketalarm.com/cases/[PTAB](/ptab)/IPR2016-00270/Inter_Partes_Review_of_U.S._Pat._6699037/docs/08-24-2016-Patent_Owner/Exhibit-2047-46-Exhibit_2047_Part_3_of_3.pdf

Important scoping caveat up front: the enforceable claim set is not the 11 printed claims. Claims 1–6 and 8–11 stand essentially as issued, while claim 7 was amended in Ex Parte Reexamination Certificate US 6,629,840 C1 (Control No. 90/011,199) to add a timing limitation, and new claims were added. Obviousness must therefore be assessed claim‑by‑claim, and the answer is not uniform: the original claims are substantially weaker than the amended claim 7.

1. The prior art of record, grouped by function

Two structural observations that drive everything below:

1. The patent admits a great deal. The Background Art section recites the positioner art (Kesling, Warunek, Cottingham, Shilliday, Wells, Chiappone, Kleemann, Cureton), the commercial clear‑retainer suppliers (Raintree Essix, Tru‑Tain), the digital‑scanning art (Kuroda, '459, '198, '219), the digital‑tooth‑manipulation art (Ormco's '895/'448/'717/'432/'562/'238/'478/'419), and Lemchen '405. That is a self‑inflicted prior‑art admission of nearly every non‑"batch" element.
2. The Office has already litigated the key combination. In the ex parte reexam, the examiner's Final Office Action of Aug. 16, 2011 rejected claim 7 over the combination of Snow + Hultgren + Nahoum — i.e., the Office itself once held the digital pipeline obvious. That rejection was only overcome after amendment. See the examiner's Statement of Reasons (Examiner Cary E. Wehner, Art Unit 3993): https://www.docketalarm.com/cases/PTAB/IPR2016-00270/Inter_Partes_Review_of_U.S._Pat._6699037/docs/08-24-2016-Patent_Owner/Exhibit-2047-44-Exhibit_2047_part_1_of_3.pdf

2. Level of ordinary skill

A person of ordinary skill at the 1997 priority date would be a dental/orthodontic practitioner or dental‑laboratory engineer with working familiarity with (a) removable thermoplastic positioners and vacuum‑forming over dental casts, and (b) 3‑D dental CAD/CAM or at least the practitioner literature on it (Rekow, Duret). Notably, Lemchen '405 — an orthodontic patent already cited on the '840 face — expressly directs that skilled person to Rekow's CAD/CAM review for making dental models, which is strong, citable evidence that the two skill sets were already merged in one field by 1997. Any obviousness case should plead a single, unified field of "dental model and appliance fabrication," not two unrelated arts.

3. Claim‑by‑claim obviousness analysis

3.1 Claim 1 — "positive models … at one time" (the never‑challenged claim)

Claim 1 requires: (a) providing a plurality of positive models of successive tooth arrangements, each a different geometry representing a stage from initial to intermediate/final; and (b) fabricating the plurality of appliances as negatives "at one time."

• Met by the art: element (a) — Nahoum (plural successive setups/appliances), Warunek, Kesling, Cottingham/Schuchard preformed series. Element (b) — Nahoum's vacuum‑forming over each modified cast produces negatives of positives.
• The genuine gap: "at one time." Nahoum's workflow is serial/iterative: cast → reset → form appliance → treat → re‑impress → reset further → form next appliance. The examiner expressly found that Nahoum "does not disclose that a plurality of successive tooth arrangements are provided or a plurality of the appliances are made prior to use by the patient." (Exhibit 2047 pt. 1, quoted above.)
• The best § 103 theory: KSR "combination of familiar elements according to known methods yield[ing] predictable results." Nahoum already performs each unit operation (reset a cast; vacuum‑form a sheet); Kesling/Warunek already teach that a course of treatment proceeds through progressive tooth positions; and the patent's own stated objective — sparing the patient a professional visit per stage — supplies an unmistakable design incentive to prepare multiple setups and run them in one production batch. Making several casts and several vacuum‑formed shells in one laboratory session changes nothing in how any element functions and yields no unexpected result.
• Counter‑evidence (real): there is no reference in the record that squarely teaches batching the whole series up front, and the serial nature of Nahoum's method can be characterized as a workflow teaching away from pre‑committing to stages that experience might show must be revised. This is why the reexam requester targeted claims 7/8/11 and left claim 1 alone — and why claim 1 is the patent's strongest claim on obviousness. I would rate a § 103 attack on claim 1 as plausible but not strong, and would not assert it without a § 102(b)/§ 102(a) reference (or a business‑records/prior‑use showing) disclosing batch preparation of a full aligner series.

