Comparative evaluation of clinical andradiographic success, gingival health and adhesion of S.Mutans to stainless steel and zirconia crowns in primary molars: A split mouth clinical trial study.

NEED FOR STUDY:

Preservation of primary teeth is essential to ensure normal development of the child. Deeply decayed primary teeth require endodontic treatment and comprehensive restoration. Stainless steel crowns are widely used and are very popular in paediatric dentistry due to its superiority and durability compared to multi surface amalgam restorations. However, the major disadvantage is poor esthetics. Aesthetic management of primary teeth has become essential, as parents are more involved in the clinical

decision-making and are more demanding of aesthetic restorations. Zirconia crowns have been used for over two decades in permanent dentition with high acceptability. In 2008, EZ Pedo introduced the first commercially available paediatric zirconia crown. Advantages of zirconia crown are excellent aesthetics, biocompatibility and full coverage of the treated tooth. Adhesion and colonization of oral microbes on tooth surfaces and restorations is crucial in the development of secondary caries and periodontal disease. Hence, evaluation of S. mutans adhesion to tooth surfaces and restorative materials is of most importance for their success. Keeping in mind the paucity of literature, this study is designed to explore clinical and radiographic success, gingival health and adhesion of S. Mutans to zirconia crowns against the Stainless-Steel Crowns in primary molars.

Research Question: Are Zirconia crowns better than stainless steel crowns in terms of clinical and radiographic success, gingival health maintenance and lowered adhesion of S. Mutans in primary molars?

Research Hypothesis: Zirconia crowns are better than stainless steel crowns in terms of clinical and radiographic success, gingival health maintenance and lowered adhesion of S. Mutans in primary molars.

METHODOLOGY:

• 25 children of age group 6-9 years who fulfil the inclusion criteria will be enrolled for the study, procedure will be carefully explained and informed consent will be obtained from parents.

• A split mouth design will be adopted where all patients will receive Stainless steel crowns (Group A) and Zirconia crowns (Group B) on either side primary mandibular molars which will be randomly assigned.

• Oral prophylaxis will be done prior to crown placement and oral hygiene instructions will be given and reinforced at every visit.

• The tooth preparation and crown placement will be done by a single operator trained in the field of Pediatric dentistry.

• Local anesthetic will be administered prior to preparation of the tooth in both Group A and Group B.

• Occlusion will be checked followed by rubber dam application.

• Group A- Tooth preparation for Stainless Steel crowns (SSC) will be done by reducing the occlusal surface uniformly by 1–1.5 mm using a No.169L bur. The interproximal reduction of the mesial and distal surfaces will be done using the long-tapered bur. The line angles will be rounded off. The buccal and lingual surfaces will not be reduced as they serve as a retentive feature. A feather edge finish line will be given. The SSC will be selected by trial-and-error method. The crown will be trimmed accordingly using a green stone bur. The crown will be adapted by contouring and crimping with the use of pliers. Once the snap fit is obtained, the crown will be cemented using Type I GIC. Consistent finger pressure will be placed while waiting for the cement to set. The

excess cement will be removed with a sharp explorer buccally and lingually and with the help of dental floss proximally, and the occlusion will be checked.

• Group B, Crown size will be selected according to the mesiodistal width of the teeth prior to crown preparation. Occlusal reduction of 1 to 1.5 mm will be done using No.169L bur. Tapered diamond bur will be used for proximal reduction. The tooth will be trimmed circumferentially by 0.5 to 1.25 mm as per requirement. Feather edge finish line will be given. The point angles and line angles will be rounded with 169L bur and trial fit of the crown will be done. Followed by cementation with dual cure resin cement according to manufacturer’s instructions.

• The performance of the 2 crowns will then be evaluated for clinical success and gingival health at 1,3,6 and 12 months follow up respectively. The crowns will be evaluated for clinicals success and gingival health using customised scoring criteria prepared using previous studies.

Crown retention

0 = yes

1 = no

|Stain resistance

0 = no change

1 = minor staining

2 = noticeable staining

|Surface abrasion of the antagonist teeth

0 = no abrasion

1 = minor abrasion of the cusps

2 = abrasion more than on the cusps

|Position of the crowns regarding gingival margin

0 = subgingival

1 = supragingival

|Occlusion

0 = contact (marked or superficial)

1 = no contact

|Location on the arch curve

 0 = normal

1 = with rotation

2 = wrong position

|Proximal contacts

 0 = good (floss passing)

1 = weak contacts

2 = no contact

|Gingival index

0 = normal gingiva

1 = Mild Inflammation

2 = Moderate Inflammation

3 = Severe Inflammation

|Plaque index

0 = no plaque

1 = a thin film of plaque adhering to free gingival margin

2 = moderate plaque adhering to free gingival margin

3 = abundance of plaque adhering to free gingival margin

·  Radiographic examination will be done using bitewing radiographs. A standardized angulation of the X-ray will be applied using the Rinn  XCP positioning device. Radiographic success will be measured at placement and 12 months, using following scoring criteria:

Radiographic evaluation of pulpal treatment

0 = appropriate treatment

1 = short

2 = overflowed root canal treatment

|Radiographic evaluation of crown margins

0 = Well adapted at CEJ

1 = Too short of CEJ

2= extending beyond CEJ

|Radiographic evaluation of presence of pathology

 0 = healthy, no pathology

1 = presence of a pathology that does not require immediate treatment

2 = presence of pathology requiring immediate treatment

Assessment of S. Mutans adhesion to stainless steel crowns and zirconia crowns:

• Plaque sample will be collected with sterile cotton swabs from buccal and occlusal surfaces of both

the crowns.

• Swabs will then be immersed in 1mL phosphate buffered saline and stored at 40C and transported

to the laboratory in transport containers.

• Prior to plating, the sample will be vortexed and serially diluted. 0.1mL of this diluted sample will

be inoculated and plated on to TYCSB (Tryptone-Yeast-Cystine-Sucrose-Bacitracin) Agar. The

plates will be incubated at 370C in 5-10% CO2 for 48hrs. The number of Colony Forming Units

(CFU) will then be counted manually.