primate experiments on mandibular growth direction

1
CURRENT LITERATURE Primate Experiments on Mandibular Growth Direc- tion. Tomer BS, Harvold EP. Am J Orthod 82: 114, 1982 This study is one of a series of reports on the effect of function on growth patterns of the face. Various factors have been proved to affect mandibular growth patterns. including large adenoids, patients with cleft palate treated orthodontically, and physical displacement of the tongue. This study tested the effect of induced change in recruit- ment of orofacial muscles on mandibular position and growth direction. Sixteen male rhesus monkeys, eight experimental ones and eight for control. were used. In each animal, two stainless steel pins were placed on either side of the man- dible, one close to the lower border in the anterior region and the other near the lower border to the gingival angle. These were used as markers to assess morphologic change by lateral cephalograms. Films were taken at three-month intervals over a three-year period. The ex- perimental animals were fitted with nose plugs made of soft silicone, which were then sutured into both nostrils, allowing for only oral respiration. Study results were based on linear measurements (sella-nasion, condylar upper contour-symphysis, nasion symphysis, symphysis- occlusal plane, bone markers-lower border) and angular measurements (between S-N and a tangent to mandibular posterior border, between posterior ramus border and a tangent to mandibular lower border, between posterior ramus border and a line through the marker pins, between S-N and lower border, and the angle of growth direc- tion [Bjork’s method]). Results were as follows. In the linear measurements, the only statistically different results were an increase of the nasion-symphysis dimension in the experimental group. Among the angle measurements, the experimental animals showed a significantly larger increase of the go- nial angle and the angle between S-N and the lower man- dibular border. No statistically significant difference or growth trend was derived from the other angular mea- surements. The net result was an increase in facial height. The authors believed that obstructing the nasal airway forced the animals to breathe orally. This led to a recruit- ment of orofacial musculature to accommodate a lower mandibular position. This position was reinforced by sub- sequent extrusion of maxillary teeth accompanied by downgrowth of the maxilla. Interestingly, though, the posterior ramus borders always maintained the same orientation to the skull. The authors feel that this shows that though the suprahyoid and facial muscles were re- cruited to aid in the lower mandibular positioning, the masticatory muscles constitute an independent functional system, as they acted to bring about remodeling at the ramus to maintain its inclination to the skuII.-NORMAN GOLD Reprint requests to Dr. Harvold: Center for Correction of Craniofacial Anomalies, University of California, San Francisco, California. Clinical Investigation of Marsupialization for the Cys- tic Lesions of the Jaws. Hanada K, Yoshimura Y, Sugata T, Yoshiga K, Takahashi Y, Seyama A, Takada K. Jpn J Oral Surg 28: 1089, 1982 Marsupialization was used for the treatment of six radicular cysts, five dentigerous cysts, 12 odontogenic keratocysts, and seven cystic ameloblastomas. The ages of the patients ranged from 7 to 64 years. In radicular cysts, the lesions clinically disappeared in eight months to one year. and the process was accompanied by regenera- tion of new bone. A tendency to reduction was faster in dentigerous cysts that occurred in younger patients, whereas in odontogenic keratocysts complete resolution took one to two years. A tendency to resolution was slower in cysts arising in the ascending ramus. but no recurrence was encountered. In ameloblastomas, the procedure resulted in an evident reduction in size to a small depression over a period of two to three years in five cases, with no sign of recurrence. whereas in the other two cases, mandibulectomy was performed six months and two years after marsupialization because of tumor growth. Although the results of marsupialization depend on the nature, size, and location of the lesions as well as on the age of patients. marsupialization could be a treatment of choice in varying cystic lesions in the jaws in patients of all ages. With ameloblastoma, wide opening of the lesion by complete removal of one side of the cystic wall seems to be essential to maintain the patency of the opening and to enable close examination of the inner sur- face to detect proliferation of the tumor at the earliest date.-TAM10 NAKAJIMA Gas-Liquid Chromatography in the Diagnosis of Anaerobic Infections: A Three-year Experience. Watt B, Geddes PA, Greenan DA, Napier SK, Mitchell AJ. Clin Path01 35:709, 1982 Gas-liquid chromatography (GLC) has been used as a method for rapid determination of anaerobic infections. The purpose of this study was to evaluate its effectiveness in a clinical laboratory. Over a three-year period, 1929 routine specimens of various culture sites were examined. Conventional aerobic and anaerobic incubation was done. The GLC for volatile fatty acids (VFA) was also performed. Seventy-six per cent of the samples yielded no VFA, and 24% yielded one or more VFA. Of the VFA negative sam- ples, 1.4% grew anaerobes on culture (false negatives). Of samples yielding one or more FVA nearly 10% gave no growth on culture. Some of the patients may have been receiving concurrent antimicrobial therapy. Nearly half of the VFA positive samples yielded aerobic growth only, usually only one or two VFA. Samples that grew anaerobic bacteria gave a more complex VFA pattern. Gas-liquid chromatography appears to be a useful screening test for the presence or absence of anaerobic infections but not of aerobic infections.-JOSEPH E. VAN SICKELS Reprint requests to Dr. Watt, Central Microbiological Labora- tories. Western General Hospital, Crewe Road, Edinburgh, EH4 2XU. Scotland. Cardiac Effects of Prolonged and Intense Exercise Training in Patients with Coronary Artery Disease. Ehsani AA, Martin WH III, Heath GW, Coyle EF. Am J Cardiol 50:2, 1982 These data demonstrate that prolonged and vigorous exercise training for one year produced favorable cardiac adaptation in eight men with coronary artery disease and a mean age of 52 ? 3 years. In contrast to a nonexercising control group of five patients, these subjects showed a 42% increase in maxima1 oxygen uptake capacity, signifi- cantly lower heart rate at rest, submaximal heart rate and 274

