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Biomedical subjects

D G Woodside

Publications and source records attributed to D G Woodside.

At least 19 recordsLinked to original sources
PubMed1995

A radiographic comparison of apical root resorption after orthodontic treatment with the edgewise and Speed appliances.

Apical root resorption is a serious iatrogenic problem sometimes associated with orthodontic treatment. The Speed appliance (Strite Industries, Ltd., Ontario, Canada) provides a continuous rotatory and torque action through its spring clip mechanism, in contrast with the edgewise appliance that may provide an interrupted force. The effect of continuous action on root resorption compared with the interrupted action of the edgewise system has not been investigated previously. The purpose of the present investigation is to test the null hypothesis that there is no difference in the apical root resorption seen after orthodontic treatment with the edgewise straight wire and the Speed appliance systems. Pretreatment and posttreatment periapical radiographs of 63 patients, (30 treated with the Speed 0.018 bracket and 33 with the 0.018 edgewise bracket) were studied. The long cone paralleling technique was used for all the radiographs. Any image distortion between the pretreatment and posttreatment radiograph was calculated and compensated for by using the crown length measurements, on the assumption that the crown length remains unaltered during the treatment period. Quantitative measurements of crown and root lengths for the maxillary and the mandibular central and lateral incisors were compared. Means and standard deviations for the percentage root resorption per tooth group were calculated. A three-factor analysis for variance (ANOVA test) was performed to determine whether there was an appliance, treatment, or gender effect on the amount of root resorption seen after treatment. No statistically significant difference in root resorption between the two appliance systems was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Variation in maxillary and mandibular molar and incisor vertical dimension in 12-year-old subjects with excess, normal, and short lower anterior face height.

Maxillary and mandibular molar and incisor vertical dimensions were evaluated in subjects who had excessive, normal, and short lower anterior face height in relation to upper face height. Sexual dimorphism was also investigated. The dentoalveolar heights were compared between Class I and Class II, dental and skeletal malocclusions. The sample was drawn from the Burlington Growth Centre sample and consisted of 188 male and 156 female subjects at age 12 years, for whom lateral head films were available. This sample was classified into excessive, normal, and short lower anterior face height, using the ratio upper anterior face height/lower anterior face height (UAFH/LAFH). The results showed that the dentoalveolar heights are significantly different between faces with excessive, normal, and short lower anterior face heights, except for the lower posterior dental height, which showed no difference between short and normal lower anterior face height subjects. All dentoalveolar heights are larger for male subjects except for the upper posterior dental height. Dentoalveolar heights are similar between Class I and Class II dental and skeletal malocclusions. The upper teeth present a higher correlation to the UAFH/LAFH ratio than the lower teeth. Stepwise regression analysis shows that 22% of the variation in the ratio is explained by the maxillary and mandibular molars and 41% is explained by the maxillary and mandibular incisors.

Cephalometry↗
PubMed1993

Normalization of incisor position after adenoidectomy.

Changes in incisor inclination and position in both jaws of children during the first 5 years after adenoidectomy were studied. The main change is a significant increased labial inclination of the incisors for the adenoidectomy groups. All variables that measure the labiolingual position of the mandibular incisors confirm a significant labial incisor positioning for both sexes. Stepwise regression analysis shows that 41% to 44% of the incisor proclination after adenoidectomy is accounted for by two regressors--sex (female) and increase in the sagittal size of the nasopharynx. The study supports the hypothesis that a changed mode of breathing after adenoidectomy is associated with significant labial positioning of the incisor teeth.

Adenoidectomy↗
PubMed1991

Mandibular and maxillary growth after changed mode of breathing.

The amount of maxillary and mandibular growth and the direction of maxillary growth were studied in 38 children during the 5 years after adenoidectomy for correction of severe nasopharyngeal obstruction. The amount of mandibular growth measured between successive gnathion points on superimposed radiographs was significantly greater in the group who had an adenoidectomy than in the matched controls. In the boys the difference was 3.8 mm (p less than 0.001), and in the girls the difference was 2.5 mm (p less than 0.01). The boys also showed a tendency toward greater growth in the maxilla as measured between successive subnasal points (1.2 mm, p less than 0.05). We detected no difference in the direction of maxillary growth between who had undergone adenoidectomy and the controls.

Adenoidectomy↗
PubMed1991

Relationship between mandibular incisor crowding and nasal mucosal swelling.

In this study, cephalometric and dental cast variables relating to 30 male and 20 female children, 8 to 13 years old with chronic nasal mucosal swelling, were compared with those relating to age- and sex-method controls. These controls were orthodontically untreated subjects with no histories of airway obstruction. The children with chronic nasal mucosal swelling had been referred because of chronic difficulties with nasal breathing to the Department of Otolaryngology Airflow Laboratory at the Hospital for Sick Children in Toronto. Previously active posterior rhinomanometry with a head-out volume displacement plethysmograph had been used to measure nasal resistance in 1000 consecutive subjects. Participants in the study reported here were selected from subjects whose nasal resistance fell markedly following administration of a decongestant spray. The subjects selected were found to have significantly (p less than 0.001) more mandibular incisor crowding, significantly (p less than 0.01) smaller mandibular arch widths than the controls, and significantly (p less than 0.001) smaller maxillary arch widths than the controls. The male subjects had significantly (p less than 0.01) smaller mandibular arch widths than the male controls.

