US 5890899

I'll verify the patent against live sources before summarizing.

US 5,890,899 — "Dental Isolator"

Verification note: I searched for this specific number (Google Patents, FreePatentsOnline, and general web queries aimed at USPTO/CAFC materials). I found no CAFC 2026 docket activity, no district-court litigation, and no USPTO post-grant proceeding referencing 5890899. Absence of results in my searches is not proof of absence of litigation — I could not access PACER or the CAFC docket system directly — so treat "no litigation found" as a search result, not a certified clearance. The bibliographic data below matches the full patent text supplied.

Bibliographic data

Abstract (as issued)

The device has a buccal member and a lingual member disposable on one side of the mouth to isolate the buccal and lingual sides of the mandibular teeth respectively. The buccal member is curved to follow the outer contour of the mandibular arch and deflects the cheek; the lingual member corrals and deflects the tongue and has a neck portion that rests on the mandibular teeth. Distal ends of the two members are spaced apart to permit independent movement. One embodiment adds a prop stem releasably attachable to the maxillary teeth; another substitutes an elongated chin bar extending downwardly to grip the patient's chin.

Claim set structure

Important: the patent contains 13 claims in which only claim 1 is independent. Claims 2–5 depend from claim 1 (adding an aspiration attachment), claim 6 from claim 1, claims 7–10 from claim 1 (adjustment mechanism), and claims 11–13 from claim 1 (internal fluid circuit). Notably, the chin-bar embodiment described at length in the specification (FIGS. 10–13, device 60) is never claimed — it is disclosed subject matter only.

Independent claim 1 — plain language

A dental device for isolating part of a patient's mandibular arch, comprising four cooperating elements:

1. A prop stem — an elongated body with a top section and bottom section, long enough to span the mouth opening (i.e., a bite-prop).
2. An upper maxillary support — a generally U-shaped body attached to the top of the prop stem, releasably securable to the patient's maxillary arch (upper teeth).
3. A buccal member — a pliable elongated body angling downward from the bottom of the prop stem, curved to follow the outer contour of the mandibular arch, adapted to push the cheek away from the arch.
4. A lingual member — a pliable plate-like body angling downward from the bottom of the prop stem, curved along the inner contour of the arch and extending away from the buccal member, configured to corral and laterally deflect the tongue; it has a neck portion where it meets the prop stem, shaped to rest on the mandibular arch.

So the single independent claim is a bite-prop-plus-cheek/tongue-retractor combination anchored by the upper teeth, with pliability required for both the buccal and lingual members.

Key dependent claims (for context)

• 2–5: Aspiration feature — a projecting portion at a distal end of the buccal and/or lingual member; a detachable aspirating device with a ring that slidably receives the projection; the suction tube has a sidewall conduit with multiple apertures.
• 6: A resilient layer (e.g., silicone) on the outer surface of the buccal and/or lingual member for patient comfort/tissue protection.
• 7–10: Height adjustment — a threaded stud on one part and a mating internally threaded sleeve on the other so relative rotation adjusts the axial distance between the maxillary support and the prop stem; claim 9 adds a rotative coupling (screw through an opening) so the sleeve can be turned without rotating the maxillary support; claim 10 restates the U-shaped maxillary support.
• 11–13: Internal fluid circuit — a first conduit and aperture in the prop stem sidewall in fluid communication with a second conduit/aperture in the buccal member (claim 11) or the lingual member (claim 12), and claim 13 adds a third conduit/aperture in the lingual member functioning as a second circuit with the first conduit. The stem aperture serves as the vacuum-tube outlet; the member apertures are the inlets.

Minor drafting observations (not legal conclusions)

• Claim 2 recites "said distal end of at least one of said buccal member and said lingual member," but claim 1 does not itself recite "distal end," creating a potential antecedent-basis question — though the specification's spacing language addresses distal ends.
• Claim 9 contains a claim-numbering typo: it reads "The dental device of 7" rather than "of claim 7." Per the operating rule I have not auto-corrected this; I note it as it appears in the printed patent.
• Claim 10 re-recites the U-shaped maxillary support already required by claim 1 (via claim 7), making it arguably redundant over its parent.

Uncertainty statement

Bibliographic fields, dates, claims, and the abstract above are grounded in the authoritative full text of US 5,890,899 that you supplied, corroborated by the Google Patents and FreePatentsOnline records returned in search. I do not have authoritative confirmation of (a) any litigation or CAFC docket involving this patent, or (b) the precise chain of title beyond the single recorded assignment from Sclafani to Intellitech Corporation. If you need negative-clearance confidence on litigation, that requires a direct PACER/CAFC docket query rather than the open-web searches I ran here.

I'll search for litigation involving US patent 5890899.

Initial searches returned only patent documents. Let me search litigation-specific sources.

No litigation found yet. Let me check dedicated litigation databases directly.

Litigation search results for U.S. Patent No. 5,890,899

Bottom line: I found no evidence of any litigation involving U.S. Patent No. 5,890,899. No district court case, ITC investigation, or Federal Circuit appeal naming this patent appeared in any of the sources I was able to query.

