Fracture resistance of endodontically treated mandibular first molars with conservative access cavity and different restorative techniques: An in vitro study

Abstract

The aim was to investigate in vitro the fracture resistance (FR) of endodontically treated teeth (ETT) with conservative access cavity restored using various direct and indirect restorative materials and techniques. Seventy-two mandibular first molars were equally divided into six groups. Teeth in Group 1 were untreated (controls). In Groups 2, 3, 4, 5 and 6, teeth were restored with amalgam, composite resin, ceramic inlay, ceramic onlay and zirconium crown, respectively. A fracture test was performed on all teeth using a static load. Compared with other groups, teeth in Groups 3 (P < 0.05) and 6 (P < 0.05) had the highest FR values with no significant difference in-between them. Teeth in Group 4 had the lowest FR than other groups (P < 0.05). All restorative techniques tested led to a significant reduction in FR. It is necessary to consider type of fracture when evaluating fracture resistance of endodontically treated teeth. Crowned molars had the highest favourable fractures among the five treatment groups. Although the results of this in vitro study showed variations between tested techniques in ETT with a conservative access cavity, further long-term controlled clinical trials are required to confirm these in vitro findings.

Impacts of Contracted Endodontic Cavities on Instrumentation Efficacy and Biomechanical Responses in Maxillary Molars

“…Preserving pericervical dentin in conjunction with minimally invasive endodontics has been promoted (6,9-11) but clinical evidence of outcomes is deficient (11). While it has been well corroborated by several in-vitro studies that removal of coronal tooth structure impairs the tooth's overall strength (13,46,68), future studies should explore the effects of instrumentation and removal of pericervical dentin in particular, a region critical for stress concentration (67,103,125,126).…”

“…Contracted endodontic cavity (CEC) designs are intended to preserve tooth structure to maintain fracture strength of treated teeth (6,(9)(10)(11)46,68) (Fig. 1A), in line with modern dentistry's increasing focus on minimally-invasive interventions (5).…”

“…The materials selected for restoration of the endodontic cavity impact the physical properties of the restored tooth (68). Mandibular molars with Class I cavities restored with amalgam exhibited significantly lower fracture strengths (73,74).…”

Influence of Three Different Restorative Materials on the Fracture Resistance of Endodontically Treated Tooth

“…Although the marginal ridges were left intact in the present investigation, the strength of the restored teeth was significantly reduced when compared to unrestored sound teeth regardless of the restoration type used. 12 The loss of one marginal ridge resulted in a 46% loss in tooth rigidity, and a MOD preparation resulted in an average loss of 63% in relative cuspal rigidity. 1 Amalgam has traditionally been used as the best buildup material.…”

Effect of Preparation Design on Mechanical Properties of Endodontically Treated Teeth

“…A lot of factors cause the loss of tooth structure such as dental caries, therapeutic procedures as access cavity preparation, restorative cavity preparation and root canal preparations (2,3).…”