Compensation in Class III Malocclusions: Analysis of Tooth Crown Inclination on Digital Dental Casts / Compensação da Má Oclusão de Classe III: Análise da Inclinação das Coroas dos Dentes em Modelos Digitais

The objective of this study was to evaluate the tooth crown inclination in maxillary and mandibular arches in Class III malocclusion individuals, to identify the presence and magnitude of compensation. The study was conducted on 46 plaster casts of individuals with Class III malocclusion, of both genders (25 males and 21 females), with mean age 21 years and 1 month, with indication for compensatory orthodontic treatment. The dental casts models were scanned and the tooth crown inclinations were measured and compared with standard values by the independent t test. All tests considered a significance level of 5% (p<0.05). According to the results there was extensive variation in tooth inclination in Class III malocclusions. Values distribution for incisors highlighted the significant concentration of maxillary incisors in the area of positive values, compared with a very expressive concentration of mandibular incisors in the area of negative values. Compared with normal standards, in Class III malocclusions, the maxillary posterior teeth exhibited smaller palatal inclination than normal, while the mandibular incisors and second molars presented greater lingual inclination. It was concluded that the analysis of inclinations of all crowns of both dental arches in Class III malocclusions, compared with normal standards, evidenced the presence of natural compensation for maxillary posterior teeth, with reduced palatal inclination, as well as increased lingual inclination in mandibular incisors. The parameters of compensation naturally present in Class III malocclusions described, especially in lower incisors, would help clinicians when compensatory treatment is considered. (AU)

O objetivo deste estudo foi avaliar a inclinação das coroas dentárias nas arcadas superior e inferior em indivíduos com má oclusão de Classe III, para identificar a presença e a magnitude da compensação. O estudo foi realizado em 46 modelos de gesso de indivíduos com má oclusão de Classe III, de ambos os sexos (25 homens e 21 mulheres), com média de idade de 21 anos e 1 mês, com indicação de tratamento ortodôntico compensatório. Os modelos de gesso foram digitalizados e as inclinações da coroa dos dentes foram medidas e comparadas com os valores de normalidade pelo teste t independente. Todos os testes estatísticos adotaram um nível de significância de 5% (p <0,05). De acordo com os resultados, houve grande variação na inclinação dentária nas más oclusões de Classe III. A distribuição dos valores para os incisivos destacou a concentração significativa de incisivos superiores na área de valores positivos, em comparação com uma concentração muito expressiva de incisivos inferiores na área de valores negativos. Comparados aos padrões de normalidade, nas más oclusões de Classe III, os dentes posteriores superiores exibiram inclinação palatina menor que o normal, enquanto os incisivos e segundos molares inferiores apresentaram inclinação lingual maior. Concluiu-se que a análise das inclinações de todas as coroas de ambas as arcadas dentárias nas más oclusões de Classe III, comparadas aos padrões de normalidade, evidenciou a presença de compensação natural para os dentes posteriores superiores, com diminuição da inclinação palatina, bem como aumento da inclinação lingual dos incisivos inferiores. Os parâmetros de compensação naturalmente presentes nas más oclusões de Classe III descritos, especialmente nos incisivos inferiores, podem auxiliar o clínico quando o tratamento compensatório é considerado. (AU)

Application of Dahl concept on fractured teeth using direct composite resin restorations: A case report

@#Traumatic dental injuries are frequent problems among teenagers, affecting aesthetics, functionality and quality of life. With regards to the present case, there was an inadequate restorative space for anterior restorations due to the dentoalveolar compensation two years after a traumatic event and was particularly challenging. The use of the Dahl concept to create restorative space is well documented particularly in patients with localized tooth wear. However, there are no evidence to justify the feasibility of Dahl concept application on the fractured teeth. The purpose of this article is to provide a detailed description regarding this technique to create the necessary restorative space of the fractured teeth.

Fabrication of surgical splint by using of surgical jaw relator

Dentoalveolar compensation according to skeletal discrepancy in Normal occlusion / 대한치과교정학회지

The purpose of this study was to investigate the dentoalveolar compensation according to anteroposterior skeletal discrepancy in normal occlusion and to evaluate cephalometric parameters that quantitatively describe dental compensations. The study consisted of 90 subjects (50 males, 40 females) who were selected among specimens of normal occlusion at Seoul National University Dental Hospital, Dept. of Orthodontics. Lateral cephalograms in centric occlusion were traced and digitized for each subject. According to the anteroposterior skeletal pattern, the sample was divided into three groups. Cephalometric data were analyzed for the three groups using the SPSS program. Independent t-test, correlation analysis and regression analysis were carried out. The results were as follows: Dentoalveolar compensation was found in upper and lower incisor inclination and occlusal plane inclination. As the mandible located anterior to the maxilla, the maxillary incisors inclined more labially, the mandibular incisors more lingually, and the occlusal plane continued to flatten. The dental parameters most correlated with anteroposterior skeletal discrepancy were L1 to SN and L1 to FH. Among the compensatory dentoalveolar changes, lower incisor inclination was strongly related to the anteroposterior jaw relationship and played an important role in obtaining a normal incisor relationship. U1 to PtGn and L1 to APog were constant irrelevant to anteroposterior skeletal discrepancy.

