US 5516286

Summary — US Patent 5,516,286

Note on sourcing: The patent's full authoritative text was provided in the prompt (fetched from Google Patents on 2026-09-07), and a web search returned the USPTO-published patent-image PDF (patentimages.storage.googleapis.com US5516286) whose claims text matches that source. No CAFC (Federal Circuit) 2026 docket entries referencing patent number 5516286 were found in either search; one search returned an unrelated PTAB/IPR document about a different dental-isolation mouthpiece patent, which I am disregarding per your instruction not to return similar-number results. I have no authoritative indication that this patent was involved in CAFC litigation in 2026.

Bibliographic data

• Title: Dental isolation tray particularly suited for use when applying dental sealants and method for its use
• Patent number: US 5,516,286 A (application no. 08/243,173)
• Inventor: Philip Kushner
• Original/current assignee: Individual (listed on Google Patents as "Individual"; original assignee field likewise "Individual"). No corporate assignee is shown.
• Filing date: May 16, 1994
• Issue (publication) date: May 14, 1996
• Legal status: Expired – Lifetime (maintenance fees paid through the 12th year; anticipated expiration listed as 2014-05-16)
• Family: Also published as WO 1995/031151 A1, EP 0906067 A1, AU 25153/95 A (all now inactive/abandoned/withdrawn)

Abstract

A dental isolation tray has an outer side wall, an inner side wall, and a roof joining the inner and outer side walls. An aspiration conduit having spaced-apart aspiration ports is molded into the peripheral edges of the side walls and into the interface between the interior side wall and the roof. An aspiration coupling fluidly connects the conduit with a suction tube. A portion of the roof and outer side wall is pre-cut to expose the occlusal and buccal aspects of preselected teeth. An adjustable bite block is mounted on or adjacent to the roof and extends substantially perpendicular to it. Full-arch (one or two quadrant cut-outs), half-arch/quadrant, and upper-arch variants are described. The tray is dimensioned with generous spacing between the side walls and teeth so the lingual aspect of exposed teeth is accessible while still isolated from the tongue.

Independent claims (plain-language overview)

There are 25 claims; the independent claims are 1, 11, 12, 15, 20, 21, 22, 23, 24, and 25.

• Claim 1 — A dental isolation tray for use with a single arch: an inner side wall, outer side wall, and joining roof; a fluid conduit along a peripheral portion of one side wall with multiple fluid ports and a coupling for an aspiration hose; a cut-away-capable portion of roof and adjacent side wall to expose part of the arch; dimensioned to fit over an upper/lower arch or quadrant with teeth substantially covered while maintaining unfilled space between teeth and sidewalls so water/air spray is deflected into that space for aspiration; and a bite block extending substantially orthogonal to the roof, engageable with the opposite arch to keep the mouth open.
• Claim 11 — A method of use: (a) removing a portion of the outer side wall and adjacent roof; (b) attaching an aspiration hose; (c) placing the tray over a single arch so some teeth are covered and at least one tooth is exposed while retaining the unfilled-space deflection feature; (d) positioning the bite block so the patient bites to stabilize the tray; (e) performing a dental procedure on the exposed tooth; (f) removing the tray.
• Claim 12 — A method specifically for applying sealant: same steps as claim 11 through tray placement and bite-down, then (e) activating vacuum, (f) applying acid etchant to all surfaces of the exposed tooth, (g) washing off the etchant, (h) air-drying, (i) applying dental sealant, (j) letting it cure, (k) removing the tray.
• Claim 15 — A broader tray claim (no explicit unfilled-space/deflection limitation): inner/outer side walls, roof, fluid conduit with ports and coupling, and a substantially orthogonal bite block; cut-away-capable roof/side-wall portion; dimensioned so teeth are substantially covered and the tray is stabilized by the bite block.
• Claim 20 — A tray claim without a bite block: inner/outer side walls, roof, and a fluid conduit extending along a peripheral portion of one side wall and along the interface between the inner side wall and the roof, with ports and a coupling; cut-away-capable portion; dimensioned to fit comfortably with unfilled space maintained between the teeth and the inner side wall.
• Claim 21 — Combines the tray structure of claim 1's type with a specific bite block: substantially L-shaped member having a flat biting surface and contiguous stem received in a hub adjacent one of the side walls; unfilled-space deflection limitation included.
• Claim 22 — Tray with a different bite block: a removable bite block having an upper biting surface and a lower roof-engaging slot; unfilled-space limitation included (recited as space between teeth and inner side wall).
• Claim 23 — Tray with an upper-arch adaptation: posterior end portions of the side walls extended in height, and posterior roof portions angled so that when placed over the upper arch the angled portions are substantially parallel to the lower arch; unfilled-space limitation included.
• Claim 24 — Tray with hub-mounted L-shaped bite block (similar to claim 21 but without the unfilled-space/deflection clause; stabilization by the bite block recited).
• Claim 25 — Tray with the removable slot-mounted bite block (similar to claim 22 but without the unfilled-space/deflection clause; stabilization by the bite block recited).

Uncertainty flags

• CAFC 2026 docket: Searches returned no results tying 5516286 to any 2026 CAFC docket. I cannot confirm whether any such proceeding exists; absence of results is not definitive proof of absence.
• Assignee: Google Patents lists the assignee as "Individual," which may simply mean no recorded assignment to a corporate entity. I did not independently verify USPTO Assignment records.
• Exact claim grouping (which claims are independent vs. dependent) is my analysis of the claim text: claims 2–10, 13–14, and 16–19 read as dependent. Claims 20–25 each recite a full, self-contained combination and do not reference another claim, so I treat them as independent — though several are narrow variations of claims 1 and 15.

Based on my searches, I found no known litigation involving US Patent No. 5,516,286 ("Dental isolation tray particularly suited for use when applying dental sealants and method for its use").

Search results summary

I ran multiple targeted searches for this patent number and its subject matter:

• Searches for the literal patent number ("5516286") and its formatted version ("5,516,286") in connection with "litigation," "lawsuit," and patent-litigation portals returned no responsive results — the only hit returned was an unrelated case (Baseball Quick, LLC v. MLB Advanced Media) that merely discussed a different patent number (7,628,716) in a declaration.
• Searches combining the inventor's name (Philip Kushner) with the dental isolation tray subject matter also returned no litigation results.

Conclusion

To my knowledge — and based on these searches — there is no publicly known district-court litigation, CAFC appeal, or PTAB proceeding specifically involving US Patent 5,516,286. I am not aware of any plaintiff/defendant, case number, filing date, or outcome tied to this patent.

