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Biomedical subjects

W H Bell

Publications and source records attributed to W H Bell.

At least 19 recordsLinked to original sources
PubMed1992

Location of the nasolacrimal canal in relation to the high Le Fort I osteotomy.

The positional relationship between the high-level Le Fort I osteotomy and the nasolacrimal canal was studied in standard posteroanterior and lateral cephalograms made of 100 adult dry skulls after orienting the Frankfort horizontal of each skull to the natural horizontal plane. The simulated high-level Le Fort I osteotomy in all of the 100 skulls was under the level of the inferior orifice of the nasolacrimal canal by a mean distance of 5.2 mm (range, 0.5 to 11.5 mm). The average distance between the canal orifice and a line which extended from the lacrimal fossa to the anterior attachment of the inferior turbinate was 0.7 mm (range, 2.0 mm medially to 3.5 mm laterally). The maxillary height was strongly correlated to the height of the infraorbital foramen (r = .59, P less than .001) and the simulated osteotomy (r = .57, P less than .001). The results indicate that the osteotomy, when made just beneath the infraorbital foramen and extending into the piriform rim at the level of anterior attachment of the inferior turbinate, will usually not jeopardize the nasolacrimal duct within its bony canal. A line drawn from the lacrimal fossa to the anterior attachment of the inferior turbinate on the anterior aspect of the maxilla is a good approximation of the course of the nasolacrimal canal.

Humans↗
PubMed1992

Temporomandibular joint adaptation following inferior repositioning of the maxilla in adult monkeys.

Treatment of adults with vertical maxillary deficiency (short faces) has continually been an intriguing challenge for surgeons and orthodontists. For this category of patients, the introduction of simultaneous bone grafting and Le Fort I osteotomy has opened the door for improved treatment. However, despite the improved surgical techniques, surgeons have been reluctant to increase the vertical dimension of the maxilla by Le Fort I osteotomy with interpositional bone grafts because of inconsistent and variable stability after surgery. This study examines structural and functional adaptation of the adult temporomandibular joint and stability in a primate model following surgical lengthening of the maxilla in the vertical dimension. Results suggest that maxillary surgery and autorotation can alter condylar stress within physiologic ranges. However, further studies are indicated to clarify the surgery's long-term effect.

Adaptation, Physiological↗
PubMed1991

Bone resorption, stability, and soft-tissue changes following large chin advancements.

Large advancement genioplasties were performed in 10 patients (mean advancement, 11.7 mm) by horizontal osteotomy of the inferior border of the mandible, with preservation of a musculoperiosteal pedicle to the advanced genial segment. Preoperative, immediate postoperative, and long-term follow-up lateral cephalometric radiographs were retrospectively analyzed to evaluate the osseous and soft-tissue changes of the chin. After a mean follow-up period of 15 months, 76% of the initial advancement was preserved, representing 24% osseous resorption. The enveloping soft tissues of the chin followed the bony movement in a ratio of 1:0.88. Horizontal osteotomy of the inferior border of the mandible was a relatively stable procedure when used for large chin advancements. The broadcast possible musculoperiosteal pedicle should remain attached to the advanced genial segment to minimize osseous resorption and to achieve more predictable soft-tissue changes.

Adolescent↗
PubMed1991

Condyle position and mobility before and after intraoral vertical ramus osteotomies and neuromuscular rehabilitation.

Correction of dentofacial deformities in patients with existing temporomandibular dysfunction and pain by intraoral vertical ramus osteotomies may result in improved function and resolution of symptoms. A prospective study of condylar position and mobility was made in nine patients with anterior disk displacements with reduction and associated temporomandibular pain and dysfunction. Each patient was treated by bilateral intraoral vertical ramus osteotomies with 2 to 3 weeks of maxillomandibular fixation and no interosseous fixation of the proximal segment. Condylar position and mobility in the surgical group were compared with normative values derived from seven individuals without discernible pain or dysfunction. Immediately postoperatively, the condyle was consistently positioned anteriorly and inferiorly, but the condyles tended to return to their preoperative position. Condylar mobility after surgery exceeded presurgical mobility and was associated with improved mandibular function.

Centric Relation↗
PubMed1979

Combined orthodontic-surgical correction of moderate mandibular deficiency.

Carefully planned, coordinated, and executed orthodontic and surgical treatment is a viable alternative to traditional orthodontic treatment of patients with moderate mandibular deficiency. Recognition of their clinical manifestations is essential to distinguish between relative and absolute mandibular deficiency. If after clinical analysis of the Class II patient, esthetic priorities are established to maintain a balanced relationship between the upper lip and nose and not reduce the prominence of the upper lip, mandibular deficiency must be treated by surgical advancement of the mandible, superior repositioning of the maxilla, and consequent autorotational movement of the mandible forward and upward, or a combination of these procedures. The common denominator of successful therapy of absolute mandibular deficiency involves surgery to advance the mandible; relative mandibular deficiency, on the other hand, is treated by maxillary surgery to reposition the maxilla superiorly to allow forward and upward movement of the retropositioned mandible (autorotation). In actual clinical practice many patients manifest a combination of absolute and relative mandibular deficiency and are treated by maxillary and mandibular surgery. Lateral maxillary osteotomies, in concert with rapid maxillary expansion and genioplasty to alter the dimensions of the chin, are essential adjunctive surgical procedures to achieve three-dimensional esthetic and occlusal balance.

