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Biomedical subjects

G Altuna

Publications and source records attributed to G Altuna.

18 recordsLinked to original sources
PubMed1995

Surgically assisted rapid orthodontic lengthening of the maxilla in primates--a pilot study.

Orthodontic and surgical treatment of patients with maxillary retrusion and/or midface hypoplasia is challenging. This study was designed to show that the maxilla can be successfully lengthened by surgical assisted rapid orthopedic movement, using the principles of distraction osteogenesis. Three experimental and three control adolescent cynomolgus primates were used in this study. Metallic markers were placed in the cranial base and the maxilla and cephalometric x-ray films were taken. An orthodontic appliance was constructed with a Glen-Ross screw (Dentaurum, Newtown, Pa.) oriented anteroposteriorly. Anterior supraapical osteotomies of the maxilla were carried out. Bilateral horizontal and interdental osteotomies were created between the first premolars and the canine; the anterior six tooth dental-osseo segment was completely mobilized in all animals. Beginning 1 week after surgery, the orthodontic appliance was opened a quarter turn every 2 days until the anterior segment was advanced by 4 mm in two animals and 6 mm in one animal. Animals were killed at 6, 8, and 12 weeks after completion of the maxillary orthopedic advancement. Computerized tomographic scans of the maxillae were completed, and the specimens were then prepared by routine histologic methods for examination by light microscopy. The computerized tomographic scans showed bone deposition in the osteotomy sites, which was confirmed by histologic observations. Since this technique demonstrated repair by bone rather than soft connective tissue in the osteotomy sites, this procedure could be a useful method of treating midface retrusion.

Animals↗
PubMed1995

Rapid orthopedic lengthening of the mandible in primates by sagittal split osteotomy and distraction osteogenesis: a pilot study.

This study proposes the development of an intraoral surgical approach to distraction osteogenesis to treat maxillofacial defects. Bilateral sagittal split osteotomies were made in the ascending ramus and body of the mandible of two adult cynomologus primates, and the dento-osseous segment was completely mobilized. A distraction device was fabricated from a Glen-Ross screw soldered between two mini bone plates. The bone plates were fixed by self-tapping screws to both right and left proximal and distal mandibular segments. Beginning 1 week postoperatively, both distraction plates were opened 1 mm every day until the mandible was advanced a total of 10 mm. Comparison of cephalometric radiographs and study casts prepared preoperatively, at the completion of the mandibular orthopedic advancement, and up to 12 weeks postdistraction, showed that mandibular advancement was successful and stable. There was radiographic evidence of bone filling the osteotomy sites, and there was no scar tissue formation or evidence of relapse.

Animals↗
PubMed1995

Surgically assisted-rapid orthopedic lengthening of the maxilla in primates--relapse following distraction osteogenesis.

A recent study has shown that the maxilla in primates can be successfully lengthened (0.5 mm every other day up to 6.0 mm) by means of surgically assisted-rapid orthopedic movement, using the principles of distraction osteogenesis. The present study was designed to determine if the maxilla can be advanced at a faster rate and if relapse would occur after removal of the orthodontic appliance. Metallic markers were placed in the cranial base and maxilla of two Cynomolgus primates, and cephalometric radiographs were taken. Bilateral horizontal and interdental osteotomies were created between in the first premolars and the canines, and the anterior segment was completely mobilized. An orthodontic appliance was bonded to the teeth and the screw was closed, compressing the osteotomy site. One week postoperatively the appliance was opened four quarter turns every day until the anterior segment was advanced by 10 mm. Cephalometric radiographs were taken at 6, 8, and 12 weeks postadvancement. At 12 weeks, the orthodontic appliance was removed, and at that time and 2, 4, and 6 weeks later, cephalometric radiographs were taken and study models fabricated. At the end of the postretention period, the animals were sacrificed, and the maxillae were evaluated by light microscopy. Results showed that the maxilla can be successfully advanced at a faster rate and for longer distances, and that the advanced maxilla does not relapse during the 6-week postretention period.

Animals↗
PubMed1991

A statistical assessment of orthodontic practices, product usage, and the development of skin lesions.

Recently there has been great interest in skin lesions on the hands of orthodontic personnel who are exposed to a wide variety of metals, bonding agents, and other materials. Thus this 1985 national survey of 448 Canadian orthodontists (response rate 49%) was undertaken to examine orthodontic practice activities, bonding agent and wire product use, and prevalence of skin lesions on the hands and their possible association with these products. About 13% of the 213 responding orthodontists and at least one other staff member in 18% of the orthodontic practices reported the occurrence of hand lesions (reactions) over the preceding 3 years typical of exposure to dental materials. In nearly one fourth of the offices, at least one person was affected. Regarding product use. Concise, Mono-Lok, and Endur bonding agents and stainless steel, Nitinol, and Elgiloy wires were used most often. The orthodontists reported frequent involvement in bonding activities and infrequent use of gloves. Of all the individual and combined materials and practice characteristics and activities tested singly and multivariately for statistical association with hand lesions, only the orthodontists' use of Mono-Lok, gloves, and the activity of frequently cleaning excess bonding agent were statistically related to the lesions. Multiple logistic regression suggested that the statistical effects of Mono-Lok use and removal of excess bonding agent were independent; thus removal of excess agent may have consequences for lesion development separate from Mono-Lok use.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1990

Effect of functional appliances on jaw muscle activity.

