Bolton Standards Research Articles

Cranial Affinity among Chronological Populations in Sardinia, Italy: Biometric Insights for Orthodontic Purposes

Since human skulls may be used as a benchmark of the evolutionary process, the aim of the present study is to assess the cranial affinity of Sardinian populations from different chronological periods, with a standard index to evaluate its benefits for orthodontic purposes. Craniometric variables from four throughout cephalograms (anterior and lateral) of 72 units from historical Sardinian populations, two prehistoric, one medieval, and one modern were compared to the Bolton standard. A one-way analysis of variance (ANOVA) was performed for means comparison. A hierarchical cluster analysis and the bootstrap technique for the reliability of the dendrogram were used. Length data revealed statistically significant results (p < 0.01). Usually, the medieval population showed higher mean values compared to the other groups; the prehistoric population presented the highest value of Euclidean distance when compared to the medieval; the modern showed no affinity to prehistoric populations nor to the Bolton standard. The length and the breadth of the neurocranium, maxillary–alveolar length, orbital height, maximum cranial breadth, and external palate breadth contributed to the dissimilarity among populations. The dissimilarities in the craniometric measurements of Sardinian populations are remarkable. Therefore, the main outcome showed that the craniometric standards of the Bolton standard are not applicable across the Sardinian population.

Evaluation of the anterior and overall tooth ratios in the Saudi population versus Bolton's standards.

Understanding tooth-size discrepancy is essential in the process of diagnosis of maxillary and mandibular relationship. Due to the high incidence of tooth-size disproportion, Practitioners should consider the high incidence of tooth-size disproportion when planning treatment for their patients, as in many cases, this can be a hindrance to obtaining an ideal result. This study aimed to determine the anterior and overall tooth ratios in the Saudi population and compare them with Bolton's standards. A total of 356 patients were recruited. For the anterior ratio, around 25% of the patients had a ratio equal to Bolton's standards (77.2%). Most subjects (53.7%) had a ratio above 77.2%, and the remaining (20%) had a ratio below 77.2%. The mean amount of anterior mandibular excess was 2.17 ± 2.12 mm, and the mean amount of anterior maxillary excess was 2.16 ± 2.08 mm. For the overall ratio, less than half of the participants (43%) had a ratio equal to Bolton's standards (91.3%). Almost 34% had a ratio above 91.3%, while 23% of the participants had a ratio below 91.3%. The mean amount of overall mandibular excess was 2.54 ± 2.37 mm, and the mean amount of overall maxillary excess was 3.31 ± 3.33 mm. The majority of the study sample had an overall and anterior Bolton ratio that is different from the norms of Bolton's standards, with a tendency for increased overall and anterior ratios. Having specific standards for the Saudi population is important for better clinical assessment and treatment outcomes.

Measuring tooth size discrepancies using Bolton analysis: a comparative cross-sectional study among major ethnicity in Malaysia

BackgroundThe Bolton analysis is one of the commonly used tooth size analysis or diagnostic tools in deriving a treatment plan for orthodontic patients. Many studies have indicated and concluded that normal measurements for one group should not be considered normal for other ethnic groups. The aims and objectives of this study were to investigate the applicability of Bolton’s ratios in the orthodontic population of Malaysian main ethnics, Malay, Chinese, and Indians. Comparisons were made in terms of size and distribution of tooth size discrepancy in the Malaysian orthodontic population and the findings were converted in terms of millimeters.MethodsHundred fifty pre-orthodontic study casts comprised of 52 Malay, 54 Chinese, and 44 Indian patients were selected. Digital calipers (Fowler Pro-Max) linked to Hamilton Tooth Arch Software were used to measure the tooth width and ratios. Statistical analysis was carried out to test for gender differences (independent t-test), to identify the effects of malocclusion and ethnic groups (Two-way ANOVA), and to compare the means of the current study with Bolton’s standards (one sample t-test).ResultsThis study showed that there was no significant difference between the genders of the sample of each ethnicity. There was no correlation found between ethnic groups and malocclusion classes. There was a significant difference when comparing Bolton values with the Malay sample for both ratios. It was found that more Malay subjects presented with maxillary excess contrary to Chinese and Indians who presented more maxillary deficiency for the anterior and overall ratio.ConclusionThere was a significant difference found between the TSD of the three major ethnicities in Malaysia. The Bolton standards can be applied to Malaysian Chinese and Indians but not to Malays orthodontic populations for both anterior and overall ratios. Subsequently, a specific standard should be used for the Malays orthodontic population. It was found that more Malay subjects presented with maxillary excess contrary to Chinese and Indians who presented more maxillary deficiency for the anterior and overall ratio.

