Enhanced aesthetics with all ceramics restoration.

The demand for the dentist to achieve excellence in esthetics and function has driven modern advances in materials and restoration fabrication. The development of various casting alloys and precise casting systems has contributed to the successful use of metal-based restorations. However, patient requests for more aesthetic and biologically "safe" materials that have led to an increased demand for metal-free restorations. The following case presentation illustrates a successful aesthetic and functional application of this exciting computer-aided design/computer-aided manufacturing-digital zirconia-based system for a natural smile.

Dentistry has undergone a revolution in the last 30 years, not only with regard to the introduction of new materials and techniques, but also with regard to the scientific evidence supporting their clinical applications. As ceramic materials for dentistry evolve and as patient's demand for esthetic restorations increases, practitioners must keep up with the science as well as the demand of the patients.[1] Proper guidance to the practitioner is required in selecting the appropriate system for crowns as well as the knowledge of the optical properties of available ceramic systems, which will enable the clinician to make appropriate choices when faced with the various esthetic challenges.

Recent innovations in the strengthening of dental ceramics have led to the development of new ceramic restorative systems for the direct application of porcelain on an opaque ceramic base instead of on a metal framework. The various new ceramic restorative systems generally can withstand relatively high compressive forces and offer a range of flexural strengths.[234]

Full ceramic crowns with opaque cores are superior in strength, with good esthetics, and can be used for posterior teeth as well as for the anterior teeth with heavy discoloration. Crowns with the zirconia core are recommended for fixed partial dentures. One can use resin or conventional luting agents for cementation as the color of the cement will not affect the shade of the crown. When restoring anterior teeth with these crowns, it is advisable to end the margin subgingivally as there could be a mismatch in shade between the tooth margin and the restoration. The strength of these restorations is dependent on the ceramic material used, the core-veneer bond strength, the crown thickness, and the design of restoration.[5]

The following case report describes the restoration of both upper and lower central incisors, lateral incisor, canines and illustrates a successful aesthetic and functional application of this exciting digital zirconia-based system for a smile makeover.

Case Report

A 30-year-old young male patient reported to our Department of Prosthodontics. On intraoral examination, there was protrusion of both upper and lower anterior teeth with spacing. The dental history revealed that the spacing is present from the past 3 years [Figure 1].

Figure 1

Preoperative

Treatment plan

Different treatment options were presented to the patient. Because of the large-sized space and completely flared upper and lower anterior teeth, the patient was informed of the guarded prognosis of these teeth [Figure 2a–c]. He was thus offered the option of extracting the upper incisors and for lower central incisors root canal treatment. The patient was offered a smile makeover through computer-aided design (CAD) computer-aided manufacturing (CAM) ceramic restoration.

Figure 2

a: Intraoral frontal b: Intraoral right lateral c: Intraoral left lateral

In order to address the patient's chief esthetic concerns, the plan included the following elements: Development of a diagnostic mock-up on the study casts to evaluate proper tooth morphology and tooth length for better esthetics and proper gingival contours [Figure 3]. This was presented to the patient to assist in determining the course of treatment.

Figure 3

Wax mock-up

Preparation and provisionalization

As an initial step, tooth No. 11 and 21 was extracted. Preliminary impressions were taken before and after extraction to create study models. Teeth preparation was done in relation to 12, 13, 22, 23, 31, 32, 41 and 42 for all ceramic restoration [Figure 4]. After preparation impressions was made using elastomeric impression material with two stage double mix technique for both upper and lower arch [Figure 5]. An interocclusal record was made using bite registration material. Provisional restorations were fabricated with a tooth colored auto polymerizing acrylic resin and cemented with noneugenol temporary cement [Figure 6]. Then dies were made from final impression and dies of prepared crowns were scanned in scanner ceron - eye: Dentsply (Australia) Pvt Ltd the dimensions and shape of zirconia copings on three dimensional images of maxillary lateral incisors and canines, mandibular central incisors and lateral incisors were modified and finalized with the help of cercon-art. The saved data was then sent to the milling machine (Cercon-brain): Aidite high - technical ceramics Co. Ltd for fabrication of copings for prepared teeth.

Figure 4

Tooth preparation

Figure 5

Final impressions maxillary and mandibular

Figure 6

Temporization

After 2 days, temporary crowns were removed then all-ceramic coping trial was done; and after 1-week, temporary crowns were removed and internal fit of all-ceramic restorations was evaluated intraorally with a disclosing agent and occlusion was assessed in intercuspal and excursion position. The crowns were cemented with self-etch unicem luting cement [Figure 7]. Patient was satisfied with the crown length, width and esthetics which was improved and equal to adjacent natural teeth [Figure 8].

Figure 7

Final restoration

Figure 8

Postoperative

Discussion

Many all-ceramic systems are available. Out of all these zirconia all-ceramic crowns were selected in this case. Heffernan et al.[6] suggested that zirconia restoration would be better suited to match opaque, high-value teeth. In this study, the translucency of several all-ceramic systems was compared under transmitted light, and the zirconia system was found to be as opaque as the metal ceramic. There are other restorative systems available that use zirconia for fabrication of coping. One of them is DCS smart-fit is a CAD/CAM system that utilizes fully sintered yttrium-tetragonal zirconia polycrystals (Y-TZP) under the hot isotonic pressure. This result in an extremely hard and dense ceramic that require mill time of around 2–4 h for coping.[7]

In contrast dens system crown employ partially sintered Y-TZP milling blocks that are weak but easy to mill. One other system (Inceram Zirconia, Vident, Ivoclar, Vivadent. USA) employs a glass-infiltrated 35% zirconia 65% alumina material for fabrication of posterior crown and fixed dental prostheses that can be slip cast or milled from presintered blocks. Its flexural strength is about 620 MPa,[8] which is lower than that reported for densely sintered zirconia.

Conclusion

Happiness is a state of mind. It is brought about by a feeling of well-being, security and confidence in one's self. The dentist should render the patient, the confidence that none of these fine senses will be in jeopardy. The development of a pleasing oral and facial expression for the patient depends upon the dentist ability to replace the missing teeth, both in contour and color especially for the anterior teeth.