What the patent is (for identification)

• Patent: US 5,890,899 — "Dental isolator"
• Inventor: Adam Sclafani
• Assignee: Intellitech Corp (originally Intellitech Corporation, New York)
• Filing date: 1997-06-27 (App. No. 08/883,820) | Grant date: 1999-04-06
• Family: WO1999000069A1 (PCT/US1998/013114), AU82628/98A — both now inactive (WO "Ceased," AU "Abandoned")
• Status: Expired — fee related. Per the Google Patents legal-events record, a maintenance-fee reminder issued 2006-10-25, the patent lapsed for failure to pay maintenance fees effective 2007-04-06, and it expired under 37 CFR 1.362 (recorded 2007-06-05).

Litigation found

None. No known litigation.

Sources checked and what they showed

The only "References" associated with the patent are patent citations, not litigation:

• 23 references cited against it (e.g., US 1,202,264 Brown; US 2,830,371 Dahl; US 3,396,468 Dayhoff; US 4,053,984 Moss; US 4,994,046 Univ. of Tennessee; US 5,516,286 Kushner), and
• 79 documents citing it forward (e.g., Innerlite/Zyris intraoral device family, Ultradent cheek retractors, Solmetex/DryShield intraoral devices, King Saud University retractors).

These are prior-art/prosecution citations, not infringement suits.

Important disambiguation warning

Several of my searches surfaced cases involving different patents with superficially similar numbers. None of these concern US 5,890,899 and should not be attributed to it:

• U.S. 7,256,899 / 7,336,375 — Cedar Lane Technologies v. 3Shape (D. Del. 1:23-cv-00950), 3D shape sensing.
• U.S. 9,402,899 — Bristol-Myers Squibb v. AstraZeneca (D. Del. 1:17-cv-01028 and the 2023 refiling), anti-PD-L1 antibodies.
• U.S. 6,614,899 — asserted by Spherix in N.D. Tex. telephone cases (2013).
• U.S. 8,513,899 — Seoul Semiconductor LED-driver suit against SATCO.

Confidence and caveats

• High confidence that no litigation is recorded for US 5,890,899: multiple independent patent databases and general litigation searches returned nothing, and nothing in the patent's own record (which shows no assignments to litigious entities or NPEs) suggests enforcement.
• Practical context: The patent went abandoned for fee non-payment in 2007 and would have expired by its 2017 term at the latest. Given the six-year damages look-back period, any infringement action would realistically have had to be filed by roughly 2013, and none appears to exist.
• Limitations: My access was via web search; I could not run direct API/database queries against PACER/RECAP, Docket Alarm, Lex Machina, or the Unified Patents caselist. Those archives may under-index older 1990s–2000s filings, so a final negative clearance would ideally be confirmed by a direct PACER/RECAP party-name search for "Intellitech" and "Sclafani" and a Lex Machina/Unified Patents search on the patent number. Based on everything retrievable, however, the answer is that no litigation is known.

I'll verify the "no proceedings" default against live sources before writing.

Let me run a few more targeted checks (patent owner name, litigation history, and any CAFC docket).

Proceedings overview

Zero AIA trial proceedings have ever been filed on US 5,890,899 — the USPTO Open Data Portal returns no IPR, PGR, or CBM for this patent, and independent web searching surfaced no PTAB proceeding, no Final Written Decision, and no Federal Circuit appeal referencing this patent number. The bottom line for a defendant is therefore not "the patent has survived two IPRs and is hardened," but something much stronger: no claim of this patent has ever been tested at the PTAB, and the patent itself expired for failure to pay maintenance fees effective 2007-04-06 — roughly ten years before its nominal 2017-06-27 expiry.

Proceedings by patent

There are no proceedings to itemize. I am not going to manufacture a proceeding number, a petitioner name, or a panel to fill this section.

Canonical source (USPTO ODP structured block): no AIA trial proceedings on file as of the most recent ingest.

Independent verification performed (2026-09-10):

• Searches for US 5890899 IPR, "5,890,899" PTAB, "IPR201"/"IPR202" "5890899", and patent-owner-name queries (Intellitech, Sclafani + PTAB/IPR) returned no petition, institution decision, FWD, or appeal referencing this patent. The only hits were the patent documents themselves (Google Patents, FreePatentsOnline) and later patents that merely cite the '899 as prior art.
• No Unified Patents (or similar defensive aggregator) filing was found in the chain. Note that "Unified Patents v. NavBlazer, LLC" surfaced in search but concerns US 9,885,782 — a different patent entirely; do not conflate the two.

Where to re-verify at any time:

• PTAB E2E / Patent Trial Practice Guide docket search: https://e2e.uspto.gov/ (search by patent number 5890899)
• PTAB Decisions: https://www.uspto.gov/patents/ptab/decisions
• CourtListener docket search: https://www.courtlistener.com/?q=5890899&type=r
• CAFC: https://cafc.uscourts.gov/

Strategic summary

Claim status: every claim is UNTESTED at the PTAB. US 5,890,899 issued 1999-04-06 on application US08/883,820 (filed 1997-06-27, priority 1997-06-27) to Intellitech Corp., inventor Adam Sclafani, with 13 claims. No claim has ever been canceled, confirmed, or even challenged in an AIA trial. Claims 1–13 all stand in their as-issued form in the sense that no adjudicative body has narrowed them — but "as-issued and unchallenged" is not the same as "live." This patent is not a hardened patent; it is a dead patent that no one ever bothered to challenge because there was nothing left to attack.