Digital evaluation of Bolton's tooth size discrepancies among different malocclusions categories of Egyptian adolescent orthodontic population: A retrospective study

This retrospective investigation aimed to compare Bolton's ratios among different malocclusion groups of Egyptian adolescent orthodontic patients with original Bolton's standards. Pre-treatment dental casts of 588 Egyptian subjects, 290 males and 298 females with mean age 16.7±2.2 years, were randomly selected and classified into 220 class I (108 males and 112 females), 230 class II (112 males and 118 females), and 138 class III (68 males and 70 females) groups. Mesiodistal widths from first molar to first molar were measured on 3-dimensionally scanned models via software and ratios were calculated. Two-way analysis of variance compared ratios as a function of skeletal classification and gender. Additionally, percentages of significant discrepancy outside 2 standard deviations (SDs) were calculated. The anterior mean ratio for the total sample were higher (79.4±4.7) and overall mean ratio was lower (90.1±5) than Bolton's standards. The differences between the obtained and standard values were statistically significant (P<0.001). However, there were no significant differences in either anterior ratio (P=0.637) or overall ratio (P=295) regarding gender. Class I cases showed the highest mean anterior ratio of 80±5.7 whereas class II and class III cases had the lowest ratio of 78.5±4.6 and 78.7±3.5, respectively. Concerning overall ratio, class III subjects had the highest ratio of 91.8±2.6 with no substantial distinction from class II cases (90.2±4.7) but was significantly different from class I cases that demonstrated the lowest ratio (89.7±5, P=0.020). High percentages of patients displayed clinically significant tooth size discrepancies (TSD), exceeding either above or below 2SD of Bolton's values, which were more marked in the anterior ratio. These were 25.2% and 7.4% for anterior ratio and 3.4% and 15.4% for overall ratio. Tooth size ratios of Egyptian orthodontic patients are generally different than the original Bolton's standards. Patients with class I and class III malocclusions had greater anterior and overall ratios than those with class II malocclusions with no considerable gender differences in either ratio.

The Tooth Size Discrepancy among Orthodontic Patients and Normal Occlusion Individuals from Saudi Arabia: A Three-Dimensional Scan Analysis of Diagnostic Casts.

Background/Purpose:Tooth size discrepancy is one of the causative factors of malocclusion. This study aimed to establish the TDS among various malocclusion classes and normal occlusion subjects in a Southern Saudi population.Materials and Methods:The study casts of orthodontic patients from Southern Saudi Arabia (mean age: 19.6 years ± 2.45; n = 120) were randomly selected and grouped into eight equal classes based on Angle's classification and gender. An additional 30 study casts, devoid of malocclusion, having excellent intercuspation and class I occlusion, were grouped into two controls (n = 15) based on gender. The study casts were three-dimensional scanned to measure mesiodistal widths of all the teeth. The calculated anterior ratios (AR) and overall ratio (OR) were statistically analyzed with analysis of variance and t-tests.Results:There were no significant differences in “OR” and “AR” between the genders (P > 0.05) and among the malocclusion and control subgroups (P > 0.05). The mean “OR” (92.01 ± 0.18) and “AR” (78.60 ± 0.27) of the malocclusion group were significantly higher than that of Bolton's ratios (P > 0.05). The “AR” of the control group was significantly higher than Bolton's standards (P = 0.048). However, “OR” was no different (P = 0.105). Malocclusion patients displayed a discrepancy (±2 standard deviation) in “AR” of 22.5% and 'OR' of 6.7% from Bolton's mean (BM). Similarly, the control group displayed a discrepancy in “AR” of 20% and “OR” of 10% from BM.Conclusion:The mean “OR” and “AR” of the Southern Saudi population showed no sexual dimorphism and no significant difference among various malocclusion and control subgroups. The “AR” of the malocclusion and control subgroups did not comply with Bolton's standards.