The electromyographic (EMG) activity of masticatory muscles was monitored longitudinally with chronically implanted EMG electrodes to determine whether functional appliances produce a change in postural EMG activity of the muscles. Preappliance and postappliance EMG levels in four experimentals that had been fitted with functional appliances were compared against the background of EMG levels in controls without appliances. The insertion of two types of functional appliance to induce mandibular protrusion was associated with a decrease in postural EMG activity of the superior and inferior heads of the lateral pterygoid, superficial masseter, and anterior digastric muscles; the decrease in the first three muscles was statistically significant. This decreased postural EMG activity persisted for approximately 6 weeks, with a gradual return toward preappliance levels during a subsequent 6-week period of observation. Progressive mandibular advancement of 1.5 to 2 mm every 10 to 15 days did not prevent the decrease in postural EMG activity.

Activator Appliances↗
PubMed1987

The influence of functional appliance therapy on glenoid fossa remodeling.

This study investigates the remodeling changes in the condyle and glenoid fossa following a period of progressively activated and continuously maintained mandibular advancement using the Herbst appliance. Progressive mandibular advancement was achieved by adding stops to the telescopic arms of the appliance, with the total activation reaching 7.0 to 10.0 mm, dependent upon the length of the treatment phase. This mandibular advancement produced extensive remodeling and anterior relocation of the glenoid fossa, which contributed to anterior mandibular positioning and altered jaw relationships.

Activator Appliances↗
PubMed1987

The reaction of skin to primers used in the "single-step" bonding systems.

A large number of direct bonding systems have been introduced for use by dentists and dental hygienists. Although these agents are used for direct bonding of brackets to enamel, contact with skin, oral mucosa, and gingiva is not uncommon. These products have wide clinical use, but their biocompatibility characteristics have not been extensively investigated. The present study was undertaken to determine the effects of the primer component of Mono-Lok (Rocky Mountain) and the primer component of Control (Lancer Pacific) on skin. Three adult Macaca mulatta monkeys were used in the study. The skin on their backs was shaved and the primer component of Control, primer component of Mono-Lok, and saline solution were applied at different sites every 3 days for up to four applications. The skin was examined clinically and, 5 days after the last application, a biopsy was performed for histologic evaluation. The skin in contact with the primer component of Mono-Lok exhibited pronounced inflammatory changes and was characterized by swelling, vesiculation, and ulceration. Histologic observations confirmed these findings by showing a marked inflammatory cellular response characterized by eosinophils. In contrast to these findings, the skin in contact with the primer component of Control or saline solution exhibited normal architecture. Histologic observations supported this appearance and showed minimal inflammatory cell infiltration. These results show that there are differences in the biocompatibility of direct bonding systems and that further studies are needed to clarify their long-term effects on patients and dental personnel.

Allergens↗
PubMed1985

Tissue reaction to primers used in the "single-step" bonding system.

A large number of direct-bonding systems have been introduced for use by orthodontists. Although these agents are used for direct bonding of brackets to enamel, contact with skin, oral mucosa, and gingiva is not uncommon. While these products have wide clinical use, their biocompatibility has not been extensively investigated. The present study was undertaken to determine the effects of the primer component of Mono-Lok and the primer component of Control on gingiva. Three adult and one juvenile Macaca mulatta monkeys were used in this investigation. In two adults and the one juvenile animal, the primer component of Mono-Lok was applied to the right buccal surfaces of teeth; in the remaining adult animal, the primer component of Control was applied to the right buccal surfaces of teeth. The excess material was extended 5.0 mm onto the gingival tissues and for 3 minutes the cheeks and saliva were kept away from the sites to be tested. Saline solution was applied to the left buccal segments in all animals. Primer and saline solution were applied at 3-day intervals for a period of 21 days. The gingival tissues were examined clinically and biopsied for histologic evaluation. The gingiva in contact with the primer component of Mono-Lok exhibited pronounced inflammatory changes and was characterized by redness, swelling, and spontaneous bleeding. Histologic observations confirmed these findings by showing a marked inflammatory cellular response characterized by eosinophils. In contrast to these findings, the gingiva that was in contact with the primer component of Control or saline solution exhibited normal gingival architecture.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Primate experiments in malocclusion and bone induction.

It has been recognized for many years that muscle function influences bone formation and morphology. It is hypothesized here that the movement of bone into new positions within a muscle system results in rearrangement of the stress distribution and reorganization of shape and internal structure. To test the above hypothesis, clinical and animal experiments involving the use of posterior occlusal bite blocks, Herbst appliances, and temporal and masseter muscle stimulation were undertaken. Chronic or continuous alteration in mandibular position within the neuromuscular environment with the posterior occlusal bite block and the Herbst appliance in a sample of monkeys produced extensive condylar remodeling and change in mandibular size. Short periods of induced hyperactivity in the masseter and temporal muscles were associated with the production of malocclusion symptoms. Excess induced temporal muscle activity of specific frequency and intensity may interfere with the remodeling of bone grafts placed under the temporal muscle, while a lesser level of activity was associated with bone remodeling.

Animals↗
PubMed1983

Use of a facemask to protect the intra-oral area in cynomolgus monkeys.

A custom fiberglass facemask was designed for cynomolgus monkeys to protect an orthodontic appliance. The mask was constructed from impressions and models made of the animal's head. It prevented the fingers from entering the mouth to dislodge the intra-oral appliances. The facemask permitted normal physical activity, eating, and drinking.

Animals↗