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PubMed2001

A comparison of 3 computerized Bolton tooth-size analyses with a commonly used method.

Four methods of conducting overall and anterior Bolton tooth-size analyses were compared using 22 (11 pretreatment and 11 posttreatment) sets of models. No more than 3 mm of crowding existed in any of the models, and all were in good condition. An analysis employing vernier calipers was completed 3 times to set a standard. Pearson correlation coefficients revealed a high degree of intra-operator reliability with mean R values of 0.930 and 0.843 for the overall and anterior discrepancies, respectively. The mean Vernier caliper results were compared with each of the following computerized methods: QuickCeph, Hamilton Arch Tooth System (HATS), and OrthoCad. No statistically significant error was present for any of the methods using repeated-measures analysis of variance testing and paired t-tests (p < .05). Clinically significant differences (>1.5 mm) were present for each method. Absolute differences were calculated, and linear regression and R values were determined. The HATS analysis had the highest degree of correlation (R = 0.885 for overall and 0.825 for anterior), followed by OrthoCad (R = 0.715, 0.574), and QuickCeph (R = 0.432, 0.439). Each method also was compared based on the time required to complete each analysis. The QuickCeph was the fastest (1.85 minutes) followed by HATS (3.40 minutes), OrthoCad (5.37 minutes), and Vernier caliper (8.06 min).

Analysis of Variance↗
PubMed2001

A morphometric study with setup models for bracket design.

This study was designed to obtain basic data on bracket design for the Asian patient. Setup models of 125 Japanese orthodontic patients seeking treatment were measured relative to the occlusal plane by the Andrews' method. A single experienced dental technician fabricated all setup models to provide one-tooth-to-two-teeth occlusal relationship, maximum intercuspation, ABC contacts, flat occlusal planes, canine guidance, and anterior guidance. Means and standard deviations of the crown angulations, inclinations, facial prominence, vertical contour, horizontal contour, and maxillary molar offsets were measured to reach the following conclusions: (1) No difference was observed in crown angulation between groups with one-tooth-to-two-teeth relationships. (2) Crown inclinations of the mandibular central and lateral incisors and canine were greater in the Class II setup group. (3) Maxillary molar offset averaged approximately 7 degrees in the Class II setup group. (4) The data from the Class I setup group showed minor differences from other researchers' data.

Adolescent↗
PubMed2002

Does the canine dental follicle cause resorption of permanent incisor roots? A computed tomographic study of erupting maxillary canines.

We performed computed tomography (CT) on 107 children and adolescents aged 9-15 years with 176 unerupted maxillary canines (152 erupting ectopically and 24 erupting normally) to determine whether there is an association between widened dental follicles of the maxillary canines and resorption of the adjacent incisors during eruption. Contiguous axial (transverse) CT scans were obtained through the maxilla in the region of the canines. The width and shape of the dental follicles were recorded, as were any contacts between the follicles and the crowns of the maxillary canines and neighboring incisors. Fifty-eight lateral incisors (38%) and 14 central incisors (9%) had some type of root resorption. The position of the maxillary canine in relation to the root of the lateral incisor varied greatly, as did the width and shape of the canine dental follicle. Follicle width ranged from 0.5 mm to 7.0 mm. The mean +/- SD width of dental follicles was, on average, larger for the ectopically positioned canines (2.9 +/- 0.8 mm) than for the normally erupting canines (2.5 +/- 0.8 mm) (P < or = .01). We found that during eruption, the follicle of the erupting maxillary canine frequently resorbed the periodontal contours of adjacent permanent teeth but not the hard tissues of the roots. We concluded that the dental follicle did not cause root resorption of permanent teeth. Resorption of neighboring permanent teeth during maxillary canine eruption was most probably an effect of the physical contacts between the erupting canine and the adjacent tooth, active pressure during eruption, and cellular activities in the tissues at the contact points, all of which are part of the eruptive mechanism. The findings also confirm an association between root resorption of deciduous canines and the dental follicles of erupting permanent canines.

Adolescent↗
PubMed2002

New regression equations for predicting the size of unerupted canines and premolars in a contemporary population.

