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PubMed2001

Periodontal status of mandibular incisors after pronounced orthodontic advancement during adolescence: a follow-up evaluation.

The purpose of this study was to analyze whether pronounced orthodontic advancement of the mandibular incisors during Class II correction in the mixed dentition results in gingival recession. Through mandibular superimposition of the pretreatment and posttreatment cephalograms of 67 Class II patients who were treated with reverse headgear to the mandibular dentition, 45 patients with a minimum of a 1-mm advancement of the cementoenamel junction (CEJ; mean, 2.18 +/- 0.87) and a minimum of a 2-mm advancement of the incisal edge (mean, 3.87 +/- 1.34) were identified. Using the same protocol in Class II patients, 30 individuals who finished treatment at a similar time and age, but without reverse headgear and with no advancement of the CEJ (mean -0.43, SD 0.53) and a maximum of 1-mm advancement of the incisal edge (mean -0.26, SD 1.15) were identified. Before treatment, the mandibular incisors were more retruded, relative to the line from point A to pogonion and relative to the mandibular plane in the patients with pronounced advancement than in those with no advancement of the mandibular incisors; no differences were found at the time of appliance removal. A total of 30 patients with pronounced advancement and 21 patients with no advancement could meet for a follow-up examination a mean period of 7.83 years (SD, 4.44) and 9.38 years (SD, 4.39) after treatment, respectively. Clinical examinations at the time of follow-up revealed no differences in the amount of recession, the width of attached gingiva, the length of supracrestal connective tissue attachment, the probing pocket depth, and gingival bleeding index or visible plaque index of the mandibular incisors between the patients in the 2 groups. An examination of color slides demonstrated no differences in the number of mandibular incisors that developed recession from before treatment to after treatment and from after treatment to follow-up. Measurement of mandibular incisor crown height on the study models demonstrated no difference in the increase in clinical crown height from after treatment to follow-up between the patients in the 2 groups. It was concluded that pronounced advancement of the mandibular incisors may be performed in adolescent patients with dentoalveolar retrusion without increasing the risk of recession.

Adolescent↗
PubMed2001

Eruption of third permanent molars after the extraction of second permanent molars. Part 1: Assessment of third molar position and size.

The eruptive path of third molars after extraction of second molars was examined in 63 patients. Panoramic radiographs from the start and the end of active treatment and 3 or more years after treatment were assessed. Study models were used to compare the size of the second and third molars and to assess the final position of the third molars. All third molars erupted; none became impacted. During eruption, maxillary third molar crowns uprighted and maintained their angulation as they came into occlusion. Mandibular third molar crowns continued to upright significantly mesiodistally after active treatment, with space closure the result of horizontal translation rather than mesial tipping. Further uprighting occurred once occlusion was established, although few became as upright as the second molars they replaced. However, mandibular third molar roots were frequently curved distally, thus the third molar crown position was invariably better than the overall tooth angulation would suggest, by 16.5 degrees on average. Model analysis (Richardsons' scoring system) showed 96% of mandibular and 99% of maxillary third molars erupted into a good or acceptable position. Limitations of this scoring system are discussed. The mesiodistal size of third molars was suitable to replace second molars; on average, mandibular third molars were 0.55 mm larger and maxillary third molars were 0.7 mm smaller than second molars.

Adolescent↗
PubMed2001

Eruption pattern of autotransplanted premolars visualized by radiographic color-coding.

Eruption patterns and root growth were visualized with the use of a new technique, radiographic color-coding, for comparison of the development of autotransplanted premolars with contralateral control teeth. Rates of eruption and root growth were studied. The eruption pattern and rate was assessed relative to the first molar. Maximum rates were found to occur between 30 and 60 days after transplantation. There were no significant differences between transplants and their contralaterals. Two distinct categories of eruption patterns were demonstrated. One group showed a tendency toward an initial rate of transplant eruption that was somewhat faster than that of the contralaterals. The other group showed initially retarded eruption. Possible explanations were discussed. Because no significant differences between the transplants and the contralaterals were observed, it was concluded that autotransplantation is a sound treatment option for substitution of missing teeth, at least from a tooth development point of view.

