Quintessence International, 05/1990

Vision is one of the most important factors involved in the control of head posture. Therefore, head posture is different in blind persons. The purpose of the present study was to determine the posture of the head and cervical column in relation to the true vertical and horizontal and to record craniofacial and dentoalveolar morphology in a group of blind subjects. The sample consisted of 20 blind subjects, who had been totally blind since birth, and 20 normal-sighted persons. The analysis of head posture showed that the intraindividual and interindividual variation in the craniovertical angles was larger in the blind group than it was in the control group, but the variation in the craniocervical angles was similar in both groups. The different head posture in the blind group was produced by forward-downward tilting of the head and neck in combination with an unchanged craniocervical angulation. In the blind group, the difference in head posture affected the mandibular position so that the craniofacial and dentoalveolar morphology showed a difference: an increase in the mandibular angle and in vertical jaw relationships and at the same time a decrease in inclination of the mandibular incisors.

The surgical template can be described as a device that aids in the placement of fixtures during implant surgery. The template helps to achieve not only an accurate position but also the correct angulation. Methods of construction for both the same-arch template and opposing-arch template are described.

Sixty-four samples of four types of composite resin were uniformly finished to a 600-grit smoothness and subjected to uniform manual manipulation (curette), ultrasonic manipulation, and sonic manipulation to simulate dental scaling to determine the degree of surface alteration of the resin resulting from each type of instrumentation. All specimens were hydrated and weighed before and after being subjected to instrumentation. Control samples were retained for each type of composite resin and were finished but not instrumented. Measurements of surface roughness were made before and after instrumentation using a Surfindicator and samples were subjectively viewed and photographed under scanning electron microscope. Statistical analyses were done to determine the significance of surface alterations by the three methods of simulated dental scaling. All three types of manipulation altered the composite resin surfaces significantly but the hand curettes yielded the most significant alterations.

The tensile bond strength of two composite resin cements was evaluated using two different bonding procedures with each cement. There was no significant difference in tensile bond strength achieved by the two luting cements under the same test conditions (P > .05). Reducing the amount of bonding agent by gentle blowing significantly increased the tensile bond strength (P < .05). Applying the bonding agent, without blowing, to both the enamel and metal surfaces prior to the application of the luting cement did not significantly increase the bond strength (P > .05). The fracture patterns observed were mostly a combination of adhesive and cohesive fractures.

Shrinkage of composite resin during polymerization is responsible for the formation of a microgap at cavity margins that permits the ingress of bacteria and oral fluids. This study investigated four methods of incremental insertion of composite resin into mesio-occlusodistal cavity preparations to determine the effect of each method on microleakage at cervical margins. Four groups of 10 extracted teeth were prepared with mesio-occlusodistal cavities in which one proximal box ended on enamel and the other ended on the root surface. Teeth in each group were restored with a light-curing, hybrid composite resin and its bonding agent. In group 1, the composite resin was inserted in one increment. In group 2, insertion was in two equally thick horizontal layers in the proximal box and one layer in the occlusal portion. In group 3, the composite resin was inserted in two diagonally placed layers in the proximal box and one increment in the occlusal portion. In group 4, the composite resin was inserted in the same way as in group 3 except that a glass-ionomer liner was first placed on the axial wall and gingival floor. All teeth were thermocycled, stained with silver nitrate, sectioned mesiodistally and scored for microleakage. The diagonal insertion technique in group 3 had the most leak-free margins when the proximal box ended on enamel. In all groups, cervical margins that ended on the root surface had extensive microleakage.

Dental twinning anomalies in the primary dentition have been well documented. An unusual case of dental twinning in both primary and permanent teeth in one dental quadrant is described in this report. Potential diagnoses for the respective defects using traditional nomenclature are suggested, and problems inherent to classifying such abnormalities are reviewed.

The treatment of a dilacerated maxillary incisor requires a multidisciplinary approach. Orthodontic, endodontic, and periodontal considerations are essential for successful treatment. A case that demonstrates the periodontal aspects of the treatment of this anomaly is presented. Treatment included (1) a conservative surgical technique for crown exposure that preserved a wide band of keratinized gingiva; (2) initial periodontal preparation before active orthodontic movement as well as a supplemental intensive maintenance program that continued throughout orthodontic treatment; and (3) a vestibular extension procedure designed to alleviate the shallow vestibular depth that can result in poor oral hygiene. Careful monitoring is essential to the long-term success of treatment.

Overdentures provide a valuable treatment alternative in situations in which patients have congenital or acquired defects involving the jaws and teeth. In the treatment of patients with ectodermal dysplasia, overdentures can be particularly advantageous in restoring esthetics and function. A problem associated with overdenture treatment in these situations can be the development of soft tissue inflammation and hyperplasia adjacent to the remaining teeth. The inflammation of the gingival tissues surrounding the remaining teeth may be caused by trauma from the overdenture itself. When the overdenture is tooth supported, the likelihood of soft tissue inflammation developing as a result of trauma from the denture base will be significantly reduced. In addition, follow-up treatment at regular intervals is necessary to ensure satisfactory soft tissue health.

Many patients, because of trauma or periodontal disease, are missing their permanent maxillary incisor teeth. Conservative and esthetic restorative treatment for many of these patients would be a maxillary dual-path of insertion removable partial denture. However, in many patients this type of restoration is contraindicated, because of the flat lingual anatomy of the maxillary canines. This problem has been defined as deficient canine cingula. A process that uses the dual-path concept and the maxillary first premolar teeth to circumvent this problem is described.

A technique for the removal of the overhanging margins of restorations is described. This technique is part of a treatment philosophy that is referred to as quadrant iatrodontics. The aim of treatment is to eliminate subgingival calculus and overhanging restorative margins, thereby facilitating interproximal cleaning. Recontouring of existing restorations whenever possible is suggested, while the replacement of restorations unless definitely indicated is discouraged.

Orthodontic treatment cannot properly begin until the malocclusion is described. Angle's classification of malocclusion, developed a century ago, is still the subject of debate and controversy. A review of the literature is presented and the differing viewpoints are discussed.