Comparison of soft tissue profile changes in serial extraction and late premolar extraction.

To assess soft tissue profile changes through time, a comparison was made of patients treated by serial extraction without subsequent orthodontic treatment (n=28), patients treated with serial extraction and orthodontic treatment (n=30), and patients treated orthodontically with late extraction (n=30). Cephalometric radiographs were traced and digitized; linear and angular measurements were made with a custom computer program that allowed digitization of specific soft tissue points. Maxillary, mandibular, and overall cephalometric superimpositions and linear measurements of change from the superimpositions were done by hand. Statistical analyses were made to determine if significant differences existed within each group at each time period and between groups at each time period, as well as between males and females at each time period. Data were also analyzed to determine if significant correlations existed between any hard tissue variable and any soft tissue variable, or between any soft tissue variable and any other soft tissue variable. It was found that in those patients treated with late premolar extraction, the most labial point of the mandibular incisor was more posterior from pretreatment to posttreatment than in the serial extraction group. While a great number of associations existed between variables, no significant differences were found between the soft tissue profiles of these three groups of patients. The gender differences that were found to exist were most likely due to normal maturational changes, not the treatment itself.

An investigation of maxillary superimposition techniques using metallic implants.

The purpose of this study was to determine if there are discernable, stable, anatomic landmarks in the maxilla that may reliably be used for maxillary superimposition. It was hypothesized that, through the evaluation of cephalometric radiographs of patients with metallic implants, such anatomic landmarks could be identified. The material for this study consisted of pairs of cephalometric radiographs from 50 subjects, 23 males and 27 females ages 8.7 to 20.3 years. All films were taken at least 3 years apart. The mean age at the time of the first film was 11.9 +/- 1.4 years, and the mean age at the time of the second film was 16.0 +/- 1.7 years. The two serial tracings from each subject were superimposed on the implants and evaluated for best fit of anatomic structures. The maximum distance that the structures varied from perfect superimposition was measured. Rotational changes of the maxilla relative to the cranial base and of the palatal plane relative to the maxilla were evaluated. In the vertical plane, the floor of the orbit raised more than the palatal plane lowered by an average ratio of 1.5 to 1 mm. The maxilla demonstrated varying degrees and directions of rotation relative to the cranial base. The palatal plane demonstrated varying degrees and directions of rotation within the maxilla. Internal structure of the palate was of limited value as a stable area of registration. Infraorbital foramen, PTM, ANS, PNS, A point, and superior and inferior borders of the palate were not found to be stable landmarks for maxillary superimposition.(ABSTRACT TRUNCATED AT 250 WORDS)

Case report FG. Orthodontic treatment to correct major dental asymmetries.

The correction of major dental asymmetries in adults can be challenging. Many adult patients modify their behavior to compensate for skeletal disharmonies, functional shifts and missing teeth. Some skeletal components, including the temporomandibular joint, also adapt in non-growing patients. Extracting premolars will not always correct a marked asymmetry and orthognathic surgical procedures are frequently inappropriate. In the case of Patient FG, extraction of a mandibular central incisor resulted in improved function and esthetics in a relatively short time with minimal expense and trauma.