Bicuspid↗
PubMed2001

An evaluation of growth and stability in untreated and treated subjects.

This retrospective longitudinal study compared skeletal and dental changes in orthodontically treated patients with changes in a comparable untreated group to evaluate the relationship between skeletal changes and mandibular incisor crowding. Cephalograms and models of 44 untreated subjects from the Broadbent-Bolton Growth Study and 43 treated patients were evaluated at "posttreatment" (14.3 +/- 1.5 and 15.2 +/- 1.1 years, respectively) and at "postretention" (23.2 +/- 3.4 and 28.9 +/- 3.6 years, respectively). Cranial base and mandibular superimpositions were used to measure cephalometric changes. Tooth-size-arch-length discrepancy, contact irregularity, and space irregularity were measured. In both groups, growth in the vertical dimension was twice that in the horizontal dimension. The untreated subjects, who were younger, exhibited greater yearly vertical growth increments than did the treated subjects. The treated subjects exhibited greater overjet and overbite increases than did the untreated subjects. Yearly changes in tooth-size-arch-length discrepancy were greater in the untreated than in the treated subjects, but there were no differences in the changes in irregularity between the 2 groups. A multivariate regression model, relating posterior facial height (Ar-Go) increase and lower incisor eruption to change in space irregularity, explained 42% of the variation in the untreated group (r = 0.64; P <.001). A weaker relationship was found in the treated group. Overjet change was negatively correlated with tooth-size-arch-length discrepancy. Changes in lower incisor crowding were related to growth in the vertical dimension and lower incisor eruption in both untreated (r = 0.64) and treated (r = 0.51) subjects.

Adolescent↗
PubMed2001

Tooth-size discrepancies among different occlusion groups of southern Chinese children.

The purpose of this study was to compare Bolton anterior and overall ratios among different occlusion groups of southern Chinese children. Fifty plaster casts with Class I occlusion, 30 with Class II occlusion, and 30 with Class III occlusion were selected from a random sample of 1247 12-year-old southern Chinese children in early permanent dentition in Hong Kong. For the anterior ratio, a statistically significant difference was found between the Bolton standard and the Class III occlusion group. For the overall ratio, statistically significant differences were found between the Bolton standard and the Class II occlusion group, and between the Class II and the Class III occlusion groups. Thus specific standards are required for Class II and Class III cases from the southern Chinese population.

Asian People↗
PubMed2001

Dentoalveolar changes related to mandibular forward growth in untreated Class II persons.

The purpose of this study was to investigate dentoalveolar changes related to mandibular forward growth in persons with Class II malocclusions. The longitudinal cephalometric films of 40 subjects with untreated Class II malocclusions from mean age 8.8 to 17.8 years (before and after pubertal growth) were analyzed and compared with the Bolton norms. There was no statistically significant difference in mandibular growth between the Class II samples and the Bolton norms upon cross-sectional comparison. In the Class II subjects, forward growth of the mandible was greater than that of the maxilla by 4.36 mm on average; the dentoalveolar complex moved forward relative to the maxillary basal bone (point A) 2.16 mm and moved backward relative to the mandibular basal bone (pogonion) 2.28 mm; a strong linear relationship (almost a 1:1 ratio) existed between mandibular forward growth and dentoalveolar complex movement (r = 0.881; y = 0.976 x + 0.183). Results indicated that the effect of forward growth of the mandible, which could potentially bring the lower dentition forward, vanished into the adaptation movements of the dentoalveolar complex through intercuspal locking. Disarticulating the occlusion to minimize the effects of the adaptive mechanism and taking advantage of normal mandibular forward growth could be fundamental biological bases in treating Class II malocclusions in growing patients.

Adaptation, Physiological↗
PubMed2002

Critical assessment of a device to measure incisor crown inclination.