Estoppel landscape: empty. Because no petitioner ever filed, there is no § 315(e)(2) estoppel binding anyone — no party is barred from any ground, and no printed publication, patent, or combination has been "used up." That is nominally good news for a defendant, but it is moot here: IPR/PGR on an expired, unasserted patent is a waste of money, and the more important bar is not estoppel but the patent term itself.

The controlling fact is the fee lapse, not the PTAB. The prosecution history shows the 4-year maintenance fee was paid 2002-10-07; the next maintenance fee reminder was mailed 2006-10-25; the USPTO mailed a Lapse for failure to pay maintenance fees on 2007-04-06 and recorded "PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362" on 2007-06-05, effective 2007-04-06. Google Patents' verbatim legal status is "Expired - Fee Related." The anticipated expiration date was 2017-06-27; the patent actually died about ten years early. No petition to revive appears on the record, and even if one were attempted, 35 U.S.C. § 41(c)(2) protects intervening rights of parties who made, used, or sold during the lapse — protection that would cover essentially any modern dental-isolation product.

Pattern signals: none in either direction. The patent owner (Intellitech Corp.) did not pursue PTAB appeals — there was nothing to appeal. The same petitioner did not file multiple IPRs — there were no petitioners at all. The absence of PTAB activity is a stronger signal than mere non-assertion: well-asserted patents reliably attract IPRs (the search results themselves document how crowded this art space is — Innerlite, Ultradent, Solmetex/DryShield, Armor Dental all built families around similar intraoral isolation devices). This one attracted none, consistent with a patent that was never commercially enforced.

Data caveat: the Google Patents page for this patent lists a "Cited By (38)" table in one rendering and "Cited By (79)" in another, and its "Cited By" rows mix genuine third-party citations with pagination artifacts (e.g., 1998-priority Innerlite assets appearing under the 1998 ledger). Treat the citation count as approximate; none of those citing documents are PTAB proceedings in any event.

Recommended next steps

1. If you have received a demand letter citing US 5,890,899, treat it as a legal-status problem before an invalidity problem. Link the examiner-facing record and quote the disposition verbatim from the source: "Lapse for failure to pay maintenance fees" (2007-04-06) and "PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362" (recorded 2007-06-05), as reflected at https://patents.google.com/patent/US5890899/en. There can be no infringement of an expired patent for any conduct after 2007-04-06, and 35 U.S.C. § 286's six-year damages lookback bars the residual 2007 tail as well. A demand built on this patent has no damages theory attached to it.
2. Do not file an IPR. There is no live patent to invalidate and no § 315(e)(2) benefit to be gained. Spending a six-figure petition budget here buys nothing; the correct response is a status-based refusal letter, not a PTAB filing.
3. Preserve the prior-art estate for other purposes. The '899 is itself cited as prior art in the intraoral-isolation space (Innerlite, Ultradent, Solmetex/DryShield, Armor Dental families all cite it), and it carries 23 examiner-cited references including US 1,202,264 (Brown, combined saliva-ejector and tongue-fender), US 2,830,371 (Dahl, combined tongue-holder and saliva-ejector), DE 650,629 (Buehler, cheek and tongue holders), and US 5,516,286 (Kushner, dental isolation tray). If you are defending against a different, later dental-isolation patent, this art — plus the '899 itself — remains fully available, with no estoppel of any kind attached.
4. No trial milestones to track. There is no institution-decision deadline, no oral hearing, and no statutory one-year § 316(a)(11) FWD date, because no trial was ever instituted. If a proceeding does appear later, re-run the PTAB E2E patent-number search first — and verify the number digit-by-digit, since searches in this space readily surface lookalike numbers (e.g., US 9,885,782 in Unified Patents v. NavBlazer is unrelated to this patent).

Confidence statement: I have high confidence that no AIA trial proceeding exists for this patent — the ODP structured block says so and my searches corroborate it. I have not attempted to characterize district-court litigation history, because none is recorded in the provided materials and my searches returned nothing; if you need that, a PACER or Docket Navigator query on "Intellitech Corp." would be the authoritative next step, and I would not extrapolate "never asserted" from "never IPR'd."

I'll verify the assignment record against live sources before reconstructing the chain.

Let me dig further into the assignee, inventor, and any litigation or further transfers.

Let me verify the assignee entity and any additional Adam Sclafani patents/assignments.

Assignment & Ownership Chain — US 5,890,899 "Dental isolator"

Primary source caveat up front: I could not open a live, field-level USPTO Assignment Center record for this patent. assignmentcenter.uspto.gov and assignment.uspto.gov returned no retrievable field data through my searches, and I hit my tool-call limit before I could complete a direct query. What I can verify is the legal-events record on Google Patents, which reproduces the Assignment Center abstract. The correspondent (recording attorney/agent and firm) is not exposed in any source I could retrieve. Per your instruction not to fabricate, I am leaving that field explicitly unpopulated rather than guessing. That is the single most important gap in this analysis and it is worth a manual lookup.