Cautions / caveats

• Patent-litigation records are not always indexed by patent number in general web search, and older cases (the patent is from 1994) may predate full-text PACER/electronic docket availability. My searches may not be exhaustive.
• The patent's own legal-status history (per Google Patents) shows it was maintained through fee payments until at least 2008 (12th-year fee) and reached its anticipated expiration on 2014-05-16, with status "Expired - Lifetime." An expired patent could still appear in litigation over past damages, but I found none.
• If you want a definitive check, the authoritative sources to query directly would be:
  • PACER (federal dockets) — nationwide case-name/number search
  • USPTO Patent Center / Assignment & Litigation searches
  • Unified Patents portal (https://portal.unifiedpatents.com/litigation/caselist)
  • Docket Navigator / RPX / LexisNexis PatentAdvisor (subscription databases)

I cannot state with absolute certainty that no litigation ever existed, but I found no evidence of any for US Patent 5,516,286.

Proceedings overview

The USPTO Open Data Portal lists zero AIA trial proceedings (IPR/PGR/CBM) for US 5516286, and independent web searches surfaced no older or recently-filed PTAB petitions, no PTAB Final Written Decisions, and no Federal Circuit appeals citing this patent number. Breakdown: 0 active · 0 claims invalidated · 0 claims sustained via IPR · 0 settled · 0 institution denied. Defensive posture: there is no PTAB history on file — a defendant facing assertion cannot lean on any prior IPR victory, but also faces no estoppel from prior proceedings against this patent.

No proceedings identified

• Type: N/A
• Filed: N/A
• Status: None — no AIA trial proceeding (IPR, PGR, or CBM) has been filed against US 5516286 according to the USPTO ODP ingest, and web searches (including PTAB-focused queries and site-restricted searches of ptab.uspto.gov) returned no matching proceeding numbers.
• Judge panel: N/A
• Petition grounds: N/A
• Institution decision: N/A
• Final Written Decision: N/A
• Settlement / termination: N/A
• Appeal: N/A
• Defensive value: Zero PTAB mileage exists. I will not invent proceeding numbers, panels, or outcomes — none are public.

Strategic summary

Claim-level status. Because no AIA trial has ever been instituted on US 5516286, all 25 claims (1–25) remain exactly as granted on 1996-05-14 — none are canceled, none have been "sustained" through a PTAB merits decision, and none have been tested. The claims that a demand letter would most plausibly cite (independent claims 1, 15, and the method claim 12, plus apparatus claims 20–25) have never been the subject of a PTAB ground. The patent expired from its original term — Google Patents' legal-status timeline shows an anticipated expiration of 2014-05-16 and an "Expired - Lifetime" status, with maintenance fees paid through the 12th year (2008). Note, however, that pre-AIA term extensions/adjustments or terminal-disclaimer issues are not reflected in that data; if the patent is being asserted today, confirm the actual expiration date rather than assuming it is dead.

Estoppel landscape. With no prior petitioner, § 315(e)(2) estoppel is a non-issue — no defendant is barred from raising any ground, and no prior petitioner's privies are locked out. Every § 102/§ 103 ground over the prior art cited during prosecution (e.g., Swan-Gett U.S. Pat. No. 3,772,790; Thompson U.S. Pat. No. 2,637,107; the saliva-ejector patents U.S. Pat. Nos. 2,701,916, 2,873,528, 3,049,806; and the others of record) and any newly located art remains fully available for an IPR petition or district-court invalidity defense. One structural caveat: because the patent is expired (or very near expiration), an IPR may be time-barred or of limited practical value — PTAB discretion and the lack of forward-looking injunctive relief against an expired patent can make district court § 282/§ 103 defenses the more practical path.

Pattern signals. There is no pattern to read: no repeat petitioner, no defensive-aggregator chain (no Unified Patents or similar entity appears in the assignment or proceeding history), and no patent-owner PTAB appellate behavior to evaluate. The only related litigation-adjacent data point is that the same inventor (Philip Kushner) later filed US 2008/0009313 / US 8,376,742 ("Dental tray"), which was cited in later art — but that is a different patent and is not before us. The absence of PTAB activity on a 1990s-era dental device patent is unsurprising: the patent is old, the technology niche is narrow, and the commercial value that typically attracts IPR petitions was likely never high.

Recommended next steps

1. Treat PTAB as a dead end unless new facts emerge. Say plainly: no IPR/PGR/CBM has ever been filed on US 5516286. Before investing in an IPR, verify the patent's current expiration/status at USPTO Patent Center and PAIR — an expired patent generally cannot support prospective relief, and the PTAB may exercise discretion against review where the patent is expired and no stay value exists.
2. If you are the defendant in a live demand or suit, focus on: (a) confirming the patent's enforceable life and whether any term extension applies; (b) building a district-court § 103/§ 102 defense over the Swan-Gett '790 shield and the 1950s-era dental evacuation trays cited on the face of the patent (U.S. Pat. Nos. 2,637,107, 2,701,916, 2,873,528, 3,049,806) — all of which are unencumbered by estoppel; and (c) evaluating claim-scope arguments (the "maintaining unfilled space" and "bite block extending substantially orthogonal to the roof" limitations of claims 1, 15, and 20–25).
3. Monitor the ODP feed and PTAB E2E for any late-filed petition. Given the 1994 priority date and expired status, a newly filed IPR is unlikely, but if one appears, the institution decision would be due roughly 3 months after the petition's filing and a Final Written Decision within 12 months of institution.
4. Do not cite any FWD or CAFC disposition — none exists. Any adverse counsel or marketing material claiming "claims of 5,516,286 were canceled in IPR" is fabricating; the file history shows only maintenance-fee events through 2008 and the 2014 anticipated expiration.

Inventors

• Philip Kushner (listed in later-family filings as Philip Victor Kushner) — sole named inventor on US 5,516,286.
• Employer at the time of filing: not determinable from the patent record. The application (US 08/243,173, filed 1994-05-16) issued to the inventor personally, with no corporate assignee identified. Kushner remained active in the dental-isolation space long after filing — he filed a later dental-tray application in 2008 (US 2009/0009313 → US 8,376,742) — so the "all inventors depart within 12 months" pattern does not apply; there is only one inventor and no original corporate employer to depart from.

Original assignee

• Per Google Patents, the Original Assignee and Current Assignee are both listed as "Individual" — meaning the patent issued to inventor Philip Kushner personally, not to a company.
• No operating company shipped a product under this patent, because no operating company ever owned it. The patent record shows no corporate entity in the chain.
• Status: The patent was maintained through fee payments (4th-year fee 2000, 8th-year 2003, 12th-year 2008 per Google Patents legal events) and reached its anticipated expiration on 2014-05-16, with status "Expired - Lifetime." No acquisition, merger, or bankruptcy is recorded for the owner because the owner is a natural person.

Assignment timeline

I found no recorded assignments for US 5,516,286. Searches of general web indexes and the Google Patents legal-events feed surfaced zero assignment events — the legal-events history shows only grant (1996) and maintenance-fee entries (2000, 2003, 2008). Google Patents' "Current Assignee: Individual" also reflects no post-issuance transfer.

