John M. Yancey

Enhancement of Streptococcus mutans Colonization by Direct Bonded Orthodontic Appliances

Patients undergoing orthodontic therapy were evaluated for longitudinal changes in relative S. mutans numbers in plaque at discrete sites on the tooth surface associated with direct bond appliances. There was a significant linear increase in the percentage of S. mutans in the total streptococci isolated from the last pre-bracket sample through the last bracket sample.

Clinical versus quantitative assessment of headgear compliance

This study was undertaken to determine if clinicians could accurately evaluate headgear compliance. Headgear timers were used covertly to quantitatively assess the headgear compliance of 28 patients over 3 consecutive months. Investigators subjectively evaluated the patients to determine how many hours per day they felt the patient had been wearing the headgear. Investigators were divided into three groups: (1) 5 orthodontists (2 board certified, 3 board eligible--total of 50 years of orthodontic experience); (2) 10 residents; and (3) 11 assistants. At least two investigators from each group evaluated the same person for all three appointments. The average error values were 2.86 hours, 3.27 hours, and 3.61 hours, respectively, for the three groups. The standard deviations were also very large, indicating that no group could accurately or consistently assess headgear wear. In this study no difference was found in compliance between sexes. Patients 10 to 12 years of age were more compliant than those 12 to 14 years of age, which were more compliant than the > 16 age group. The least compliant was the 14 to 16 year age group.

The role of the headgear calendar in headgear compliance

This study was undertaken to determine the role of the headgear calendar and its relationship to headgear compliance. Headgear timers were used covertly to monitor actual headgear wear of 28 patients for three consecutive orthodontic appointments. Fourteen patients were asked to monitor their daily headgear wear by using a headgear calendar. The other 14 did not use a calendar. The results show that patients who monitor their headgear wear with a headgear calendar are more compliant than those patients who do not (7.9 hours compared with 5.3 hours). All age groups in this study wore their headgear more when a headgear calendar was used with the exception of the > 16-year-old group. There is a high degree of correlation (r2 = 0.60) between the number of hours recorded on the calendar compared with the number of hours actually worn. There was a poor correlation (r2 = 0.02) between the number of hours the patient said he wore his headgear compared with the actual number of hours worn.

Ten rules for reading clinical research reports

This was not a scientific assessment of the scientific quality of the papers published by The American Journal of Surgery. It was an informal audit of the adequacy of the data analysis in the clinical research reports appearing in the 1987-1988 issues. As one who has devoted more than three decades to helping a great variety of people make sense of scientific data, I found the overall quality of data analysis in these papers to be above average for the medical literature; and yet, I found many instances of errors so serious as to render invalid the conclusions of the authors. My 10 proposed rules for reading clinical research reports constitute only an interim solution to a very worrisome problem. The real solution must come from the producers of and the gatekeepers for the medical literature.

The Prevalence of Juvenile Periodontitis ("Periodontosis") in a Dental School Patient Population

In order to obtain additional information about the prevalence of juvenile periodontitis, a retrospective, cross-sectional study was performed utilizing the dentulous patient pool of an urban dental school. For a one-year period, 2.4% of patients between the ages of 13 and 30 were found to have juvenile periodontitis.

Repeated measures analysis of geometrically constructed and directly determined cephalometric points

Cephalometric landmarks were directly determined visually from bony anatomy on lateral cephalometric radiographs and compared with geometrically constructed cephalometric landmarks for repeated measures reliability of identification. Three groups of four orthodontists, grouped by level of experience, identified 18 landmarks on each of four cephalometric radiographs. This measurement procedure was repeated four times in 1-week intervals. The variability, main associations and interactions among the variables of tracer experience, quality of radiograph traced, and the anatomic landmarks traced were assessed by means of the repeated measures analysis of variance and follow-up Tukey HSD test. The coefficient of variation was used to compare the relative variability of replicate identification of the 18 cephalometric landmarks. Rank order and statistically significant groupings by variability are listed. The level of observer experience and quality of radiograph were statistically unrelated to landmark variability on replicate examination. The geometrically constructed landmarks tested were not statistically different from the reliability of the directly determined bony-based landmarks. This finding would lend support to the techniques of geometric construction used in the Ricketts cephalometric analysis.

Longitudinal predictability of AF-BF value in Angle Class I patients

AF-BF is a linear cephalometric measure of the anteroposterior jaw relationship in the sagittal plane. A retrospective, longitudinal study was made to determine the mean Caucasian American AF-BF values at ages 8 and 18 years for 30 male and 32 female participants of the Bolton Growth Study. Mean AF-BF values (+/- s.d.) for males were 7.3 +/- 2.7 mm at 8 years and 6.5 +/- 4.2 mm at 18 years. Mean AF-BF values (+/- s.d.) for females were 6.7 +/- 2.1 mm at 8 years and 5.2 +/- 2.9 mm at 18 years. No significant difference was found between the mean AF-BF values for males and females at either age group (P < 0.05). The decrease in AF-BF mean values with increasing age both for males and females was statistically significant. The correlation (r) for the AF-BF values was 0.49 (P < 0.05) for females and 0.86 (P < 0.05) for males. With increasing age, the mean difference between ANB values for females was 1.40 +/- 1.60 and 1.10 +/- 1.40 for males. The correlation of ANB angle and AF-BF provides a clinically useful tool for the cephalometric assessment of anteroposterior sagittal discrepancies of maxillary and mandibular denture bases.

Submentovertex Radiology: Cephalometric Considerations in Temporomandibular Dysfunction

Controversy exists in the literature concerning the association between the radiographic and the clinical features of the temporomandibular dysfunction (TMD). Hence, this study reinvestigated possible correlations between radiographically detected asymmetries and the clinical signs and symptoms of TMD. Complete clinical and radiographic records were gathered from 52 patients sequentially referred for corrected angle tomographs of the temporomandibular joint (TMJ). Measurements from submentovertex (SMV), lateral and posterior-anterior (PA) cephalographs and corrected angle parasagittal tomographs and recorded clinical signs and symptoms of TMD were the data inputs. Significant findings were as follows: a) as the discrepancy in the posterior condyle to pogonion measurement increased, the pogonion and both maxillary and mandibular incisors shifted laterally towards the shorter side; b) as the ANB angle increased, so did the difference in condylar angle measurements between the two condyles; c) the side with the larger condylar angle was positioned forward on the SMV; and d) a perpendicular bisector (Marmarys Centerline) of the line drawn between the right and left foramen spinosum was found to be a reliable baseline reference for SMV analyses. No statistically significant relation was found linking specific signs and symptoms of TMD to maxillofacial asymmetries recorded on SMV, lateral or PA cephalographs. None of the radiographic signs studied were found to be good predictors of specific signs and symptoms in TMD.

Nd:YAG laser treatment of herpes and aphthous ulcers: a preliminary study

Previously herpes labialis and recurrent aphthous ulcers have not been successfully treated. A preliminary study with a pulsed Nd:YAG laser evaluated the results with a protocol of four minute non-contact exposures for both types of lesions. Most patients experienced relief of symptoms. The progress of herpes lesion was halted and aphthous lesions became desensitized.