Model demonstrations of tooth preparation rules

by Dr. Manish Agrawal

1-MAXILLARY CENTRAL INCISOR

11 minutes

Anterior teeth preparation presents numerous challenges- especially the maxillary central incisor. The preparation design needs to be well planned and should be in line with the final goal-whether it is increasing the length of the tooth, correcting a rotation, or repositioning the incisal edge in the final restoration.

Preparation areas, like the labial cervical area and the lingual plane area, can be tricky because we aim at obtaining a natural emergence profile and providing adequate clearance for restorative material to maintain natural jaw movements. The use of a putty index for assessing sufficient clearance has been shown in the detailed video demo on the model.

2- MANDIBULAR MOLAR

16 minutes

How to use a putty index and a measurement gauge to assess for appropriate interocclusal clearance has been demonstrated step by step on a model. Tooth preparation for a mandibular molar to receive an All-Ceramic restoration or metal-ceramic crown requires adequate clearance. The preparation design, especially in metal-ceramic restoration, needs to factor accommodating the metal layer, opaquer thickness and the final ceramic layer.

3- MAXILLARY CANINE

7 minutes

The toughest full crown for replication of anatomy and function by far is the maxillary canine. This cornerstone of your patient's smile requires to be prepared in different planes to maintain the anatomy and to provide adequate clearance to the technician to produce a natural-looking restoration. The lingual slope of the final restoration also decides the amount of disocclusion and forces on teeth and TMJ and hence is of great importance.

4- MANDIBULAR CENTRAL

7 minutes

Mandibular central incisors are one of the most difficult teeth for preparation. The small size of the tooth and many a clinical situation when attrition has set in, to provide sufficient clearance for the lab to work with is quite challenging. Model demo for tooth preparation designs for PFM and metal-free full crowns has been shown.

5- FPD- 3-UNIT BRIDGE

14 minutes

The parallelism between walls of individual abutments and the amount of taper of the preparation is of importance for a unique path of insertion when it comes to a 3-unit bridge. Adequate clarence and bevels on preparation design on functional cusps need to be incorporated.

6- ONLAYS or TABLETOPS

9 minutes

Tabletop restorations or Onlays are the most conservative treatment modalities when the intent is to raise vertical dimension while preserving maximum tooth structure. Deciding on the finish line, margin and depth of this preparation are critical for the bonded restoration that is planned. This video covers all the details of the same.

7- BURS, FINISH LINES AND MARGINS

9 minutes

Not only the shape, the size and the grit of a diamond bur is important but of equal importance is the angulation of the bur head while preparing any aspect of the tooth. This video focuses on how minimal number of burs in your inventory can work for all your tooth preparation needs. Specific applications of these burs during preparation for metal ceramic or All-ceramic restorations have been captured. The video highlights the types of finish line or margins of the preparation design and the bur used for the same.

A clinician can maintain a minimum inventory of burs to be able to efficiently carry out all types of tooth preparations whether metal-free or metal-ceramic restorations. While preparing the tooth, some standard rules need to be followed and these rules can be specific to specific shapes of teeth. It is not just the shape size or grit of the bur that is important but the knowledge of what role these 3 bur attributes play while preparing an aspect of the tooth is equally important. The angulation of preparation, the direction of movement, the amount of pressure given-all have been taught in this course.

The first six sections of the course are individual tooth preparations for full crowns namely-maxillary central, mandibular central, mandibular molar and maxillary canine and tooth preparations for a 3 unit bridge and also for conservative onlay preparations on premolar and molars demonstrated on models. Step by step reduction of planes, smoothening of edges and final position and design of finish lines has been closely described in these videos.

The last section is exclusively on burs, their application and proper use for efficient working.

Dr. Manish Agrawal

Dr. Manish graduated from Nair Dental College & Hospital, Mumbai and proceeded to do his masters in Prosthodontia from GDC, Mumbai. He has a flair for teaching, lecturing and research and conducts multiple courses for dentists.