Caveat: I was not able to directly query the USPTO Assignment Center database (assignmentcenter.uspto.gov / assignment.uspto.gov) in this session, and general web search does not reliably index assignment records by patent number. It is possible that a recordation exists that my searches could not reach. However, the independent Google Patents legal-events feed, which typically mirrors recorded assignment events, shows none.

If the USPTO Assignment Center indeed has no records, that is itself a finding: the original owner — the individual inventor — most likely retained ownership for the life of the patent. There is no evidence of any transfer to a company, LLC, or assertion entity at any point between issuance (1996) and expiration (2014).

Timeline diagram

timeline
    title Ownership of US 5516286
    1994 : Filed by Philip Kushner
    1996 : Patent issued to inventor
    2000 : Maintenance fee paid
    2003 : Maintenance fee paid
    2008 : Maintenance fee paid
    2014 : Patent expired

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. No transfer of any kind is recorded; the patent never moved to an LLC, IP-holding company, or registered-agent address.
2. Known asserter in the chain — Not present. No Acacia, Marathon, IV, Wi-LAN, Mosaid, or any Unified Patents / RPX-listed plaintiff appears anywhere in the record because no corporate assignee appears at all.
3. Repeat correspondent across the chain — Not present / unclear. With no recorded assignments, there is no correspondent of record to analyze. (Note: because recordation is ministerial and my access was indirect, absence here is weaker evidence than a direct database query would provide.)
4. Cascading transfers — Not present. No chained assignments exist.
5. Pre-litigation transfer — Not present. Consistent with the prior litigation summary, there is no known infringement suit naming this patent, so no assignment timed to enable one.
6. Bankruptcy fire-sale — Not present. The sole owner is a natural person; no Chapter 7/11 proceedings are associated with the patent.
7. Privateering — Not present. No operating company ever held the patent to transfer it to an NPE.
8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN — it terminates at the inventor.

Verdict

Insufficient data (no records found, and what little record exists shows only the original inventor-owner chain).

The patent issued to the individual inventor with no corporate assignee, and no post-issuance assignment events appear in the Google Patents legal-events feed — consistent with inventor ownership for life and no assertion activity. However, I could not perform a direct query of the USPTO Patent Assignment Search database in this session, so I cannot certify with absolute certainty that no recordation exists. A definitive check can be run at the USPTO Assignment Center (https://assignmentcenter.uspto.gov/) by searching patent number 5516286; the absence of any hits there would confirm the "inventor retained ownership, no NPE involvement" conclusion above.

USPTO search confirmation — Patent 5516286

I searched the literal identifier 5516286 (and its USPTO-sourced Google Patents record). The only responsive result was the correct patent — US5516286A, "Dental isolation tray particularly suited for use when applying dental sealants and method for its use" (inventor Philip Kushner; application 08/243,173 filed 1994-05-16; issued 1996-05-14). No similar-number results (e.g., 7,628,716-type hits) were returned or included. The patent-image PDF at patentimages.storage.googleapis.com corroborates the claim text used below.

Legal framework note: Because the application was filed May 16, 1994, pre-AIA 35 U.S.C. § 102 governs. Every patent citation listed below issued before that filing date, so each is prior art under § 102. A reference "potentially anticipates" only if it discloses every limitation of the claim, arranged as in the claim; where I could not verify full disclosure of a given limitation from the record, I say so rather than overstate. These references were all cited by the USPTO examiner during prosecution (the "*" markers in the Google Patents citation list) and the claims nonetheless issued — so in the examiner's view none was a complete anticipation, and the realistic threat for most of these is § 103 obviousness in combination rather than single-reference § 102 anticipation.

The 12 patent citations, in the order they appear on the face of US5516286

1. US1498219A — Williams, "Mouth prop for dentists"

• Filed: 1922-12-22 | Published: 1924-06-17
• Description: An early dentist's mouth prop — a device to hold the patient's jaws apart during dental work. It is a bite-support/prop device only; it has no tray, side walls/roof, aspiration conduit, or tooth-isolating structure.
• § 102 potential: Cannot anticipate any tray claim (claims 1, 15, 20–25) because it lacks the tray structure, fluid conduit, and cut-out features. It is relevant only to the bare bite-block element (claim 1 element (e); claims 4–9, 16–19, 21–22, 24–25) and would at most support a § 103 combination — a "bite block extending substantially orthogonal to the roof" was not new per se.

2. US1986275A — Henry, "Combination anterior mouth support and saliva ejector"

• Filed: 1933-11-10 | Published: 1935-01-01
• Description: Combines an anterior bite/mouth support (jaw-prop function) with a saliva ejector/suction line in one appliance. This is one of the earliest references pairing (i) a mouth-open-maintaining bite support with (ii) aspiration — the two functional pillars of claims 1, 11, 12, and 15.
• § 102 potential: Likely does not fully anticipate the tray claims because it lacks an inner side wall/outer side wall/roof tray that covers the teeth, the cut-away-capable roof/side-wall portion, and the unfilled-space deflection geometry. It is most probative against the bite-block-plus-suction combination (claims 1, 15 and dependent claims 4–9, 16–19) and as § 103 groundwork for the method claims (11–12), which recite nothing more than bite-down stabilization plus aspiration during a procedure.

3. US2637107A — Thompson (inventor: Bert J. Daigle), "Dental isolation tray for use with air abrasive techniques"

• Filed: 1952-05-20 | Published: 1953-05-05 (USPTO patent image verified: "Patented May 5, 1953, 2,637,107")
• Description: The single most title-relevant reference: a "dental isolation tray." A hollow, substantially oval plastic body (main chamber 10) with an entrance opening for the tooth/teeth to be isolated, anatomically recessed grooves (15, 18) that receive the occlusal surfaces of the upper and lower sets of teeth, a lip groove, a suction passage (9) and neck (8) for attaching suction, and an opening (20/21) through which the treated tooth projects into the chamber. It is expressly stated to "provide a support for the mandible and maxilla when in place in the mouth" — i.e., the tray body itself functions as an inter-arch bite support, and it removes debris/aspirates via the suction passage.
• § 102 potential: This is the strongest structural antecedent for the tray + suction-chamber + tooth-access-opening + inter-arch support combination. It plausibly comes closest to claims 20 (tray body, fluid conduit with ports/coupling, cut-away/open portion exposing a tooth, dimensioned to cover the arch) and to claim 15's elements if the dual-occlusal-groove body is read as both a tray and an integrated bite block. However, it is a two-arch device (upper teeth seat in groove 15 and lower teeth in groove 18 simultaneously), whereas claims 1, 15, 20–25 each require a tray dimensioned to fit over one arch/quadrant while the opposite arch engages a separate bite block. It also lacks the claimed inner/outer side wall + roof geometry, the conduit-along-the-interface placement (claim 20), and the explicit unfilled-space/deflection spacing (claims 1, 20–23). I therefore rate it as a partial/§ 102(b)-close but not clean anticipation, and the most dangerous § 103 combination anchor against claims 15 and 20.

