Contemporary All-ceramic Systems – Part 2

Abstract

Advantages of all-ceramics over metal ceramic systems• Aesthetic advantages of all-ceramic systems are proved by replacing the light blocking metal substructure by more opaque high strength ceramic. • Wide range of patients' tooth shades ('value' in Munsell scale) can be satisfied.• Because of colour, finish line can be at gingival margin or 0.5 mm subgingival without compromising aesthetics.• All-ceramic systems have reduced thermal conductivity, resulting in less thermal sensitivity and pulpal irritation.• Because of lesser accumulation of bacteria on ceramic surfaces, it can be used over implants in the sub gingival area (20). • More biocompatible.• Emergent profile of all-ceramic crowns is less likely to be over-contoured. In vitro and in vivo dataAll-ceramic crowns/bridges The metal ceramic system is the longest studied FPD system; it would be better to compare the all-ceramic system with the data of metal ceramic system. Walton's retrospective study of 515 metal-ceramic FPDs showed the cumulative survival rate of FPDs was 96 % for 5 years, 87 % for 10 years, and 85 % for 15 years. Reported modes of failure for metal ceramic FPDs were tooth fracture (38 %), periodontal breakdown (27 %), loss of retention (13 %), and Caries (11 %) (24). In literature review there are 5 ceramic systems which were studied in detail. They are: a. Glass infiltrated alumina (In-ceram alumina, Vita). b. Leucite-reinforced glass (Empress, Ivoclare), c. Glass infiltrated magnesium aluminate spinell (In ceram spinell, Vita), d. Poly crystalline alumina (Procera, Noble Biocare) e. Zirconium-oxide Ceramics A reported failure rate appears to be lower for anterior crowns than molar crowns. The least amount of failure was reported for posterior restorations manufactured by high strength all-ceramic systems (All Ceram alumina; Procera, In-Ceram Alumina; Vita). Documented data is in agreement with reported data of metal ceramic systems. Long term follow up of newer Zirconium system results are widely expected. Selection criteriaAn ideal ceramic material for the fabrication of artificial replacement should allow for control of substrate colour Summary: Current all-ceramic materials offer a accepted level of fracture resistance, fit and aesthetics. High fracture resistance recommends it to be a material to support fixed partial denture (FPD) in a stress bearing area with clinical success. This part of the present literature review covers the success rate, selection criteria of all ceramic systems, cementation technique, finishing and polishing. In vitro and in vivo studies of new high strength ceramics were well documented. Data suggest that single crowns in the anterior and posterior region are more predictable than bridges. Well-studied longterm success rate for FPDs are very limited.

Replacement of missing lateral incisors with lithium disilicate glass‐ceramic veneer‐fixed dental prostheses: a clinical report

“…Moreover, the full‐anatomic design gives the prosthesis an additional strength rather than building layering porcelain over a framework . IPS e.max glass‐ceramic has high bond strength to resin cement compared to oxide ceramics . All these factors encourage the use of this kind of ceramic in fabricating all‐ceramic veneer FDPs.…”

“…Contrary to oxide ceramics, IPS e.max, which is a silica‐based lithium disilicate ceramic, is an etchable ceramic. Therefore, a strong and durable resin–ceramic bond can be obtained by hydrofluoric acid etching and silane application . This clinical report describes the use of veneer FDPs made from a lithium disilicate glass ceramic for the replacement of two congenitally missing maxillary lateral incisors.…”

Advances in dental veneers: materials, applications, and techniques

“…At this stage, care must be taken to avoid contamination with saliva and breath moisture, which can reduce the surface energy of the enamel. Therefore, isolation with a rubber dam is highly recommended, which lowers stress input during the clinical procedure 32. While the etching of enamel with phosphoric acid leads to a “frosty” surface – a sign of a successful procedure, because of its inorganic composition and perfect etchability – the effect of dentin-bonding agents on dentin is difficult to control, due to its different composition of inorganic and organic parts and tubular structure.…”

Advances in dental veneers: materials, applications, and techniques

“…Therefore, isolation with a rubber dam is highly recommended, which lowers stress input during the clinical procedure. 32 While the etching of enamel with phosphoric acid leads to a "frosty" surface -a sign of a successful procedure, because of its inorganic composition and perfect etchability -the effect of dentin-bonding agents on dentin is difficult to control, due to its different composition of inorganic and organic parts and tubular structure. It is difficult to obtain the correct dryness or wetness of the surface, which is elementary for a successful bond.…”