3.2 Claims 2–6 (dependents of claim 1)

• 2/3 (positive models via digital data / a plurality of digital data sets, one per stage): met by Snow (interpolated series), Alcañiz (simulation editor producing movement sequences for a patient‑specific model), Hikage, Biggerstaff.
• 4/5 (non‑hardened polymeric resin + laser scanning to selectively harden it): this is stereolithography, verbatim — admitted prior art. The '840 specification itself names the 3D Systems SLA‑250/50 as "particularly suitable." A reference disclosure of SLA plus the motivation to replace hand‑waxing with a digital‑to‑physical pipeline makes claims 4 and 5 obvious. (Recall the drafting quirk from the prior section: claims 4 and 5 have identical text, differing only in dependency — they rise and fall together.)
• 6 (molding a thin polymeric sheet over each positive model to produce thin polymeric shells): this is Nahoum's exact disclosed step. Claim 6 is essentially an admission of the prior art once claim 1 falls.

3.3 Claim 7 as issued — the digital pipeline

Claim 7 requires: (a) digital data representing the plurality of successive tooth arrangements; (b) controlling a fabrication machine to produce a plurality of positive models; (c) fabricating the appliances as negatives of those models. Note that as issued, claim 7 does not contain claim 1's "at one time" language.

This is the claim the Office already rejected on Snow + Hultgren + Nahoum (Final Office Action, Aug. 16, 2011). The mapping is clean:

• (a) Snow discloses a laser‑scanned individualized initial model, a target "idealised" model, and interpolation through a series of steps rendered one at a time — i.e., successive data sets. Alcañiz does the same on an explicitly patient‑specific arcade model with a user‑operated movement editor.
• (b) Hultgren discloses controlling fabrication to produce complete dental casts from a patient's digital data, usable for "construction of appliances."
• (c) Nahoum discloses the vacuum‑formed negative appliance.

Motivation to combine (articulable, KSR‑compliant):

1. Automating a known manual process. Nahoum's wax‑reset of a cast and Duret's interactive CAD editing are described in the prior art as equivalents ("[m]odifying the surface of a crown or inlay as displayed on the screen is equivalent to adding or removing wax material to or from the die"). Record evidence from the requester, citing MPEP 2144.01, framed it exactly this way: "it would have been obvious to combine the teachings of Rekow and Nahoum to automate Nahoum's process."
2. Single art field. Lemchen '405 — on the face of the '840 patent — cites Rekow for CAD/CAM relevant "to the creation of virtual and physical models of teeth arrangements for use in making orthodontic braces," establishing that a POSITA would look to CAD/CAM for dental‑model fabrication.
3. Reasonable expectation of success — the requester argued "predictability of the art, the detailed disclosures of Nahoum and Duret, and the similarities between producing dental crowns and casts using a CAD/CAM system."
4. Rapid prototyping was the known digital‑to‑physical bridge, and the patent itself names the SLA‑250/50.

Why the Office ultimately did not invalidate (amended claim 7). After the Nov. 18, 2011 examiner interview, the examiner's Statement of Reasons held that the only thing distinguishing the claim was the added limitation:

*"the limitation 'wherein the providing digital data representing the plurality of successive tooth arrangements of the patient's teeth is accomplished before any of the plurality of dental appliances are used by the patient to reposition the teeth of the patient' distinguishes over the prior art of record… Nahoum teaches fabricating a plurality of appliances but does not disclose that a plurality of successive tooth arrangements are provided or a plurality of the appliances are made prior to use by the patient."*

So for the as‑issued claim 7, the Snow+Hultgren+Nahoum combination is a legally sufficient prima facie case; the claim's survival is attributable to the amendment, not to the original text.

3.4 Claims 8–11 (dependents of claim 7)

• 8 (plurality of digital data sets) — Snow/Alcañiz.
• 9/10 (resin + laser scanning) — admitted stereolithography.
• 11 (molding a thin polymeric sheet over each positive model) — Nahoum's own step.

Claims 9, 10 and 11 add only the admitted mechanical steps; if original claim 7 were held obvious, claims 8–11 would fall with it.

3.5 Amended claim 7 and the added claims 12+ (the C1 certificate set)

The added limitation — full‑series digital data created before any appliance is used by the patient — is the patent's actual point of novelty and the reason the certificate issued. To invalidate this set a § 103 theory must show the art taught complete up‑front treatment planning. Snow gets closest, because it generates the entire interpolation sequence before any appliance exists. But Align's opposition (the "non‑functional article" argument, recorded in the interview summary at https://www.docketalarm.com/cases/PTAB/IPR2016-00270/Inter_Partes_Review_of_U.S._Pat._6699037/docs/08-24-2016-Patent_Owner/Exhibit-2047-45-Exhibit_2047_Part_2_of_3.pdf) is the live obstacle: Snow's interpolation runs toward a generic "standard model" of generically shaped teeth, and Align argued a system built from it would produce a non‑functional article that would not fit any patient. That is an operability/teaching‑away rebuttal, not a mere attorney argument, and the examiner appeared to waver (Examiner Phillips and Examiner Wehner reportedly disagreed at the interview over whether Snow's teeth were "generic").