The determination of a tooth-size to arch-length discrepancy in the mixed dentition requires an accurate prediction of the mesiodistal widths of the unerupted permanent teeth. This is an essential factor in treatment planning. The aim of this study was to validate Tanaka and Johnston's analysis on 600 Syrian patients aged 14-22 years. Tanaka and Johnston's tables, equations, and approximations were modified in order to improve the accuracy of the prediction. The correlation coefficients found between the size of the permanent mandibular central incisors and maxillary first molars (31, 41, 16, and 26) and the maxillary and mandibular canines and premolars were high (r = .72 and .74, respectively). New, more accurate prediction tables applicable at earlier ages, and new regression equations were constructed. In addition, new easier approximations were developed to allow the prediction of the size of the unerupted maxillary canines and premolars by adding 6 mm to the half-widths of teeth 31, 41, 16, and 26. The analogous prediction of the size of the unerupted mandibular canines and premolars was obtained by adding 5.5 mm to the half-widths of same teeth, 31, 41, 16, and 26.

Adolescent↗
PubMed2003

Evaluation of the validity of tooth size and arch width measurements using conventional and three-dimensional virtual orthodontic models.

Measurements and different analyses of dental casts are essential for precise diagnosis of an orthodontic case. At present, virtual computerized models, such as OrthoCAD, are available for clinicians, supplemented by dedicated software for performing needed measurements on them. The purpose of this study was to test the accuracy of measuring casts with the aid of calipers or OrthoCAD and compare these two techniques. Twenty setups using artificial teeth corresponding to various malocclusions were created. Impressions were taken of them, providing 20 plaster and 20 virtual orthodontic models. Measurements of mesiodistal tooth dimension as well as intercanine and intermolar width were made on both. Additionally, values of tooth size were calculated from the isolated artificial teeth removed from the setups and of arch width from the existing setups. The resulting values were compared by the use of nonparametric statistics, and methods' errors were also calculated. Results showed the methods being highly valid and reproducible for both tooth size and arch width. For the tested clinically applicable methods, measurement with digital calipers on plaster models showed the highest accuracy and reproducibility, closely followed by OrthoCAD. Digital calipers seem to be a more suitable instrument for scientific work. However, OrthoCAD's accuracy is clinically acceptable, and most likely, considering its present advantages and future possibilities, the examined or an equivalent 3D virtual models' procedure would become the standard for orthodontic clinical use.

Calibration↗
PubMed2003

Bolton anterior tooth size discrepancies among different malocclusion groups.

Orthodontic treatment comprises different phases with unique characteristics and challenges. The orthodontic "finishing" phase is recognized for the multitude of details necessary to achieve an excellent result. In some cases, the finishing phase is very difficult, requiring the production of complicated biomechanical forces to reach a satisfactory orthodontic solution. A high percentage of these finishing-phase difficulties arise because of tooth size imbalances that could have been detected and considered during initial diagnosis and treatment planning. The present study aimed to investigate the correlation between anterior tooth size discrepancies and Angle's Class I, II, and III malocclusions, as well as their prevalence in the Brazilian population from Belo Horizonte. We assessed the mesiodistal width of six anterior teeth in 300 patients, who were selected randomly. These patients were allocated to three groups according to their malocclusion. A chi-square test was performed to statistically compare the prevalence of anterior tooth size discrepancies among the three malocclusion groups and two genders. Analysis of variance was used to compare the mean Bolton anterior tooth size ratios as a function of Angle classification and gender. Statistical differences were determined at the 95% confidence level (P < .05). The important conclusions of our study are as follows: (1) Individuals with Angle Class I and Class III malocclusions show significantly greater prevalence of tooth size discrepancies than do individuals with Class II malocclusions; and (2) Mean anterior tooth size discrepancy for Angle Class III subjects was significantly greater than for Class I and Class II subjects.

Analysis of Variance↗
PubMed2003

Regression equations for determining mesiodistal crown diameters of canines and premolars.

In this study, regression equations (prediction equations) were established for the purpose of accurately predicting the widths of the crowns of unerupted canines (C) and premolars (P1 and P2) on the basis of the measured mesiodistal diameter (MDD) and vestibulooral diameter (VOD) of the crowns of the erupted central and lateral incisors (I1, I2) and first permanent molars (M1). On the plaster casts of 120 subjects (60 boys and 60 girls), MDD and VOD of the crowns of I1, I2, C, both P1 and P2, and M1 on both sides in both jaws were measured twice, with a time distance between measurements. Gradual regression equations were derived on the basis of the measurement results, by which the sums of the widths of crowns of C, P1, and P2 can be predicted using three to five predictors. The coefficients of multiple correlations regarding the sex and the jaw varied from 0.79 to 0.85.

Adolescent↗
PubMed2003

Crown-root shape of the permanent maxillary central incisor.