4. US2701916A — Jarboe, "Dental saliva ejector"

• Filed: 1953-10-13 | Published: 1955-02-15
• Description: A dental saliva ejector — a suction device for removing saliva from the oral cavity during dental procedures.
• § 102 potential: Cannot anticipate any full tray claim — no side walls/roof, no tooth-covering tray, no bite block, no cut-out. Relevant only to the generic fluid-conduit/coupling element (claims 1, 11, 12, 15, 20–25) in a § 103 combination. Aspiration conduits with ports and couplings were long known.

5. US2823455A — Sprague, "Dental instrument"

• Filed: 1956-04-24 | Published: 1958-02-18
• Description: A dental instrument (per the patentee's title). The record I have confirms only the bibliographic data and title; I did not retrieve the full text to confirm its operative disclosure. Based on its citation by the examiner alongside saliva-ejector and mouthpiece art, it is likely an evacuator/suction-type instrument, but I will not speculate further.
• § 102 potential: Cannot be assessed as a clean anticipator of the tray claims on the available record; at most it is background suction-art relevant to the fluid-conduit limitation. Flag: full-text review needed before any § 102/§ 103 position is taken.

6. US2873528A — Thompson (Elbert O.), "Mouthpiece assembly for dental suction evacuators"

• Filed: 1956-09-19 | Published: 1959-02-17
• Description: A mouthpiece for dental suction evacuators: a length of flexible, perforated tubing formed into an elongate loop with an adapter fitting for connection to a suction hose. The inventor's related reissue (USRE24693E, which surfaced in my search of this number) adds an optional jaw spacer and support — a platform member resiliently supported against the teeth of the opposite alveolar ridge to hold the jaws apart while dental work proceeds. That combination — perforated suction loop + a member bearing on the opposite arch to hold the mouth open — is structurally and functionally close to the "aspiration conduit + bite block" cooperation of claims 1, 11, 12, and 15.
• § 102 potential: Does not anticipate the tray claims because it lacks the tray (inner side wall/outer side wall/roof) that substantially covers the teeth, the cut-away roof/side-wall portion, and the unfilled-space deflection spacing. It is, however, strong § 103 evidence that the bite-block-engaging-the-opposite-arch + integrated suction combination (claims 1, 15, 21–22, 24–25; method claims 11–12) was old.

7. US3049806A — Cofresi (Rafael), "Multiple saliva ejector"

• Filed: 1959-10-09 | Published: 1962-08-21
• Description: A saliva ejector with multiple intake ports — i.e., a suction manifold for the mouth.
• § 102 potential: Cannot anticipate the tray claims (no tray, no bite block, no cut-out). Relevant only to the "plurality of fluid ports" limitation common to all tray claims — i.e., a § 103 combination at best. Multi-port aspirating conduits were old.

8. US3396468A — Dayhoff, "Dental appliance"

• Filed: 1966-05-18 | Published: 1968-08-13
• Description: A dental appliance (per the title). I did not retrieve the full text; based on its grouping in the citation list with ejector/mouthpiece references, it appears to be suction/isolation-related dental art. Flag: full-text review needed.
• § 102 potential: Not assessable as a clean anticipator on the available record.

9. US3772790A — Swan (Swan-Gett), "Tooth isolating shield" — the closest cited reference

• Filed: 1971-08-09 | Published: 1973-11-20 (USPTO patent-image PDF verified)
• Description: This is the reference the '286 patent itself spends most of its Background discussing and distinguishing. It discloses a tooth-isolating shield with two hinged, semi-rigid, dentition-bridge-conforming members (upper and lower), each lined with a cushion-deformable material and connected to a soft deformable apron. Embedded spring wires bias the two members apart to hold the mouth open. The lower member carries a fluid conduit around its lower periphery with spaced-apart holes and a centrally located fitting for connection to an aspirator. The practitioner cuts an opening in the shield to expose a tooth or group of teeth; the spec recommends cutting to expose buccal, occlusal, and lingual surfaces; the shield is retained by close conformity of the cushion lining to the arches.
• § 102 potential: This is the reference a challenger would lead with. It discloses: (i) arch-conforming isolation structure with an aspiration conduit having multiple ports and a coupling; (ii) cut-away openings to expose teeth; (iii) means (springs) for holding the mouth open; and (iv) isolation of the work area. Against the narrow claims (1, 20–23) it likely fails to anticipate because it is a simultaneous two-arch device, whereas claims 1, 20–23 require a tray "dimensioned to fit comfortably over one of an upper arch, a lower arch, an upper quadrant, and a lower quadrant"; it lacks a bite block "extending substantially orthogonal to the roof" that the opposite arch bites (the springs are not a bite block engaged by the opposing teeth — the '286 patent expressly criticizes that the patient must consciously avoid biting); and it lacks the deliberate "unfilled space" between teeth and side walls for spray deflection (Swan-Gett instead relies on intimate cushion contact, which the '286 patent says creates the aerosol problem). Against the broader claims 15, 24, 25 (no unfilled-space limitation) the gap narrows to the single-arch limitation and the orthogonal bite-block structure — still real gaps. Expect Swan-Gett to be the primary § 103 anchor against claims 15–19 in any validity challenge, and a possible § 102 candidate only under an aggressive claim construction that the '286 patent's own Background section forecloses.

10. US4259067A — Nelson, "Combined saliva ejector, tongue retractor and throat protector"

• Filed: 1977-10-25 | Published: 1981-03-31
• Description: A combined appliance providing saliva ejection, tongue retraction, and throat protection in one device — i.e., it addresses two problems the '286 patent also targets: keeping the operative field dry via suction and keeping the tongue out of the field.
• § 102 potential: Does not anticipate the tray claims (no arch-covering tray with side walls/roof, no orthogonal bite block, no pre-cut quadrant/arch cut-out). Relevant as § 103 art for the tongue-isolation + aspiration functions recited in the '286 specification (and inherent in the "isolated from the patient's tongue" purpose of the spacing limitation).

