Management of Tooth Surface Loss of Varying Etiology with Full Mouth all Ceramic Computer-Aided Design/Computer-Aided Manufacture Restorations.

The anatomical form of a tooth can undergo changes leading to loss of tooth form. The loss of tooth surface can be due to varying etiology. Dental caries, attrition, abrasion, erosion, involving any surface of the tooth can lead to loss of tooth structure. The rate of tooth destruction may proceed to such an extent that the esthetics, function and comfort may be lost. The role of a practioner lies in identification and screening of such case and motivate for oral rehabilitation that includes habit cessation. Computerized dentistry has raised the bar as far as esthetic restorations are concerned. Demanding esthetics has made zirconia crowns as the material of choice in full mouth rehabilitations. However, appropriate treatment planning with scientific evidence and a recommended treatment protocol with careful implementation results in successful restorations and satisfied patients.

INTRODUCTION

In modern day dental practice, the demand for esthetic restorations has witnessed a rapid increase. This is largely met with advances in materials and techniques.[1] With the introduction of computer-aided design/computer-aided manufacture (CAD/CAM) dentistry, earlier laborious have become simplified.[23] Computerized dentistry has raised the bar as far as esthetic restorations are concerned.[4] The ease of impression making and the time saved has changed the repertoire available to the prosthodontist. The anatomical form of a tooth can undergo changes leading to loss of tooth form. The loss of tooth surface can be due to varying etiology.[5] Causes of tooth surface loss are caries, attrition, abrasion, erosion, involving the occlusal, palatal, lingual, or the buccal surface. Several systemic disorders and habits such as gastrointestinal disorders and bruxism have been related to this type of tooth loss. Depending on the severity of habits, rate of attrition differs and thereby the symptoms vary. The rate of tooth destruction may proceed to such an extent that the esthetics, function, and comfort may be lost.[6] The role of a practioner lies in:

Identification/screening of a case

Patient may or may not be aware of the ongoing pathology. Patients tend to report only when symptoms such as discoloration, tooth disfiguration, muscle soreness, headache, and shoulder ache is clinically evident. A temporomandibular joint (TMJ) examination is mandatory if a generalized tooth surface loss is evident.

Confirming loss of vertical dimension

This is well appreciated by measuring the loss of vertical dimension if noncarious tooth surface loss is the contributing etiology. However, any clinical symptoms are confirmed with relevant investigation procedures, namely, radiographs, etc.

Etiology

History of a patient plays a dominant role in identifying the etiology. Not all patient's report the history and habits, as a few may not even be aware of the habits, for example, nocturnal bruxism.

Drafting a treatment plan

The role of the practitioner is to identify the symptoms as localized or generalized. Generalized tooth destruction should alert the prosthodontist. Patient with minimal attrition and/or erosion can be advised of about their habits cessation by counseling, dietary advices, habit breaking appliances, or a combination of these. However, severe cases are indicated for full mouth rehabilitation with appropriate treatment planning. The following case series details tooth surface loss of varying etiology and habits and their management by full mouth rehabilitation with all ceramic esthetic restorations using CAD CAM technology.

CASE REPORTS

Case 1

A 44-year-old male patient reported to the Department Of Prosthodontics with a complaint of severe sensitivity pertaining to his posterior teeth and generalized discoloration of his teeth. The patient's history did not reveal any habits pertaining to his complaints, but his spouse reported about night grinding habits. Extraorally no loss of vertical dimension was noted [Figure 1a and b]. On intraoral examination, severe attrition of posterior teeth was noted. Mild attrition was noted in the anterior teeth [Figure 1b, 1c and 1d]. This case was diagnosed according to Turner and Misserlian classification[7] as category 2. The patient was referred to the Department Of Endodontics for opinion on sensitivity and discoloration. As per patient's request, a more conservative method of management was preferred initially. Hence, root canal for the sensitive teeth and bleaching of all the anterior teeth was done to improve esthetics. The patient reported with a severe sensitive condition in his posterior teeth 3 months later and was dissatisfied with the bleaching. By then, the rate of attrition had not changed as measured at 36 and 13. Root canal for the posterior teeth and subsequent crowns were thought to be a more appropriate treatment plan. The loss of vertical dimension was assessed. Although there was no clinical evidence of volume of distribution (VD) loss, the patient had a freeway space of 4 mm but restoring posterior teeth alone would have resulted in a more esthetic anterior open bite. Hence, it was decided to prepare anterior teeth as well. Face bow transfer was done, and the diagnostic casts were articulated. Then a diagnostic wax up was done for provisional restoration at existing vertical dimension [Figure 1e-g]. Tooth preparation was done, retraction cords were placed and an optical impression was made with Cerec 3 system (sirona dental systems) [Figure 1h and i]. Centric relation was recorded using extra oral tracing. Zirconia copings were fabricated with CAD/CAM designing and milling and tried in the patient's mouth [Figure 1j and k]. After verifying the fit of the copings, full tooth morphology was created using D’sign ceramic material (Ivoclar-Viva). Apreglaze verification was done to evaluate esthetics and occlusion. Final glazing was done and the crowns were cemented with a Rely-X 3M resin cement [Figure 1l and m]. A soft splint was advised postinsertion as a precautionary measure and the patient followed up for 1 year. At 1-year posttreatment, the patient had no complaints of sensitivity and was satisfied with the esthetic crowns

