Statement of problem: The dental literature has shown a 3% to 25% pulpal necrosis rate as a result of tooth preparation for complete coverage restorations.
Purpose: The purpose of this retrospective study was to examine clinical and radiographic records for evidence of pulpal necrosis in teeth prepared for complete coverage restorations at ultrahigh speed when air coolant alone was used.
Material and methods: The 1847 teeth in this study (182 fixed partial denture abutment teeth and 1665 single teeth restored with 21 all-ceramic, 1095 metal-ceramic, and 731 all-metal restorations) were prepared with diamond instruments (burs) in a sweeping or painting motion with the use of light pressure (1-3 oz) at ultrahigh speed with air coolant alone from the handpiece. New burs were used for each patient and then discarded. Each bur was used on no more than 4 teeth. All impressions were made with reversible hydrocolloid. Provisional restorations were fabricated on a stone cast and cemented with zinc oxide and eugenol cement. Provisional restorations were removed at 3 to 4 weeks and definitive restorations placed. Between 1970 and 1989, 6 different luting agents (zinc phosphate, resin, glass ionomer, ortho-ethoxybenzoic acid, carboxylate, and polycarboxylate) were used to place definitive restorations. All patients were questioned about symptoms of tooth sensitivity, tenderness, or pain at their regular (4- to 6-month) hygiene recall appointments. Success was defined as any definitively restored teeth that remained free of radiographic evidence of periapical radiolucency and clinical signs and symptoms of pulpal sensitivity or pain recorded in the clinical record. The results were compared with rates of pulpal necrosis for teeth prepared with water coolant as reported in the dental literature published between 1970 and 1997.
Results: Of 638 teeth prepared between 1970 and 1979, the pulpal necrosis rate was 2.19% (14 teeth: 12 single teeth and 2 fixed partial denture abutment teeth) (97.81% success rate). Of 1209 teeth prepared between 1980 and 1989, the pulpal necrosis rate was 0.66% (8 teeth: 7 single crown teeth and 1 partial denture abutment tooth) (99.34% success rate). Of 1825 teeth prepared between 1970 and 1989, radiographic evidence of pulpal necrosis was found in 0% (100% success rate). No clinical symptoms of pain or sensitivity were recorded in the patient records for the surviving teeth during the time period of this study, which was conducted in May 2001. No crowns were repaired or removed as a result of carious lesions. No higher incidence of pulpal necrosis relative to the type of luting agent was observed.
Conclusion: Within the limitations of this retrospective study, it is suggested that tooth reduction procedures can be completed with minimal damage to the pulp when only air coolant from the dental handpiece is used.