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Page 1: Primate experiments on mandibular growth direction

CURRENT LITERATURE

Primate Experiments on Mandibular Growth Direc- tion. Tomer BS, Harvold EP. Am J Orthod 82: 114, 1982

This study is one of a series of reports on the effect of function on growth patterns of the face. Various factors have been proved to affect mandibular growth patterns. including large adenoids, patients with cleft palate treated orthodontically, and physical displacement of the tongue. This study tested the effect of induced change in recruit- ment of orofacial muscles on mandibular position and growth direction.

Sixteen male rhesus monkeys, eight experimental ones and eight for control. were used. In each animal, two stainless steel pins were placed on either side of the man- dible, one close to the lower border in the anterior region and the other near the lower border to the gingival angle. These were used as markers to assess morphologic change by lateral cephalograms. Films were taken at three-month intervals over a three-year period. The ex- perimental animals were fitted with nose plugs made of soft silicone, which were then sutured into both nostrils, allowing for only oral respiration. Study results were based on linear measurements (sella-nasion, condylar upper contour-symphysis, nasion symphysis, symphysis- occlusal plane, bone markers-lower border) and angular measurements (between S-N and a tangent to mandibular posterior border, between posterior ramus border and a tangent to mandibular lower border, between posterior ramus border and a line through the marker pins, between S-N and lower border, and the angle of growth direc- tion [Bjork’s method]).

Results were as follows. In the linear measurements, the only statistically different results were an increase of the nasion-symphysis dimension in the experimental group. Among the angle measurements, the experimental animals showed a significantly larger increase of the go- nial angle and the angle between S-N and the lower man- dibular border. No statistically significant difference or growth trend was derived from the other angular mea- surements. The net result was an increase in facial height.

