All Ceramic Resin Retained Bridges in the Anterior

All Ceramic Resin. Retained Bridges in the Anterior Aesthetic Zone MJDF PBL Lynsey Rennison

Advantages of Metal RRB’s Simple n Minimally invasive n Can be used interim or definitive n Reduced biological consequence n Now regarded as predictable long-term tooth replacement option n 5 year survival at 87. 7% (compared with conventional bridges >90% and implant retained single crowns 94. 5%) n

Disadvantage Metal RRB’s Greying effect through abutment (shine through) n Rare – higher corrosion rate and allergenic potential n

All-Ceramic RRB’s developed for anterior aesthetic region.

All-ceramic RRB’s n Review by Conrad et al highlighted how difficult it is to plan and prescribe an allceramic RRB Not a single universal ceramic material or system for all clinical situations. n Very hard for clinician to match materials, manufacturing techniques & cementation/bonding with each clinical situation n

All-ceramic RRB’s n Review by Miettinen & Miller stated annual failure rates: All-ceramic RRB: 11. 7%, n Metal-framed RRB: 4. 6%, n n Lack of evidence, but appears metal RRB’s perform better over time.

All-ceramic RRB’s compared with metal RRB’s n Advantages n n n Improved aesthetics Reduced plaque accumulation Bio-compatability n Disadvantages n n n Higher failure risk Poor long-term data Difficult to repair Increased thickness, so could have more destructive prep & bulkier prostheses High lab fee

Ceramic types for all-ceramic RRB’s Zirconia n Glass Infiltrated Alumina n Lithium Disilicate Glass Ceramic n n (In dental update article, the RRB’s shown were formed of IPS e. max, a leucite-based glass ceramic, reported as having high compressive strength, a variety of shades and translucency & opacity for good aesthetics)

Zirconia n Pro’s: n n n Superior strength Superior fracture resistance Superior toughness n Cons: n Inability to attain adhesive bond (thought due to lack of silica and glass phase within it, & its acid resistance making it ineffective to traditional glass-etching treatments with hydrofluoric acid & bonding with subsequent silane application). Surface treatments and a variety of primers are being looked at & showing positive results in improving bond strengths, but more studies needed

Zirconia n n Long term success of RRB’s strongly dependant on bond between restoration and tooth so zirconia not seen as a predictable material to use in RRB’s, however study by Sailor and hammerle assessing all ceramic zirconia RRB’s with 8 year follow-up showed 100% success, though only 15 bridges looked at (& 2 had early debonds that were successfully recemented) Potential for veneering porcelain to fracture if veneer technique used.

Glass Infiltrated Alumina n n Improved physical properties with addition of alumina 8 yr study by Galiasatos & Bergou found success of 85. 18%. Complications included debonding and fracture of porcelain. Study by Kern showed over 5 years success rates of: 1 wing: 92. 3%, 2 wing : 67. 3%. This study also showed most common complication, & largely with 2 wing prostheses, was fracture of the porcelain Cantilever rather than 2 wing best.

Lithium Disilicate Glass Ceramic Composed of lithium disilicate crystals within a glass matrix n High Strength n Good aesthetics (esp due to good translucent properties) n Studies have shown high success rates over 3 years, but very small numbers in the studies (only between 22 & 35 bridges) n

Lack of evidence to support one ceramic material over another for All-Ceramic RRB’s

Complications of all-Ceramic RRB’s n Higher failure rate n n n Fracture of framework, this commonly occurs at the connector, esp when there is inadequate thickness of the connector for specific ceramic used. More common with lower strength ceramics e. g. glass infiltrated alumina Debonding, more common with zirconia, less common with lithium disilicate Delamination of the ceramic veneer material (if this used) as veneering technique reduces strength of the structure

Clinical Considerations n n n Comprehensive treatment planning Careful consideration of connector (recommendation is for it to be larger & thicker where possible, depending on type of ceramic, but always check with manufacturers guidelines). Increased thickness of connector can lead to overcontoured restorations or heavier prep on abutment Wider connector may look like longer contact point, which may not be aesthetic Diagnostic wax-up useful

Clinical Considerations Improved aesthetics, esp for teeth with increased translucency n For teeth in sub-optimal position, reasonable aesthetics can be achieved without compromising surface area of wing for bonding n Single wing more successful than 2 wing (cantilever minimises sheer and torque, attributed to differential tooth movement of abutments during function) n

Clinical Considerations n n n Occlusion must be considered, esp as retainer will be thicker. Careful case selection Where there is a lack of inter-occlusal space options include: n n n greater prep of tooth (though if prep into dentine, reduced bond strength, therefore higher failure risk) Increase OVD using Dahl concept. Place restoration high in occlusion and allow dentition to reestablish occlusal contact over time (not appropriate if too excessive)

Clinical Considerations n Cementation Allows retention of RRB n Prevents microleakage n Increases fracture resistance n Always follow manufacturers instructions n n Lack of evidence to support which bonding system is best.

Clinical considerations Execute to high standard n Ensure appropriate lab support n Maintain and review n

Source: Dental update, March 2017, Volume 44. Number 3