Inventors

• Pattern noted: the assignment was executed pre-filing (effective 1997‑06‑20 vs. filing 1997‑06‑27) but recorded only ~12 months later (1998‑06‑26). That is the signature of a routine employment/obligation-to-assign being papered at filing and recorded later — not the delayed-recording pattern you see when an inventor is shopping a patent.
• Departure signal: not determinable. I found no evidence of Sclafani leaving Intellitech within 12 months, nor any evidence he stayed. Google Patents/GoodIP attribute 3 patents to "Sclafani Adam" at Intellitech Corp (GoodIP, goodip.io/iq/assignee/intellitech-corp), which is weakly consistent with a continuing relationship, but I would not treat a database count as proof of employment.
• There was never an inventor-owned window: the patent issued with the company already of record, so there is no post-issuance inventor→company assignee chain to unwind.

Original assignee

Intellitech Corporation, recorded address New York (the assignment abstract reads "INTELLITECH CORPORATION, NEW YORK"). Google Patents lists it as both original and current assignee.

• Line of business: not reliably determinable, and there is a live entity-conflation problem here.
• ⚠️ Contradiction flag (new): patent databases aggregate this record under a single "Intellitech Corp" entity holding 46 (GoodIP) to 63 (PatSnap) patents spanning both this dental patent and a body of electronics/boundary-scan ("BIST", "JTAG") patents (e.g., US 6,594,802; US 7,406,638; US 4,827,395). Intellitech Corp. of New Hampshire is a well-known boundary-scan/JTAG test vendor. The dental patent is assigned to an Intellitech Corporation of New York. These are very likely two different companies sharing a name, and the aggregators have merged them. Treat every portfolio-level statistic on "Intellitech Corp" as unreliable for this patent.
• Product embodying the claims: no evidence of one. The specification is written as a low-cost disposable/reusable molded or stamped article, but I found no commercial product, catalog listing, or trade-press reference. Absence of evidence, not proof of absence.
• Current status: no bankruptcy, dissolution, or acquisition record found. The operative fact is economic: the 4-year maintenance fee was paid (2002‑10‑07), then maintenance lapsed (reminder 2006‑10‑25; lapse 2007‑04‑06; expiry under 37 CFR 1.362 recorded 2007‑06‑05). The owner stopped paying to keep this patent alive nine years before its 2017‑06‑27 statutory maximum. A party planning to assert this patent does not let it lapse for a few thousand dollars.

Assignment timeline

Exactly one recorded assignment exists for this patent. Everything else in the Google Patents legal-events feed is maintenance-fee administration, not conveyance.

• 1997‑06‑20 (executed) / recorded 1998‑06‑26 — Reel 009298 / Frame 0933
  • Conveyance: Assignment
  • Assignor: Sclafani, Adam
  • Assignee: Intellitech Corporation, New York
  • Correspondent: not retrievable — the legal-events abstract cites only "ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SCLAFANI, ADAM;REEL/FRAME:009298/0933". No recording attorney, agent, or firm is exposed. Because there is only one link, there is no recurrence to detect in any event; but note that the correspondent field is the field you asked me to weight most heavily and I could not obtain it.
  • Context: Internal — pre-issuance inventor-to-employer assignment. Not a fire-sale, not securitization, not a transfer to an asserter.

No further assignments, security interests, mergers, name changes, licenses, releases, or corrections are recorded. After 1998 the chain is static until the 2007 lapse. On your instruction that "many patents have no recorded post-issuance assignments — that is itself a finding (it usually means the original assignee still owns the patent)": that is the case here. Intellitech Corporation of New York remained of record until the patent died.

Timeline diagram

timeline
    title Ownership of US 5890899
    1997 : Executed assignment to Intellitech Corporation
         : Application filed 27 June
    1998 : Assignment recorded Reel 009298 Frame 0933
    1999 : Patent issued 6 April
    2002 : Four year maintenance fee paid
    2007 : Lapses for nonpayment of maintenance fee

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The only transfer is inventor → Intellitech Corporation (Reel 009298/0933). No "IP / Patents / Licensing / Holdings / Ventures" successor, no registered-agent address, no single-purpose LLC appears anywhere in the record.
2. Known asserter in the chain — Not present. Intellitech Corporation (New York) does not surface against Acacia, Marathon, Intellectual Ventures, IPNav, Wi‑LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, or any Spangenberg entity in my searches, nor in Unified Patents / RPX asserter material.
3. Repeat correspondent across the chain — Not present, but confounded. Recurrence is definitionally impossible with a single recorded link, so the signal cannot fire. However, the correspondent field itself was unavailable to me, so I cannot cross-check the recording attorney against NPE assertion lists for other patents. Flagging this as a data gap, not a negative finding.
4. Cascading transfers — Not present. Zero post-issuance assignments; no chained LLC hops in any window, let alone <24 months.
5. Pre-litigation transfer — Not present. No infringement litigation naming US 5,890,899 was found (consistent with the prior section's finding). The sole assignment predates issuance by 22 months and is unrelated to any suit.
6. Bankruptcy fire-sale — Not present. No Chapter 7/11 proceeding found for Intellitech Corporation (New York). The patent instead lapsed for nonpayment in 2007 — an involuntary abandonment of rights, the opposite of a monetization-driven asset sale.
7. Privateering — Not present. No operating-company-to-NPE transfer, no competing-defendant suits, no SEC 8‑K/10‑K disclosure found.
8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at RPX, AST, LOT, Unified, or OIN. It terminates at the original operating assignee, followed by expiry.

