In vivo fractures of endodontically treated posterior teeth restored with amalgam

Abstract

The cumulative survival rate (retention of both cusps) and the fracture pattern of 1639 endodontically treated posterior teeth were assessed in a retrospective study. All teeth had an MO/DO or an MOD cavity restored with amalgam without cuspal overlays. The 20-year survival rate of teeth with an MO/DO cavity was markedly higher than that of teeth with an MOD cavity. The lowest survival rate was found for the upper premolars with an MOD cavity: 28% of these teeth fractured within 3 years after endodontic therapy, 57% were lost after 10 years, and 73% after 20 years. Generally, the cusp most prone to fracture was the lingual one, and lingual fractures caused significantly more damage to the periodontal tissues than did facial or total crown fractures. The severity of periodontal damage increased with posterior location of the tooth. By far the most serious failures, irrespective of the cavity type, were found for the upper second molar, as 10 of 29 fractures led to extraction. It is concluded that amalgam, especially in MOD cavities, is an unacceptable material for restoration of endodontically treated posterior teeth if used without cuspal overlays.

Three-year Clinical Evaluation of Cuspal Coverage with Combined Composite–Amalgam in Endodontically-treated Maxillary Premolars

“…4,11,14 Full amalgam coverage of sufficient strength is capable of restoring form and function and providing adequate fracture resistance in restored teeth. 10,13,26 Clinical observations have indicated high survival rates (from four to 15 years) of amalgam restorations with cusp coverage.…”

“…ness of the cusp, leading to cusp elongation, can result in deflection of the cusp and increased susceptibility of endodontically-treated maxillary premolars to fracture. 4,11 Full cuspal coverage is advised to protect the remaining cusps from splitting.…”

“…11 In response, and in an attempt to preserve tooth structure, replacing indirect restorations with amalgam-based cusp coverage was suggested. This easily performed and economically more accessible alternative has the advantage of producing a reversible restoration.…”

“…7 Full amalgam coverage or amalgam crowns have shown excellent results in in-vitro and in-vivo studies. 1,7,[10][11][12][13] Nevertheless, this type of restoration is esthetically less pleasing, particularly in maxillary premolars. Frequently, patients find it hard to accept the appearance of a facial cusp protected with a 2-3 mm layer of amalgam.…”

Fracture Resistance of Cuspal Coverage of Endodontically Treated Maxillary Premolars with Combined Composite-Amalgam Compared to Other Techniques

“…3,4 Numerous studies have reported a high incidence of fracture in endodontically treated maxillary premolars. 2,5,6 Susceptibility to fracture is the result of the loss of marginal ridges and the pulp chamber roof during access preparation 2,7,8 and is a concern, particularly in maxillary premolars, because their anatomy facilitates separation of the cusps during mastication. 9 Fractures in the unsupported tooth structure can lead to restorative difficulties and even extraction if the tooth is unrestorable.…”