Mandibular second molar impaction. Part I: Genetic traits and characteristics.

Introduction: Detection of mandibular second molar (MM2) impaction is imperative for orthodontic diagnosis and treatment. In this study, we examined a possible genetic trait in MM2 impaction in 2 populations and defined distinctive characteristics.

Methods: Initial panoramic radiographs of patients of Israeli (n = 3500) and Chinese-American (n = 3000) origin, aged 11 to 15 years, were examined.

Rootless eruption of a mandibular permanent canine.

The purpose of this article was to describe the rootless eruption of a mandibular permanent canine in a 10-year-old boy; his mandible had been fractured in a car accident. The fracture was at the region of the developing canine, resulting in arrested root formation and causing abnormal, rootless eruption. Current theories on tooth eruption and the important role of the dental follicle in the process of eruption are discussed.

Self-ligation esthetic brackets with low frictional resistance.

Objective: To test the frictional resistance forces (FRS) generated between several archwires and (1) interactive self-ligating (ISL) brackets and (2) conventionally ligated (CL) brackets.

Materials And Methods: Frictional forces produced between three different archwire combinations and self-ligating (SL) brackets (ceramic and metal-slot or all-metal) and CL brackets (metal or ceramic) were evaluated in a dry environment. The three ISL brackets tested were In-Ovation-C, In-Ovation-R, and Damon 3.

Unusual intraosseous transmigration of a palatally impacted canine.

Intraosseous migration of impacted teeth across the midline to the opposite side of the jaw is a rare dental anomaly of unknown etiology. Transmigration of an impacted mandibular canine through the symphysis to the contralateral side of the arch has been documented. Transmigration of an impacted maxillary canine across the midpalatal suture to the opposite side of the maxilla has not been previously observed and is reported here for the first time.

Early detection and prevention of mandibular tooth transposition.

Distal migration of the mandibular permanent lateral incisor happens rarely and it can be discovered radiographically in the early mixed dentition. If unattended, the tooth may erupt ectopically, usually distal to its normal anatomical position and occlusal to the developing first premolar, and it can become transposed with the permanent canine. Early detection and immediate interceptive removal of the retained deciduous lateral incisor and canine, followed by uprighting the ectopic lateral incisor to its normal anatomical position in the arch, will intercept the problem and prevent the developing transposition.

Intrabony migration of impacted teeth.

Intrabony migration of impacted teeth is a rare dental anomaly, which occurs only in the permanent dentition of the lower jaw. The teeth involved in this phenomenon are the mandibular lateral incisor, canine, and second premolar. Migration of the lateral incisor is usually in a distal direction, resulting in transposition with the canine.

Condyle-fossa modifications and muscle interactions during Herbst treatment, Part 2. Results and conclusions.

Herbst appliances were activated progressively in growing nonhuman primates, and the results were compared with primate and human controls. The methods and materials of this research are explained in Part 1 of this study. The results are discussed here in Part 2.

Condyle-fossa modifications and muscle interactions during herbst treatment, part 1. New technological methods.

Changes in the condyle, the glenoid fossa, and the muscles of mastication were investigated in subjects undergoing continuous orthopedic advancement of the mandible with a Herbst-block appliance. The total sample consisted of 56 subjects and included 15 nonhuman primates (in the middle mixed, early permanent, and permanent dentitions), 17 human Herbst patients in the early permanent dentition, and 24 human controls from the Burlington Growth Center. The 8 nonhuman primates in the middle mixed dentition were the focus of this study.