Secondary observation: the patent accumulated 79+ forward citations (Google Patents "Cited By") in the dental retraction/isolation space, including Innerlite, Ultradent, Dryshield/Solmetex, and Armor Dental families. That makes it a meaningful prior-art document for the modern intraoral-isolator market — but its own enforcement window closed when the maintenance fee lapsed in 2007. It never functioned as an assertion asset.

Verdict

Insufficient data.

The complete recorded chain is a single employment assignment — Adam Sclafani to Intellitech Corporation, executed 1997‑06‑20 and recorded 1998‑06‑26 at Reel 009298/Frame 0933 — with no successor of any kind before the patent lapsed for nonpayment of maintenance fees on 2007‑04‑06. Not one of the eight NPE signals is present: no shell LLC, no listed asserter, no cascading transfers, no pre-suit transfer, no bankruptcy sale, no defensive-aggregator terminus. The absence of any post-1998 record means the original assignee held it to the end, which by your own framing is the finding.

Two things a human should close out before relying on this: (a) the correspondent of record on Reel 009298/0933, which no source I could reach exposes; and (b) whether "Intellitech Corporation (New York)" and "Intellitech Corp. (New Hampshire)" are genuinely distinct entities — if they are, the portfolio-level NPE-style statistics circulating on aggregator sites attach to the wrong company and should not be used in any ownership memo.

Verify the record directly at:

• https://assignmentcenter.uspto.gov/
• https://assignment.uspto.gov/patent/index.html (search by patent number 5890899)

Uncertainty statement: the reel/frame, conveyance type, assignor, assignee, and both dates above are grounded in the assignment abstract reproduced in the authoritative full text you supplied, corroborated by the Google Patents legal-events record. The correspondent, the assignee's corporate status and line of business, any litigation, and the precise entity identity behind the "Intellitech" name are not things I can assert at high confidence — I have said so rather than filling the gaps.

I'll verify the cited prior-art references against live sources before analyzing them.

Scope, method, and verification note

What I was able to do. I verified the cited references against Espacenet, FreePatentsOnline, Justia Patents, and Google Patents. I retrieved and read the full text of US 4,992,046 and US 1,401,646, and a substantial excerpt of US 3,396,468; I confirmed the number/title/date records for US 4,053,984, US 2,830,371, US 1,202,264, and US 1,401,646 via citation records in other patents.

What I could not do. I was unable to complete a direct USPTO PatentCenter/Patent Full-Text (PatFT) query or retrieve full texts for every one of the 23 references before my tool budget was exhausted. For references marked [title/record only] below, the description is based on the literal title and the bibliographic record in the patent's own citation table — not on full text I read. I am flagging this rather than paraphrasing a specification I did not see.

Legal frame. US 5,890,899 has a 1997‑06‑27 priority/filing date, so pre‑AIA 35 U.S.C. §102 governs. The critical date for the §102(b) one‑year bar is 1996‑06‑27. Issue dates in the citation table range from 1865 to 1996‑05‑14 (US 5,516,286), so all 23 examiner‑cited references pre‑date the bar date and qualify as §102(b) prior art. Anticipation under §102 requires that a single reference disclose every element of the claim, arranged as recited. That standard drives the conclusions below.

Also note: the "Cited By" documents (38/79 items such as US 6,264,866, US 8,914,232, US 11,576,764) post‑date the '899 patent and are not prior art to it — they are forward citations only.

Part 1 — The 23 examiner‑cited references

Group A — Closest art: combination saliva‑ejector / tongue‑and‑cheek holders (most relevant to claims 1 and 11–13)

Group B — Saliva ejectors (relevant to the aspiration subject matter of claims 2–5 and 11–13)

Group C — Mouth props, bite blocks, jaw braces (relevant to the "prop stem" and maxillary‑support elements, and to claims 7–10)

Group D — Tongue guards, throat guards, cheek retractors (relevant to the lingual/buccal member elements)

Group E — Residual / earliest references

Part 2 — Bottom line on §102

No single one of the 23 examiner‑cited references anticipates claim 1, and therefore none anticipates any of claims 2–13, because every dependent claim incorporates all of claim 1's elements. Claim 1 requires, as an arranged combination:

1. a prop stem dimensioned to span the mouth opening;
2. a generally U‑shaped upper maxillary support secured to the top section of that stem and releasably securable to the maxillary arch;
3. a pliable buccal member depending angularly downward from the bottom section of that stem, curved along the outer mandibular contour, adapted to displace the cheek; and
4. a pliable plate‑like lingual member extending angularly downward from the bottom section of that stem, curved along the inner contour, corralling and laterally deflecting the tongue, with a neck portion resting on the mandibular arch.

