Unlike composite, porcelain restorative materials are mostly made of glass particles which give them characteristics of high durability without flexibility (i.e. very brittle) and with limited wearability. Due to its strength, porcelains are employed in medium to large restorations where there is an inadequate sound tooth structure for support. Like composite, when porcelain restorations are properly designed and utilized, they have been shown to increase strength and integrity of the restored tooth to that of its original unprepared tooth. Porcelain restorations can also be layered, stained, and glazed to better mimic natural tooth characteristics. The following Before and After case photographs exemplify the use of porcelain restorative material.
Pre-operative: Existing amalgam restoration composing of metal alloy which expends and contracts with change in temperature within oral cavity results in the fracture of this tooth. Amalgam also contains mercury which is known to be a toxic substance although the amount of mercury ingested during the chewing cycle is unclear in literature. Fracturing of teeth from amalgam restoration is a very common occurrence and it is directly proportional to the size of the restoration (i.e. the greater the volume of amalgam restoration occupied within the tooth, the greater the chance that the tooth will be fractured). At times, the fracture can be so extensive that the tooth can no longer be salvage.
Post-operative: Following removal of the failing amalgam restoration, the tooth was conservatively restored with porcelain onlay. This restoration is conservative because it only requires refinement of the remaining tooth structure, and it is far superior to amalgam restoration because of its physical properties which are similar to tooth but also because of its ability to strengthen the remaining tooth structure through bonding and thereby reestablishing the integrity of the tooth. With today's technology, every step must be taken to increase the longevity of the tooth by being conservative and this type of restoration is not only conservative but it is predictable.
Pre-operative: Failing amalgam restoration with recurrent caries requiring replacement of restoration.
Design of the onlay restoration is generated in reference to the anatomical features of the tooth and the opposing tooth.
This tooth has a prior history of root canal therapy with severely broken down existing large occlusal composite restoration. Given that this tooth is nonvital and has lost a significant amount of tooth structure, it would not be predictable to restore this tooth with another composite restoration but instead it will be more prudent to restore this tooth with porcelain restoration which will allow it to regain its strength and integrity.
Every cosmetic dentist understands the difficulty in restoring a single maxillary incisor in order to achieve a seamless integration of the restoration with the rest of the natural dentitions in the smile zone. This patient has a small maxillary right lateral incisor which was enlarged with a composite as a child and is looking for options to have more definitive treatment to obtain better esthetics. He also has significant incisal wears on all canines of maxillary and mandibular dentitions without any wear facets on any of the posterior teeth indicating the possibility of nocturnal parafunctional habits.
In order to develop proper width and length of the lateral incisor, the worn incisal edges of the canines must be restored and the development of proper functional and occlusal scheme must be established. Due to increased longevity of the porcelain restorations, the lateral incisor was restored with porcelain veneer using CEREC Technology. The macro anatomy was developed during the designing phase of the restoration and the micro anatomy involving integration of characterizations from adjacent teeth was obtained through detailed staining and glazing which allows seamless integration of the restoration in the smile zone. The incisal edges of the canines were then conservatively restored with composites to meet both the functional needs and cosmetic demands of the veneer. Finally, occlusal guard was fabricated to protect the newly fabricated restorations from destructive nature of parafunctional habits. This case demonstrated the use of CEREC Technology and conservative treatment with proper diagnosis in achieving a successful functional and esthetic results.