Search PubMed⌕ Search

Biomedical subjects

S D Keeling

Publications and source records attributed to S D Keeling.

34 records · Page 2Linked to original sources
PubMed1994

Risk factors associated with temporomandibular joint sounds in children 6 to 12 years of age.

The relationship between temporomandibular joint (TMJ) sounds and a person's dental and skeletal characteristics is poorly understood. In this study, data were obtained from 3428 grade schoolchildren (mean age = 9.0 years, SD = 0.8, range 6 to 12 years), without a history of orthodontic treatment. Each child had been examined independently by one of six orthodontists to assess: TMJ sounds (none, click, crepitus), gender, age, race (white/black), skeletal relationships (convexity, maxillary, and mandibular positions), malocclusion (molar class, overjet, overbite, anterior crowding, posterior crossbite), maximum opening, chin trauma (none, cut, scar), and history of lower facial trauma. Temporomandibular joint sounds were present in 344 children (10.0% of the sample); 276 (8.1%) had an isolated unilateral sound, 254 (7.4%) had unilateral clicking, 50 (1.5%) had bilateral clicking, 22 (0.6%) had unilateral crepitus, and 11 (0.3%) had bilateral crepitus. Univariate analyses compared children with and without sounds for each variable; logistic regression analyses examined the relationship between groups of variables and TMJ sounds. The prevalence of TMJ sounds was associated with examiner (chi 2 = 23.4, df = 5, p < 0.001); increased prevalence of TMJ sounds occurred in children with maxillary anterior crowding (t = 2.8, p < 0.006), mandibular anterior crowding (t = 3.0, p < 0.002), and increased maximum opening (t = 4.7, p < 0.001). In contrast to other reports on children, the prevalence of joint sounds was not associated with age, race, gender, or molar class.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1994

Evaluation of a training program intended to calibrate examiners of temporomandibular disorders.

The adequacy of a training program intended to calibrate examiners of temporomandibular disorders (TMD) was evaluated. Eight examiners blindly rated 12 subjects with various TMD signs and symptoms after participating in a 5-h intense training procedure. Some examiners had earlier experience of TMD examinations, and some were newly trained. The Craniomandibular Index was used as the assessment instrument. Agreement within the whole group of examiners was low. Training tended to increase the probability of correctly registering signs. It is concluded that the program was not sufficient to create reliability among multiple examiners. More extensive training, not only to a standard but also between the different examiners, appears necessary. Revision of the examination technique is suggested, and recommendations for strengthening the calibration procedures are made.

Adult↗
PubMed1993

Serum and alveolar bone phosphatase changes reflect bone turnover during orthodontic tooth movement.

Acid and alkaline phosphatase changes have been demonstrated histochemically and biochemically during the early stages of an orthodontic tooth movement cycle. However, quantitative data on neither alveolar bone nor serum phosphatase changes over an entire tooth movement cycle have been reported. This study examined acid, tartrate-resistant acid (TRAP), and alkaline phosphatase changes in serum and alveolar bone during an orthodontic tooth movement cycle in 288 adult male Sprague-Dawley strain rats. The effect of differing initial force magnitudes on phosphatase changes was also examined. Data were obtained from four groups: sham control and three treatment groups (20, 40, and 60 gm activations). Each group (n = 72) was subdivided equally into six sacrifice subgroups (1,3,5,7,10, and 14 days). Treated animals received a precisely loaded orthodontic tipping force to the maxillary molars. Phosphatase measures were obtained by colorimetric assays. Analysis of variance (ANOVA) procedures were performed to examine for differences within groups across time and among groups at each time point. Data from treated animals were combined, adjusted for control values, and examined across time to permit comparisons with previously described histomorphometric changes. Analysis of variance indicated no differences occurred in the control group across time. Significant differences in serum values occurred across time within the force groups (p < 0.01), and among force and control groups at various times in both sera and bone (p < 0.05). In the pooled treatment data, a peak in serum acid phosphatase occurred at day 1 and in bone at day 3 (the later mirroring histomorphometric findings) (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
PubMed1993

Histomorphometric study of dental pulp during orthodontic tooth movement.

Orthodontic tooth movement has been implicated in secondary changes to the dental pulp. The purpose of this study was to correlate the effects of orthodontic tooth movement on the dental pulp by histomorphometric parameters. Four groups, each consisting of 36 male adult Sprague-Dawley strain rats, were studied with differing force magnitudes. These included a sham group in addition to groups with bilaterally placed appliances activated to 20, 40, and 60 g of initial force designed to mesially tip the maxillary first molars. Six rats were killed at 1, 3, 5, 7, 10, and 14 days. Specimens were fixed, embedded, and stained with tetrachrome. Pulpal measurements were made with an image analyzer and included changes in predentin and vascularity. Findings indicated a significant increase (p < or = 0.05) relative to time and force magnitude in capillary number. An initial pulpal hyperemia was observed following activation of orthodontic force which was unrelated to force magnitude. A force-dependent increase in predentin width was measured at the peak of the tooth movement cycle.