Figure 1

(a) Extra oral appearance, (b-d) intraoral view with attrition, (e) diagnostic wax up, (f and g) provisional restoration, (h and i) digital impression, (j and k) Zirconium coping trial to verify the marginal fit, (l) final Cementation, (m) posttreatment smile

Case 2

A 45-year-old patient reported with a complaint of difficulty in chewing and tooth loss occurring gradually over a period of 6 years. No relevant medical history was reported. The clinical situation was more suggestive of habitual history, but the patient reportedly had no history of bruxism, chewing hard foods, or gastrointestinal disorder. The patient could not correlate his problem with his habits or may be unaware of it. No evidence of loss of vertical dimension extra orally [Figure 2a]. On intraoral examination, severe noncarious tooth surface loss, with multiple fixed partial denture on remaining teeth was noted [Figure 2b]. Worn out fixed partial denture was indicative of severe grinding of teeth. The severity of tooth loss did not correlate with the patient's history. The loss of VD was determined by the jaw relation procedure. A definitive diagnosis of Turners and Missirlian classification category 3 was arrived. Since the patient was concerned about esthetics, ceramic restoration with zirconium coping was the material of choice. To get crown height and sufficient resistance form for the restoration a decision to increase the vertical dimension was made. A hard splint was adviced to deprogram the muscle. After 6 weeks, the patient was recalled. Any tenderness in the TMJ region was evaluated. After confirmation of asymptomatic TMJ, diagnostic wax up [Figure 2c] was done. An orthopantograph revealed no pathology in the periodontium. Inadequate crown heights necessitated the need for intentional root canal treatment for multiple tooth and crown lengthening procedure. Endodontic treatment was done for the anterior teeth. Crown lengthening was performed for lower incisor teeth [Figure 2d]. Full mouth tooth preparation was done. Heat cure acrylics were used for temporization [Figure 2e and f]. Retraction cords were placed and optical was made with cerec 3 system. Zirconia copings were fabricated and verified for marginal fit. For crowns with endodontic postmetal copings were fabricated. Ceramic veneering and preglaze trial were done. After verifying the contacts and esthetics, final cementation [Figure 2g and h] was done with Rely X resin cement and followed for 1 year.

Figure 2

(a) Extra oral profile, (b) Intra oral view, (c) diagnostic waxup, (d) endontics and crown lengthening, (e and f) temporization done, (g) final cementation, (h) posttreatment profile

DISCUSSION

The use of CAD CAM has largely eased the tedious impression making procedure in full-mouth impressions. The time consumed for impression making and fabrication of the zirconia copings was much lesser than the routine laboratory procedures that involve fabrication of metal copings. The comfort of the patient was satisfactory as well as the number of appointments has been reduced due to use of the CAD/CAM.[8] However, fluid control and access to the posterior teeth was difficult to obtain. The marginal fit of the copings were verified, and the coping with marginal discrepancy were repeated to achieve a good marginal fit. In case 2, teeth treated with endodontic post were given metal copings. Demanding esthetics has made zirconia crowns as the material of choice in full mouth rehabilitations with decreased vertical dimension. The strength of zirconia in cases of heavy masticatory and para functional forces and the adhesion of veneering ceramic to zirconia has always remained a topic of interest to scholars.[9] Zirconia restorations have been indicated in such cases with good survival rates.[1011] The compressive strength of Zirconia is higher than the alloys and can be undoubtedly indicated in cases of bruxism.[12] However, the bonding of ceramic to the zirconia has resulted in higher debonding rates and chipping, fracture of ceramics which have been documented as a cause of failure[13] in all ceramic restorations. The full mouth rehabilitation of patients with para functional forces using all ceramic restorations have remained a controversy in the past.[14] However, a few cases of successful restoration with higher survival rates have been reported.[15] Another disadvantage of CAD/CAM restorations were the marginal discrepancy of the copings. However, with meticulous designing, this disadvantage could be avoided. The above cases were advised soft splints for period of 6 months and were reviewed every month for up to 1 year. After 1 year, the cases are being reviewed at 3 months intervals. The choice of veneering ceramic meticulous veneering technique and periodical reviews can overcome the disadvantages of CAD/CAM ceramics and enhance the survival rate of the restorations.

CONCLUSION

Full mouth rehabilitation has become technically less complex with CAD/CAM. The use of computerized dentistry for full mouth rehabilitation has increased patient satisfaction due to increased comfort and decreased chair side time. However, appropriate treatment planning with scientific evidence and a recommended treatment protocol with careful implementation results in successful restorations and satisfied patients.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.