Intraoral vs Extraoral Cementation of Zirconia Bridges on Ti-Bases: Microstrain Evaluation

Influence of Cementation Technique on Microstrain in Three-Unit Bridges on Ti-Bases Evaluated by Strain Gauges

This prospective clinical study compares two cementation techniques for implant-supported zirconia fixed partial dentures on titanium bases (Ti-bases): extraoral cementation performed on the working model and intraoral cementation performed chairside. Thirty clinical cases with two osseointegrated implants requiring a multi-unit zirconia restoration will be recruited at the UIC Dental Clinic. For each case, two restorations with identical design will be produced: one will be cemented extraorally (control) and an identical replica will be cemented intraorally (test). Micro-deformation will be assessed as peri-implant microstrain (µε) using a standardized strain-gauge setup and the same recording protocol for both techniques. The primary analysis compares microstrain between intraoral and extraoral cementation within each case; implant/prosthetic events will be recorded descriptively.

This study will evaluate whether the cementation approach of zirconia restorations onto Ti-bases influences peri-implant strain. Two clinical workflows are compared: (1) extraoral cementation of the zirconia restoration to Ti-bases on the working model prior to delivery, and (2) intraoral chairside cementation of an equivalent restoration to Ti-bases using the same intended clinical seating conditions.

For each enrolled case, two restorations with the same design will be fabricated so that both cementation approaches can be assessed within the same case. After cementation, restorations will be evaluated using a standardized strain-gauge measurement setup on a model reproducing the clinical implant relationship, applying the same torque and recording procedure for both techniques.

All clinical procedures will be performed at the UIC Dental Clinic, and strain-gauge recordings will be performed at the collaborating center (Universidad Europea Miguel de Cervantes, UEMC) following a consistent protocol. Data will be handled using study codes, and only study-coded technical files will be shared with the collaborating center.

Inclusion Criteria:

• Adults (≥18 years old) in good general health.
• Presence of an edentulous space requiring rehabilitation with a three-unit implant-supported fixed bridge.
• Presence of two already osseointegrated Essential Cone implants (Klockner) indicated for a three-unit implant-supported restoration in the edentulous area.
• Ability and willingness to participate and attend study visits and follow-up.
• Signed informed consent.

Exclusion Criteria:

• ASA III or ASA IV.
• Current or previous treatment with bisphosphonates.
• Smoking >10 cigarettes/day.
• Extraction in the study area <3 months before implant placement with incomplete healing.
• Guided bone regeneration in the study area with <6 months of healing time.
• Signs of active periodontal disease (e.g., poor plaque control and/or bleeding on probing above acceptable levels).