Animals↗
PubMed1993

Systematic and random errors associated with Johnston's cephalometric analysis.

This study examined intra- and interexaminer systematic and random errors associated with Johnston's cephalometric method of assessing skeletal and dental changes from pairs of radiographs. Data were obtained from the tracings of radiographs of 30 mixed dentition subjects, who had been treated to correct a Class II malocclusion. Measurements included molar and incisor crown movements relative to basal bone, apical base change, maxillary and mandibular displacement relative to the cranial base, and total molar and overjet reduction. In addition, the change in axial inclination of the incisors and molars was determined. A paired t-test for each pair of replicates for each measure was performed to examine inter- and intra-examiner bias. Estimates of the random error, the coefficient of reliability, and confidence limits (95 per cent level) of a single determination were undertaken. No systematic errors occurred between/within examiners for any linear or angular measure. Interexaminer random errors, based on the standard deviation of the mean difference between replicates, were greater than intra-examiner random errors for 12 out of 13 parameters. Measures assessing molar correction and overjet reduction had the least amount of random error variance within and across judges, while changes in mandibular position had the greatest. Because considerable random errors occurred, the Johnston analysis when used to assess skeletal changes, as well as individual molar and incisor movements, may have limited utility in clinical practice for the individual case.

Bias↗
PubMed1992

Long-term orthodontic tooth movement response to short-term force in the rat.

Both the amount of force applied and the duration of the application affect tooth movement. To study the effect of duration, adult male Sprague-Dawley rats were fitted with orthodontic appliances delivering a 40-gm initial mesial tipping force to the maxillary molars. The animals were divided into two longitudinal groups (I: 1 hour and II: 24 hours; N = 15). Sham-treated control (III) and 14 day (IV) continuous cross-sectional force tooth movement data were also included for comparison (72 rats per group). Extraoral cephalometric radiographs were obtained at appliance placement and at 1, 3, 5, 7, 10, & 14 days. Tooth movement was determined with respect to palatal implants. ANOVA indicated significant differences existed over time in each group (p = 0.0001). Continuous force applied for 14 days generated a classic three-part tooth movement curve. Short-term forces were characterized by initial mesial movement, a distal relapse period (d3-d5), and a late mesial movement period (d7-d14). The results suggest short-term forces of 1 and 24 hours initiate remodeling events, which result in tooth movement 7 to 14 days later and that the minimum effective duration of a 40-gm activation is less than 1 hour in this animal model.

Activator Appliances↗
PubMed1991

Histomorphometric study of alveolar bone turnover in orthodontic tooth movement.

Selected histomorphometric parameters were measured in alveolar bone adjacent to rat molars treated with a 40-gram tipping force designed to tip the molar mesially and with a sham procedure. Undecalcified parasagittal sections of teeth and surrounding tissues were prepared for static and dynamic histomorphometry at 1, 3, 5, 7, 10, and 14 days. Initial tooth displacement was assessed by measuring differences between groups in the widths of the day-1 periodontal ligaments (PDL) at various vertical locations and correlating these using linear regression analysis. All parameters were measured in the alveolar bone adjacent to four quadrants around the teeth (mesial-distal; occlusalapical). Means and standard errors for each parameter in each group were calculated and compared for time- and group-specific differences using ANOVA and pairwise comparisons with Scheffe's multiple comparison tests. In sham-treated rats, bone resorption predominated on the distal alveolar surface, but significant surface-related differences between mesial and distal surfaces in bone formation were not demonstrated. Time-specific effects in bone resorption were not evident on either surface in the shams. These findings suggested that molar distal drift in the sham rat is facilitated by resorption in the distal alveolar bone. PDL width changes in orthodontically-treated rats were greatest in the mesial occlusal half of the root and decayed linearly toward the apex indicating that the greater initial tooth displacement occurred in the occlusal half of the root surface. Histomorphometric parameters of alveolar bone turnover were also seen to be greater in these locations, suggesting that these processes were sensitive to the increased tooth displacement.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Bone Loss↗
PubMed1991

Analysis of repeated-measure multicycle unilateral mastication in children.

