Comparative evaluation of CAD-CAM milled custom made Polymethyl methacrylate crown and custom made Zirconia crown in primary maxillary incisors in 3-6 year old children – A Split mouth Randomized clinical study.

•       At the start of the study, 38 patients will be selected according to the inclusion and exclusion criteria after acquiring consent from the parents.

•       38 patients will be divided into two groups randomly, 19 patients each (19 teeth on right and 19 on the left)

Group A- CAD-CAM milled custom made Polymethyl methacrylate crown

Group B- CAD-CAM milled custom made Zirconia crowns

 Brief medical and dental history of the patient in the presence of child’s parent or guardian will be recorded. For every selected patient oral prophylaxis will be performed.

•       After the teeth selection, caries excavation would be done followed by tooth preparation. In both the groups, principles followed for the tooth preparation will be similar.

GROUP A :

Tooth will be prepared to receive CAD-CAM milled custom made Polymethyl methacrylate crown.

A coarse tapered round diamond bur will be used to reduce the incisal edge, mesial, distal, labial and palatal surfaces by 1mm. A torpedo diamond bur will be used for preparing a thin chamfer margin placed equigingivally. The finishing of the tooth preparation will be done by using a fine tapered diamond bur. After the tooth preparation is completed, maxillary impression will be made by using condensation silicone impression material and mandibular impression by using alginate impression material. The impressions would be poured by using dental stone and the casts made would then be retrieved and trimmed accordingly. The casts would be sent to the dental laboratory for fabrication of crown on the respective teeth. The fabricated crown will then be completely air dried and filled with Type I luting Glass Ionomer Cement and cemented. Excess of the cement was removed using an explorer and floss

•       In GROUP B:

Tooth will be prepared to receive custom made Zirconia crown. A coarse tapered round diamond bur will be used to reduce the incisal edge, labial palatal, mesial and distal surfaces by approximately 1-1.5mm. A torpedo diamond bur will be used to provide a deep chamfer finish margin which would be prepared supragingivally.  The finishing of the tooth preparation will be done by using a fine tapered diamond bur. After the tooth preparation is completed, maxillary impression will be made by using condensation silicone impression material and mandibular impression by using alginate impression material. The impressions would be poured by using dental stone and the casts made would then be retrieved and trimmed accordingly. The casts would be sent to the dental laboratory for fabrication of crown on the respective teeth. The fabricated crown will then be completely air dried and filled with Type I luting Glass Ionomer Cement and cemented. Excess of the cement was removed using an explorer and floss.

Standard postoperative instructions, including oral hygiene guidelines and dietary requirements, such as avoiding sticky foods to prevent the dislodgement of crowns were given

•       The evaluation of the teeth restored with crowns at follow-up visits will be done at 1 month, 3 months and 6 months respectively by calibrated examiner. The patients will be evaluated clinically according to the following criteria:

a.     Gingival health -Loe H and Silness P Index (1963)

b.     Plaque accumulation-Silness P and Loe H Index (1967)

c.     Parental acceptability- 5 point Likert scale

d.     Restoration failure- USPHS Alpha rating criteria(1980)

e.     Marginal integrity-  Modified USPHS Alpha rating criteria

The absence or presence of these evaluation criteria at the end of 1 month, 3 months and 6 months will be used for determination of cumulative success and failure of crowns respectively