Interpretation of radiographic data on longitudinal loss of periodontal support

Factors associated with radiographic vertical bone loss around implants placed in a clinical study

The loss of vertical bone height over time has been assessed radiographically as part of the Dental Implant Clinical Research Group studies. Radiographs were assessed from implant placement, uncovering surgeries, and recall appointments. Overall, the study implants experienced most peri-implant vertical bone loss in the first year after placement, followed by a dramatic decrease in bone loss rate through the subsequent study intervals. Stratified analysis of data up to 72 months after implant uncovering indicates different bone loss patterns by: 1) arch; 2) jaw region; 3) case type; 4) bone quality; 5) surface type; 6) implant design; 7) smoking status; and 8) postoperative antibiotic treatment. These results will be used to build statistical mixed models to indicate which clinical factors are most predictive of peri-implant vertical bone loss, controlling for confounding and accounting for correlation of data over time and within study patients.

Radiographic assessment of peri-implant vertical bone loss: DICRG Interim Report No. 9

Vertical bone loss is being assessed radiographically as part of the Dental Implant Clinical Research Group studies through direct measurements on study radiographs taken longitudinally at surgery and recall appointments. Preliminary results and trends for the period between implant placement and 6 months after implant uncovering show more bone loss in implants that are 1) not coated with hydroxyapatite; 2) placed in the maxilla; 3) placed in anterior regions of the jaws; 4) in completely edentulous cases; and 5) placed in bone scored as having lower quality. Confounding relationships between predictor variables will require controlled statistical analyses when data collection is completed.

The use of radiographic techniques in the diagnosis and management of periodontal diseases

Radiographs continue to play an important role in the diagnosis and management of periodontal disease although opinions as to the most appropriate form of assessment vary. It is important to recognize the limitations of each technique in terms of resolution, repeatability and accuracy so that radiographs can be correctly interpreted to the benefit of the patient. The value of intra-oral and panoramic radiography is reviewed, with particular reference to articles published over the past five years, followed by a consideration of developing computer-aided techniques which may, in time, prove of value to the dental practitioner in the diagnosis and management of periodontal disease.

Measures of treatment efficacy

Measures of treatment efficacy are those numbers we think about when we decide whether one treatment is "better" than another. Such measures quantify the differences between treatments and help patients and clinicians make informed choices. The usual measure of treatment efficacy in periodontal research has been the mean difference between treatments in probing level measures. This measure has frustrated clinicians and researchers alike for its failure to communicate the size of the association between treatment and clinical outcome. How does one interpret the clinical relevance of a small mean difference between treatments, such as 0.4 mm? This report compares the advantages and disadvantages of the different measures of treatment efficacy: the mean difference, the relative risk, significance levels (P-values), the risk difference, and, the preventable fraction.

General issues in efficacy, equivalency, and superiority trials: clinical considerations

The design of clinical trials aimed at treating different types of periodontal diseases must take into account the prevalence of the disease in the population and the relationship of various descriptors, which may vary from disease to disease. For screening purposes, patients should be selected with disease in the high-severity range, in order to maximize the likelihood of detecting a therapeutic effect. Subsequent trials may be designed around a more representative group of subjects. Therapies must be evaluated on the basis of actual clinical changes, rather than their effect on presumed etiologic factors. The observed changes must be of clinical as well as statistical significance. The distribution of periodontal diseases within a dentition may affect as few as one or as many as over one hundred sites. Strategies are needed to correlate events observed at sites within the dentition, i.e. tooth surface-based measurements or scores, with events that are subject-based, e.g. concentration of blood or salivary components.