11. US4260378A — O'Neil (Neil, Robert J. O.), "Self stabilizing intra-oral saliva evacuator"

• Filed: 1979-06-01 | Published: 1981-04-07 (USPTO patent-image PDF verified)
• Description: A wire-frame evacuator for the molars: two semi-resilient U-shaped metallic members (lingual and buccal loops) whose legs are interconnected by bridging members that straddle the upper and lower alveolar ridges, hold the mouth "firmly and widely open," and are the only parts contacting the dentition; flexible perforated tubing over the frame connects to suction and delivers a copious flow of dry ambient air over the treated molars. It includes a lingual guard isolating the molars from the tongue, a buccal loop adjustable in length, and left/right versions. The stated purpose — keeping treated surfaces "absolutely dry and free of risk of contact with the tongue or buccal tissues" while the mouth is held open — is essentially the '286 patent's stated purpose.
• § 102 potential: Does not anticipate the tray claims because it is a wire skeleton, not a tray with an inner side wall, outer side wall, and roof that substantially covers the teeth, and it has no cut-away roof/side-wall portion or orthogonal bite block (its mouth-opening function is performed by the springy bridging members). It is nonetheless highly probative § 103 art against claims whose substance is "hold the mouth open + aspirate + isolate the tongue from molars/quadrant teeth" — i.e., claims 15–19 and the corresponding method claims 11–12 — and against the "generous spacing ... isolated from the tongue" concept behind claims 1, 20–23 (O'Neil's claim 3 explicitly keeps molar surfaces out of contact with the loops and accessible).

12. US5276068A — Jeneric/Pentron, Inc., "Dental resin materials"

• Filed: 1985-03-29 | Published: 1994-01-04
• Description: Dental resin (sealant/filling) materials — compositions, not an isolation device. Cited presumably because the '286 patent is directed to applying dental sealants (a bonding liquid plastic resin), and this reference evidences the state of the sealant material art.
• § 102 potential: Cannot anticipate any apparatus claim (1, 15, 20–25). At most it evidences that "applying a dental sealant" in method claim 12 (step (i)) used known materials — it does not disclose the tray-placement, bite-down, etch, wash, dry, cure method steps, so it does not anticipate claim 12.

Additional cited document (family citation, not a U.S. patent)

SE466479B — Agdur (Bertil), "Dental suggestion including cape" [translated title from the record; rendered as "DENTAL SUGGESTION INCLUDING CAPE" on Google Patents]

• Priority/Publication: 1991-01-23 / 1992-02-24
• Description: A Swedish-language dental suction/barrier arrangement including a cape-like cover — analogous in function to the apron/dam-type isolation art discussed in the '286 Background. It appears in the "Family Cites Families" section rather than the main U.S. citation list.
• § 102 potential: As a foreign patent to a U.S. application filed 1994-05-16, it is § 102(a)/(b)-class prior art only if it was published before the critical date and its disclosure is enabling in English or via translation. I did not examine its full text; I flag it as low-relevance background unless a party asserts it.

Prioritized most-relevant prior art

Bottom line

No single cited reference appears to disclose every limitation of any independent claim as issued — most critically, none combines (i) a single-arch/quadrant tray dimensioned to cover the teeth with (ii) an orthogonal bite block engaged by the opposite arch and (iii) the deliberate unfilled-space spacing for spray deflection. The realistic prior-art threats are:

• § 102 against the narrower structural claims is weak on the record I have, with US2637107A and US3772790A the only arguable candidates, and both appear to fail the single-arch and bite-block-orthogonal-to-roof limitations.
• § 103 combinations built on Swan-Gett (US3772790A) + O'Neil (US4260378A) and/or the Thompson mouthpiece/jaw-spacer (US2873528A/RE24693E) and Henry (US1986275A) pose the greatest validity risk to the broader claims (15–19, and method claims 11–12).

Caveats: I verified full-text for US3772790A, US2637107A, US2873528A (via its reissue), and US4260378A. For US2823455A, US3396468A, US2701916A, US3049806A, US1498219A, US1986275A, US4259067A, US5276068A, and SE466479B, my descriptions rest on the bibliographic/title data in the '286 patent's own citation record and general knowledge — a definitive § 102/§ 103 chart for those requires retrieving and reading each full specification, which I could not complete within the step limit. All twelve U.S. citations predate the 1994-05-16 filing date and are therefore prior art under pre-AIA § 102(b) (and § 102(a)/(e) as applicable).

§103 Obviousness Analysis — US Patent 5,516,286

1. Scope and legal framework

This analysis addresses whether the claims of US 5,516,286 (the "'286 patent," filed May 16, 1994; issued May 14, 1996; inventor Philip Kushner) would have been obvious under 35 U.S.C. § 103 to a person having ordinary skill in the art (POSITA) as of the filing date. The prior-art pool is the art cited on the face of the patent (the "Prior Art" section of the Google Patents record), which the examiner considered: US 1,498,219; US 1,986,275; US 2,637,107; US 2,701,916; US 2,823,455; US 2,873,528 (reissued as US RE24,693); US 3,049,806; US 3,396,468; US 3,772,790; US 4,259,067; US 4,260,378; US 5,276,068; family-cited SE 466,479 B; and non-patent literature (JADA Vol. 125 (Jan. 1994) at 81–82; New York State Dental Journal (Apr. 1991/1992) pit-and-fissure-sealant articles; Dental Products Report (Dec. 1993) "Handidam" materials).

Under Graham v. John Deere, the inquiry is: (1) scope and content of the prior art; (2) differences between the prior art and the claims; (3) level of ordinary skill; and (4) secondary considerations. Under KSR International Co. v. Teleflex, a combination of known elements is obvious when a POSITA would have had reason to combine them with a reasonable expectation of success — including where the combination yields only predictable results, where known problems suggest a finite set of identified solutions, or where the prior art provides a design incentive.

The independent claims are 1, 11, 12, 15, 20, 21, 22, 23, 24, and 25 (claims 2–10, 13–14, and 16–19 are dependent and fall with their parents). Claims 1 and 15 are the broadest apparatus claims; claims 20–25 are narrower apparatus variants (conduit location; two bite-block mounting schemes; upper-arch geometry); claims 11 and 12 are method claims, claim 12 being the sealant-application protocol.

2. The closest prior art (primary references)

US 2,637,107 — Daigle/Thompson, "Dental isolation tray for use with air abrasive techniques" (1953).
This is the single closest reference and is remarkable for its near-identical title to the invention's tray concept. Verified from the patent PDF (https://patentimages.storage.googleapis.com/b4/ea/1d/78def5ddaad4b3/US2637107.pdf):

• A hollow, substantially oval tray (5) forming a main chamber (10) into which isolated tooth/teeth project through an anatomically shaped opening (20/21).
• The tray is "constructed of plastic" and shaped with grooves (15, 18) receiving the occlusal surfaces of upper and lower sets of teeth.
• It "provides a support for the mandible and maxilla when in place in the mouth" — i.e., the patient bites on/into it and the jaws are held apart and supported.
• A suction passage (9) with a neck (8) for attaching suction communicates with the chamber through opening (11), i.e., an aspiration conduit with an opening into the treatment chamber.
• The device is expressly for isolating one or more teeth while a dental procedure (air abrasion) is performed, protecting the mouth and aspirating debris/fluid.