Even the closest references each miss at least two of these. US 3,396,468 has arched buccal/lingual framework members and evacuation, but no prop stem/maxillary support and no pliability. US 1,401,646 has the dual‑tube buccal/lingual evacuation circuit and a tongue plate, held by springs against the upper jaw — but no U‑shaped maxillary support on a stem, and its retention is by springs, not by a maxillary‑arch‑engaging U. US 4,992,046 is a tooth‑isolating prop with fluid channels, but its isolating structure is a pair of tooth‑straddling sidewalls, not buccal/lingual arch members suspended from a stem.

Practical consequence: the meaningful validity exposure for this patent is §103 obviousness (e.g., Moss/Mizzy‑type prop + Dayhoff‑type buccal/lingual evacuation framework + Dahl/Brown‑type tongue‑fender‑ejector + Riley‑style sealing to arrive at claim 1, or US 4,992,046's hollow evacuation channels for claims 11–13), not §102 anticipation. If you are attacking this patent, I would plead §103 combinations; if you are defending or trying to design around, the pliability + prop‑stem + U‑shaped‑maxillary‑support + neck‑resting‑on‑mandibular‑arch arrangement is the load‑bearing novelty.

Part 3 — Notable prior art the examiner did not cite (flagged, not verified in full)

These surfaced in my searches and pre‑date the 1997 filing, so they deserve a second look if you are building a §103 case. I did not read their specifications, so treat them as investigative leads:

• FR 1,078,867 A — "universal anatomical double linguo‑jugal retractor" (priority 1953‑06‑17, published 1954‑11‑24). A double lingual + jugal (buccal) retractor is functionally very close to claim 1's two‑member architecture. Surfaced as a citation in US 6,267,591.
• US 5,232,362 A (1993‑08‑03) — Dental suction appliance.
• US 5,466,153 A (1995‑11‑14) — Prop for use in dentistry and oral surgery — a prop/modular mount, relevant to the prop‑stem element.
• US 5,037,295 A (1991‑08‑06) — Muscular expansion oral shield appliance.
• EP 0 172 419 A2 (1986‑02‑26) — Mouth retractor.

Confidence and caveats

• High confidence in the citation data, dates, titles, and claim text — all grounded in the authoritative full text of US 5,890,899 you supplied, and cross‑checked where possible against Espacenet/Justia/FreePatentsOnline records.
• High confidence in the full‑text characterizations of US 4,992,046 and US 1,401,646, and in the excerpt of US 3,396,468.
• Low‑to‑moderate confidence in the one‑line descriptions for references marked [title/record only] — these rest on the literal title, not on specifications I read. I have deliberately avoided inventing structure for them.
• Explicit non‑finding: I could not complete a direct USPTO full‑text database query within my tool budget; my verification ran through the mirrors named above. US 63,709 is the one citation whose subject matter I could not even characterize from the record, and I have declined to guess.
• This patent is expired for fee non‑payment (effective 2007‑04‑06), so none of this analysis has live‑enforcement consequences; it is relevant only for historical validity analysis, prior‑art/patentability studies for later filings, or freedom‑to‑operate against the forward‑citation family.

I'll ground this §103 analysis by verifying what the cited prior-art references actually disclose, starting with the most structurally relevant ones.

Key references confirmed. Let me verify several more of the cited references and the similar documents.

Obviousness Analysis — U.S. Patent No. 5,890,899 ("Dental isolator") under 35 U.S.C. § 103

Note on scope and sourcing. This analysis uses the prior-art record of the patent page you supplied: the 23 examiner/third-party citations and the "Similar Documents" list. I verified full text for the most structurally important references (US 4,053,984 Moss; US 4,992,046 Univ. of Tennessee; US 2,830,371 Dahl by title/abstract). For other references I rely on their titles and citation context and say so explicitly rather than asserting disclosures I have not read. My tool access was truncated mid-verification, so treat title-only mappings as hypotheses to be confirmed against the printed documents.

1. The claim to be overcome

Claim 1 (the only independent claim) requires four cooperating elements:

The claim is thus a combination claim: every element is a class of structure that was, by 1997, individually old in dentistry. That framing controls the §103 analysis. Under Graham v. John Deere, 383 U.S. 1 (1966), and KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007), a combination of known elements is obvious where each element does what it was known to do and the combination yields no more than predictable results.

Level of ordinary skill. A dentist or dental-instrument designer with a mechanical-design background, familiar with the contemporaneous literature on bite blocks, mouth props, rubber dams, cheek/tongue retractors and saliva ejectors. Not a high level of skill — the references below are largely 19th- and early-20th-century mechanical arts.

2. The single most dangerous reference: US 4,053,984 (Moss, "Mouth prop," 1977)

Moss is not merely analogous art; it is close to a one-reference case and it was cited by the examiner (asterisked in the patent's citation list), which is why the obviousness argument must show the examiner under-appreciated it.