Analysis of dentoalveolar compensation and discrimination of skeletal types / 대한치과교정학회지

The purpose of this study is to analyze dentoalveolar compensation in normal occlusion samples previously classified into 9 skeletal types, and to provide clinically applicable diagnostic criteria for individual malocclusion patients. Cephalometric measurements of the 294 normal occlusion samples previously divided into 9 types were analyzed. The descriptive features of dentoalveolar variables were compared for the 9 types using analysis of variance, followed by post hoc multiple comparisons. In addition, the correlation between skeletal and dentoalveolar variables were analyzed. Discriminant analysis with a stepwise entry of variables was designed to find out several potential variables for use in skeletal typing. The dentoalveolar compensation pattern of the skeletal types varied, especially with regards to the variables that indicated the inclination of incisors and the occlusal plane. Stepwise variable selection identified four variables: AB- MP, SN-AB, PMA and ANB. Discriminant analysis assigned a classification accuracy of 87.8% to the predictive model. On the basis of these results, this study could provide rudimentary information for the development of diagnostic criteria and treatment guidelines for individual skeletal types.

Dentoalveolar Characteristics according to facial types of Class III Malocclusion / 대한치과교정학회지

This study was performed to compare the pattern of dentoalveolar characteristics in different vertical and anteroposterior skeletal types in skeletal Class III malocclusion. The samples selected for this study were consisted of 60 subjects(29 males and 31 females, mean age; 19.7 years) in Class III group, 43 subjects(14males and 29 females, mean age: 20.5 years) in normal group. The findings of this study were as follows; 1. The IMPA of the Class III group was smaller than that of the Class I group(p<0.01). 2. In the Class III groups, SNB and NtoPog had negative correlation with IMPA(p<0.01). The SNB and NtoPog had correlations with SNU1, FHU1 and PalU1(p<0.01) in the male samples, and in the female samples, the SNB and NtoPog had correlations with SNU1(p<0.01). 3. In the Class III male samples, SNMP, FMA, PalMP had negative correlation with IMPA(p<0.01). SNMP, FMA, PalMP had not significant correlation with SNU1, FHU1, PalU1. In the Class III female samples, FMA, PalMP had negative correlation with IMPA(p<0.01). 4. In the high angle group of Class III samples, SNU1, IMPA is smaller than that of low angle group of Class III samples(p<0.05).

Dentoalveolar Compensation according to Skeletal Patterns of Normal Occlusion / 대한치과교정학회지

In general, Orthodontists make problem lists and treatment plans based on norms of several cephalometric standards. But consideration of dentoalveolar compensation, which tends to maintain normal dental arch relationship in various skeletal jaw relationships, helps orthodontists make more individualized treatment objectives and plans. The purpose of this study was to classify skeletal pattern of normal occlusion samples by cluster analysis and to investigate the dentoalveolar compensation according to skeletal patterns. The subjects were consisted of 125 subjects who were normal occlusion samples at Seoul National University Dental Hospital, Department of Orthodontics. Lateral cephalograms in centric occlusion were traced and digitized. The skeletal patterns of normal occlusion samples were classified into three horizontal groups and three vertical groups by cluster analysis and ANOVA on the skeletal and dentoalveolar measurements among the groups were carried out. The results were as follows; 1. Anteroposterior and vertical skeletal relationships of normal occlusion samples were very variable. 2. As the mandibular position was anterior to the maxilla, the maxillary incisors inclined more labially, the mandibular incisors more lingually, and the occlusal plane was flattened due to the anteroposterior dentoalveolar compensation. 3. As the vertical skeletal pattern was prominent, the upper anterior dentoalveolar height was increased, the lower posterior dentoalveolar height was decreased and upper posterior teeth was uprighted to the palatal plane and lower incisors and lower posterior teeth to the mandibular plane. 4. Lower incisors were more strongly associated with the dentoalveolar compensation than upper incisors according to the anteroposterior and vertical skeletal relationship.