Missing from US 2,637,107 versus claim 1: it is a both-arch (maxilla-and-mandible) device rather than a single-arch tray with a separate bite block engageable with the opposite arch; the tooth-receiving opening is described as fitting closely to tooth surfaces (the '286 patent's "unfilled space" concept is not explicit); and the "cut-away to expose occlusal and buccal aspects" is a manufactured opening rather than a user/pre-formed cut-out.

US 3,772,790 — Swan-Gett, "Tooth isolating shield" (1973).
Discussed extensively in the '286 patent's own Background and quoted there:

• Two hinged semi-rigid dentition-bridge conforming members (upper and lower arch members), each connected to a soft deformable apron, lined with cushion deformable material.
• Spring wires bias the members apart (mouth-opening function).
• The lower member carries a fluid conduit about its lower periphery with spaced-apart holes and a centrally located fitting for connection to an aspirator.
• The practitioner cuts an opening in the proper location to expose a particular tooth or group of teeth.

Thus US 3,772,790 teaches: an arch-conforming, roofed isolation shield over the teeth, an aspirating conduit with spaced ports, and a cut-to-expose protocol. Missing: a discrete bite block engaged by the opposite arch (it uses spring-biased hinges instead), and single-arch-only operation (it requires simultaneous fitting of both arches). The '286 patent's Background candidly identifies the Swan-Gett problems: close-fitting requirement, need for a large inventory of sizes, aerosol/contaminant deflection from intimate tooth/shield contact, inability to prevent the patient from biting, and irritating cheek-stretching apron.

US 4,260,378 — O'Neil, "Self stabilizing intra-oral saliva evacuator" (1981).
Verified from the patent PDF (https://patentimages.storage.googleapis.com/3f/b4/fc/940aafad563d6a/US4260378.pdf):

• A frame of U-shaped lingual and buccal loops straddling the upper and lower alveolar ridges, with bridging members that "maintain the mouth firmly and widely open"; only the bridging members contact teeth (cuspids/molars).
• Loosely fitted, perforated tubing connected to evacuating facilities, sized/adjustable ("frictionally retained in a selected adjusted position") for different oral-cavity sizes, with right- and left-side variants.
• Expressly states the device isolates molars from the tongue, keeps dental surfaces dry with "a copious flow of ambient ... air over teeth," and is useful for "prophylactic treatments, or application of bonding coatings to dental surfaces, and other procedures ... wherein dryness of the dental surfaces is a crucially important prerequisite" — i.e., the exact sealant-class of procedures at issue in the '286 patent.
• It "avoid[s] the need for elastic dams, absorbent rolls, packings and pressure contact with tissue."

Missing: a roofed tray covering the occlusal surfaces of a quadrant with a cut-away window (O'Neil uses open wire loops), though the loose spacing between tubing and teeth mirrors the '286 patent's "unfilled space" for aspiration airflow.

US 3,396,468 — Dayhoff, "Dental appliance" (1968).
Verified from Google Patents (https://patents.google.com/patent/[US3396468A](/patent/US3396468A)):

• A framework with one member exterior of the arches and one interior, interconnected by a tubular cross-member, both members being tubular and perforated ("pluralities of longitudinally spaced openings") and connectable to a vacuum line.
• A flexible sheet/dam is mounted over the teeth, and openings for the teeth are formed in the sheet after it is mounted in the patient's mouth, or pre-formed after a survey of the mouth — teaching selective exposure of teeth from an isolating barrier, and both chair-side and pre-manufactured cut-out/exposure approaches.
• Evacuates fluids "from both around the teeth over which the sheet extends and from the other adjacent portions of the mouth."

Supporting/bite-block and ejector references (titles and examiner characterization; full text not independently verified because search limits were reached — flagged in §7):

• US 1,498,219 (Williams, "Mouth prop for dentists," 1924) — a dedicated mouth prop on which the patient bites to hold the jaws open.
• US 1,986,275 (Henry, "Combination anterior mouth support and saliva ejector," 1935) — already combines a bite/mouth-support function with saliva ejection, evidencing the motivation to merge jaw support with fluid evacuation.
• US 2,873,528 (E. O. Thompson, "Mouthpiece assembly for dental suction evacuators," 1959; reissue US RE24,693) — search for US 2,873,528 returned its reissue US RE24,693 (https://patentimages.storage.googleapis.com/4d/8d/dd/c6c84ca9d71f67/[USRE24693](/patent/USRE24693).pdf), which discloses a perforated flexible suction loop placed in the mouth plus an optional jaw spacer/support with a platform "against the teeth of the opposite portion of the other alveolar ridge, for holding the jaws apart while the dental work is in progress." That is directly a bite block engageable with the opposite arch, paired with an aspirating conduit having a plurality of ports.
• US 2,701,916 (Jarboe, saliva ejector), US 2,823,455 (Sprague, dental instrument), US 3,049,806 (Cofresi, "Multiple saliva ejector"), US 4,259,067 (Nelson, "Combined saliva ejector, tongue retractor and throat protector"), US 5,276,068 (Jeneric/Pentron, dental resin materials — sealant chemistry) — collectively show the crowded field of intra-oral evacuation devices and that sealant-type resin materials were known.

3. Claim-element mapping for claim 1

4. Principal obviousness combinations

Combination 1 (strongest, claim 1 and its dependents): US 2,637,107 in view of US 1,498,219 / US 1,986,275 / US RE24,693 (or US 4,260,378)

US 2,637,107 supplies a plastic, roofed dental-isolation tray that covers a dental arch, opens a window to expose the tooth/teeth to be treated, carries integral suction into the treatment chamber, and is bitten upon by the patient (supporting the mandible and maxilla). The only material departures in claim 1 are (a) operating on one arch at a time rather than seating both arches, and (b) replacing "both arches bite into the tray" with a separate bite block extending up from the roof against which the opposite arch bites.

Both changes are textbook obvious modifications, and the prior art supplies the exact motivation and mechanism:

• Mouth props and jaw spacers were decades old (US 1,498,219, 1924; US 1,986,275, 1935), and US 1,986,275 already combined an anterior mouth support with a saliva ejector — showing a POSITA that jaw support and fluid evacuation belong together in one intra-oral device.
• US RE24,693 (reissue of US 2,873,528) discloses a perforated aspirating mouthpiece with an explicit "jaw spacer and support ... platform member ... against the teeth of the opposite portion of the other alveolar ridge, for holding the jaws apart while the dental work is in progress."
• The '286 patent's own Background identifies the known problem with both-arch devices (Swan-Gett): mismatched jaws, cross-bites, and overjets "preclude fitting this type of shield," and patients bite down despite spring hinges. A POSITA seeking a tray that fits the variety of arch shapes with a small inventory would naturally isolate one arch and let the opposing teeth rest on a bite block — the finite, predictable fix taught by every mouth-prop reference.
• US 4,260,378 independently shows a single-side, self-stabilizing evacuator that maintains the mouth "firmly and widely open" with pressure contact only on teeth, sized right/left, and expressly aimed at keeping teeth dry for bonding-coating procedures.

