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Biomedical subjects

R G Alexander

Publications and source records attributed to R G Alexander.

11 recordsLinked to original sources
PubMed1991

Lip bumper therapy for gaining arch length.

With the use of pretreatment and posttreatment lateral cephalograms and study models, lip bumper therapy for two groups of 20 patients was evaluated. One group was treated with lip bumpers fabricated from stainless steel round wire covered with shrink tubing and activated every 2 to 3 months. The second group was treated with larger prefabricated lip bumpers covered with acrylic shields from canine to canine and activated every 4 to 5 weeks. Yearly rates of treatment change indicate that the type of lip bumper used and the method of clinical manipulation have no effect on mandibular incisor position. Both groups showed similar rates of controlled incisal tipping with the center of rotation at the apex. Dental movements of the posterior segment were significantly different between groups. The second group displayed significantly more molar tipping than the first group. The second group also showed significantly greater transverse expansion of the canines, first premolars, and first molars.

Acrylic Resins↗
PubMed1987

A computerized analysis of the shape and stability of mandibular arch form.

To determine whether a particular ideal orthodontic arch form could be identified, the mandibular dental casts of 30 untreated normal cases, 30 Class I nonextraction cases, and 30 Class II nonextraction cases were examined. Following computerized digitizing and the use of a mathematic function called polynomial of the fourth degree, arch forms were generated for each sample and then compared to 17 commercially produced arch forms. Results showed that no particular arch form predominated in any of the three samples. A shape representing a combination of the "Par" and "Vari-Simplex" arch forms approximated to only 50% of the cases in the three samples. The remaining 50% of the cases displayed a wide variety of arch forms. Cases that had changes in arch form during nonextraction treatment frequently were not stable; almost 70% showed significant long-term posttreatment changes. Customizing arch forms appears to be necessary in many cases to obtain optimum long-term stability because of the great individual variability in arch form found in this study.

Adolescent↗
PubMed1987

Nonextraction orthodontic therapy: posttreatment dental and skeletal stability.

To assess the long-term stability of nonextraction orthodontic treatment, the dental cast and cephalometric records of 28 cases were evaluated. Thirty cephalometric and seven cast parameters were examined before treatment, posttreatment, and an average of almost 8 years postretention. Results showed overall long-term stability to be relatively good. Relapse patterns seen were similar in nature, but intermediate in extent, between untreated normals and four first premolar extraction cases. Significant decreases were seen in arch length and intercanine width during the postretention period despite minimal changes during treatment. Incisor irregularly increased slightly postretention; intermolar width, overjet, and overbite displayed considerable long-term stability. Mandibular incisor mesiodistal and faciolingual dimensions were not associated with either pretreatment or posttreatment incisor crowding. Class II malocclusions with large ANB values and shorter mandibular lengths showed increased incisor irregularity, shorter arch lengths, and deeper overbites at the postretention stage, suggesting that the amount and direction of facial growth may have been partially responsible for maturational changes seen during the postretention period.

Adolescent↗
PubMed1986

Differential diagnosis and treatment planning for the adult nonsurgical orthodontic patient.

Increasing numbers of adult patients are seeking orthodontic care and some, despite significant skeletal malocclusions, elect not to have combined orthodontic-surgical treatment. The purpose of this article is to outline some of the diagnostic and therapeutic principles that can be used in the adult nonsurgical orthodontic patient. The importance of realistic goal setting in the face of compromised occlusions is emphasized. Diagnosis should include evaluation of all three dimensions and recognize the limitations of therapy in each dimension for the nongrowing patient. Periodontal considerations, extraction decisions, and retention regimens are of vital importance to the achievement and maintenance of an optimum result. Clinical records will demonstrate four commonly seen problems and their resolution.

Adolescent↗
PubMed1977

Surgical correction of the long face syndrome.

The combined efforts of different specialists are needed for the successful treatment of patients with the long face syndrome. Both surgeons and orthodontists who recognize their own capabilities and limitations must combine their skills to achieve the best possible occlusion and facial esthetics. The surgical and orthodontic plan of therapy is designed to correct the patient's dentofacial deformity. Surgical reduction of facial height and proper alignment of the teeth by orthodontic means are common denominators of successful treatment. By properly planned and executed Le Fort I maxillary osteotomies, the vertical dimensions of the face can be shortened to improve the esthetic balance between the nose, upper lip, teeth, and chin and achieve lip competency. Variable open-bite and nonopen-bite maxillary deformities in forty adults with the long face syndrome were corrected by Le Fort I osteotomy and orthodontic treatment. The technical problems encountered in planning and executing treatment are discussed and illustrated by selected case reports.

Adolescent↗