Long-term impact of pediatric endoscopic endonasal skull base surgery on midface growth.

Cranial base development plays a large role in anterior and vertical maxillary growth through 7 years of age, and the effect of early endonasal cranial base surgery on midface growth is unknown. The authors present their experience with pediatric endoscopic endonasal surgery (EES) and long-term midface growth. This is a retrospective review of cases where EES was performed from 2000 to 2016. Patients who underwent their first EES of the skull base before age 7 (prior to cranial suture fusion) and had a complete set of pre- and postoperative imaging studies (CT or MRI) with at least 1 year of follow-up were included. A radiologist performed measurements (sella-nasion [S-N] distance and angles between the sella, nasion, and the most concave points of the anterior maxilla [A point] or anterior mandibular synthesis [B point], the SNA, SNB, and ANB angles), which were compared to age- and sex-matched Bolton standards. A Z-score test was used; significance was set at p < 0.05. The early surgery group had 11 patients, with an average follow-up of 5 years; the late surgery group had 33 patients. Most tumors were benign; 1 patient with a panclival arteriovenous malformation was a significant outlier for all measurements. Comparing the measurements obtained in the early surgery group to Bolton standard norms, the authors found no significant difference in postoperative SNA (p = 0.10), SNB (p = 0.14), or ANB (0.67) angles. The S-N distance was reduced both pre- and postoperatively (SD 1.5, p = 0.01 and p = 0.009). Sex had no significant effect. Compared to patients who had surgery after the age of 7 years, the early surgery group demonstrated no significant difference in pre- to postoperative changes with regard to S-N distance (p = 0.87), SNA angle (p = 0.89), or ANB angle (p = 0.14). Lesion type (craniopharyngioma, angiofibroma, and other types) had no significant effect in either age group. Though our cohort of patients with skull base lesions demonstrated some abnormal measurements in the maxillary-mandibular relationship before their operation, their postoperative cephalometrics fell within the normal range and showed no significant difference from those of patients who underwent operations at an older age. Therefore, there appears to be no evidence of impact of endoscopic endonasal skull base surgery on craniofacial development within the growth period studied.

Overall and Anterior Tooth Size Ratios in a Group of Emiratis.

Objectives:The aims of this investigation in a group of Emiratis were (1) To study overall and anterior tooth size ratios in Class I normal occlusion, (2) To estimate overall and anterior tooth size ratios in different malocclusion groups, (3) To compare overall and anterior tooth size ratios in Class I normal occlusion with the Bolton standards, and (4) To determine the distribution of overall and anterior tooth size ratios ± 2 SD from Bolton mean values in all occlusion groups.Materials and Methods:In this cross-sectional investigation, consecutive patients’ files, including dental casts, were selected from the archives of orthodontic clinics of the Dubai Health Authority. The final sample was formed following the application of specific inclusion criteria. The sample consisted of 521 pairs of dental casts representing both sexes (males: 188; females: 333) and different malocclusion groups (Class I: 288; Class II: 110; Class III: 30) and Class I normal occlusion (93). The mean age of patients was 16.18y for Class I, 15.73y for Class II, 15.83y for Class III, and 16.55y for Class I normal occlusion. The dental casts were scanned and digitized by the first author using the Ortho Insight 3D laser scanner. Measurements were made regarding maxillary and mandibular sums of mesiodistal tooth dimension of the overall (6-6) and anterior (3-3) groups of teeth. Statistical analysis included descriptive statistics, paired t-test and Analysis of Variance (ANOVA). The level of significance was set at p<0.05.Results:There were statistically significant differences among malocclusion groups with regard to overall and anterior tooth size ratios. However, the comparison between the Class I normal occlusion group and the Bolton standards showed no statistically significant differences. Only five cases in Class II malocclusion presented an anterior tooth size discrepancy outside plus 2 SD from Bolton mean values and one case in Class I malocclusion presented with an overall tooth size discrepancy outside plus 2 SD from Bolton mean values.Conclusion:This study of the different occlusion groups of the Emirati sample concluded that (a) Class I normal occlusion cases presented similar overall and anterior tooth size ratios to Bolton standards; (b) Overall and anterior tooth size ratios among different malocclusion groups exhibited statistically significant differences; (c) Five cases in Class II malocclusion presented an anterior tooth size discrepancy outside plus 2 SD from Bolton mean values, and (d) One case in Class I malocclusion presented an overall tooth size discrepancy outside plus 2 SD from Bolton mean values.