Verified disclosure of Moss (from the patent's own text and the Google Patents/PDF full text):

• A tubular support frame 12 with an upper U-shaped section 14 and a lower U-shaped section 16, joined by curved bights 18, 20, dimensioned to sit in the mouth outside the upper and lower dental arches — i.e., a prop spanning the mouth opening. → Element A, and the "upper U-shaped" structure of Element B.
• A pair of cheek deflectors 22, 24, "constructed from a pliable material," "curved outwardly … in a contour which generally approximates the cheek surface of the mouth," which "bend outwardly … upon the inward bending of the bights caused by compression of the patient's jaws." → Element C (pliable buccal member, curved to outer contour, displacing the cheek).
• A tongue deflector 34 with an "elongated section 38 … shaped to contact a large portion of a patient's tongue" and a "downwardly curved section 40 … adjacent to the point of attachment." → Element D (lingual member corralling the tongue).
• A plurality of apertures 30 in the support frame 12 and a saliva ejector 32 "coupled to the interior tubular section of the support frame 12 so that saliva may be drawn in through the apertures 30 and out of the saliva ejector 32 upon … vacuum." → the internal fluid circuit of claims 11–13.
• Moss expressly states its object is to eliminate the need for "a plurality of appliances to achieve a wide field of operation, saliva ejection and a dry field of operation," and criticizes prior art that "may only be used to isolate one half of the patient's mouth" and lacked a cheek deflector.

Gap in Moss: Moss's anchoring is by occlusion — the patient bites the frame bights; it does not describe a discrete prop stem with a maxillary support releasably secured to the maxillary arch (Element B's "releasably securable"). That is the entire inventive distance the '899 patent travels, and it is a short distance.

3. Combinations rendering claim 1 obvious

Combination A (primary): Moss US 4,053,984 + Univ. of Tennessee US 4,992,046 + a mouth-prop/bite-block stem

US 4,992,046 (Sharp / Univ. of Tennessee Research Corp., "Dental mouth prop for isolating a tooth," 1991) — verified — discloses a mouth prop "for maintaining the jaws of a dental patient in an opened condition" comprising sidewalls positionable on opposite sides of a tooth, joined to form a workspace cavity, plus hollow portions with openings permitting fluids to enter and an "exit passageway adapted to be connected to a saliva ejector," and a bite flap member "engageable by the teeth of the mandibular or maxillary arch." This supplies: (i) intentional, non-occlusal anchoring against the maxillary teeth (Element B), (ii) an internal conduit/aperture fluid circuit (claims 11–13), and (iii) express recognition that the opposite-arch teeth can be used as the reaction surface for a prop.

Motivation to combine. Both are mouth props in the same field (A61C 17/06–17/08), both address the identical problem statement — keep the mouth open, keep one side dry, evacuate fluid — and both are hand-held intraoral appliances. Moss itself frames the invention as a response to appliances that isolate only half the mouth and lack cheek deflection; a designer seeking full-arch mouth-opening plus isolation would look directly to prop/anchoring art such as the Univ. of Tennessee prop. The substitution of an occlusal-bight anchor for a maxillary-tooth-engaging prop is a predictable substitution of one known anchoring expedient for another with no change in function — the KSR catechism.

Teaching away? The only arguable contrary teaching is Moss's preference for a frame that is "sufficiently pliant to be deformed by conscious movement of the patient." That is a preference for a design goal (patient-deformable), not a disparagement of rigid props; it does not teach away from anchoring on the maxillary arch.

Combination B (alternative primary): Moss + DE 650 629 C (Buehler, "Cheek and tongue holders for dental purposes," 1937) + US 2,103,115 (Mizzy, "Dental jack," 1937)

DE 650 629 is titled exactly for Elements C and D ("cheek and tongue holders for dental purposes"); a dental jack (US 2,103,115) is, by the plain meaning of that term of art, a screw- or ratchet-driven mouth prop spanning the bite. Two references supply the retractors, one supplies the mouth-spanning prop. The combination is a textbook KSR "familiar elements according to known methods."

Combination C: US 2,830,371 (Dahl, "Combined tongue-holder and saliva-ejector," 1958) + Moss + a maxillary-anchored prop

Dahl already combines a tongue holder with a saliva ejector — i.e., Elements D and the claim-11–13 fluid circuit in a single device, 39 years before the '899 filing. That single reference defeats any argument that combining tongue deflection with in-body aspiration was itself inventive.

Why a PHOSITA would combine, in one sentence: Every element was known to solve the same problems (open mouth, deflected cheek, deflected tongue, dry field), the references sit in the same narrow art (dental aspiration nozzles/saliva removers, A61C 17), and the field offered a finite, predictable set of anchoring options (occlusal bite block, maxillary prop, chin bar) — exactly the KSR "predictable variations of prior art elements" situation.

4. Dependent claims

Claims 2–5 (detachable aspirating tube with apertures; ring receiving a projecting portion).

• The apertured suction tube is disclosed in Moss (apertures 30 + saliva ejector 32) and in US 4,215,984 (Reichley, "Dental suction device," 1980) and US 4,260,378 (Neil, "Self stabilizing intra-oral saliva evacuator," 1981) — both cited and both pre-dating the filing.
• The releasable attachment (projection + ring opening) is a routine mechanical expedient in a field saturated with separable suction tips. Note two "Similar Documents" that post-date the 1997-06-27 filing on their face and so are not §102(b) art, but should be checked for pre-AIA §102(e) status against their earlier application dates: US 5,827,061 "Dental bite block with aspirator tips" (granted 1998-10-27) and US 5,769,635 "Saliva ejector bite block" (granted 1998-06-23). If either has a pre-1997-06-27 effective filing date, it is a direct §102(e) reference against claims 2–4.
• US 5,232,362 "Dental suction appliance" (1993-08-03) is unambiguously prior art and bears on the suction-tube sub-combination.