This study examined systematic and random errors associated with repeated-measure, multiple-cycle unilateral mastication in children during single recording sessions with the Replicator system. Twenty-six recording sessions with 17 children (10 boys, 7 girls) were examined. Nine of these children had a functional-shift unilateral crossbite malocclusion and were recorded before and after crossbite correction. Repeated recordings (trials) of mandibular movement during each session were made of right-side chewing of similar-sized pieces of cheese. The following variables were computed for each chewing cycle (stroke): time closed, maximum closure velocity, maximum opening velocity, chewing rate, vertical opening, and lateral deviation. From the multiple cycles of each trial, two pattern descriptors--the average and standard deviation--were determined for each variable. In addition, the mean and variance of these pattern descriptors were determined from the multiple trials of each recording session and were the dependent variables in a stepwise multiple regression analysis, with treatment status, sex, age, dentition stage, crossbite presence, and right side status the independent variables. The results disclosed bias in repeated measures of human chewing in response to adaptation to the recording session; this was evident in the average response but not in the variability of the measures. Sex and functional status of the subjects were associated with the mean and variance of measures describing the chewing pattern.

Adolescent↗
PubMed1991

Measuring dental drift and orthodontic tooth movement in response to various initial forces in adult rats.

A method for the quantification of orthodontic tooth movement in the rat is presented. Reliability, sensitivity, and validity were assessed and tooth movement kinetics were determined for initial forces of 20, 40, and 60 gm. The appliance consisted of a 9 mm length of closed coil spring suspended between a cleat and bonded to the occlusal surface of the maxillary first molars and the maxillary incisors. Initial tipping forces were placed by suspending known weights from the anterior end of these coils before fixation to the incisors. Tooth movement was quantified from enlarged cephalograms by measuring the position of a reproducible landmark on the molar cleat with respect to either zygomatic amalgam implants or a barbed broach placed submucosally on the palate. All measurements were made along the molar-incisor vector by projecting at 90 degrees to this line. Validity and sensitivity were assessed by quantifying molar distal drift and comparing these results with reports of bone turnover rates adjacent to distally drifting adult rat molars. Reliability was obtained by estimating the error of a single measurement in a longitudinal study of 12 adult male Sprague-Dawley rats (180 to 200 days) receiving both amalgam and broach implants and a cross-sectional study of 72 animals divided equally into six groups to be killed at 1, 3, 5, 7, 10, and 14 days. No orthodontic forces were used in this portion of the study. Implant stability within the craniofacial complex was assessed by measuring bilateral broaches as a function of time with respect to each other. There were no systematic errors between replicate films for either the amalgam or the broach method. The 95% confidence limit for a single determination of molar position was 62 microns using the amalgams and 47 microns for the broach (p less than 0.001). The latter could be reduced to 23 microns when the average of four independent determinations was used. Homologous implants did not differ with respect to each other in the sagittal plane but did in the transverse plane (p less than 0.01), migrating laterally 9 microns/day. Linear regression analysis of molar distal movement over time predicted 7.7 microns/day distal drift (p less than 0.01), which compared favorably with reports of 6.7 microns/day of alveolar bone turnover during this drifting process. Characteristic three-part cumulative tooth movement kinetics were obtained for the 40 and 60 gm initial force groups. No individual time point at 60 gm differed from its counterpart at 40 gm.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of Variance↗
PubMed1991

Effect of folic acid on recurrence of phenytoin-induced gingival overgrowth following gingivectomy.

This study examined the effect of folic acid supplementation on the recurrence of phenytoin-induced gingival overgrowth following gingivectomy. 8 residents of an institution for the developmentally disabled were randomly assigned to a treatment (N = 4) or control (N = 4) group. Subjects in the treatment group received an oral supplementation of 5 mg of folic acid daily during the study; those in the control group did not. A gingivectomy with an external beveled incision made to the crest of the alveolus was completed by quadrants. The following data were obtained prior to gingivectomy, 2 weeks following the last quadrant of surgery, and at 3 and 6 months post-surgery: plaque and gingival index scores, red blood cell folic acid levels, free phenytoin blood levels, photographs, and impressions. % change in overgrowth was determined from cross-sectional area measurements made on dies obtained from bucco-lingual cuts on stone models. Differences across time between and within groups were tested by a two-factor repeated measure analysis of variance. The groups did not differ in plaque and gingival index scores or free phenytoin blood levels. The treatment group had significantly higher red blood cell folic acid levels (p less than or equal to 0.0001). Reduction in gingival overgrowth as a result of surgery was similar in both groups. Although the treatment group had significantly less recurrence of gingival overgrowth (p less than or equal to 0.05), the mean differences amounted to only 6-7% at 3 and 6 months.

Adult↗
PubMed1990

The malpractice morass and practice activities of orthodontists.

