Clinical crown length of the maxillary anterior teeth preorthodontics and postorthodontics

BACKGROUND: Prevalence information on excessive gingival display in postorthodontic patients is limited. By studying the size relationship of the clinical crowns of teeth, in an orthodontic population, we can begin to quantify their need for periodontal plastic surgery. METHODS: Preorthodontic and postorthodontic crown dimensions were measured on 200 plaster models, and after 5 years, 31 of the subjects were recalled to repeat the measurements in a clinical examination. The measurements included clinical crown lengths and widths of the six anterior teeth, and these values were compared to known ideals. RESULTS: This study revealed a significant increase in the length of the maxillary anterior crowns over the three examinations, yet these values were still approximately 1.5 mm shorter than ideal. The mean crown width-to-length ratio was 87% to 88% for maxillary central incisors, clearly above the accepted "ideal." In addition, 61% to 71% of maxillary central incisors exceeded allowable crown width-to-length ratios, and 61% of subjects displayed asymmetry in gingival architecture. CONCLUSIONS: Although this study only examined one aspect of excessive gingival display, to our knowledge it is the first study to show that in a predominantly young, postorthodontic population, the prevalence of non-ideal width-to-length ratios is >65% and the presence of asymmetry is >60%. Therefore, close interaction between the periodontist and the orthodontist is necessary to diagnose these conditions to provide patients with all options for improving their smile.     

Long-term evaluation of bilateral cleft lip and palate patients after early secondary closure and premaxilla repositioning

The aim of this retrospective, mixed longitudinal study was to assess the long-term outcome of early secondary closure and premaxilla osteotomy in 40 bilateral cleft lip and palate patients who underwent early secondary osteotomy of the premaxilla and bone grafting at the age of 8-12 years. Clinical and cephalometric evaluations of profile, lip relation, nasolabial angle and position of the maxilla preoperatively, postoperatively and at adolescence were compared to normal values of non-cleft individuals and the reported data of 90 bilateral cleft lip and palate patients treated in Oslo. In 68% of patients the profile was considered acceptable, but in 26 maxillary growth appeared to be impaired by cephalometric standards. In four patients a Le Fort I osteotomy was carried out and nine patients would have benefited from such a procedure. This study reveals a trend towards maxillary growth retardation partially compensated by orthodontic and dental treatment. Since the results are comparable to those reported for the Oslo group with regard to maxillary growth, the surgical protocol followed does not require revision. Considering the benefits, i.e. closure of alveolo-palatal cleft, continuity of dental arch, eruption of canine in the graft and closure of oro-nasal communications, this mode of treatment should be continued.     

The effects of computer-aided anteroposterior maxillary incisor movement on ratings of facial attractiveness.

BACKGROUND: Before planning orthodontic treatment, it is necessary to understand societal preferences for facial esthetics. The anteroposterior (AP) position of the maxillary incisors affects the appearance of the soft tissue profile and can be manipulated by orthodontic techniques. To improve the ability to predict the most suitable maxillary incisor position, numerous cephalometric and profilometric measurements have been suggested. Among them are the Six Elements to Orofacial Harmony proposed by L. F. Andrews, whereby forehead angulation is used to dictate maxillary incisor sagittal position. Our aim was to evaluate differences in preference for the AP position of the maxillary incisor between orthodontic and lay panels. METHODS: A smiling profile photograph was taken of a female subject who best fit the chosen soft tissue normative values and whose maxillary incisors were in an Element II position. The photograph was manipulated to simulate maxillary protrusion and retrusion at 1-mm increments to a maximum of +/-4 mm. Panels of orthodontists and nonorthodontists scored the attractiveness of the photographic variations according to a 100-mm visual analogue scale. RESULTS: The 4-mm retrusive photograph was significantly less desirable than all others, which suggests that, from an esthetic standpoint, it is preferable to either leave a normally protrusive maxillary dentition where it is or advance rather than retract the maxillary anterior teeth. Orthodontic training did not significantly affect the magnitude of the ratings or pattern of preference in our sample. CONCLUSIONS: Andrews' Element II provides an additional useful method to evaluate attractiveness relative to the maxillary incisor position.     

Thermal analysis of commercial Gutta-percha using differential scanning calorimeter and dynamic mechanical thermal analysis.

