Printed maxillary flat-plane guards for electromyographically confirmed sleep bruxism are produced as full-arch occlusal stabilization devices with a flat occlusal table and a minimum functional thickness of 1.5 mm across the cusp tips. The resin is used as supplied; dilution with isopropyl alcohol, methyl methacrylate monomer, or low-viscosity aliphatic urethane acrylate is incompatible with the free-radical photopolymerization and depresses crosslink density below the threshold required for prolonged mucosal contact. On a Formlabs Form 3B or Form 3BL station operating at 405 nm with a 100 μm layer height, build orientation is set to 30–35° from vertical, and support touchpoints are confined to the polished buccal and labial surfaces at a spacing of 1.2 mm; occlusal support placement is prohibited because residual nibs create premature contacts that require chairside adjustment and disrupt the flat plane. After printing, the guard is washed in a Form Wash with 95–99 % isopropyl alcohol for 10 minutes at 25 °C, dried with oil-free compressed air until a haze-free surface is obtained, and post-cured in a Form Cure at 60 °C for 30 minutes. A post-cure interval below 20 minutes leaves unreacted methacrylate groups that elevate leachables beyond the level established for surface-contacting oral devices under ISO 10993-1:2018, Clause 5.3; a post-cure temperature above 70 °C initiates thermal yellowing and may warp thin occlusal tables. Biological evaluation for this appliance class is anchored to ISO 10993-5:2009 using quantitative MTT cytotoxicity on polymer extracts and to ISO 10993-10:2010 for oral mucosal irritation, with the resin categorized as a surface-contacting medical device with prolonged mucosal exposure. The terminal product is a clear flat-plane maxillary night guard that is adjusted on the master cast with 8 μm red articulating foil and polished with a felt wheel and pumice slurry at a surface temperature below 45 °C; silicone polishing pastes are preferred over methyl methacrylate-based glaze to avoid surface swelling.

What Happens When an Anterior Bite Plane Requires Selective Reduction in High-Force Bruxism?

In high-force bruxism patients with masseter hypertrophy, an anterior bite plane is designed with a raised incisal platform angled 15° relative to the occlusal plane and a posterior disclusion of 0.5 mm measured at the second molar. The print workflow for this geometry uses a 100 μm layer height and orients the incisal platform away from the build platform; support pillars of 0.8 mm diameter are placed along the facial cervical third at a touchpoint density of 1.0 mm⁻¹ rather than on the lingual incline, because lingual support nibs cannot be polished without changing the guidance slope. The resin is processed neat, but working viscosity must be verified at 25 °C before each build; a cartridge stored below 15 °C must be warmed to room temperature for 3 hours and homogenized by gentle inversion, otherwise recoating defects appear at thin incisal edges. Washing is performed in two successive 5-minute isopropyl alcohol baths at 25 °C, with the first bath saturated after six full build plates; the second bath is used until turbidity exceeds 0.1 % by volume of suspended oligomer. Post-curing at 60 °C for 30 minutes is followed by seating on the trimmed master cast; selective reduction of the incisal platform is performed with a slow-speed handpiece and a carbide bur, and no more than 0.4 mm of reduction is permitted before verifying posterior disclusion with 8 μm foil. Compliance for this anterior repositioning device includes ISO 10993-1:2018, Clause 5.2, for biological evaluation planning, ISO 10993-5:2009 for extract cytotoxicity, and ISO 10993-10:2010 for delayed-type sensitization and oral mucosal irritation; the device is not intended for patients with an anterior open bite or for mandibular advancement beyond 3 mm. The terminal product is a maxillary anterior bite plane with canine guidance, polished on all tissue-bearing aspects and left with a matte occlusal platform for chairside adjustment.

Full-arch stabilization splints prescribed for arthrogenous TMD are generated from a centric relation bite registration, not from maximum intercuspation, and are designed with bilateral occlusal contacts at a total posterior thickness of 0.5–1.0 mm over the cusp tips. The build uses a 50 μm layer height on a Formlabs Form 3BL to reduce staircase artifacts on the occlusal fossae; support anchors are placed on the buccal vestibular surface with a spacing of 1.5 mm, and the occlusal surface is oriented at 45° to the build platform to avoid a planar cross-section that would generate large peel-force zones. Resin viscosity is monitored at 25 °C with a cone-and-plate viscometer at 10 s⁻¹ before each fill; deviation above 15 % from the manufacturer’s certificate of analysis indicates moisture uptake or partial polymerization and requires cartridge rejection. The splint is allowed to rest at 23 °C and 50 % relative humidity for 1 hour between washing and post-cure, which reduces solvent-induced microcrazing on the thick centric relation stops; the resin is not diluted, and attempts to lower viscosity with 1–2 % isopropyl alcohol before printing produce undercured interlayer regions outside the validated workflow. Post-curing at 60 °C for 30 minutes is performed with the splint supported on a customized silicone jig, not on a flat glass tray, because unsupported posterior extensions undergo creep under elevated temperatures. Mechanical conformity is checked against ISO 178:2019 three-point flexural specimens printed in the same batch; batch-to-batch flexural modulus deviation above 15 % from the release value triggers full revalidation. Water sorption is assessed by immersion at 37 °C for 7 days according to the gravimetric method of ASTM D570-98; published data for this specific resin grade are limited, but an increase above 2.0 % by mass would invalidate the splint because occlusal contact positions shift by more than 0.1 mm after overnight saliva exposure. The terminal product is a hard full-arch stabilization splint with bilateral balanced occlusion, delivered with a written adjustment schedule and no resilient lining.