This study aimed to determine whether the lateral cephalometric crown-root shape differs among the permanent maxillary central incisor in Class I, Class II division 1, Class II division 2 and Class III malocclusions and to identify the nature of any differences. Of the 499 lateral cephalograms recorded at a university orthodontic clinic during 2001, 361 satisfied the inclusion criteria. Sixty cephalograms were selected from the four malocclusion groups and were digitized in random order. The configurations of the 10 landmarks characterizing the crown-root shape of the permanent maxillary central incisor were then optimally superimposed using Procrustes algorithms. Discriminant analysis of the principal components of shape determined the incisor shape differences between the malocclusion groups. The crown-root shape of the permanent maxillary central incisor did not differ significantly among the Class I, Class II division 1, and Class III groups (P > .05); however, the crown-root shape of the Class II division 2 permanent maxillary central incisor was significantly different (P < .001) from that of the Class 1, Class II division 1 and Class III. The shape discrimination involved axial bending of the Class II division 2 incisors. Principal components 1, 2, and 3 accounted for 63% of the Class II division 2 incisor shape variance, encompassing a shorter root, a longer crown, and axial bending of the incisor, in addition to a reduced labiopalatal thickness. These shape features could precipitate the development of a deep overbite in Class II division 2 malocclusion and may limit the amount of palatal root torque during fixed appliance therapy.

Algorithms↗
PubMed2004

A systematic review of the consequences of premature birth on palatal morphology, dental occlusion, tooth-crown dimensions, and tooth maturity and eruption.

This systematic review addresses the question whether prematurity results in alteration of palatal morphology, dental occlusion, tooth-crown dimensions, and tooth maturation. A literature survey from the PubMed database covering the period from January 1966 to November 2002 used the Medical Subject Headings terms "infant, premature," and "infant, low birth weight" in combination with "jaws," "dental physiology," "dentition," and "tooth abnormalities." Controlled studies written in English and with definitions of premature birth according to the World Health Organization were selected. Two reviewers selected and extracted the data independently and also assessed the quality of the studies. The search strategy resulted in 113 articles, of which 13 met the inclusion criteria. Scientific evidence was found for altered palatal morphology in the short term among the premature children, and oral intubation was a contributing factor to the alterations. If corrected age was considered for the premature children, no delay in dental development and eruption was found compared with normally born children. Thus, the early birth of premature children must be taken in account when planning for orthodontic treatment. Because of the contradictory results and lack of longitudinal studies, the scientific evidence was too weak to answer the questions whether premature birth causes permanent alteration of palatal morphology, alteration of dental occlusion, and altered tooth-crown dimensions. To answer these questions and obtain reliable scientific evidence whether premature children are at risk for malocclusions from possible alterations of palatal morphology such as asymmetry and high arched palates, further well-designed controlled studies as well as longitudinal studies are needed.

Dental Research↗
PubMed2004

Comparison of dental arch and alveolar widths of patients with Class II, division 1 malocclusion and subjects with Class I ideal occlusion.

This study evaluates dental arch and alveolar widths of patients with Class II, division 1 malocclusion. Thirty female patients with Class II, division 1 malocclusion were compared with 30 female subjects with Class I ideal occlusion. Patients with posterior crossbites even in a single tooth were excluded from the study. According to our results, arch widths measured between maxillary second premolars and maxillary first molars were found narrower in the Class II, division 1 group, and mandibular intercanine widths were narrower in the Class I group. Interalveolar widths showed no difference between the groups. These results suggested that transverse discrepancy in Class II, division 1 patients originated from upper posterior teeth and not from the maxillary alveolar base. Therefore, slow maxillary expansion rather than rapid maxillary expansion may be considered before or during the treatment of Class II, division 1 patients.

Adolescent↗
PubMed2004

The effect of premolar extractions on tooth size discrepancies.

The purpose of this study is to investigate the effect of premolar extractions on tooth size discrepancy. A total of 213 plaster casts were divided into a Bolton big (BB), a Bolton normal (BN) and a Bolton small (BS) group according to the Bolton normal value plus or minus one standard deviation. The Bolton overall ratio of each group was measured and compared before and after hypothetical premolar extractions. The Bolton overall ratios after premolar extractions were smaller than those before extraction in each group. Some of the patients in the BN group and BB group were moved into the BS group and BN group after premolar extractions. A tooth size discrepancy occurred in some patients with normal overall ratios after premolar extractions, but a tooth size discrepancy might be corrected in some patients with big overall ratios after premolar extraction.