Gutta-percha is the most widespread root canal filling material and knowledge of its chemical and thermomechanical properties is of a great interest to its use in clinical dentistry. In the present investigation, the results from differential scanning calorimeter were compared with those obtained by dynamic mechanical thermal analysis. A significant correlation was established between these results and the chemical composition of six different commercial samples of gutta-percha.     

Frontal cephalometric study of dentofacial morphology in children with bilateral clefts of lip, alveolus and palate

The transverse dentofacial morphology of 36 children with bilateral cleft lip, alveolus and palate was studied by means of a frontal proportional cephalometric analysis at the ages of three, eight and twelve years. Comparison of the variables of the cleft group was made with the normal dimensions as obtained from the Bolton cephalometric templates. The results indicated that the BCLP group presented characteristics and significant differences from the normal in the dimensions of the nasal septum width and the mandibular intergonial width as they are both related to the interorbital width, the maxillary intermolar width as it is related to the mandibular intermolar width and the maxillary width as it is related to the mandibular intergonial width at all three ages. The maxillary base and intermolar widths, although significantly different at the ages of three and eight years, showed no significant deviation from normality at the age of twelve years. Following orthodontic treatment between the ages of seven to twelve years, the maxillary intermolar width of the treated subgroup was significantly larger than in the untreated subjects.     

Okklusion,Kiefergelenke und kieferorthopädische Behandlung

Zusammenfassung Für die Okklusion und den Gelenkbereich sind Zuordnungsnormen existent. Dies ist im Seitenzahnbereich die Höcker-Fossa-Relation, im Frontzahnbereich die Zuordnung der Unterkiefer-Inzisalkanten zu der Nullpunktlinie der palatinalen Konkavitäten im Oberkiefer und im Gelenkbereich die physiologische Kondylenposition. Letztere läßt sich im Pantogramm durch den Wendepunkt der von der Achse bei sagittaler Grenzführung gezeichneten Kurve präzisieren, in Übertragung aber auch im Röntgenbild ermitteln.Ziel der kieferorthopädischen Behandlung sollte die physiologische Zuordnung von Seitenzähnen, Frontzähnen und Gelenken sein. Das vorgestellte Funktionsmodell gibt Hilfestellungen bei der Behandlung auf ein funktionelles Optimum hin.Die Gelenke sind bei der Behandlung wie ein eigenes terminales Okklusionspaar zu betrachten. Ihre korrekte Einstellung läßt sich bisher nur durch Röntgenbilder und durch die pantographische Aufzeichnung darstellen.

---

Summary We are convinced that there is a relation between the occlusion and the temporomandibular joint. In the molar region the correlation is known as the cusp-fossa relationship. In the incisor region the corresponding structures are the mandibular incisor tips and the palatal concavities of the upper incisors. We have designated the correlation in the TMJ-region as the physiological condyle position, which can be identified in the sagittal pantogram by the turning point of the traced sigmoid curve. Similarly this position can be shown by our method on the TMJ-radiograph.The aim of orthodontic treatment should be a physiological positioning of molars, incisors and joints. The functional model presented above can render assistance in achieving a functional optimum in treatment.The temporomandibular joints must be regarded in treatment as additional occluding points. Up to now their correct positioning has been visible only through the use of TMJ-radiographs and pantographic tracings.

---

Résumé Il existe des normes structurelles correspondantes entre l'occlusion et l'articulation temporomandibulaire; à savoir dans les zones latérales d'arcades la relation cuspide-sillon, dans le segment antérieur l'arête des incisives inférieures glissant le long des faces palatines des incisives supérieures jusqu'à la ligne d'arrêt et au niveau de l'articulation la position physiologique du condyle. Cette corrélation s'établit dans le plan sagittal du pantogramme par l'existence d'un point tournant du tracé sigmoïde; on peut transposer cette position dans l'image radiographique.Le but d'un traitement orthodontique est de coordonner physiologiquement les segments latéraux et antérieur d'arcades et l'articulation temporo-mandibulaire. Des moulages fonctionnels préétablis nous aident à obtenir la meilleure fonction au cours du traitement.On doit considérer la double articulation temporo-mandibulaire comme une occlusion finale. Seuls la radiologie et les tracés pantographiques permettent de juger de la position correcte des condyles dans leurs fosses glénoïdes.

---

---

In memoriam Herrn Prof. Dr.G. Müller von seinen ehemaligen Schülern und Mitarbeitern.