Textbook of Preclinical Conservative Dentistry Nisha Garg, Amit Garg
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Introduction to Preclinical Conservative DentistryCHAPTER 1

Nisha Garg
CHAPTER OUTLINE
  • → Introduction
  • → Causes of Loss of Tooth Substance
  • → Objectives of Operative Dentistry
  • → Objectives of Preclinical Conservative Dentistry
  • → Armamentarium
  • → Preclinical Tooth Preparations
  • → Viva Questions
 
INTRODUCTION
“Operative dentistry is science and art of dentistry which deals with diagnosis, treatment and prognosis of defects of the teeth which do not require full coverage restorations for correction. Such treatment should result in the restoration of proper form, function and esthetics while maintaining the physiologic integrity of the teeth in harmonious relationship with the adjacent hard and soft tissues, all of which should enhance the general health and welfare of the patient”. It plays an important role in enhancing dental health and now branched into dental specialties. But before practicing operative dentistry, one should understand the concept of tooth preparation because operative dentistry deals with diagnosis, prevention, interception and restoration of the defects of natural teeth.
Preclinical operative dentistry is a branch of operative dentistry where practical training is given for tooth preparation and restoration of teeth with various materials on dummy models in simulated oral environment.
 
Need for Preclinical Conservative Dentistry
As we know oral cavity is a small area which consist of lips, cheeks, palate and a mobile tongue. To do tooth preparation in this area, a great skill is required. So in order to have proper understanding of anatomical and dimensional considerations, it is always recommended to do tooth preparations on artificial acrylic teeth called typhodont teeth. Typhodont teeth are screwed on to the phantom head. By doing tooth preparation in dummy models, a person is able to juxtapose his acquired skill in clinical patient easily. Repeated tooth preparations in extracted natural teeth increase the skill and efficiency of the person. Moreover this training increases the confidence and psychomotor skills for handling tissues.
Basic purpose of preclinical conservative dentistry is to make the students to gain expertise for restorative procedures before handling the patient. This develops confidence in the student before they manage the patient.
 
CAUSES OF LOSS OF TOOTH SUBSTANCE
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Figure 1.1: Clinical picture showing pit and fissure caries in premolar
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Figure 1.2: Clinical picture showing generalized attrition of mandibular anterior teeth
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Figure 1.3: Clinical picture showing generalized abrasion of teeth
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Figure 1.4: Clinical picture showing generalized erosion of maxillary anterior teeth
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Figure 1.5: Clinical picture showing fractured central incisor which can be corrected by esthetic treatment
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Figure 1.6: Clinical picture showing spacing between teeth which can be corrected by restorative procedures
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Figure 1.7: Clinical picture showing fractured amalgam restoration requiring replacement
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Figure 1.8: Clinical picture showing intrinsic discoloration of teeth which can be corrected by esthetic restorations
 
OBJECTIVES OF OPERATIVE DENTISTRY
Following are the objectives of operative dentistry:
 
Diagnosis
Diagnosis is determination of nature of disease, injury or other defect by examination, test and investigation.
 
Prevention
It includes the procedures done for prevention before the manifestation of any sign and symptom of the disease.
 
Interception
It includes the procedures undertaken to prevent the disease from developing into a more serious or full extent.
 
Preservation
Preservation of the vitality and periodontal support of remaining tooth structure is obtained by preventive and interceptive procedures.
 
Restoration
It includes restoring form, function, phonetics and esthetics.
 
Maintenance
After restoration is done, it must be maintained for providing service for longer duration.
 
OBJECTIVES OF PRECLINICAL CONSERVATIVE DENTISTRY
  • To have knowledge about anatomy of teeth
  • To gain expertise for restorative procedures before handling the patient in simulated clinical conditions
  • To gain expertise for restorative procedures before handling the patient by performing restorative procedures in simulated clinical conditions
  • To gain expertise for manipulation of different dental materials
  • To have knowledge of different instruments used in restorative dentistry
  • To understand the fundamentals of tooth preparation.
 
ARMAMENTARIUM
Armamentarium (instruments) used in preclinical conservative dentistry should be arranged as following (Fig. 1.9):
  • Exploring instruments: Mouth mirror, straight probe, explorer and tweezers
  • Excavating instrument: Spoon excavator
  • Cutting instruments: Chisel, hatchet, gingival marginal trimmer and hoes
  • Mixing instruments: Cement mixing spatula, mortar and pestle
  • Filling instrument: Plastic filling instrument, amalgam carrier, teflon-coated instruments
  • Condensers: Round and parallelogram condenser4
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    Figures 1.9: Photograph showing armamentarium required for restorative procedures
  • Carvers: Diamond shaped (Frahm's), Hollenback's carver
  • Ball burnishers
  • Others: Glass slab, Ivory no. 1 and 8 retainers and bands, Toffelmire retainer and bands, wedges, dappen dish
  • Contrangle micromotor hand piece, round, straight, tapered, inverted cone diamond points.
 