Applicability of bolton’s tooth size ratios among mediterranean, japanese and japanese-brazilian populations

Objective: The aim of this study was to determine if Bolton’s tooth size ratios can be applied to Mediterranean, Japanese and Japanese-Brazilian populations. Materials and methods: The sample comprised 90 pairs of dental casts of untreated individuals with normal occlusion, divided into 3 groups according to ethnical characteristics: White (30 Mediterranean descendant subjects, with a mean age of 13.64 years), Japanese (30 subjects with Japanese ancestry, with a mean age of 15.63 years) and Japanese-Brazilian (30 Japanese-Brazilian subjects, with a mean age of 13.96 years). A digital caliper was used to measure the maxillary and mandibular mesiodistal widths from first molar to first molar on each dental cast. The anterior and overall tooth size ratios were calculated. T test was applied for comparisons between Bolton standards and the ethnical groups for anterior and overall ratios. Results: Only the Japanese-Brazilian group showed significantly greater ratios than Bolton standards. Conclusion: It was concluded that Bolton’s ratios are not applicable to the Japanese-Brazilian population. Therefore, it is suggested that Bolton’s ratios may not be suitable for different populations.

138 Endoscopic Endonasal Skull Base Surgery in Pediatric Patients and Impact on Midface Growth

Abstract INTRODUCTION Cranial base development plays a large role in anterior and vertical maxillary growth through age 7, and the effect of early endonasal cranial base surgery on midface growth is unknown. We present our experience with pediatric endoscopic endonasal surgery and long-term midface growth. METHODS This is a retrospective review (2000-2016). Pediatric patients were grouped by age at first endoscopic endonasal skull base surgery (&lt;7 yo and &gt;7 yo). Included patients had both pre- and post-operative (&gt;1 yr) imaging. Radiologists performed measurements (Sella-Nasion distance and angles from S-N to maxilla and mandible (SNA, SNB, ANB)), which were compared to age- and sex-matched Bolton standards. Z score test was used; significance was set at P &lt; 0.05. RESULTS &gt;The &lt;7 yo group had 11 patients, averaging follow-up of 5 yrs; the &gt;7 yo group had 33 patients. Most tumors were benign; one patient with a panclival AVM was a significant outlier for all measurements. Comparing the &lt;7 yo group to Bolton standard norms, there was no significant difference in post-operative SNA (P = 0.10), SNB (P = 0.14), or ANB (0.67). SN distance was reduced both pre- and post-operatively (SD = 1.5, P = 0.01 and P = 0.009). Sex had no significant effect. Compared to patients who had surgery in the &gt;7 yo group, the &lt;7 yo group demonstrated no significant difference in pre- to post-operative changes with regard to S-N (P = 0.87), SNA (P = 0.89), and ANB (P = 0.14). Tumor type (craniopharyngioma, angiofibroma, and other types) had no significant effect in either age group. CONCLUSION Though our cohort of patients with skull base tumors demonstrate some abnormal measurements before their operation, their post-operative cephalometrics fall within normal standard deviations and generally have no significant difference compared to patients who underwent operations at an older age. Therefore, there appears to be no evidence of impact of endoscopic endonasal skull base surgery on craniofacial development within the growth period studied.

