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Biomedical subjects

A D Holmes

Publications and source records attributed to A D Holmes.

31 records · Page 2Linked to original sources
PubMed1995

Osseointegration in sinus-forming bone.

Osseointegration, using bone-anchored titanium fixtures, is a well-established technique for both intraoral and craniofacial prosthetic rehabilitation. The use of this technique in children can be complicated by craniofacial growth and sinus development. This study evaluates the effects of sinus formation and growth on the fate of osseointegrated titanium fixtures in the growing porcine model. At 3 weeks of age, six Landrace White cross male pigs had a 3.75 x 3.0 mm titanium fixture (Noblepharma) inserted into their right frontal bone where the right frontal sinus would subsequently develop. Preoperative CT scans with three-dimensional reconstructions were used to determine the insertion site. To follow the effects of growth and sinus formation, CT scans with three-dimensional reconstructions and cephalometric radiographs were taken at 1, 3, 6, and 9 weeks postoperatively and at sacrifice. The pigs were sacrificed serially, and direct osteometric measurements were taken to determine skull symmetry. All skulls were sectioned, and osseointegration was determined clinically, radiologically, and histologically with light and scanning electron microscopy. Five of the six fixtures osseointegrated. There were no apparent growth disturbances due to the fixtures. As growth progressed, the osseointegrated fixtures submerged into the frontal bone in a posteroinferior direction to become completely intraosseous 14 weeks after insertion. As the frontal sinus pneumatized, the fixtures remained osseointegrated, but progressive amounts of the fixtures became exposed in the sinus. From this study it would appear that osseointegrated titanium fixtures do not have any effect on calvarial growth and gradually submerge into the growing bone. As sinus development ensues, the fixtures remain integrated but become partially exposed within the sinus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

End-plate displacement during compression of lumbar vertebra-disc-vertebra segments and the mechanism of failure.

Seventeen specimens of lumbar discs, attached to the caudal and cranial halves of the adjacent vertebral bodies, were subjected to a maximum compressive load of 5.5 kN in six stages. The time between each stage was about 15 seconds. At each stage of compression, a radiograph of the specimen was recorded, and the bulging of the end-plate into the caudal vertebra was measured using a displacement transducer. After compression, the ash content of a bone sample and the water content of a sample of the nucleus of the disc were measured for each specimen. Sections through the specimens were examined by light microscopic study. Eight specimens did not fail, although end-plate displacement occurred during compression. The remaining nine specimens experienced fracture or permanent deformation of the end-plate. Specimens that failed had significantly lower rigidity of the end-plate and underlying trabecular bone; this rigidity was correlated with bone ash content.

Adult↗
PubMed1992

Experimental calvarial growth disturbance by micro-plate and screw fixation.

A study was designed to help ascertain the effects of rigid internal fixation in the growing skull. Five piglets underwent plating of the left coronal suture at 3 weeks of age. At the time of surgery metal markers were placed to follow bone growth. Cephalometric radiographs, direct osteometry at sacrifice, gross pathological examination and specimen radiography revealed a localized disturbance of growth. There was a restriction of sutural displacement and appositional bone growth at the site of the plate. Local restriction of sutural growth was almost complete during the experimental period. There was an alteration to a 'mature' suture morphology, without synostosis, of the suture on the plated side not seen on the control side. A plagiocephalic pig was not produced nor was there an orbital deformity. A large local contour deformity developed and by the end of the experimental period the plate had become completely incorporated in bone. These effects were statistically significant as well as clinically significant. The clinical use of this type of fixation in reconstructive surgery of the infant craniofacial skeleton is questioned in light of the result.

Animals↗
PubMed1990

The use of tissue expansion for immediate breast reconstruction after mastectomy.

A series of 139 patients who had a total mastectomy underwent breast reconstruction using the method of tissue expansion. In 127 patients a tissue expander was inserted at the time of mastectomy and in 12 patients this was done as a delayed procedure. The reconstruction was successfully completed in 87% of cases and the patient acceptance of this method of reconstruction has been high. We believe that tissue expansion should be offered to all women having immediate reconstruction after total mastectomy and that it also has a significant role in delayed breast reconstruction after mastectomy.