The authors believed that obstructing the nasal airway forced the animals to breathe orally. This led to a recruit- ment of orofacial musculature to accommodate a lower mandibular position. This position was reinforced by sub- sequent extrusion of maxillary teeth accompanied by downgrowth of the maxilla. Interestingly, though, the posterior ramus borders always maintained the same orientation to the skull. The authors feel that this shows that though the suprahyoid and facial muscles were re- cruited to aid in the lower mandibular positioning, the masticatory muscles constitute an independent functional system, as they acted to bring about remodeling at the ramus to maintain its inclination to the skuII.-NORMAN

GOLD

Reprint requests to Dr. Harvold: Center for Correction of Craniofacial Anomalies, University of California, San Francisco, California.

Clinical Investigation of Marsupialization for the Cys- tic Lesions of the Jaws. Hanada K, Yoshimura Y, Sugata T, Yoshiga K, Takahashi Y, Seyama A, Takada K. Jpn J Oral Surg 28: 1089, 1982

Marsupialization was used for the treatment of six radicular cysts, five dentigerous cysts, 12 odontogenic keratocysts, and seven cystic ameloblastomas. The ages

of the patients ranged from 7 to 64 years. In radicular cysts, the lesions clinically disappeared in eight months to one year. and the process was accompanied by regenera- tion of new bone. A tendency to reduction was faster in dentigerous cysts that occurred in younger patients, whereas in odontogenic keratocysts complete resolution took one to two years. A tendency to resolution was slower in cysts arising in the ascending ramus. but no recurrence was encountered. In ameloblastomas, the procedure resulted in an evident reduction in size to a small depression over a period of two to three years in five cases, with no sign of recurrence. whereas in the other two cases, mandibulectomy was performed six months and two years after marsupialization because of tumor growth. Although the results of marsupialization depend on the nature, size, and location of the lesions as well as on the age of patients. marsupialization could be a treatment of choice in varying cystic lesions in the jaws in patients of all ages. With ameloblastoma, wide opening of the lesion by complete removal of one side of the cystic wall seems to be essential to maintain the patency of the opening and to enable close examination of the inner sur- face to detect proliferation of the tumor at the earliest date.-TAM10 NAKAJIMA

Gas-Liquid Chromatography in the Diagnosis of Anaerobic Infections: A Three-year Experience. Watt B, Geddes PA, Greenan DA, Napier SK, Mitchell AJ. Clin Path01 35:709, 1982

Gas-liquid chromatography (GLC) has been used as a method for rapid determination of anaerobic infections. The purpose of this study was to evaluate its effectiveness in a clinical laboratory. Over a three-year period, 1929 routine specimens of various culture sites were examined. Conventional aerobic and anaerobic incubation was done. The GLC for volatile fatty acids (VFA) was also performed. Seventy-six per cent of the samples yielded no VFA, and 24% yielded one or more VFA. Of the VFA negative sam- ples, 1.4% grew anaerobes on culture (false negatives). Of samples yielding one or more FVA nearly 10% gave no growth on culture. Some of the patients may have been receiving concurrent antimicrobial therapy. Nearly half of the VFA positive samples yielded aerobic growth only, usually only one or two VFA. Samples that grew anaerobic bacteria gave a more complex VFA pattern.

Gas-liquid chromatography appears to be a useful screening test for the presence or absence of anaerobic infections but not of aerobic infections.-JOSEPH E. VAN SICKELS

Reprint requests to Dr. Watt, Central Microbiological Labora- tories. Western General Hospital, Crewe Road, Edinburgh, EH4 2XU. Scotland.

Cardiac Effects of Prolonged and Intense Exercise Training in Patients with Coronary Artery Disease. Ehsani AA, Martin WH III, Heath GW, Coyle EF. Am J Cardiol 50:2, 1982

These data demonstrate that prolonged and vigorous exercise training for one year produced favorable cardiac adaptation in eight men with coronary artery disease and a mean age of 52 ? 3 years. In contrast to a nonexercising control group of five patients, these subjects showed a 42% increase in maxima1 oxygen uptake capacity, signifi- cantly lower heart rate at rest, submaximal heart rate and

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