The aims of this study were to critically assess the use of a disposable device--the tooth inclination protractor (TIP)--to record incisor crown inclination and to compare its reliability and validity with that of traditional cephalometric radiographic analysis. The sample comprised 30 dental students with lateral cephalometric radiographs and dental casts. Four examiners were trained and calibrated to digitize radiographs and to use intraoral (on patients and dental casts) and extraoral (on dental casts) TIPs. The following angles were measured on the radiographs: maxillary incisor to maxillary plane, mandibular incisor to mandibular plane, maxillary incisor to occlusal plane, and mandibular incisor to occlusal plane. Measurements were also made with the TIP: maxillary incisor to occlusal plane and mandibular incisor to occlusal plane. All techniques were reliable between examiners. There were statistically significant systematic differences between the TIP and the radiographic assessments. The following differences were found. The TIP tended to record maxillary incisor crown inclination an average of 14 degrees less than maxillary incisor to maxillary plane. The TIP tended to record mandibular incisor crown inclination as similar to mandibular incisor to mandibular plane. The TIP recorded mandibular crown inclination 19 degrees less than mandibular incisor to occlusal plane. The disposable TIP was shown to be a simple, inexpensive, reliable, and valid method of assessing incisor inclination.

Cephalometry↗
PubMed2002

Dental morphologic characteristics of normal versus delayed developing dentitions with palatally displaced canines.

An earlier study reported on the delayed dental age in about 50% of patients with palatally displaced canines (PDC), suggesting the possible existence of 2 different PDC phenotypes. The present study aimed to determine whether the PDC subgroup with late dental age displays different dental features from the PDC subgroup with normal dental age, supporting the above assumption. The 3 dental parameters examined were mesiodistal and buccolingual tooth sizes, the presence of anomalous maxillary lateral incisors, and other congenitally missing teeth. Fifty-eight subjects with PDC, 37 girls and 21 boys, were divided according to dental age and compared with age- and sex-matched controls. The results revealed marked sexual dimorphism. Delayed dental development was twice as prevalent among the PDC males. The existence of 2 distinct PDC subgroups was supported for males only. One subgroup was characterized by delayed dental development, smaller-than-average teeth, and a marked increase in the prevalence of anomalous lateral incisors. The second subgroup more closely resembled the controls, presenting a timely developed dentition, a moderate and nonsignificant increase of anomalous lateral incisors, and a reduction in the dimensions of only the central incisors and the first molars. In females, although the prevalence of anomalous lateral incisors was slightly increased in the late dental age subgroup, tooth sizes were remarkably similar, negating the existence of 2 distinct subpopulations. Studying the overall PDC group as a single entity produced confusing results because important differences were obscured when the 2 sexes and the 2 dental age subgroups (in males) were combined.

Adolescent↗
PubMed2002

Dental arch space and permanent tooth size in the mixed dentition of a skeletal sample from the 14th to the 19th centuries and 3 contemporary samples.

Dental arch space and permanent tooth size in the mixed dentition were studied in 4 cohorts: (1) 48 skulls from the 14th to the 19th centuries from The Schreiner Collection in the Department of Anatomy, University of Oslo; (2) 39 boys and 34 girls of Sami origin born in the 1980s living in northern Norway; (3) 31 boys and 30 girls born in the 1960s living in southern Norway; and (4) 32 boys and 26 girls born in the 1980s living in the same part of southern Norway as the previous group. The sexes were unknown in the skeletal sample, and the groups were analyzed with the sexes pooled. The crown sizes of the permanent teeth in the mixed dentition of the Norwegian children who had lived between the 14th and the 19th centuries were smaller than those of contemporary children living in the same country. Probable reasons for this increase in tooth size include improved nutrition and reduced morbidity, because this study ruled out attrition as a major cause of the discrepancy in tooth size. The relative space (arch perimeter minus tooth size) in the group born in the 1960s deviated from that in the other 3 groups, indicating a greater degree of crowding in this group. The relative space in the skulls did not differ significantly from that in the groups born in the 1980s. This means that the improved caries situation during the last decades has changed the dental arch space in these populations. The irregularity index of the 4 mandibular permanent incisors was larger in the skulls than in the modern samples.