Adolescent↗
PubMed2004

Dentoskeletal features associated with unilateral or bilateral palatal displacement of maxillary canines.

The aim of the present study was to analyze the prevalence and distribution of palatally displaced maxillary canines (PDC) in a large orthodontic population, and to investigate the associations between PDC, craniofacial features, and other dental anomalies such as aplasia or small-sized upper lateral incisors. An initial sample of 5000 subjects was evaluated. The reference values were calculated in a control group of 1000 subjects that was extracted from the initial sample. Chi-squared tests were used for statistical comparisons. The prevalence rate of PDC was 2.4%, with a male-to-female ratio of 1:3. PDC subjects with low angle vertical relationships showed a significantly high prevalence rate (60.2%). Unilateral PDC was significantly associated with aplasia of upper lateral incisors, whereas bilateral PDC was associated with aplasia of third molars. PDC showed reciprocal significant associations with bilateral small-sized upper lateral incisors. None of the three hypotheses offered in support of the "guidance theory" in the etiology of PDC were corroborated by the findings of the present study. The occurrence of other dental anomalies concurrent with PDC, sex differences, and the bilateral expression of PDC, all confirm the genetic component in the etiology of this tooth disturbance.

Adolescent↗
PubMed2004

Factors contributing to mandibular anterior crowding in the early mixed dentition.

The aim of this study was to uncover the possible factors contributing to mandibular anterior crowding in the early mixed dentition. Mandibular dental casts of 60 children in the early mixed dentition were divided into two groups according to the severity of mandibular anterior crowding. The space available for the mandibular permanent incisors, total incisor width, deciduous intercanine width, deciduous intermolar widths, permanent intermolar width, interalveolar width, and total arch length were compared between the crowded group (CG) and noncrowded group (NCG), and correlations with crowding were investigated. The mandibular deciduous intercanine width, mandibular deciduous intermolar widths, mandibular permanent intermolar width, mandibular interalveolar width, space available for the mandibular permanent incisors, and total arch length were significantly larger in the NCG. The total width of the four mandibular incisors did not differ significantly between CG and NCG. Significant inverse correlations were found between crowding and available space, deciduous intercanine width, deciduous intermolar widths, permanent intermolar width, and interalveolar width. Total incisor width was directly correlated with crowding. No significant correlation was found between crowding and total arch length. The results of this study suggested that individual variations play an important role in treatment planning. However, one must not overlook arch length discrepancies and transverse discrepancies in patients with mandibular anterior crowding.

Cephalometry↗
PubMed2004

Relationship between mandibular anterior crowding and lateral dentofacial morphology in the early mixed dentition.

Mandibular anterior crowding is identified as the discrepancy between mesiodistal tooth widths of four permanent incisors and available space in the alveolar process. However, incisor crowding is not merely a tooth-arch size discrepancy. Many variables such as direction of mandibular growth, early loss of deciduous molars, the oral and perioral musculature and incisor and molar inclination can be associated with crowding. Only few studies evaluated the relationship between mandibular anterior crowding and cephalometric measurements in the early mixed dentition. It was the aim of this study to search for dentofacial factors that might be associated with mandibular crowding in the early mixed dentition. Lateral cephalograms and dental casts of 60 children (33 girls, 27 boys) were evaluated. It was determined that patients with crowding had smaller lower incisor to NB angles, maxillary skeletal lengths, mandibular skeletal length, and mandibular dental measurements. They also had greater interincisal angles, overjet, overbite, and Wits appraisal measurements. Significant inverse correlations were found between crowding and SNB, lower incisor to NB angle, anterior cranial length, mandibular length, maxillary length, mandibular dental measurement and direct correlations between crowding and interincisal angle, overjet, overbite, and FMIA. According to these results, we conclude that crowding of the mandibular incisors is not only a tooth-arch size discrepancy. Dentofacial characteristics also contribute to this misalignment.

Alveolar Process↗
PubMed2004

Tooth width ratios in crowded and noncrowded dentitions.