Adult↗
PubMed1988

Cephalometric and anthropomorphic observations of Binder's syndrome: a study of 19 patients.

Binder's syndrome (maxillonasal dysplasia) is a disorder characterized by nasomaxillary hypoplasia. To ascertain the extent of underdevelopment of the midfacial skeleton and soft tissues, 19 of 29 patients with Binder's syndrome were retrospectively evaluated, both with cephalometry and anthropometry. Ten females and nine males were placed collectively into three age groups: 6 years, 10 years, and 16 to 17 years. Cephalometric measurements disclosed a short anterior cranial base (S-N), a normal length of the vertical maxilla (SE-PNS), a decreased horizontal maxilla (PNS-A, Co-A), a recessed orbitale (SNO), and a high-normal mandibular length (Co-Gn). Anthropometry revealed a large nasofrontal angle, acute nasal inclination and nasolabial angle, decreased nasal prominence (Sn-Prn), a decreased columellar length (C-Sn), and a normal vertical nose (N-Sn) and upper lip (Sn-Sto) length.

Adolescent↗
PubMed1988

Arteriovenous malformation in the mandible of a young child.

Arteriovenous malformations rarely occur in the jaws, particularly in the very young child. The vascular and haemodynamic nature of the lesion is important in determining treatment and providing for a favourable prognosis, particularly in the high-pressure malformations. If the lesion is unstable and active, that is, there is enlargement, pain, bleeding or ulceration, successful treatment will depend upon early pre-operative embolization and surgical extirpation of the lesion. A 4-year old boy is presented who had a moderately active arteriovenous malformation of the left mandibular body. Angiography disclosed an arteriovenous malformation supplied by the inferior alveolar, lingual and facial arteries on the left side with no contralateral contribution. Pre-operative embolization via selective catheterization of the major arterial feeder was performed. Five days later, the involved portion of the mandible was resected and a corticocancellous bone-graft was placed. The 6-month follow-up disclosed no evidence of new arterial feeders or contralateral involvement.

Arteriovenous Malformations↗
PubMed1987

Maxillonasal dysplasia (Binder's syndrome): a critical review and case study.

Binder's syndrome (maxillonasal dysplasia) is a disorder of unknown etiology characterized by nasomaxillary hypoplasia and a 40-50% association of an underdeveloped frontal sinus and cervicospinal abnormalities. The midfacial retrusion is similar to that in chondrodysplasia punctata, resulting in confusion regarding diagnosis. This paper outlines the distinguishing features of Binder's syndrome, the treatment considerations, and presents 24 patients seen and treated. The facial and skeletal characteristics and developmental findings are emphasized to affirm the diagnosis of Binder's syndrome. A familial finding of Binder's features in five patients raises the possibility of a genetic mechanism, a previously undisclosed finding.

Abnormalities, Multiple↗
PubMed1983

Effects of porcelain/alloy interfacial diffusion zones on thermo-mechanical strain.

Chemical bonding between dental porcelains and alloys results from interdiffusion of porcelain and metal ions. An interfacial diffusion zone is created which, most likely, has properties different from those of bulk materials. The changed interface might affect experimental measurements of thermo-mechanical strain. To determine the magnitude and conditions under which this would occur, the interface was modeled as the intermediate layer of a three-layered porcelain-veneered split-metal ring. Layer thicknesses and coefficients of thermal expansion were varied, and the effects on gap change after cooling through 500 degrees C were calculated. Results are presented in a series of 14 Figs., ten curves each, which depict not only interfacial effects, but are extended for use in interpretation of the effects of properties of opaques and glazes as well. Under most conditions, the interface will not affect experimental measurements; some special exceptions are noted.

Chemical Phenomena↗
PubMed1979

Use of the temporalis muscule flap in blanking out orbits.

We report the use of the temporalis muscle as a transposition flap to obliterate the orbit in 5 patients. In 4 of the cases we split the muscle coronally and passed the anterior part through a window in the lateral orbital wall. In two of these patients, skin grafts were put on both sides of the temporalis muscle-fascia flap, to restore nasal lining and to cover the facial surface simultaneously. In the remaining patients, the muscle was split sagittally to provide a large surface for coverage. The temporalis muscle flap is a versatile one for filling orbits after exenteration.

Adult↗