Sensitivity and specificity in a longitudinal temporomandibular disease study.

A longitudinal prospective study on the development of temporomandibular disease (TMD) in children was initiated in 1970. The study ended in 1990. One of several diagnostic TMD criteria applied was osteoarthrosis, defined as a 'morphological and/or structural deformity of the condyle' diagnosed on radiographs. Although these radiographic techniques are suspect in terms of falsenegative findings, 'morphological and/or structural deformity of the condyle' has been shown to be associated with a characteristic craniofacial form. As such, it has confirmed diagnostic significance. The present study will test the reliability of this diagnosis using cross-sectional and longitudinal findings for objective signs and subjective symptoms that are attributed to TMD. Signs and symptoms of TMD performed poorly as predictors for 'morphological and/or structural deformity of the condyle'. Thirty-seven percent of the participants had a 'morphological and/or structural deformity of the condyle' diagnosed at least once during the 20-year study period. In two thirds of the cases, 'morphological and/or structural deformity of the condyle' was not a stable characteristic through time. Normal radiographic anatomy of the condyle was often associated with signs and symptoms. We arrive at the conclusion that TMD is an umbrella, housing several overlapping problems that may manifest themselves at irregular intervals or even may disappear completely.

Taking stock: passing the torch, who has the light? Reflections about teaching orthodontics at the occasion of the retirement of Prof. Lysle E. Johnston, Jr PhD.

In the Marburg (Germany) 5-year dental curriculum, students enter the orthodontic department in the middle of their third year. Our teaching is student-centered and problem-solving oriented. From day 1 our students are trained to diagnose in three separate levels of development i.e. (i) craniofacial growth, (ii) development of the dentition and (iii) maturation of function. These three levels are kept separate throughout patient examination and up to the strategic treatment planning phase. The examination is performed with the help of three checklists, one for the facial morphology, one for the dentition and one for function. The three resulting problem lists then undergo reduction by selecting one 'key problem' for each level. Next, for every key problem three 'standard solutions' are offered, not in the form of appliances but as vectors that can modify growth. Finally, in a strategic planning phase, one treatment option from each of the three levels is selected and combined in a single, be it hypothetical, treatment plan. Parallel to these, students are exposed to treatment mechanics through the presentation of selected orthodontically treated patients. In our experience the advantage of this diagnostic procedure lies in the structured organization that serves as a GPS system for student and teacher and enables them a clear communication about where they are and what has to be done. By design, treatment options have taken priority over treatment mechanics. We are confident that our students, equipped with real life diagnostic skills, are well prepared for their orthodontic future.

Regional size differences in four commonly used cephalometric atlases: the Ann Arbor, Cleveland (Bolton), London (UK), and Philadelphia atlases compared.

OBJECTIVE: To explore regional influence on size in roentgenocephalometric atlases. DESIGN: Comparisons of the size of 10 linear distances in four atlases from geographically different regions, i.e. Ann Arbor Michigan, Cleveland Ohio, Philadelphia Pennsylvania and London, UK. DISTANCES COMPARED: anterior cranial base length (S-N), posterior cranial base length (S-Ba), total face height (N-Me), upper face height (N-ANS), lower face height (ANS-Me), mandibular diagonal (Ar-Gn), corpus length (Go-Pg), ramus height (Ar-Go), maxillary length (SNP-SNA), posterior face height (S-Go). RESULTS: Correction for enlargement appeared to be a necessity before distances could be compared. After correction for enlargement, the anterior cranial base was longest in Ann Arbor, lower face height smallest in Cleveland (Bolton standards) and the maxilla was shortest in Philadelphia. CONCLUSION: Regional size variance in cephalometric data cannot be ignored.

The postglenoid tubercle: prevalence and growth.

AIM: To quantify the prevalence and growth of the postglenoid tubercle in a skull sample and in children. MATERIAL: a) ninety skulls ranging in age from between 2 years and adulthood, b) sixtyfour corrected lateral tomograms of left and right temporomandibular joints of 32 boys and girls. Their age range was between 9 and 11 years. METHOD: Impressions of the temporal fossae of the skull material were taken with a silicone type impression material, using a face-bow for leveling the base of the impression parallel to the FH plane. Each impression was divided into two halves along a paramedian plane from the tip of the postglenoid tubercle through the middle of the articular eminence and the surface was photocopied to a 200% scale. Height was measured with an electronic caliper. The presence or absence of a postglenoid tubercle was established on the corrected tomograms. FINDINGS: Seventy-nine percent of the skulls had a postglenoid tubercle. It steadily enlarged and reached almost its final dimension by the age of 13 years. On corrected tomograms, 66% of the children showed a postglenoid tubercle. CONCLUSIONS: a) the postglenoid tubercle exists in a high percentage of human temporomandibular joints b) growth is almost completed by the age of 13, and c) there exists a right-left symmetry.