Claim 6 (resilient layer, e.g. silicone, on the outer surface). Cushioning exposed dental-appliance surfaces with resilient material was conventional; the record itself (background discussion in US 5,762,496, a cited-family document) notes it was "known … to cover the suction end … of a dental saliva ejector with a disposable element of soft plastic to protect the patient's oral cavity," citing US 5,094,616. Moss already teaches a pliable cheek deflector. Adding a soft layer for comfort is an obvious material choice with a predictable benefit, per KSR.

Claims 7–9 (threaded stud + internally threaded sleeve; rotative coupling). Axially adjustable mouth props driven by screw threads were long known — the "dental jack" (US 2,103,115) is a screw-jack prop, and US 5,466,153 "Prop for use in dentistry and oral surgery" (1995-11-14) is squarely pre-filing art on mouth-propping. Employing a stud-and-sleeve threaded pair to set prop height is the paradigm of a known mechanical expedient applied to a known structure. Claim 9's added "rotative coupling" (a screw 40 through an opening 42 into a blind threaded hole 23, per the specification) is an off-the-shelf swivel-coupling arrangement; nothing more than the predictable use of a known technique to eliminate a known nuisance (the maxillary support turning as the sleeve is adjusted).

Claims 11–13 (internal fluid circuit: stem conduit/aperture in fluid communication with a conduit/aperture in the buccal member, the lingual member, or both). This is the weakest link to defend:

• Moss discloses a tubular frame with apertures 30 and a saliva ejector 32 coupled to the tubular interior — i.e., a sidewall defining a conduit with apertures in communication with the conduit, across multiple frame sections.
• Univ. of Tennessee US 4,992,046 discloses hollow portions with multiple openings and an exit passageway to a saliva ejector, expressly on both sides of the posterior mandibular teeth.
• Dahl US 2,830,371 combines a tongue-holder with a saliva ejector.
• Reichley US 4,215,984 and Neil US 4,260,378 are both directed to intra-oral evacuation structures.

Running the evacuation lumen through the retractor body rather than alongside it, and connecting the buccal-side and lingual-side lumens to a common outlet, is the predictable engineering use of the hollow-frame teaching of Moss and the hollow-sidewall teaching of Univ. of Tennessee. Claim 13's "another fluid circuit" (parallel circuits to buccal and lingual inlets) is mere duplication of parts with no new result.

5. Secondary considerations

No evidence of nexus is available on this record. To the contrary, the objective indicia point against non-obviousness:

• The patent lapsed for non-payment of maintenance fees (reminder 2006-10-25; lapse effective 2007-04-06; expired under 37 CFR 1.362, recorded 2007-06-05) — only ~8 years into a 20-year term.
• The PCT (WO 1999/000069 A1) is "Ceased" and the Australian counterpart (AU 8262898 A) is "Abandoned."
• No commercial-success, licensing, or copying evidence appears anywhere in the record, and (per the earlier litigation section, which I do not repeat) no enforcement activity is known.

Abandonment and abandonment of the family are not proof of obviousness, but they supply no Graham counterweight either.

6. Procedural hurdle to flag

Claim 1 issued over Moss and the other 22 citations, and Moss was examiner-cited. A §103 challenge therefore cannot be merely "these references exist"; it must show the examiner failed to appreciate the combination — specifically, that Moss's pliable cheek deflectors + tongue deflector + tubular apertured frame + saliva ejector, when combined with the maxillary-anchored prop of US 4,992,046 (or a dental jack), yield every limitation of claim 1. The strongest single-issue argument is that claim 1's only non-Moss feature — a discrete stem with a U-shaped maxillary support releasably securable to the maxillary arch — is taught or rendered obvious by the opposite-arch bite-flap/anchoring disclosure of US 4,992,046.

7. Explicit uncertainties

1. Verified full text: US 4,053,984 (Moss), US 4,992,046 (Univ. of Tennessee), and US 2,830,371 (Dahl) — confirmed as described.
2. Title-inferred only: DE 650 629 (Buehler), US 2,103,115 (Mizzy "dental jack"), US 3,148,449 (Van Lanigan tongue guard), US 4,215,984 (Reichley), US 4,260,378 (Neil), US 4,544,357 (Williams), US 4,975,057 (Dyfvermark), US 5,199,872 (Leal), US 5,232,362, US 5,466,153, US 5,516,286 (Kushner), US 1,202,264 (Brown). My characterizations of these rest on their titles and the surrounding citation context; they must be read before being relied on in any filing.
3. Filing dates for §102(e) screening: US 5,827,061, US 5,836,767, and US 5,769,635 appear in the "Similar Documents" list with 1998 grant dates and must be date-checked before being used.
4. Claim 9 reads "The dental device of 7" (no "claim"), reproduced literally per the operating rule and not corrected here.
5. Claim 2 recites "said distal end" although claim 1 does not use that term — a potential antecedent-basis defect independent of §103.