Post-Orthodontic Clear Overlay Retainers Fabricated with 0.75 mm Occlusal Thickness

For post-orthodontic retention after fixed appliance debonding, the clear overlay retainer is printed at a 50 μm layer height, with the digital model offset 0.05 mm on the facial aspect to produce a passive fit and the occlusal table held between 0.75 mm and 1.0 mm. Undercut engagement is limited to 0.25 mm below the height of contour; greater engagement increases insertion stress at the mesial canine and can propagate cracks along the gingival margin. The build is oriented with the occlusal plane vertical and the lingual surface facing the build platform, because this orientation places support projections in the non-visible intaglio region where they are removed with a scalpel and a 600-grit silicone wheel. Washing uses two 5-minute isopropyl alcohol stages: the first is 99 % anhydrous alcohol, and the second is a clean 99 % bath to remove residual oligomer film; 70 % alcohol is unsuitable because water ingress swells the thin retainer surface and causes white haze after curing. Post-curing is carried out at 60 °C for 20 minutes when the shell is below 1.0 mm, because longer exposure does not increase degree of conversion but raises water sorption and reduces fracture toughness under repeated insertion and removal cycles. Compliance for this long-term orthodontic appliance references ISO 20795-2:2013 for orthodontic base polymers, ISO 10993-5:2009 for cytotoxicity of extracts, and ISO 10993-10:2010 for delayed-type sensitization. The retainer must not be placed in an ultrasonic bath with water above 40 °C; thermal deformation of the palatal vault exceeds 0.2 mm at 50 °C. The terminal product is a clear overlay retainer with a labial window free of support marks and a smooth, polished gingival margin.

Implant-Protection Guard Shells and Chairside Soft Reline Recesses

A hard outer shell printed from Dental LT Comfort Resin V1.1 is designed with a 2.0 mm recess on the intaglio surface for a chairside resilient liner, protecting implant-supported fixed prostheses during parafunctional activity. The digital design leaves 0.3 mm of rigid occlusal coverage over the opposing dentition and maintains 1.5 mm of bracing wall on the buccal and lingual flanges. The shell is printed intaglio-up to eliminate support marks in the reline cavity; supports are placed on the polished external surface at 0.8 mm spacing, and the material is used as supplied without adding plasticizer. After printing, the shell is washed in 99 % isopropyl alcohol for 10 minutes and air-dried for 45 minutes before post-cure; residual alcohol inside the recess causes bubbles and poor liner adhesion when the chairside reline material is packed. Post-curing at 60 °C for 30 minutes is followed by application of a primer to the recess and packing with a tissue-conditioning reline material; the reline thickness must not exceed 2.5 mm, or the rigid walls flex and the shell loses occlusal coverage. Compliance for the printed shell itself follows ISO 10993-1:2018 for prolonged mucosal contact and ISO 10993-5:2009 for extract cytotoxicity; the chairside reline material must be evaluated separately under ISO 10139-2:2016 for denture soft lining materials. The terminal product is an implant-protection occlusal guard with a hard printed shell and a resilient intaglio liner, delivered only after verifying that the liner cuff terminates 2.0 mm away from the implant emergence profile.

If a Mixed Dentition Guard Must Accommodate Erupting First Molars

In paediatric bruxism cases with mixed dentition, the printed guard includes 4.0 mm eruption windows around partially erupted first permanent molars and 0.5 mm clearance at the gingival margin to avoid pressure on the pericoronal operculum. The appliance is designed with a 2.0 mm posterior occlusal table and 1.5 mm anterior coverage; the resin is processed at 100 μm layer height with supports placed on the facial surface opposite the eruption windows, and support tips are set to 0.6 mm diameter to reduce breakage during support removal from thin margins. Washing and post-cure follow the standard 60 °C for 30 minutes protocol, but the guard is bench-cooled inside the Form Cure for 10 minutes before extraction to prevent warping of the narrow eruption bridges. Heat-cured ethylene-vinyl acetate liner sheets are not used with this resin because differential thermal expansion at the interface can produce delamination; published cycling data for this specific combination are limited. Biological evaluation for the paediatric device is governed by ISO 10993-1:2018 with attention to leachables in a simulated saliva extract at 37 °C for 72 hours, supported by toxicological risk assessment under ISO 10993-17:2023, and ISO 10993-10:2010 for oral mucosal irritation; the guard is not indicated for children younger than 6 years without a separate airway assessment. The terminal product is a mixed-dentition night guard with eruption slots that is re-evaluated every 3 months for fit changes during active tooth eruption.