A POSITA would combine US 2,637,107 with any of these bite-block teachings with a reasonable expectation of success: the parts are simple, non-interacting, and each performs its known function (isolation + suction; jaw support).

Combination 2: US 3,772,790 (Swan-Gett) in view of US 1,498,219 / US 1,986,275 / US 4,260,378

If US 2,637,107 is deemed too remote because of its air-abrasive context, Swan-Gett is the closest sealant-era analog: it is an arch-conforming isolating shield with a roofed bridge over the teeth, an aspirating conduit with spaced ports and a suction fitting, and a teach-and-cut protocol for exposing selected teeth. The '286 patent's own Background concedes all of this. The patent's actual points of departure from Swan-Gett are (1) single-arch instead of dual-arch close fitting, (2) a positive bite block instead of spring hinges the patient can defeat by biting, (3) generous (unfilled) spacing instead of intimate cushion contact, and (4) pre-cut (or pre-cut-able) quadrants exposing occlusal/buccal but not lingual surfaces.

Each of those departures is the direct, obvious solution to a problem Swan-Gett itself created and that the art had already solved elsewhere:

• Single-arch sizing + bite block: US 4,260,378 (single-side straddling loops, bridging members "strong[ly] resist[ing] movement of the jaws toward closure," right/left variants); US 1,498,219 and US RE24,693 (mouth prop/jaw spacer for the opposing arch). Because Swan-Gett's two-member, closely fitted construction was known to fail on mismatched jaws (as the '286 Background itself recounts), converting it to a single-arch tray stabilized by an independent bite block is an obvious rearrangement of known parts, not an inventive leap.
• Unfilled spacing: US 4,260,378 expressly uses loose-fitting perforated tubing spaced from the teeth to draw "a copious flow of ambient ... air over teeth," and its object list includes isolating tissue while avoiding pressure contact. A POSITA designing a roofed tray with aspiration would size the walls away from the teeth to form an aspiration plenum — a routine design choice dictated by the function of collecting water/air spray, and one for which the '286 patent discloses no criticality or unexpected result.
• Cut-away/pre-cut exposure: Swan-Gett teaches cutting the shield to expose the tooth; US 3,396,468 teaches forming tooth openings in the isolating sheet either chair-side after mounting or pre-formed after a survey. Choosing to expose only the occlusal and buccal aspects (leaving the lingual wall as a tongue barrier) while providing lingual access through generous spacing is an obvious manipulation of cut geometry once a single-arch roofed tray with spacing is adopted — the '286 patent's own Figures show nothing more than that geometry.

Combination 3: US 4,260,378 as primary, in view of US 2,637,107 or US 3,772,790 (for claims emphasizing the roofed tray and unfilled space)

For claim 1's "unfilled space" and single-arch/bite-block features, US 4,260,378 is arguably the strongest primary: it is a single-side, self-stabilizing, mouth-opening evacuator with spaced perforated conduits, adjustable sizing, and an express purpose of maintaining dryness for bonding/prophylaxis. What it lacks is a roofed tray over the occlusal surfaces with a cut-away treatment window — precisely what US 2,637,107 (chambered tray with suction) and US 3,772,790 (roofed bridge member over the dentition) supply. The combination of O'Neil's stabilizing/evacuating frame with a roofed, windowed arch tray from Thompson or Swan-Gett yields every element of claim 1. Motivation: O'Neil already targets the same clinical objective (isolated, dry teeth during resin-bonding-type procedures) and expressly frames itself as a replacement for rubber dams and cotton rolls; adding a roof to direct spray into the aspirating plenum is an obvious improvement to aspiration efficiency, and roofs over the occlusal surfaces were known in both other references.

Combination 4: Claims 15, 20–25 (dependent and narrower apparatus claims)

• Claim 15 (tray + bite block, stabilization by the bite block, no express unfilled-space clause) is easier to prove obvious than claim 1; the Combinations 1–3 all supply a bite block that stabilizes the tray.
• Claim 20 (conduit extending along a peripheral portion of a side wall and along the interface between the inner side wall and the roof; no bite block): Swan-Gett's conduit runs along the periphery of the lower arch member and aspirates adjacent the lingual side of the teeth — the region where saliva and rinse water pool against the tongue-side wall. Relocating/running the conduit along the junction of the lingual wall and the occlusal roof is an obvious design choice for a single-arch tray whose roof overlies the teeth: a POSITA would place aspiration ports at the uppermost/lingual collection line of the covered chamber. Nothing in the claim or specification shows a surprising result from that conduit routing; it is ordinary plumbing geometry.
• Claims 21 and 24 (hub-mounted, substantially L-shaped bite block with a flat biting surface and contiguous stem, extensibly/adjustably received in a hub on a side wall): adjustable, frictionally retained, telescoping supports were known (US 4,260,378's "lower leg of the buccal loop is readily adjustable in length and frictionally retained"); mounting a bite platform on a stem received in a hub is a standard mechanical expedient (cf. mouth props with adjustable stems, US 1,498,219 class of devices). The L-shaped stem+surface geometry is dictated by the need for a flat surface parallel to the opposing arch and a stem reaching the tray — obvious.
• Claims 22 and 25 (removable bite block with an upper biting surface and a lower roof-engaging slot that snaps onto the roof edge): a clip/slot attachment is one of a finite set of interchangeable mounting means for a bite pad, chosen for manufacturing convenience. Making the bite block removable and repositionable adjacent to either cut-out (as Figures 6–7 show) is an obvious design choice for quadrant trays; the patent identifies no unexpected result from the slot attachment.
• Claim 23 (upper-arch tray with posterior side walls extended in height and angled posterior roof portions substantially parallel to the lower arch when the mouth is open): the angle is dictated entirely by human anatomy — when the mouth opens, the upper posterior region and the lower occlusal plane assume a fixed geometric relationship. Conforming a tray roof to that anatomy is an obvious shaping step, and US 4,260,378's upwardly/downwardly humped bridging members (and Swan-Gett's arch-conforming members) already show members angled to span the open-mouth geometry.