Adult↗
PubMed1979

Surgical-orthodontic correction of horizontal maxillary deficiency.

Selected maxillary osteotomies in concert with rapid maxillary expansion appliances are dependable adjuncts to treatment of the various clinical manifestations of horizontal maxillary deficiency and the accompanying crossbite. The important diagnostic, treatment planning, and technical considerations necessary for successful surgical-orthodontic correction of horizontal maxillary deficiency were discussed.

Adult↗
PubMed1978

Comparative study between the SFS and LFS rotation as a possible morphogenic mechanism.

Cephalometric tracings of twenty-seven untreated adult Caucasians, selected on a clinical impression of reduced lower facial height were studied and compared with tracings of nine untreated adult Caucasians with increased lower facial height. Various linear and angular measurements for both groups were analyzed and compared. As has been previously described for the SFS, the LFS group can be subdivided into at least two subtypes. Subtype I is characterized by a long ramus, increased OP-PP, an increased SN:MP-angle, and excessive lower anterior facial height. These persons manifest the most typical clinical characteristics of the long face syndrome and have excessively long faces. In Subtype II, however, extreme backward and downward rotation of the mandible, combined with a short or extremely short ramus, is associated with an increase in lower anterior facial height. The increase in posterior maxillary height was not striking in this subtype. It was demonstrated that many of the characteristics of the LFS group and the SFS group can be explained by clockwise or counterclockwise rotation of the mandible "in concert" with the hyoid, tongue, pharynx, and cervical spine. The LFS group was characterized by a clockwise rotation of the mandible "in concert" with the hyoid, tongue, pharynx, and cervical spine. The mandible of the SFS group rotated similarly, but in the opposite counterclockwise direction. The vital need to maintain patency of the upper airway at the level of the base of the tongue may account for rotation in the LFS.

Cephalometry↗
PubMed1978

The short face syndrome.

Cephalograms of twenty-seven untreated adult Caucasians, selected on the basis of a clinical impression of reduced lower facial height, were studied. Various linear and angular measurements were studied and compared to the Bolton standards. The short face syndrome SFS is a clinically recognizable facial type with reduced lower facial height as the common denominator. On the basis of the FPI (facial proportion index), the RH (ramus height), the OP-PP distance (or posterior maxillary height), and the SN:MP angle, two subgroups were distinguished in the SFS group. SFS, was characterized by a long ramus, sharply reduced SN:MP angle, an FPI close to 10, and a slightly reduced posterior maxillary height. In contrast, SFS2 was characterized by a short ramus, a slightly reduced SN:MP angle, an FPI with values around or below zero, and a sharply reduced posterior maxillary height. The latter group was designated as vertical maxillary deficiency.

Adolescent↗
PubMed1978

Revascularization after surgical repositioning of one-tooth dento-osseous segments.

Vascularization, revascularization, and bone healing were studied after two different surgical techniques for surgical repositioning of single-tooth dento-osseous segments in adult mongrel dogs. Microangiographic and histologic studies of both one-stage and two-stage techniques for immediate surgical repositioning of single-tooth dento-osseous segments showed early but transient vascular ischemia, minimal osteonecrosis, and osseous union between most of the osteotomized segments. The attached soft tissue provided an adequate vascular pedicle for immediate repositioning of small dento-osseous segments by interdental and subapical osteotomies. The results of these clinically analogues studies support the clinical use of techniques that maximize the attachment of the gingiva to the mobilized dento-osseous segment.

Alveolar Process↗
PubMed1978

Correction of the atrophic alveolar ridge by interpositional bone grafting: a progress report.

A retrospective study of postoperative stability and osseous changes was made on nine patients with maxillary or mandibular atrophy who were treated with interpositional bone grafting techniques. There was minimal discernible positional change or resorption of the portion of the maxilla or mandible that was moved by interpositional grafting procedures. Sequential radiographs and cephalometric tracings showed early consolidation of the grafted bone, minimal resorption of the respositioned osseous segments, and a small decrease of alveolar ridge height during an average potsoperative follow-up period of seven months.

Alveoloplasty↗
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↗
PubMed1977

Surgical correction of the atrophic alveolar ridge. A preliminary report on a new concept of treatment.

Inferior repositioning of the atrophic maxillary edentulous alveolar ridge by LeFort I osteotomy and simulataneous bone grafting, and superior repositioning of the atrophic mandibular edentulous ridge by horizontal osteotomy of the mandibular body and simultaneous bone grafting have been accomplished successfully. These two new surgical procedures add a new dimension to treatment of severe atrophy of the alveolar ridges in edentulous or partially edentulous patients.

Adult↗