This study examined the association between malpractice, measured by perception and experience scores, and practice activities of orthodontists. Data from 184 Florida orthodontists were obtained in the form of continuous/ordinal responses to survey questions in five areas: demographic, work load, personality, perception of the malpractice environment, and practice activities (malpractice experience, record taking, disclosure, and rapport). Mutually exclusive recency categories were selected on the basis of when an activity was last performed. Descriptive statistics and plots of the data were examined. A malpractice experience score for each respondent was determined by means of factor analysis procedures on the activity question responses. The association between perception/experience scores and responses to activity, demographic, work load, and personality questions were examined with the use of stepwise multiple regression procedures. The results indicated that practice activities, in the areas of record taking and doctor-patient rapport, were moderately associated with both experience scores (R2 = 0.47, p = 0.08) and perception scores (R2 = 0.29, p less than 0.06). Perception of the malpractice environment was associated with practice activities of orthodontists but to a lesser extent than active experiences in that environment were.

Dental Records↗
PubMed1990

The timing of treatment for Class II malocclusions in children: a literature review.

Two basic strategies for the timing of treatment for Class II malocclusions in children are common: (1) correction achieved in two phases, one during pre-adolescence (early treatment) and the other during the teen years; and (2) correction accomplished in one phase of active treatment during the adolescent years. The issues of efficacy and cost(risk)-benefit of these strategies have not been well delineated. Most clinical studies examining these issues have suffered serious methodological deficiencies, such as being retrospective, lacking adequate controls, and evaluating only successfully treated cases. However, despite a lack of objective data, clinicians have shown considerable interest in recent years in two-phase treatment. This paper reviews major issues of two-phase Class II treatment and concludes by delineating several important clinical questions which could be resolved by a carefully controlled prospective study.

Adolescent↗
PubMed1989

A multivariate approach to analyzing the relation between occlusion and craniofacial morphology.

This study examined the association between occlusion and craniofacial morphology using univariate and multivariate statistical methods. Data were obtained from study casts and lateral cephalometric radiographs of 164 children in the early permanent dentition. The following multiple features of occlusion were assessed: molar relation, overjet, overbite, and anterior crowding. Angular skeletal measures assessed cranial base flexure, maxillary horizontal and vertical positions, mandibular horizontal and vertical positions, horizontal and vertical maxillary-mandibular relations, and positions of the incisors. The relation between the Occlusal Index, which is a malocclusion severity index, and skeletal morphology was also investigated. Associations were examined by use of linear correlation, stepwise multiple regression, and canonical correlation analyses. Individually and in combination, occlusal features were poorly associated with individual skeletal measures (r2 less than or equal to 0.35). The strongest association occurred between a linear combination of occlusal features and a linear combination of skeletal measures (R2 = 0.66, p = 0.0001). A malocclusion severity index did not aid in the identification of craniofacial morphology. The results suggested that combinations of certain occlusal characteristics may be associated with specific skeletal types; however, a generalized statement of this concept could not be supported.

Adolescent↗
PubMed1989

Internal derangement of the TMJ: changes associated with mandibular repositioning and orthodontic therapy.

Because of its apparent success in relieving symptoms, especially pain, anterior mandibular repositioning therapy is a popular mode of nonsurgical treatment for patients with painful, clicking internal derangement of the temporomandibular joint. Posterior open bites are a frequent consequence of such therapy and may necessitate either continued appliance wear or closure by equilibration, prosthetics, or orthodontics. The anatomic and functional changes that occur subsequent to mandibular repositioning during orthodontic closure of the posterior open bite are not well understood. A case of a patient with a Class II, deep bite malocclusion and painful internal derangement of the TMJ is presented. Transcranial and cephalometric radiographs, arthrograms, and mandibular movement recordings were obtained before treatment and after both repositioning therapy and orthodontic treatment. Regarding occlusal improvement and pain relief, the treatment was successful. However, not all of the changes that occurred during repositioning therapy were maintained after orthodontic treatment. The strategy used in this case (mandibular repositioning/orthodontic finishing) was evaluated by an examination of these anatomic and functional changes with a discussion centered on the possible mechanisms involved.

Adolescent↗
PubMed1989

Skeletal changes associated with extraoral appliance therapy: an evaluation of 200 consecutively treated cases.

Questions exist concerning the degree to which orthodontic treatment alters facial form. This study has attempted to discern changes in several measures of vertical facial form which might be influenced by varying vectors and amounts of extraoral force. The data were collected from pre- and posttreatment lateral cephalograms of 200 children treated consecutively with full edgewise orthodontic appliances. The sample was divided into three pretreatment groups based on the type of extraoral force delivered; cervical, "combi," and no-headgear. All groups showed a wide range of variation in treatment response, but did not demonstrate significant differences. While the extraoral forces predictably improved horizontal maxillo-mandibular discrepancies, there was too much variation in response to predict vertical changes.

Adolescent↗