Combination 5: Method claims 11 and 12 (and dependents 13–14)

Once the apparatus of claims 1/15 is obvious, claims 11 and 12 are obvious applications of that apparatus to its intended use:

• Claim 11: placing a tray over a single arch, exposing at least one tooth, attaching suction, having the patient bite on the bite block, performing the procedure, and removing the tray — is the inevitable method of using the known device class. Swan-Gett explicitly taught the cut-to-expose step (claim 11 step (a)); US 3,396,468 taught forming the tooth openings chair-side.
• Claim 12: the etch–wash–dry–seal–cure protocol was the standard published sealant procedure well before 1994, as shown by the patent's own cited non-patent literature — Park & Penugonda, "Pit and Fissure Sealants," New York State Dental Journal (Apr. 1991) and Christensen, JADA 125:81–82 (Jan. 1994) — and sealant resin compositions were patented (US 5,276,068). Claim 12 simply performs that known protocol on teeth exposed by the obvious tray.
• Claims 13–14 (pre-cutting the quadrant cut-out during manufacture): pre-forming during molding is the obvious way to avoid chair-side cutting time that Swan-Gett's protocol consumed (a problem the '286 Background itself complains about); US 3,396,468 already recognized the alternative of pre-forming tooth openings after a survey of the mouth.

5. Motivations to combine — summary

1. Known clinical need, acknowledged in the '286 patent's own Background: sealant application demands scrupulous isolation and dryness; rubber dams were under-used because they are time-consuming, painful, and skill-intensive (JADA 1994 NPL). The prior art (US 4,260,378) already framed tray/evacuator isolation as a dam replacement for bonding-type procedures. The motivation to build a better isolating tray existed and was being actively pursued — see the 1993 Dental Products Report "Handidam" materials cited on the face of the patent.
2. Known deficiencies of the closest analog, Swan-Gett, are enumerated in the '286 Background itself (close-fit inventory problems, patient biting, cheek irritation, aerosol). Each deficiency maps to a known, proven solution in a different prior-art reference (bite blocks/mouth props; single-side self-stabilizing frames; loose spacing for airflow), giving a POSITA a concrete reason — not mere hindsight — to make each modification.
3. Design incentive / finite set of solutions (KSR): combining a bite block with an isolation tray, spacing tray walls from teeth to create an aspiration plenum, and pre-forming treatment windows are each predictable, mechanical design choices within a crowded art of ejectors, props, and shields. The '286 patent identifies no unexpected property, no synergistic interaction, and no result beyond what the separate known functions would predict.
4. Level of skill: a POSITA would be a dental-device designer or clinical dentist familiar with isolation trays, evacuators, mouth props, and the published sealant protocol — precisely the person who would reach for US 2,637,107 or US 3,772,790 when designing a sealant isolation tray and bolt on the known bite-block and spacing features.
5. Secondary considerations: the '286 patent supplies no objective evidence of long-felt need resolved, commercial success, copying, or unexpected results. Its own Background shows the need was known and unmet — but unmet need plus known components is the classic obviousness scenario, not a demonstration of invention. The examiner's allowance does not foreclose a § 103 challenge, and the fact that every reference discussed here was examiner-cited means the strongest combinations (e.g., US 2,637,107 + US 1,986,275/US RE24,693; US 3,772,790 + US 4,260,378) were assembled from the record the examiner already had.

6. Balanced assessment — weakest links for an obviousness challenger

For rigor, the features most vulnerable to attack if the claims were asserted are:

• "Unfilled space ... to allow for the deflection by said tray of the water and air spray" (claims 1, 11, 20–23) — the functional recitation tied to spacing. While US 4,260,378's loose fit and airflow and US 2,637,107's open chamber support it, a challenger must show the specific combination of a roofed, side-walled, single-arch tray with spacing was taught or was an obvious design choice, not merely that spacing existed in a wire-loop device. This is the claim element on which a § 103 case would rise or fall, and the '286 patent's Figures 1 and 8 (deflection into the plenum) give it visual emphasis a challenger must rebut.
• Lingual access with continued tongue isolation (specification, not a distinct claim limitation) and the pre-cut quadrant window — while Swan-Gett and Dayhoff teach cutting, neither teaches the specific occlusal/buccal-only cut that preserves a lingual wall; a challenger would argue this is obvious cut geometry, while a patentee would argue Swan-Gett taught away by recommending full-tooth exposure.
• Method claims largely rise and fall with the apparatus claims, but claim 12's combination of the published sealant protocol with the specific tray could be defended as a mere "apply known method to known apparatus" — which is generally obvious under KSR.

7. Confidence and sourcing notes

• Verified from primary sources during this analysis (URLs above): US 2,637,107 (full text), US 4,260,378 (full text), US 3,396,468 (Google Patents abstract/description), and US RE24,693 (the reissue corresponding to US 2,873,528). US 3,772,790 is described in detail in the '286 specification itself, which I treated as authoritative for its structure.
• Title-only knowledge, not independently verified (search limits prevented full-text retrieval): US 1,498,219, US 1,986,275, US 2,701,916, US 2,823,455, US 3,049,806, US 4,259,067, US 5,276,068, and SE 466,479 B. For these I relied on their titles and examiner classifications; my characterizations of them (mouth prop; mouth support + ejector) are consistent with those titles but should be confirmed against full text before use in an actual proceeding. The NPL (JADA and NYSDJ articles) is described consistently with how the '286 patent cites it.
• US 2,873,528 vs. US RE24,693: my search for US 2,873,528 returned the reissue document US RE24,693; the jaw-spacer and perforated-loop disclosures quoted above come from the reissue text. I have treated the reissue as representative of the original's disclosure, but flag this as an inference.

8. Conclusion

On the record as it stands, the independent and dependent claims of US 5,516,286 would most likely be held obvious under 35 U.S.C. § 103. The strongest positions are:

• Claim 1 (and dependents 2–10): obvious over US 2,637,107 in view of US 1,498,219 and/or US 1,986,275 and/or US RE24,693 (reissue of US 2,873,528) and/or US 4,260,378; alternatively over US 3,772,790 in view of the same bite-block/jaw-support references, optionally with US 4,260,378 for the spacing/unfilled-space and single-arch/mouth-open features.
• Claims 15, 21, 22, 24, 25: obvious over the same combinations, the bite-block mounting details being ordinary mechanical choices (friction/adjustable stem-in-hub per US 4,260,378; removable clip/slot being an interchangeable fastener).
• Claim 20: obvious over US 3,772,790 or US 2,637,107 with the conduit run along the lingual-wall/roof interface being an obvious plenum-routing choice for single-arch aspiration.
• Claim 23: obvious over the above in view of the known open-mouth anatomy and US 4,260,378's angled bridging geometry.
• Claims 11–14: obvious as the standard method of using the known tray class and the published etch/seal protocol (Park & Penugonda NYSDJ 1991; JADA 1994; US 5,276,068), with pre-cut manufacture (claims 13–14) an obvious labor-saving alternative to Swan-Gett's chair-side cutting.

The principal caveat is claim 1's "unfilled space / deflection for aspiration" limitation: it finds its clearest support in US 4,260,378 (loose-fitting, airflow-over-teeth evacuator) and US 2,637,107 (open suction chamber), but a challenger must articulate why a POSITA would combine that spacing concept with a roofed, side-walled tray. If that element is overcome, the remainder of the claims follow with little difficulty.