M.O.D Ceramic onlay, a Case Study

M.O.D Ceramic Onlay: A Case Study

The procedures done for the restoration of tooth number 45 were those of an all ceramic M.O.D onlay piece, and as described in the case study, the proposed treatment techniques conserves the remaining tooth structure, reestablishes function, offers satisfactory esthetics, and be considered as an alternative restoration.

For patients demanding aesthetic restoration, ceramic onlays provide a durable alternative to posterior composite resins. Dental ceramics are considered to be esthetic restorative materials with durable characteristics, such as translucence, fluorescence, and chemical stability.1,2 They are also biocompatible, have high compressive strength, and their thermal expansion coefficient is similar to that of tooth structure.3 Marginal leakage of the resin is reduced, because the luting layer is relatively very thin. A ceramic onlay is indicated for patients with a low caries rate, who have worn or carious teeth with intact buccal and lingual cusps, caries lesions not to deep into the dentin; and patients wishing to restore the tooth to its original appearance. An onlay allows the damaged occlusal surface to be restored in the most conservative manner and enables the remaining enamel to be preserved.4 Due to the improvements of the materials, fabrication techniques and bonding systems, ceramic onlays have become popular to the public demands for esthetics, and as a durable restorative material. Among ceramic materials used today are feldspahtic porcelain, castable ceramics (DicorR) and new machine glass ceramic ( Dicor R DIGG) for use with CERECR system.

Clinical Report

Oral Diagnosis

Mrs. Prisclila M. Nirvaha, a 50 year old female patient, was referred to C.E.U dental infirmary for dental treatment. She had complained of having tooth sensitivity when drinking cold beverages but the sensitivity would immediately subside when stopped, of which was first observed approximately three months ago. Past medical history was unremarkable. Though, family history reveals a history of diabetes. Upon clinical examination (fig.2), the patient demonstrates fair oral hygiene, moderate calcular deposits, with a number of small insipient caries lesion, abraded incisal edges on the her anterior teeth and a wide bucco-lingual cavity with caries occlusally on tooth number 45. Radiographic interpretation (fig.1) had yielded that the lesion does not extend too deeply into the dentin, the lamina dura was intact and the periodontal ligament was continuous making it a good candidate for a M.O.D. ceramic onlay restoration.

Fig. 1. Bite wing radiograph Fig. 2. Oral diagnostic chart

Mouth Rehabilitation

Prior to tooth preparation, the patient underwent mouth rehabilitation , which included: 1. Oral Prophylaxis 2. Extraction of root fragments (15. 44, and 27) and 3. Restoring teeth with carious lesions (18, 16, 26 , and 28). She was then instructed to rinse her mouth with Povidone-iodine (BetadineR) twice a day and take mefenamic acid as needed to relieve pain. Four days after, the patient returned to begin the proposed treatment plan for a ceramic onlay restoration. No pain or swelling were reported.

Fig. 3. A preoperative picture of Fig 4. A study cast of the patient,

tooth number 45. note the wide extent of the cavity buccally

and lingually.

Local anesthesia was administered labially, palatally, and interligamentary on tooth number 45. The tooth was then cleaned with pumice and water and isolated with a rubber damn.

Tooth Preparation

Preparation of the outline form was commenced by penetrating the central groove just to the depth of the dentin which in this case was approximately 1.7mm with a ј round bur held on the path of withdrawal of the onlay. A tapered carbide bur was then used to extend the outline mesially and distally to the height of contour of the ridge. The boxes of the M.O.D. onlay were prepared by advancing the bur gingivally and then buccally and lingually, no amount of proximal enamel remained since no adjacent tooth was present. The walls were then smoothen with the use of hand instruments. Flaring of both the boxes' labial and lingual proximal walls were prepared as well. Sharp line angles between the occlusal outline and proximal box were rounded. Remaining caries were excavated with the use of a spoon excavator.

Occlusal reduction was done by preparing the functional cusp with a straight tapering diaomond bur. Reduction was 1.3 mm deep, allowing 0.2mm for smoothing. While on the non centric cusp 1.0mm was reduced. A 1.0mm centric cusp ledge was prepared with a cylindrical carbide bur. It was extended into the proximal boxes. It was not positioned too far apically; otherwise resistance form of the boxes would have been lost. Occlusal reduction was checked by having the patient bite into soft bite wax and measuring with a prosthodontic caliper to verify sufficient clearance. A measurement of 1.7mm was observed. A 90 degree butt-joint cavo-surface margin was used along with a heavy chamfer on the centric cusp ledge.

Fig.5. Labial view of the tooth Fig. 6. Occlusal view of the tooth

preparation preparation

Impression Taking

Impression of the lower arch was done with the use of a condensing silicone (ZetaplusR Zhermack) while the upper arch was impressed with a reversible hydrocolloid (ReplicaR). after taking an impression, the prepared tooth was then filled with a temporary filling restorative material (IRMR, Dentsply) till fitting of the final restoration. A master cast of the lower arch was produced by using die stone, while plaster of paris was used for the upper arch. Casts were then articulated in a simple type of articulator under the record of a bite wax.

Fig. 7. Impression of tooth preparation Fig.8. Impression materials used

using a condensing