Occlusion & Bite Registration in Implant Dentistry Flashcards

Why must occlusal forces on implant-supported restorations be managed more carefully than on natural teeth?

Answer: Implants lack a periodontal ligament, so they have no shock-absorbing mechanism or proprioceptive feedback

Natural teeth have a periodontal ligament (PDL) that acts as a shock absorber and contains proprioceptive nerve fibers that sense bite force. Osseointegrated implants have no PDL, so they transmit occlusal forces directly to the bone without attenuation and without the fine tactile feedback that natural teeth provide.

Which occlusal scheme is generally preferred for a full-arch implant-supported fixed prosthesis to minimize lateral stress on implants?

Answer: Canine-guided (mutually protected) occlusion

Canine-guided or mutually protected occlusion is preferred for implant-supported restorations because it directs lateral excursive forces through the anterior teeth (or implants in that position), disoccluding the posterior implants and reducing the harmful lateral (non-axial) loading on posterior implants.

During bite registration for an implant-supported crown, why is it important to have the patient bite lightly rather than at maximum force?

Answer: Maximum clenching compresses natural teeth in their sockets, potentially leading to an inaccurate registration that is too thin

Natural teeth can intrude 25–100 microns in their sockets under heavy occlusal load due to the PDL. If the patient bites hard during registration, the natural teeth are compressed; when they rebound, the bite record becomes too thin, and the final restoration may be fabricated in supraocclusion.

A cantilever extension on an implant-supported bridge creates what type of potentially harmful force on the supporting implants?

Answer: Rotational and lever-arm forces that magnify stress at the implant-bone interface

A cantilever acts as a lever. Forces applied to the unsupported end are magnified at the fulcrum (the most distal implant), creating rotational moments and non-axial stress at the implant-bone interface. This significantly increases the risk of mechanical complications and bone loss around the supporting implants.

Which bite registration material is most commonly used in contemporary implant dentistry due to its dimensional accuracy and rigidity after setting?

Answer: Polyvinyl siloxane (PVS) bite registration material

Polyvinyl siloxane (PVS) bite registration materials are preferred because they have excellent dimensional stability, minimal distortion after setting, are rigid enough to maintain the recorded position during model mounting, and do not deform during trimming. Alginate lacks stability; ZOE is messy and brittle; modeling compound has thermal limitations.

Parafunctional habits such as bruxism pose a particular risk to implant-supported restorations primarily because:

Answer: The high repetitive lateral forces exceed the implant system's design limits, increasing the risk of component fracture and bone loss

Bruxism generates repetitive high-magnitude lateral forces that are poorly tolerated by implants due to the absence of the PDL. These forces can lead to screw loosening, abutment or prosthesis fracture, implant fracture, and marginal bone loss. Night guards are commonly recommended (not contraindicated) to protect implant restorations.