Analysis of Variance↗
PubMed2002

Mandibular arch dimensional and positional changes in late mixed-dentition Class I and II treatment.

The purposes of this study were to determine the range of likely mandibular arch dimensional and positional changes that occur with growth when a particular nonextraction treatment approach is used in the late mixed dentition and to search for factors that might affect those changes. The records (pretreatment and posttreatment lateral cephalograms and study casts) of 182 patients with Class I or Class II malocclusion, with or without crowding, were assessed prospectively. Considerable individual variation was found in all measurements, and anteroposterior dimensional arch changes were found to be significantly correlated with the amount of space required for leveling and relief of crowding in the mandibular arch. Despite those relationships, mandibular arch space requirements of 4 to 8 mm were found to be associated, on average, with small anteroposterior and transverse dimensional changes. By starting treatment in the late mixed dentition, it might be possible to control anteroposterior mandibular incisal changes reasonably well, even with considerable space requirements. Transverse mandibular arch changes in this sample were generally greater across the first premolars than across the canines, something previously acknowledged to improve stability after orthodontic treatment. A wide range of variation exists in the amount of available bilateral mandibular E-space; consequently, assessing the relative sizes of the deciduous second molars and their permanent successors in individual orthodontic patients is necessary.

Cephalometry↗
PubMed2002

Treatment of a patient with a crowded Class I malocclusion and a congenitally missing mandibular incisor.

This case report describes the management of maxillary and mandibular crowding in a patient with facial esthetic concerns and a tooth-size discrepancy due to a missing mandibular central incisor. The treatment included extracting the remaining mandibular central incisor and the 2 maxillary first premolars. The mandibular canines were repositioned to substitute for lateral incisors, and the mandibular premolars were used as canines.

Adolescent↗
PubMed2003

Comparison of skeletal and dental changes between 2-point and 4-point rapid palatal expanders.

Rapid palatal expansion has been a clinically accepted technique used by orthodontists for over 100 years. Its primary goal is to maximize orthopedic and minimize orthodontic movements of teeth. Historically, this was best accomplished by including 4 teeth in the appliance. However, including more teeth makes construction and insertion more difficult. The appliance also is less comfortable for patients and hinders oral hygiene. The 4-point hyrax expander can be modified by removing the 2 anterior wires, creating a 2-point expander between the first molars only. The purpose of this study was to determine the difference, if any, between midpalatal suture separation and dental expansion produced between 2-point and 4-point palatal expanders. Thirty subjects between the ages of 6 and 16 years were randomly assigned to either the 2-point (n = 15) or the 4-point group (n = 15). The groups were compared on dental and radiographic landmarks. The groups showed no statistical differences in total molar cusp width, molar gingival width, canine cusp width, canine gingival width, or diastema width. There were slight differences in arch perimeter and midpalatal suture separation. The results of this study showed that the 2-point appliance produced similar effects on the midpalatal suture and the dentition as did the 4-point appliance. It might therefore be considered instead of the 4-point appliance to successfully produce adequate skeletal and dental expansion.

Adolescent↗
PubMed2003

Peg-shaped and small lateral incisors not at higher risk for root resorption.

The purpose of this study was to examine the pattern of external root resorption for peg-shaped and small lateral incisors according to various conditions and to compare it with that of normal-shaped lateral incisors. The periapical radiographs of 114 patients with 60 peg-shaped and 54 small lateral incisors were measured before and after treatment. Crown shape was assessed by examining pretreatment study casts. Findings showed that there was no significant difference in external root resorption between peg-shaped (1.09 mm) and normal lateral incisors (0.88 mm). However, a statistically significant difference in apical root resorption between small lateral incisors (1.03 mm) and normal lateral incisors (1.62 mm) was found. Peg-shaped laterals were also coincidentally found to occur more frequently on the left side of the arch.

Adolescent↗
PubMed2003

Incisor crown shape and crowding.