Applicability of bolton's analysis to a South Telangana population

Aim: The aim of the study was to assess the anterior and overall tooth size discrepancies in different malocclusions and evaluate its effect on gender in a sample of South Telangana (Khammam) population and to compare it with Bolton standards. Materials and Methods: The study sample consisted of 311 pretreatment study casts, which were selected from records of orthodontic patients, who were residents of Khammam, South Telangana. The sample was divided into three groups based on Angle Class I, II, and III malocclusions and further subdivided into male and female groups. The mesiodistal diameters of the teeth were measured using digital calipers, and the Bolton's analysis was carried out. Statistical Analysis Used: Intraclass correlation coefficient was assessed using Dahlberg's formula. ANOVA and post hoc least significant difference test were used. Results: The mean anterior and overall ratios were 79.17 ± 2.91 and 92.3 ± 1.88, respectively. A total of 64% and 45% of the study population had tooth size discrepancies in the anterior and overall ratios when assessed for >±1 standard deviation (SD). When the sample was assessed for discrepancies >±2 SD, it was observed that a total of 33.8% and 5.5% patients had anterior and overall tooth size discrepancies. Conclusions: With significant differences being observed between Bolton's and the present study values, the need for population standards gains importance for better results at the end of orthodontic treatment.

Tooth size discrepancy among different malocclusion groups in Sudanese sample

BackgroundMany difficulties encountered during the finishing-phase of orthodontic treatment arise due to lack of intermaxillary tooth-size matching. Bolton ratio is one of the most useful calculations for precise orthodontic diagnosis as it shows whether a correct ratio between dental proportions exists or not. ObjectivesTo determine the mesiodistal tooth width in anterior and overall Bolton ratios in normal occlusion and different malocclusion groups in a Sudanese sample and compare to Bolton's standard. Materials and methodsThe sample consisted of 196 (86 male and 110 female) study models with normal occlusion, Class I, II and III malocclusions, and the age of subject 17–20 years old. Tooth size measurements were performed by electronic digital calipers. Tooth size ratios were analyzed as described by Bolton. The incidence of mesiodistal tooth size discrepancies in the malocclusion groups was analyzed and compared between male and female. The anterior and overall ratios were compared with the ratios Bolton's study. ResultsNo significant difference in the anterior and overall ratios of normal occlusion sample when compared to Bolton's standard. No significant differences were found among gender. ANOVA indicated that no significant difference was determined in the anterior and overall ratios in different malocclusion groups. ConclusionBolton's values can be used for Sudanese population until a large representative sample is studied.

Effective temporomandibular joint growth changes after stepwise and maximum advancement with Twin Block appliance

BackgroundThis study was designed to evaluate the “effective” temporomandibular joint changes (the sum of condylar modeling, glenoid fossa modeling, and condylar position changes within the fossa) and their influence on mandibular rotation in Class II Division 1 malocclusion cases treated with Twin Block appliance using a maximum and stepwise advancement approach. MethodsSixty Class II Division 1 cases with normal growth patterns in the age group of 12 to 14 years were treated with the Twin Block appliance and randomly assigned to one of two groups: 1) maximum advancement (n = 30); and 2) stepwise advancement (n = 30). The Bolton Standards served as a control group. Lateral head films were obtained before treatment and after successful treatment (mean 1 year). ResultsCompared with the control groups, both treatment groups showed significant vertical growth changes. Sagittal growth direction was posterior with maximum advancement and anterior with stepwise advancement. Resultant mandibular rotation was in the anterior direction and was greater with stepwise advancement. ConclusionsMyofunctional therapy after maximum and stepwise advancement with the Twin Block appliance showed a favorable effect in the temporomandibular joint region. Stepwise advancement showed greater vertical growth and more favorable anteriorly directed horizontal growth in the temporomandibular joint region on a short-term basis.

Comparison of Chinese and white Bolton standards at age 13

To create a combined male-female Chinese Bolton standard for age 13 and to compare it to the combined Bolton standard for white 13 year olds. Thirty-two Chinese and 32 white subjects (16 adolescent boys and 16 adolescent girls aged 13 years in each ethnic group) who fulfilled the selection criteria used to create the original Bolton standards were enrolled. Their cephalograms were traced and then averaged two at a time following the Bolton method. In addition to creating the template from the 32 subjects in each group, 43 linear and angular variables were measured and compared between the two ethnic groups and between the two sexes in each ethnic group using independent t-tests. A P value of .05 was used to assign statistical significance. The male-female combined templates for 13 year olds were also compared superimposing either in the Bolton relation or by soft tissue. No sexual dimorphism was found in the white subjects, whereas the Chinese girls had decreased upper face height (Na-ANS), more protrusive incisors (SNA-U1), and shorter cranial base (Ba-Na) and posterior cranial base (S-Ba) compared with the Chinese boys. In terms of ethnic comparison, the Chinese subjects presented shorter sagittal facial dimensions, a clockwise rotated mandible with a more acute gonial angle, and a convex facial profile with a less prominent nose and chin. However, overall vertical dimensions were similar. A 13-year-old combined male-female Chinese Bolton standard was created that demonstrated visually and with metric comparisons that Chinese and white clinically normal subjects have different craniofacial characteristics. These differences should be taken into consideration when an individualized orthodontic treatment plan is developed.

