Colin Gorfil

Biomechanical considerations in restoring endodontically treated teeth

Various concepts for dental treatment have been established without appropriate documentation, such as restoration of endodontically treated teeth. Some researchers and dentists strongly recommend including a post with the restoration to strengthen the root. Other studies have indicated that posts may substantially weaken the roots and should be avoided. An additional approach suggested that the post did not improve the resistance to fracture during occlusion and did not support the restoration. Biomechanical problems are analyzed, and a recommended clinical approach is presented.

The control of marginal microleakage in amalgam restorations using a dentin adhesive: a pilot study.

Abstract A pilot study showed that marginal microleakage in fresh amalgam restorations was eliminated at both the enamel and dentin/cementum margins of Class V restorations in an in vitro study using Scotchbond Dental Adhesive applications to the cavity margins prior to the condensation of a spherical high-copper amalgam alloy.

Restoration of Endodontically Treated Teeth Review and Treatment Recommendations

Coronal restorations and posts can positively influence the long-term prognosis of teeth following root canal therapy. Final sealing the canal by placing an appropriate post and core will minimize leakage of oral fluids and bacteria into the periradicular area and is recommended as soon as possible after completion of root canal filling. Glass ionomer or MTA placed over the residual root canal filling after post space preparation may be effective to prevent bacterial leakage. A ferrule of 1-2 mm of tooth tissue coronal to the finish line of the crown significantly improves the fracture resistance of the tooth and is more important than the type of the material the core and post are made of.

Stiffness of different designs and cross-sections of maxillary and mandibular major connectors of removable partial dentures

STATEMENT OF PROBLEM Major connectors of removable partial dentures must distribute forces bilaterally without damaging the supporting tissues. PURPOSE This study investigated which design and cross-sectional shape of major connectors most favorably influence rigidity and flexibility. METHODS AND MATERIAL Five designs for maxillary removable partial denture major connectors and 5 lingual bar major connectors of different cross-sectional forms were cast in chrome cobalt alloy on a master cast. Points M and P, which represented the position of the first premolar and second molar teeth, were positioned 20 mm apart on the casting. Vertical and horizontal forces were applied to each point while the opposite side was gripped in an Instron testing machine. A force-deflection curve was obtained for each loading point. Mean stiffness values were obtained for loading in compression and torsion. RESULTS Values for torsional loading simulating vertical forces were lower when compared with values obtained for compression loading that simulated horizontal occlusal forces. Differences in stiffness were greater in mandibular major connectors loaded at M and P. The half pear-shaped cross section was the stiffest. CONCLUSIONS In the maxillary arch, the most rigid major connector was the anteroposterior palatal bar combination placed on different horizontal and vertical planes. The most flexible was the U-shaped design. In the mandibular arch, the most important factor in achieving rigidity was the cross-sectional shape of the major connector. The half pear-shaped cross section proved to be the most rigid.

The degree of zinc phosphate cement coverage of complete crown preparations and its effect on crown retention

This investigation examined the amount of retentive area covered by cement under complete coverage crowns and its effect on retention. Sixty crowns of self-cured acrylic resin were prepared on 60 identical brass dies and were divided into six groups of 10 crowns each according to different cement applications. The results showed that retention was dependent on the amount of retentive area covered by the cement. The amount of cement in the occlusal part of the cementation space did not affect retention.

The effect of burnishing on the marginal leakage of high copper amalgam restorations: an in vitro study

Abstract This article deals with the pros and cons of burnishing amalgam restorations. An in vitro study of Class V restorations tested 2 types of high copper amalgams: admixed (Silmet) and spherical (Tytin), and 3 combinations of pre- and post-carving burnishing procedures. The Admix amalgam showed less marginal leakage after burnishing procedures (pre-carved, and pre- and post-carved combinations), while with the spherical amalgam, no significant statistical difference was noted getween burnished and unburnished restorations. The best marginal adaptation was obtained with the admixed amalgam, in which burnishing was carried out both before and after the carving procedure.