The aim of this study was to investigate correlations between the shape of mandibular incisor crowns and crowding. Study models of 50 untreated white subjects (25 men and 25 women) with varying degrees of crowding were studied. The lower incisors were sectioned and imaged at the contact point and midpoint levels, and the mesiodistal width was measured. Crowding was quantified by using both Little's irregularity index and anterior tooth size-arch length discrepancy. The ratio of the 2 mesiodistal widths was correlated with Little's irregularity index and anterior tooth size-arch length discrepancy. In the women, the ratio showed correlations of 0.52 (P =.008) and 0.55 (P =.005) for central and lateral incisors, respectively, with anterior tooth size-arch length discrepancy. No predictors of lower incisor crowding could be established from mandibular incisor crown shape in this study.

Adolescent↗
PubMed2001

Accuracy of the Third Molar Eruption Predictor in predicting eruption.

OBJECTIVE: To evaluate the possibility of applying the Third Molar Eruption Predictor to all panoramic radiographs. STUDY DESIGN: Panoramic radiographs were retrospectively analyzed from a 4-year follow-up study of third molars carried out at the University of Copenhagen, Denmark. The radiographs, taken at a mean age of 20.6 years, included 45 unerupted or partially erupted mandibular third molars in 28 subjects. Because the device was calibrated both with simple proportions and by use of the methods of Bayes' Decision Theory, the separation point of the device was therefore adjusted at 12 mm from the distal surface of the second molar. RESULTS: The predictions of future eruption or impaction made with the calibrated device and the actual clinical outcome 4 years later were in conformity for 80% of the mandibular third molars. CONCLUSION: The Third Molar Eruption Predictor may be applied to all panoramic radiographs, but it seems to require calibration before use.

Adult↗
PubMed2002

Canal length evaluation of curved canals by direct digital or conventional radiography.

OBJECTIVES: The purpose of this study was to compare the accuracy of a digital radiograph imaging system (DDR) with conventional radiography for the purpose of estimating endodontic file lengths in curved canals of mandibular molars. STUDY DESIGN: Sixty extracted human mandibular molars with root curvatures ranging from 5 degrees to 52 degrees were mounted in plastic blocks. Canal length was estimated by using on-screen DDR with both 2- and 3-click measurement and from conventional E-speed radiographs by using a millimeter ruler and x2 magnification. Two operators familiar with both radiographic methods performed the estimates. RESULTS: One-way analysis of variance and Newman-Keuls tests revealed no significant differences between the groups. Although both conventional and DDR methods of analysis overestimated the true canal length, the DDR accuracy improved as the curvature severity increased. CONCLUSIONS: The image quality of DDR systems has improved to the point that they can now be used for estimating canal lengths, even for curved canals, with accuracy comparable to that of conventional radiographs. However, further work remains to be done to optimize image quality.

Analysis of Variance↗
PubMed2002

Age-related odontometric changes of human teeth.

OBJECTIVE: The number of older patients requiring restorative treatment are likely to increase due to improvements in oral health and increased longevity. However, aging odontometric data are lacking. The aim of this study was to determine possible changes in pulp cell density, pulp area, and dentinal thickness with age. STUDY DESIGN: Incisors (50), canines (39), premolars (51), and molars (7) extracted from 60 patients aged between 10 and 59 years, were analyzed histomorphometrically for cell density (odontoblasts, subodontoblasts, and pulp core fibroblasts) and dentinal thickness. RESULTS: With increasing patient age, in both crown and root aspects of teeth, dentinal thickness increased (P <.001), while the density of odontoblasts (P <.001), subodontoblasts (P = 0.001), and pulp fibroblasts (crown, P <.011; root, P =.0015) decreased. The degree of age-related changes in teeth appeared to be asymmetrical, with decreases in the root being greater than in the crown. At all ages pulp cell densities, including odontoblasts, within the crown were greater than in the root (P <.001), even though the calculated rate of dentinal deposition was greatest in the root. CONCLUSION: Decreases in pulp cell density may reduce pulp repair activity after restorative treatments, although increases in dentinal thickness may aid pulp protection. An understanding of these age-related changes will influence the provision of restorative and endodontic care and benefit older patients.

Adolescent↗