November 1, 2006
by Oral Health
FIVE-YEAR FOLLOW-UP OF A PROSPECTIVE CLINICAL STUDY ON VARIOUS TYPES OF CORE RESTORATIONS
This study examined the five year survival rate of endodontically treated teeth restored with a cast post-and-core, versus a direct post-and-core, versus a post-free core made of composite. This study also tested whether the survival rate was affected by the height of dentin left after tooth preparation was complete. A total of 319 teeth were selected based on the following inclusion criteria, namely: endodontically treated teeth requiring single crown coverage with good periodontal condition (pockets <4mm, physiologic mobility) and an occlusal contact with a natural tooth or an RPD.
Randomization to the various treatment types was performed after the tooth was identified as expecting to have either substantial or minimal dentin height remaining after preparation was completed (>75% circumferential dentin at least 1mm thick with at least a 1mm height above the gingival defined “substantial height”). Since allocation to either substantial versus minimal dentin height was performed prior to treatment randomization, the prediction of remaining dentin height was verified via impressions made after the completion of tooth preparation.
Patients were recalled at six month intervals. Fifteen restorations failed within the five-year study. Five occurred within one month of insertion and were excluded from further study since these failures were not a result of natural aging of the restoration. No significant difference was found when comparing the survival of the different restoration types. Interestingly, remaining dentin height significantly affected the survival of these restorations. Teeth with “substantial dentin height” did significantly better than teeth with less tooth structure remaining.
This result highlights the significance of ferrule. Maintaining appropriate ferrule requires at least 1.5-2mm of the cast restoration to extend apically beyond the margin of the core onto natural tooth structure. Although much attention has been given to comparing the efficacy of various types of core restorations in the past, this study revealed that remaining dentin height appears to be of greater importance. Dentists should be encouraged to maintain adequate ferrule when preparing a tooth to receive extracoronal coverage.
Creugers, N., et al. Int J Prosthodont 2005;18:34-39. e-mail: firstname.lastname@example.org
Reviewed by: Dr. Gina Markin, Private Practice, Toronto.
PREDICTION OF TMJ ARTHRALGIA ACCORDING TO CLINICAL DIAGNOSIS AND MRI FINDINGS
The purpose of this study was to evaluate the relationship between the presence of TMJ pain as per the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD), the presence of disc displacement (DD), osteoarthrosis (OA), and joint effusions (JE). In describing the materials and methods of the study the authors review the RDC/TMD examination procedure with emphasis on palpation of the origin of the masseter muscle and the lateral pole of the TMJ. The study group consisted of 149 patients (75% women and 25% men) with a mean age of 38 years. 68 TMJs fulfilled the RDC/TMD criteria for arthralgia, the remaining 214 pain free TMJs were used as controls. All patients received a psychological assessment using the Graded Chronic Pain Scale, a depression scale, an assessment of somatization and the Jaw Disability Index. All patients of the study underwent bilateral coronal and sagittal MRI’s of the TMJs. The MRIs demonstrated disc displacement with reduction (DDWR) in 13 TMJ’s with athralgia (39 without) and DD WoR in 23 TMJs with arthralgia (53 without).
There was no correlation between a clinical diagnosis of arthralgia and structural alterations within the TMJ as diagnosed by the MRIs. This study did however show a significant association between pain from the masseter muscle at the point of origin and TMJ pain. The paper is rich in references 36 in all.
Ohlman B., RammelsbergP., Henschel V., Kress B., Gabbert O., and Schmitter M. Int J Prosthodont 2006, 19:333-338. Reprints: Dr. Brigitte Ohlman, Abteilung fur Zahnersatzkunde Universitatsklinikum Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany. Reviewed by Bruce Glazer, Prosthodontic Section Editor.
A 20-YEAR RETROSPECTIVE SURVIVAL STUDY OF FIXED PARTIAL DENTURES
This paper tries to qualify fixed versus removable partial dentures by comparing data on the survival of FPD’s over a 20 year period and then analyzing specific causes of failure. Previous clinical studies have shown FPD’s to have a mean life span of 95% after 5 years, 90% after 10 years and 65% after 15 years. This retrospective looked at 397 FPD’s made over a 20 year period. Most of the restorations were porcelain fused to gold and all post and cores were cast in gold separately from the retainer. Zinc phosphate cement was the cementing medium. 41.6% of the FPD’s were 3 unit. After 20 years 66.2% of the restorations had survived. Anterior FPD’s outlived posterior FPD’s 85% to 63.6%. Long span bridges lagged behind short span 58.7% to 70.8%. thus showing a highly significant (statistically) difference in failure rates. This is in keeping with the realization that long span bridges are far more difficult to create and fit with accuracy. This clinical study shows that the more retainers used for a FPD the shorter the life span. The use of an abutment with a cast post and core also leads to more failures.
Most failures were caries related with debonding running a close second (61.1%). Significant in the study was a previous reversible complication lead to an irreversible complication later on.
De Backer H., Van Maele G., De Moor N., Van den Berghe L. and De Boever J. Int J Prosthodont 2006; 19: 143-153. References 42. Reprints. Dr. Hein De Backer, Hulststraat 8, 8700 Tielt, Belgium. E-mail: Hein.Debacker @skynet.be. Reviewed by Bruce Glazer, Prosthodontic Editor.