Discrepancies in tooth width ratios could affect the excellence in the finishing of orthodontic cases. This study compares tooth width ratios in crowded and noncrowded dental arches. Tooth widths were measured from 143 dental casts (40 crowded and 33 spaced in male individuals and 43 crowded and 27 spaced in female individuals). Simultaneous crowded or spaced arches were selected. Tooth width measurements were made with a sliding caliper with a Vernier scale neared 0.1 mm. Inter- (0.990) and intraexaminer (0.993) reliability with mean differences of 0.03 mm (-0.03; 0.07) and 0.01 mm (-0.04; 0.05), respectively, were attained. Bolton analysis was applied to calculate the tooth width ratios (anterior and total). Descriptive statistics, Student's t-test, and analysis of variance were applied. There was no significant difference between the anterior and total tooth width ratios according to sex (P > .05). Both anterior and total ratios were significantly greater in subjects with crowding (P = .003 and P = .026, respectively), but no statistical difference by arch type in anterior and total tooth mass excess was found (P > .05). Differences among subjects with noncrowded and crowded dentitions were of 0.39 and 0.51 mm for the excess of anterior and total upper tooth mass, respectively, with respect to lower mass excess. Although the anterior and overall ratios and the differences between the upper and lower tooth width sums are greater in subjects with crowding, no clinically significant difference is observed (less than one mm).

Adolescent↗
PubMed2004

The use of an individual jig in measuring tooth length changes.

The parallel periapical radiographic technique hides several problems that might affect the image seen on the film. To overcome these problems a special jig with an external wire attached to the tooth surface and parallel to its long axis was suggested. This study examines the accuracy of using an external object for measuring root length differences due to angular changes between the tooth and the film. The rule of three was used for all calculations as a compensating formula. A human central incisor was placed in a special jig. Two different wire lengths (11.8 +/- 0.1 mm and 16 +/- 0.1 mm) were attached to the tooth in six different ways. The tooth was radiographed at four different film to tooth angulations. The tooth and wire lengths were measured on the model itself and directly on the scanned film on a computer monitor. The results reveal that a wire, placed nine mm from the crown and parallel to the long axis of the tooth was the best jig for accurately measuring tooth length changes. Neither palatal nor buccal metal wires, intimately attached to the crown of the tooth, can serve as a tool to measure tooth length changes. The study could not find a way to skip the need for a cephalometric radiograph to verify the parallelism between the wire and the long axis of the tooth for this matter.

Cephalometry↗
PubMed2004

A comparison of three methods to accurately measure root length.

Measuring the severity of root shortening after orthodontic treatment is a common problem in the dental fields as well as in litigation, legislation, and the ethics arena. The most common method to evaluate root length shortening is by using periapical radiographs. Surprisingly, root elongation after orthodontic treatment in adult patients was reported in the past. The aims of this study were to measure the effects of angular changes between the tooth and the film on the length of the image of a tooth model, to compare three methods to accurately measure root length in different films, and to find the most accurate reference points on the tooth for calculating root lengths. Five amalgam dots were placed on an acrylic model of a maxillary central incisor: ie, most apical, most incisal, mesial CEJ, distal CEJ, and most apical CEJ on the buccal side. The tooth model was placed in a special jig and radiographed at four different film-to-tooth angulations. Root and crown lengths were measured on both the model itself and on a computer monitor displaying the image that resulted from scanning the film into the computer. The results revealed that angular changes between the tooth and the film affect the measured tooth length. The midpoint between the mesial CEJ point and the distal CEJ point (median CEJ) was the best reference point for measuring root length. This was true when the calculations were done with the rule-of-three formula.

Adult↗
PubMed2005

Long-term dental arch changes after rapid maxillary expansion treatment: a systematic review.

This systematic review evaluates long-term dental arch changes after rapid maxillary expansion treatment on orthodontic patients with constricted arches. Clinical trials that assessed dental arch changes through measurements on dental casts or cephalometric radiographs were selected. No patients with surgical or other simultaneous treatment during the active expansion period were accepted. Electronic databases were searched with the help of a senior Health Sciences librarian. Original articles were retrieved from the selected abstracts, and their references were also scanned for possible missing articles. Forty-one articles met the initial inclusion criteria, but 35 were later rejected because they lacked a control group or only evaluated dental changes or used a semirapid technique. Some of them also lacked a reported measurement error. From the remaining articles, two did not report a long-term evaluation. From the final four articles, two measured changes through dental casts and two assessed changes through radiographs (one through lateral cephalometric radiographs and one through posteroanterior radiographs). Similar maxillary molar and cuspid expansion could be found in adolescents and young adults. Significantly less indirect mandibular molar and cuspid expansion was attained in young adults compared with adolescents. A significant overall gain in the maxillary and mandibular arch perimeter was found in adolescents. More transverse dental arch changes were found after puberty as compared with before, but the difference may not be clinically significant. No anteroposterior dental changes were found on lateral cephalometric radiographs.

Adolescent↗