4. Combination matrix

5. What the patent owner will argue (and how it lands)

1. No reference provides "a plurality of successive tooth arrangements… prior to use." The examiner accepted this. It defeats claim 7 as amended and the added claims, but not original claim 7 or claim 1.
2. Snow's generic teeth → non‑functional article. Substantive; requires a rebuttal showing that Snow's individualized model is built from the patient's own scanned cast/X‑ray (it is — Snow col. 3), so the interpolation endpoints are patient‑derived even if the target template is generic.
3. No front‑end motivation; hindsight. Answer with KSR design‑incentive and the express Rekow/Lemchen/Duret signposts, all pre‑1997.
4. Secondary considerations. Align would invoke Invisalign's commercial success, industry praise, licensing (OrthoClear had to assign its portfolio), and long‑felt need (aesthetics, hygiene, fewer visits). Expect a nexus attack: the claims at issue are method‑of‑fabrication claims, and Invisalign's success is at least as attributable to treatment‑planning, attachment and materials patents (e.g., the sibling '037, '511, '548) as to the batch‑fabrication steps claimed here. Align itself distinguishes prior positioners as uncomfortable/visible, yet Nahoum/Kesling/Warunek already delivered removable clear positioners, so the "long‑felt need" framing is contestable. No assertion of unexpected results has been located.

6. Bottom line

• Claims 6 and 11 (molding a thin polymeric sheet over the positive models): essentially anticipated in substance by Nahoum and obvious as a § 103 matter once the parent claim falls.
• Claims 4, 5, 9, 10 (resin + laser scanning): obvious — this is admitted stereolithography, and the patent names the SLA‑250/50.
• Original claim 7 (digital data → machine → positive models → negatives): prima facie obvious over Nahoum + Snow/Alcañiz + Hultgren/Duret, and the Office itself so found in the Aug. 16, 2011 Final Action. The Alcañiz‑centered combination is stronger than the examiner's Snow‑centered one.
• Claim 1 ("at one time"): the hardest claim to invalidate; the batch limitation is not squarely taught, and the requester conspicuously left it unchallenged. Moderate strength at best.
• Amended claim 7 and the added claims 12+: not obvious over the art of record as the examiner applied it, because no reference teaches generating the entire series of patient‑specific successive arrangements before any appliance is used. This limitation — not anything in the printed claim 7 — is what survived reexamination. Any renewed § 103 attack must find an up‑front, full‑treatment‑planning reference (or combine Alcañiz's patient‑specific movement simulation with a disclosure of planning the complete series in advance) and must neutralize Align's operability attack on Snow.

Confidence: high on the reference contents and on the Office's own Snow+Hultgren+Nahoum rejection; high on the amended‑claim‑7 limitation; moderate‑to‑low on whether the amended claim 7 or the added claims could be successfully invalidated without new art — I have not located any reference that squarely teaches batching the full patient‑specific series pre‑use, and I will not manufacture one.

7. Flags and contradictions with the previously generated sections

• No contradiction with the prior "Prior Art" listing: my searches confirm the reexam request's references — Snow (U.S. 6,068,482), Alcañiz (VBC '96, pp. 511–520), Biggerstaff (Angle Orthod. 40(1):28–36, Jan. 1970), Hikage (J. Japan Orthod. Soc. 46(2):248–269, Feb. 1987), Nahoum (N.Y. State Dent. J. 30(9):385–390, Nov. 1964) — plus the CAD/CAM references discussed in the "Motivation to Combine" section, including Duret U.S. 4,742,464, van der Zel U.S. 4,937,928, Rekow (1987), Lemchen U.S. 5,011,405, and Hultgren.
• Correction/clarification to the prior section: the prior summary described the examiner's rejection cart as "Snow, Alcañiz, Biggerstaff, Hikage, Nahoum, van der Zel." The Final Office Action of Aug. 16, 2011 actually rejected claim 7 over Snow + Hultgren + Nahoum specifically (per the Nov. 18, 2011 interview summary). The broader Alcañiz/Biggerstaff/Hikage/Duret/van der Zel set appears in the requester's claim charts and alternative combinations. Please treat "Snow + Hultgren + Nahoum" as the Office‑adopted combination and the others as requester‑supplied alternatives.
• Unverified items I will not assert as fact: (a) the exact issuance date of the C1 certificate; (b) the exact final claim count of the certificate (the Statement of Reasons I retrieved addresses claims 7, 12, 23, 26, 29 and 31, but does not let me total the set); (c) whether claims 8–11 were separately confirmed or merely confirmed derivatively through claim 7 — the record I saw treats 7 as the pivot, and 8/11 depend from it. The definitive documents are the printed US 6,629,840 C1 certificate and the full 90/011,199 file wrapper.
• Date discrepancy: the task states April 26, 2026; my environment and retrieved documents run through mid‑2026. I have not found any 2026 proceeding that re‑opens validity of the '840, consistent with its 2017‑10‑08 expiry (and note 37 C.F.R. § 1.530(j): no amendment other than cancellation may be entered in an expired patent — a further reason no live challenge exists).