The compensatory adaptation of anterior teeth according to the skeletal rolation / 대한치과교정학회지

The purpose of this study was to identify the compensatory adaptation of dentoalveolar structure according to the various skeletal relation though the statistical correlation between the anteroposterior, vertical skeletal and dentoalveolar relation, For this study, the sample were consisted of 101 adult subjects (51male and 50 female, mean age; male 23.6 years, female 21.5 years) who had good occlusion with the range of normal overjet and overbite and acceptable Angle's class I molar relationship which had not been related orthodontically. The results were as follows : 1. Even though acceptable normal occlusion, the range of measurements which represent anteroposterior, vertical skeletal relation and dentoalveolar relation were very wide. 2. Upper and lower incisor axis were significantly correlated with anteroposterior skeletal relation, which means the more lingual inclination of upper anterior teeth and the more labial inclination of lower anterior teeth according to the more anterior position of mandible to the maxilla (p0.05). 5. The correlation between the incisor axis and vertical skeletal was more closely related in upper anterior teeth than the lower anterior teeth. To summarize the above results, even though acceptable normal occlusion, skeletal and dentoalveolar relation was very widely ranged, and there were close relationship between the anteroposterior skeletal relation and the inclination of upper and lower anterior teeth and between the vertical skeletal relation and upper and lower anterior alveolar bone height. These finding can be concluded as compensatory adaptation to the different skeletal relationship

Dentoalveolar compensation of hyperdivergent skeletal pattern in children and adults / 대한치과교정학회지

Although there is a severe underlying skeletal deformity, the dentition has often maintained some occlusal contact and interdigitation by the teeth compensating in their positions for the skeletal problem, and these dental compensations are manifested in all three planes of space. The purposes of present investigation were 1) to study the pattern of dentoalveolar compensation of hyperdivergent skeletal pattern : and 2) to compare the centoalveolar compensations of hyperdivergent skeletal pattern in children with adults. The samples selected for this study were consisted of 60 subjects in normal group, 60 subjects in hperdivergent group. each was divided into two subgroups by age ; child groups(8~12yr old) and adult groups(17yr old over). The findings of this study were as follows; 1. In child, hyperdivergent subjects had smaller posterior lower facial height(p<0.01) and slightly longer anterior lower facial height than normal ones. In adults, they still expressed smaller posterior lower facial height and much longer anterior lower facial height than normal ones(p<0.01). 2. Hyperdivergent subjects had larger amount of upper and lower incisor relative eruption to their basal bone length than normal ones(p<0.05). In adult, relative eruption of upper incisor was increasing(p<0.05), although relative eruption of lower incisor remained the same as the child. 3. In child, there was no difference between hyperdivergent group and normal one in the upper and lower molar relative eruption to their basal bone length. In adult, hyperdivergent group had larger amount of upper molar relative eruption than normal ones(p<0.01), but relative eruption of lower molar was similar to normal ones. 4. hyperdivergent group had larger angle between lower occlusal plane and mandibular plane than normal group(p<0.01). Upper occlusal plane of adult group rotated more antero-superiorly than child groups, and adult hyperdivergent group had steeper upper occlusal plane than normal group(p<0.05).

The diagnosis and treatment of anterior openbite malocclusion / 대한치과교정학회지

There are varieties of severe malocdusions, which can be treated orthodontically, but with a great deal of effort. Anterior openbite, in particular, is one malocclusion thought to be more difficult to treat, and therefore, most of them have to be corrected by means of surgical intervention. To solve these problems, numerous studies pertinent to treatment modalities have been introduced with controversies on the effectiveness of treatment. Suggested treatment-modalities for anterior openbite are based directly or indirectly on the neuromuscular and morphological features and on the etiologic and/or the environmental factors. Even though the vertical relationship of the face is increased due to the growth variation, the normal occlusal relationship can be achieved by the adequate dentoalveolar compensatory mechanism, but in the case of inadequate or negative dentoalveolar compensation, openbite is likely to be present. If the skeletal dysplasia is too severe to be solved by orthodontic treatment alone, combined treatment with surgery should be done to restore the function and the esthetics of the orofacial complex. In many cases, however, orthodontic alteration of the dentition pertinent to the given skeletal pattern with the proper diagnosis and treatment planning can bring satisfactory results. The treatment changes with the Multiloop Edgewise- Archwire(MEAW), therapy occurred mainly in the dentoalveola~ region and showed a considerable similarity to the natural dentoalveolar compensatory mechanism. In other words, the MEAW technique allows orthodontists to produce the natural dentoalveolar compensation orthodontically. Even if an openbite is corrected by the orthodontic dentoalveolar compensation suitable for the skeletal pattern, relapse may still occur by the persisting etiologic factors which originally prohibited the natural dentoalveolar compensation. The etiologic factors should be determined at the time of initial diagnosis and should be controlled during treatment and retention.