Analysis of Bolton's ratio among different malocclusion groups: A hospital based study

AimThe aim of the present study was to compare overall and anterior Bolton ratio in different malocclusion groups with Bolton standards. MethodsSample comprised of 509 pre-treatment casts taken from the department of Orthodontics and dentofacial orthopaedics. Bolton's ratio was measured in different malocclusion groups, and the results were compared with the standard Bolton values. Further ratios were calculated on gender basis and were compared with standard values. Data obtained was analyzed using student's t-test. ResultsStatistically significant differences were found for the whole study group and for overall ratios of class I group. Anterior ratio of class I, class II div 1 and class II div 2 also showed statistical significant differences. There was also significant difference in the overall ratio of male and anterior ratio of male and female groups, when compared with original Bolton standards. ConclusionBolton ratio in patients with malocclusion differ from Bolton standard.

Comparison of tooth size discrepancy of three main ethnics in Malaysia with Bolton's ratio

The objective of this study was to investigate the applicability of Bolton's ratios in orthodontic population of Malaysian main ethnics; Malay, Chinese and Indians. Ninety convenient samples consisting of 30 pre-orthodontic study casts from each ethnic that fits the inclusion criteria were selected. The greatest mesiodistal widths of each tooth from six to six for overall ratio and three to three for anterior ratio were measured using a digital callipers linked to Hamilton Arch Tooth System software to the nearest 0.01mm. Means of the ratios were calculated using Bolton analysis. One sample t-test statistic analysis was carried out to compare the means with Bolton values of anterior ratio and overall ratio and one-way ANOVA was used to analyze comparison between ethnic groups of the anterior ratio and the overall ratio with the level of statistical significance set at p < 0.05. However, there were no significant differences when comparing Bolton values with Chinese and Indian anterior and overall ratios. The Bolton standards could be applied to Malaysian Chinese, Indians and Malay's female. Subsequently, a specific standard should be used for the Malays orthodontic population.

Frequência da Discrepância Dental de Bolton em Pacientes Ortodônticos Adultos

Objetivo : Este estudo investigou a incidencia das discrepâncias anterior e total de Bolton em pacientes jovens e adultos. Testou-se a hipotese de que a historia odontologica (restauracoes proximais) pode gerar maior prevalencia de discrepâncias inter-arcos quando comparado as medias de normalidade de Bolton e em jovens sem evidentes alteracoes mesiodistais decorrentes de desgastes e/ou restauracoes. Materiais e metodos: A amostra foi constituida por 60 modelos ortodonticos de gesso obtidos previamente ao tratamento e foram formados dois grupos: o grupo controle, de pacientes jovens, composto por trinta modelos de pacientes na faixa etaria entre 12 e 18 anos de idade. O grupo adulto foi formado por trinta modelos de pacientes adultos acima de 20 anos de idade, incluindo pacientes com restauracoes proximais. Foram realizadas as mensuracoes mesiodistais conforme preconizado por Bolton para a obtencao das proporcoes dentarias anterior e total por meio de um paquimetro digital. Resultados: As medias das proporcoes encontradas para o grupo controle e para o grupo adulto nao apresentaram diferenca estatisticamente significante entre si e em relacao aos parâmetros determinados por Bolton. Dos modelos avaliados do grupo adulto com restauracoes proximais, 21,05% da amostra considerando-se a proporcao total e 31,58% considerando-se a proporcao anterior, apresentaram valores maiores que mais ou menos dois desvios padrao. Conclusao: Diante dos resultados obtidos, sugere-se que a analise de Bolton e aplicavel para pacientes jovens e adultos, sem dimorfismo sexual. No entanto, foi demonstrado que a “historia odontologica” pode interferir na variabilidade da discrepância inter-arcos.