Adolescent↗
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↗
PubMed1989

Panel assessments of the facial frontal view as related to mandibular growth direction.

This paper describes study No. 6 in a series dealing with mandibular growth direction (Lundström and Woodside, 1980). Study No. 5. (Lundström, Woodside and Popovich 1987) investigated facial harmony and disharmony of the facial profile. The present paper describes a study of the frontal views of the same children as paper No. 5. A mixed panel of 17 individuals (four categories of three, four and six people in each) made an aesthetic evaluation of the frontal facial view of 64 subjects (32 of each sex) from the Burlington serial experimental group. The sample consisted of equal numbers of individuals who displayed vertical, average or horizontal mandibular growth between the ages 6-20 years. We calculated correlations between the four assessor groups and found these to be acceptable. On average the panel found no change in frontal appearance between 12 and 18 years because of the balance between individuals improving and deteriorating. Our earlier work showed systematic differences in profile view between those with vertical growth on the one hand and average o horizontal on the other. The vertical cases were more disharmonious than the other categories. Corresponding findings were made also in the frontal view. Mean overall evaluations by all assessors showed a positive correlation between profile and front view assessments.

Adolescent↗
PubMed1989

The effect of rapid maxillary expansion on nasal airway resistance.

The purpose of this investigation was to provide quantitative data describing the effects of rapid palatal expansion on nasal airway resistance. Rapid palatal expansion is an orthodontic procedure which is commonly used to widen the maxilla to correct maxillary narrowing resulting in the orthodontic abnormality of crossbite and to provide more space for alignment of crowded teeth. Recordings of nasal airway resistance were taken prior to expansion, immediately after expansion (approximately one month), after a retention period of approximately 4 months and approximately one year after initiation of treatment. Findings indicate an average reduction in nasal airway resistance of 48.7 per cent which was statistically significant at the 0.005 level. The reduction also appeared stable throughout the post treatment observation period (maximum one year) as each series of readings was statistically significantly lower than the initial reading, but not significantly different from each other. Reduction of nasal airway resistance was highly correlated to the initial nasal resistance level prior to rapid maxillary expansion. Those individuals with the greater initial resistance tended to have greater reductions in airway resistance following the expansion.

Adolescent↗
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↗
PubMed1986

Mandibular growth direction following adenoidectomy.

The purpose of this article is to test the hypothesis that the establishment of nasal respiration in children with severe nasopharyngeal obstruction can be eliminated as a factor in determining mandibular growth direction. The article describes the changes in mandibular growth direction (MGD) in a 5-year period after adenoidectomies and the establishment of nasal breathing in a population of Swedish children. Measurements of mandibular growth directions were obtained from serial cephalometric radiographs after adenoidectomies in 38 Swedish children aged 7 to 12 years with previous nasopharyngeal obstructions. These were compared with the growth directions in a control sample of 37 Swedish children with clear airways and matched for age and sex. The adenoidectomy sample initially showed significantly longer lower face heights, steeper mandibular plane angles, and more retrognathic mandibles than the matched controls. Analysis showed that during the 5 years after adenoidectomies, the girls had a more horizontal MGD (P less than 0.02) than did the female controls. A corresponding but not significant trend was found for the boys. The individual growth directions that were obtained following adenoidectomies were more variable than those found in the controls.

Adenoidectomy↗
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↗
PubMed1982

Some craniofacial variables related to small or diminishing lower anterior face height.

This study will report on some of the conditions necessary for the presence of short or diminishing lower anterior face height and test the relationship between it and selected facial and occlusal variables. The sample consisted of 120 males with complete longitudinal orthodontic records at the ages of 6, 9, 12, 14, 16, 18 and 20 years obtained from the serial experimental sample of the Burlington Growth Centre, Toronto, Canada. In addition, a sample of 162 Swedish children between the ages of 6 and 12 years with a mean age of 8 years was used to calculate correlations between airflow through the nose, mode of breathing and selected skeletal variables. The following results were observed: 1. The prevalence of small or diminishing lower anterior face height compared to the upper anterior face height was 26% in the total sample of 120 males. This represents an estimate of the prevalence of overclosure in a population of Canadian males. 2. The association between respiratory pattern and small lower anterior face height relative to upper anterior face height showed that the percentage of individuals with a clear nasal airway was 90% while 100% of the sample showed an unobstructed pharyngeal airway. Thus a clear airway may be a necessary prerequisite for the establishment of overclosure. 3. Correlation analyses showed significant negative correlations between the lower anterior face height, the overbite and the airflow through the nose. 4. Three case reports may illustrate the interrelations between mandibular growth direction expressed at the chin and environmental factors such as oral respiration. 5. The association between small or diminishing lower anterior face height and selected facial variables showed the midface normally positioned in the majority of individuals. 6. The mandibular growth direction expressed at the chin was more horizontal in overclosed cases. 7. The gonial angle was more acute in overclosed individuals in relation to population standards.

Adolescent↗