Abstract
A four-year follow-up of a novel silane heat treatment method for bonding lithium disilicate overlays to tooth structures without hydrofluoric acid etching of the ceramic surface is presented in this case report. Silane heat treatment modifies the silane layer and thus enhances resin ceramic bond strength without hydrofluoric acid etching. The standard ceramic preparation technique prior to bonding silicate ceramics to tooth structure is hydrofluoric acid etching and applying a silane coupling agent, followed by dental adhesive. In this case, the micromechanical roughening of the ceramic surface was performed by air abrasion with Al2O3. Silane heat treatment with constant 120°C airflow, applied for 60 sec, followed by dental adhesive application enhanced the resin-ceramic bond strength. After a four-year follow-up, the restorations' clinical appearance could be defined as excellent/very good according to the FDI clinical criteria for the evaluation of direct and indirect restorations. This clinical result supports many in vitro studies regarding the resin-ceramic bond strength and durability obtained through postsilanization heat treatment.
Highlights
Lithium disilicate (LiS2) is one of the most widely applied metal-free materials due to its high aesthetics, adequate mechanical properties, and favorable bonding strength, ensuring functional durability and high short- and medium-term survival rates [1,2,3,4]
No secondary or primary caries, very good periodontal response, healthy mucosa, and no general oral symptoms (Figure 5). This clinical result supports many in vitro studies regarding the resin-ceramic bond strength and durability obtained through postsilanization heat treatment
A recent study conducted a systematic comparison between different postsilanization heating temperatures. It showed the positive effect of higher temperatures on the bond strength between feldspathic ceramics and resin composite material [21]
Summary
Lithium disilicate (LiS2) is one of the most widely applied metal-free materials due to its high aesthetics, adequate mechanical properties, and favorable bonding strength, ensuring functional durability and high short- and medium-term survival rates [1,2,3,4]. LiS2 has shown promising clinical results for posterior endodontically treated teeth with or without fiber posts [7] These restorations’ success depends on many factors—tooth preparation, presence of enamel, bonding procedures, and material selection [8, 9]. The application of a silane coupling agent ensures chemical interaction between the ceramics and the adhesive resin [10]. A 120°C heating temperature of the silane was presented [21] This temperature was the most efficient treatment method, providing the highest bond strength among all heating temperatures. HF’s effect in the bonding procedure could be compensated by micromechanical roughening of the ceramic restoration and silane heat treatment to obtain high bond strength [17, 18]. Bonding procedures made from LiS2 without HF etching and a 4-year follow-up
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