PRECLINICAL TOOTH PREPARATIONS
 
Tooth Preparations on Plaster Models
Before going for tooth preparation on typhodonts or extracted teeth, it is advisable to practice on plaster models. These plaster models are prepared by pouring plaster of paris in readymade tooth moulds. Students practice class I to V tooth preparations on these models. Working on plaster models have many advantages. Students can understand concept of tooth preparation better on bigger models. Outline form, line and point angles, convergence of walls, and carving can be understood in a better way on plaster models (Figs 1.10A to C). By these, student can easily replicate tooth preparations on typhodonts and extracted teeth.
 
Tooth Preparations on Typhodonts
Before going for tooth preparation in patient's mouth, it is always advisable to practice all types of tooth preparations on typhodonts and extracted teeth. Typhodonts are artificial acrylic teeth mounted on maxillary and mandibular arches which can be fixed to human-shaped rubber faces to simulate the oral cavities. Typhodonts can also be mounted separately on plaster moulds or blocks (Fig. 1.10D). Typhodonts are advantageous because of their easy accessibility, availability in anatomical forms. But these have disadvantages like:
  • There is no separation between enamel and dentin
  • Because of their softness they get cut very fast.
 
Tooth Preparations on Extracted Teeth
After performing tooth preparations on plaster models and typhodonts, students are advised to practice on extracted natural teeth. These teeth should be mounted in plaster blocks or phantom jaws. These teeth have advantages over typhodonts because being natural, these show differentiation of enamel and dentin. But these teeth carry risk of contamination and they are not easily available.
 
Shortcomings of Preclinical Practice
  • Knowledge of saliva control and isolation can not be experienced in preclinical work
  • One can not be familiar with tongue interference which is common while working on mandibular arch
  • Retraction of soft tissues is completely different in patients
  • Patient anxiety and apprehension can not be experienced with mannequins.5
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    Figures 1.10A to D: (A to C) Photograph showing Class I and II tooth preparations on plaster model; (D) Tooth preparation in typhodont
Scope of operative dentistry
  • To have knowledge of dental anatomy and histology
  • To understand the effect of the operative procedures on the treatment of other disciplines
  • To know condition of the affected tooth and other teeth
  • To examine not only the affected tooth but also oral and systemic health of the patient
  • Provide optimal treatment plan to restore the tooth to return to health and function and increase the overall well being of the patient
  • Thorough knowledge of dental materials which can be used to restore the affected areas
  • To understand the biological basis and function of various tooth tissues
  • To maintain the pulp vitality and prevent occurrence of pulpal pathology.
VIVA QUESTIONS
Q.1. What is preclinical operative dentistry?
Ans. Preclinical operative dentistry is a branch of operative dentistry where practical training is given for tooth preparation and restoration of teeth with various materials on dummy models in simulated oral environment.
Q.2. Define Operative dentistry?
Ans. According to Sturdvent, “Operative dentistry is defined as science and art of dentistry which deals with diagnosis, treatment and prognosis of defects of the teeth which do not require full coverage restorations for correction.” Such corrections and restorations result in the restoration of proper tooth form, function and aesthetics while maintaining the physiological integrity of the teeth in harmonious relationship with the adjacent hard and soft tissues.
Q.3. Why is subject preclinical operative dentistry important?
Ans. Since oral cavity is a small area which consist of lips, cheeks, palate, and a mobile tongue. To do tooth preparation in this area, a great skill is required. Repeated tooth preparation in extracted natural teeth increases the skill and efficiency of the person.
Q.4. Why should one practice on dummy models before doing patients?
Ans. By doing tooth preparation in dummy models, a person is able to juxtapose his acquired skill in clinical patient easily. Moreover this training increases the confidence and psychomotor skills for handling tissues.
Q.5. What are different causes of loss of tooth structure?
Ans.
  • Caries
  • Noncarious loss of the tooth structure
  • Malformed, traumatized, or fractured teeth
  • Esthetic improvement
  • Replacement or repair of restoration
  • Developmental defects.