Webinar- The Role of Prosthodontic Decisions in Preventing Peri-Implant Disease

Dr Susan Tanner opens the session by reframing peri-implant disease as a largely iatrogenic complication: one created or prevented long before the patient begins maintenance therapy. She positions the prosthodontist—not the periodontist—as the first line of defence, because emergence contours, retention mode, material choices and occlusal design dictate whether plaque, overload and cement can ever reach pathogenic thresholds. The webinar lasts just over an hour and is structured around four pillars: epidemiology & rationale, risk-oriented design principles, clinical case analysis, and long-term maintenance protocols.

1. Why prosthodontic decisions matter 

Using global data (Derks & Tomasi 2015; Berglundh 2018) Dr Tanner reminds the audience that peri-implantitis affects roughly 20 % of implant patients and ~10 % of all implants after 5 years. Surgical protocols have improved, yet incidence remains steady—evidence that restorative variables drive disease once osseointegration is secured. She lists modifiable prosthetic factors in order of impact:

• Cervical contour & emergence profile – over-bulked crowns (>30° profile change) block oral-hygiene devices and trap biofilm.
• Retention mode – submucosal cement seeding is linked to up to 81 % of peri-implantitis lesions in cement-retained crowns (Wilson 2009).
• Access for probing/radiograph – deep shoulder abutments or bars limit diagnostic access, delaying intervention.
• Occlusal scheme & wear dynamics – non-axial forces accelerate bone loss around narrow implants or those placed outside the “prosthetic envelope”.

She argues that these “design errors” are often invisible on glossy lab images but become obvious once soft tissues swell or bone craters appear. Therefore, risk assessment should start with a wax-up that respects cleansability angles (<25–30°) and leaves a 2 mm “hygienic window” under pontics/bars.

2. Risk factors & design principles 

Dr Tanner dissects each variable and translates evidence into chairside rules:

1. Screw-retained where possible – eliminates cement and keeps the micro-gap supragingival for easy monitoring. If cemented, apply radiopaque provisional cement and create a vent channel to allow hydraulic escape.
2. Emergence profile – maintain a gradual flare no steeper than 25°; use convex emergence only in highly scalloped biotypes where tissue support is critical, but warn patients that cleaning becomes technique-sensitive.
3. Platform switch vs straight – platform switching moves the micro-gap medially, reducing bone loss, but only if crown contour is not over-bulked to compensate.
4. Material choice – monolithic zirconia shows less plaque affinity than veneered feldspathic ceramics; titanium bases reduce galvanic wear versus cobalt-chrome.
5. Occlusal load – eliminate working-side interferences and design a shallow guidance; implants lack periodontal ligament proprioception, so overload signs appear radiographically after damage is done.

3. Clinical cases – design errors & corrections 

The centrepiece of the webinar is a series of “forensic case audits.” Each begins with an apparently healthy restoration that failed between years 3 and 8.

• Case 1: Over-contoured anterior zirconia crown – A 46-year-old female presented with bleeding and 2 mm bone loss facially. Intra-oral scan on the day of crown removal revealed a 40° emergence angle starting 0.5 mm below the mucosal margin. Redesign to a screw-retained, narrow-profile crown plus debridement halted disease at 6 months.
• Case 2: Cement-retained molar on a 6 mm tissue-level implant – Despite meticulous cement clean-up at delivery, radiograph at 5 years showed a cement island palatal to the shoulder. Revision required flap surgery, xenograft regeneration and a screw-retained remake. Dr Tanner stresses that radiopaque cements are mandatory if one must cement.
• Case 3: Fixed bar over four implants (mandible) – Hygiene access was less than 1 mm; patient never used an irrigator. At year 7, all four implants showed circumferential bone loss. The bar was replaced by individual screw-retained crowns on conical-connection abutments, permitting inter-implant flossing.

4. Maintenance protocols & patient compliance

Even the best prosthesis fails if patients lack tools or motivation. Dr Tanner recommends a risk-graded recall: 3–4 months for patients with a history of periodontitis or complicated prostheses; 6 months for low-risk, screw-retained single crowns. Hygienists should probe implants once per year with a plastic or titanium scaler, reinforce device use (super-floss, water-flosser), and monitor occlusal wear patterns. She shows data (Monje 2022) indicating that supportive care halves peri-implantitis progression rates.

Closing remarks

Dr Tanner concludes that peri-implant disease is predictable and largely preventable by applying evidence-based prosthetic design. She challenges clinicians to audit their own work annually, as she did in Case 3, to close the feedback loop between design choices and long-term outcomes.