Overall and anterior Bolton ratio in Class I, II, and III orthodontic patients

The aim of the investigation was to compare overall and anterior Bolton ratios in different malocclusion groups with Bolton's standards. The material comprised 600 pre-treatment study casts (262 males and 338 females, aged 12-25 years), selected from the models of 3088 patients who had applied for orthodontic treatment based on the following criteria: permanent dentition from the first right molar to the first left molar and no interproximal caries or restorations. There were 162 Class I, 144 Class II division 1, 155 Class II division 2, and 139 Class III patients. Statistical analysis of the data was undertaken using a Student's t-test. Statistically significant differences were found for the mean overall ratio when compared with the original Bolton norm for the whole study group, as well as for patients with Class I and III malocclusions when the mean anterior ratio was compared with the original Bolton norm. Significant differences were observed in all malocclusion groups for both genders. Discrepancies exceeding 2 SD were found in 31.2 per cent of the studied population for the anterior ratio when compared with Bolton's norm. The highest mean values for anterior ratio were in males with Class I (79.1) and Class III (80.1) malocclusions.

Bolton Standards and Technique in Orthodontic Practice

Abstract No Abstract Available. *Presented before the 28th annual meeting of the Eastern Association of Graduates of the Angle School of Orthodontia, at Cleveland, March 16, 1937. **Director of Research of the Bolton Study of Development of the Face of the Growing Child, Anatomical Laboratory, School of Medicine, Western Reserve University.

Comparison of the Bolton Standards to longitudinal cephalograms superimposed on the occipital condyle (I-point)

To compare traditional superimposition on sella turcica and the anterior cranial base (SACB) to superimposition referenced at the occipital condyle (I-point) for demonstrating craniofacial growth and development. Tracings for ages 8, 10, 12, 15 and 18 were chosen from the Bolton Standards of Dentofacial Developmental Growth to compare superimposition with the traditional longitudinal reference at SACB (anterior curvature of sella turcica and anterior cranial base) to reference at I-point on the antero-inferior contour of the occipital condyles in norma lateralis. The serial tracings were superimposed using both the sagittal and postero-anterior (PA) tracings. Incremental growth of landmarks was measured in relation to Cartesian coordinates and compared between the superimposition methods. Sagittal and PA tracing superimpositions displayed an average 7 mm greater cephalad movement of landmarks, an average 2.4 mm greater ventral movement, and comparable transverse dimension with superimposition referenced at I-point as compared to the SACB reference. I-point superimposition demonstrates physiologic growth patterns concealed by traditional registration at sella turcica. The evolution of superimposition on SACB was based on convenience and reproducibility. Fundamental principles of bone development are consistent with the occipital condyles as a more biologic reference for relative craniofacial growth. Actual vertical growth is believed to be greater than displayed in this study, due to the cross-sectional and blended nature of the sample.

“Effective” TMJ and Chin Position Changes in Class II Treatment

To evaluate the "effective" temporomandibular joint (TMJ) changes (the sum of condylar modeling, glenoid fossa modeling, and condylar position changes within the fossa), and their influence on chin position in patients with a Class II division 1 malocclusion treated orthodontically with a multibracket appliance and Class II elastics (Tip-Edge) and orthopedically with a fixed functional appliance (Herbst). Two groups of successfully treated subjects were evaluated: Tip-Edge (n = 24) and Herbst (n = 40). The Bolton Standards served as a control group. Lateral head films obtained before treatment and after an observation period of 2.6 years (Herbst also after 0.6-year period) were analyzed. In comparison with the Herbst and control groups, the Tip-Edge group exhibited less favorable sagittal "effective" TMJ growth and chin position changes necessary for skeletal Class II correction. Orthodontic therapy with a multibracket appliance and Class II elastics seems not to have any favorable sagittal orthopedic effect on the mandible, while bite jumping with the Herbst appliance has a favorable sagittal orthopedic effect on a short-time basis.