Contacts Between Implant and Natural Tooth — Biomechanics and Occlusal Protocol

A bridge connecting an implant to a natural tooth is one of the more challenging prosthetic cases. The biomechanical difference between osseointegration and the periodontal ligament is vast – and must be taken into account in both the occlusal design and the decision to construct such a bridge.

Why an implant and a natural tooth behave differently under load

A natural tooth has a periodontal ligament (PDL). This is an elastic structure that cushions occlusal forces. Deflection of a natural tooth under load: 25–100 µm.

An implant is anchored directly in bone (osseointegration). No PDL. Deflection of an implant under load: 3–5 µm.

Deflection difference: over 10-fold. This means that with simultaneous contact between the implant and the natural tooth – the implant absorbs disproportionately more force. With dynamic loading (chewing, parafunctions), this leads to stress on the abutment screw, micro-fractures in the bone, or loosening of components.

How to design contacts in a hybrid bridge

The basic principle: contact on the implant must be lighter than on the natural tooth.

Occlusal contact protocol:

Centric Occlusion (CO): contact on the implant – Arti-Fol 8 µm foil (Bausch BK28) leaves a barely visible mark; natural tooth – clear mark
Excursive movements: guidance exclusively on natural teeth or on the implant side without lateral contact
Avoid non-working side contacts on the implant during lateral movements

Clinically: when trying on a hybrid bridge, check with Arti-Fol 8 µm foil (Bausch BK28) – the mark on the implant should be barely visible, not clear.

Hybrid bridge – when is it worthwhile, and when is it risky?

Situation	Assessment
Short span (1-2 teeth), good bone	Acceptable – with proper occlusion
Long bridge (3+ teeth), no natural teeth next to the implant	Risky – prefer implant-supported bridges
Nocturnal bruxism (documented)	Relative contraindication – requires an occlusal splint
Implants and teeth with similar mobility	Optimal – teeth with minimal PDL mobility

Clinical controversy: some authors argue that hybrid bridges are contra-indicated. The compromise is: do not connect an implant to a mobile tooth (periodontitis, loosening).

Occlusal protocol for implants adjacent to natural teeth

"Light contact" scheme on the implant:

Occlusal foil 200 µm (Bausch BK61): mark on implant = clear → grind
Arti-Fol 8 µm foil (Bausch BK28): mark on implant = invisible → OK
Lateral movement test: no guiding contact on the implant
Protrusive test: implant without frontal contact in the absence of natural anterior teeth

This is the protocol used by deltalabs. when designing occlusion for hybrid restorations.

What the laboratory needs for proper execution

Articulated model – at least a semi-adjustable articulator; without an articulator, eccentric occlusion cannot be evaluated
Centric relation record – not maximum intercuspation, but centric relation
Description of adjacent natural teeth – their mobility, periodontal status (panoramic X-ray)
Information about parafunctions – bruxism requires a different occlusal design
Implant protocol – brand, system, platform, screw tightening torque