Egyptian Dental Journal, 52, 1119: 1125, April, 2006
BOLTON ANALYSIS IN DIFFERENT CLASSES OF MALOCCLUSION IN A SAUDI ARABIAN SAMPLE
Fahad F. H. Al SuIaimani* and Ahmed Rami Afify**
ABSTRA CT Many 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 if there is a correct ratio between dental proportions. The 'aim of this study was to compare both the Bolton anterior and overall ratios for a Saudi Arabian sample of different classes of malocclusion and also to find if there is any gender difference. This study involved one hundred sixty subjects divided into three malocclusion groups: Angle's Class I, Angle's Class Il, and Angle's Class Ill. Tooth size measurements, Bolton anterior and ovcrall ratios werc performed for the study casts of the patients using the software program Ortho-one. Statistical analysis was done using one-way analysis of variance to check for intergroups differences then in• dependent sample Hest was done to find any sexual dimorphism. The result;; showed that there is no significant difference between Class I, Class Il, and Class HI malocclusions. Also no significant gender differences were found in Bolton anterior and overal1 ratios.
INTRODUCTION: 1.20 to 1.22. Lundstrom2 studied the relationship between the mandibular and the maxillary anterior Specific dimensional relationships must exist sum and named it the "anterior index". For an ideal between the maxillary and mandibular teeth to en• overbite, the optimal ratio was found to be from sure proper interdigitation, overbite, and overjet. 73% to 85%, with a mean of 79%. Bolton,3.4 re• Discrepancies in tooth size should be known early alized the importance of the harmonious re• during the initial diagnosis and treatment planning lationship between the teeth in the same arch and stages if perfect results in orthodontic finishing are between arches. He analyzed the relationshiP'-be• to be achieved. tween the mesiodistal tooth width of maxillary and Many investigators give interest to the har• mandibular teeth by studying 55 Caucasian sub• mony between the upper and lower dental arches. jects with excellent occlusion. Using the me• siodistal width of 12 teeth, he obtained an overall Neff 1 developed a proportion for the width dimen• sion of the teeth called the "anterior coefficient". ratio of 91.3 ± 1.91%; using the six anterior teeth, he obtained an anterior ratio of77.2 ± 1.65%. He found that an optimal overbite was represented when maxillary mesiodistal sum divided by the Later on other researchers 5-7 proposed new mandibular mesiodistal sum resulted in a ratio of methods to study tooth size discrepancies. Bolton
* Assistant Professor & Head of Orthodontic Division, Faculty of Dentistry, King Abdul Aziz University,Ksa. ** Associatc Professor, Orthodontic Department, Faculty of Dentistry, Mansoura University. Egypt. 1120 Fahad F. H. Al Sulaimani & Ahmed Rami Afify E.D.J. Vo!. 52. No. 2 method is still the most widely used till now for the and mandibular dentition sizes were compared. diagnosis oftooth size discrepancies. Differences in tooth size have been associated Many studies reported that the incidence of with different ethnic backgrounds and malocclu• tooth size discrepancy is high, but relatively little sions. Smith et al,14 who examined the validity of studies in the literature correlated malocclusion Bolton ratios for different ethnic groups, recently with the tooth size discrepancy. concluded that Bolton's ratios apply only to white women and should not be applied indiscriminately Sperry et aI., 8 analyzed the Bolton ratios for to white men, blacks, or Hispanics. For this reason, groups of Class I,Class II, and Class III cases. He found that Class III subjects showed greater man• the application of Bolton analysis and the proposed dibular tooth size excess than the Class II and I values for a harmonious dentition might not be val• groups did. id for other populations.
Crosby and Alexander,9 analyzed the Bolton Nourallah et al.,15 applied Bolton's tooth-size ratios for different occlusal categories. They did analysis to a sample of 55 harmonious Syrian mod• not differentiate between sexes, and they did not in• els, found values similar to the original data of an clude Class III patients. They did not find a sta• American population. They concluded that the tistically significant difference in the prevalence of analysis of and ideal values for a harmonious denti• tooth size discrepancies among the different mal• tion developed by Bolton can also be used on an occlusion groups. Arabian or at least a Syrian population.
Norderval et al.,IO showed that Bolton anterior Araujo and Souki 16 investigated the correla• ratio was significantly higher in the group with tion between anterior tooth size discrepancies and lower incisal crowding compared with the group Angle's Class I,II, and III malocclusions, as well with good alignment. as their prevalence in the Brazilian population. They concluded that individuals with Angle Class I Nie and Lin 1I found significant differences in and Class III mal occlusions show significantly the Bolton ratio among several occlusal categories. greater prevalence of tooth size discrepancies than The study was performed in 360 Chinese subjects, do individuals with Class IImalocclusions; and the and the data were analyzed according to Angle classifications Classes I, II, and III as well as ac• mean anterior tooth size discrepancy for Angle Class subjects was significantly greater than for cording to skeletal type. They concluded that the III Bolton anterior and overall ratios were greater in Class I and Class II subjects. Class III patients than in Class II and Class I sub• MA TERIALS AND METHODS jects. The samples of this study consisted of 160 Ta et al. 12, found that the Bolton standards pretreatment study casts with varying malocclu• may applied to southern Chinese children with sions chosen from the I;ecords of the Orthodontic Class I occlusion but not to those with Class II or Department, Faculty of Dentistry, King Abdul• Class III occlusions. Tooth-size discrepancy was Aziz University, KSA. found to be more frequent in the anterior region, es• The criteria for selection were as follow: pecially in the Class III occlusion group. 1. Study casts are of a good quality. Lavellel3 speculated that Class III individuals had disproportionally smaller maxillary teeth than 2. All the permanent teeth to be fully erupted Class I and Class II subjects did when maxillary except for the third molars. E.D.J. Vo/. 52. No. 2 BOLTON ANALYSIS IN DIFFERENT CLASSES OF MALOCCLUSION 1121
3. No mesiodistal and occlusal tooth abrasion. ing the software program Ortho-1 (www.enki• soft.com).The casts were scanned through the pro• 4. No proximal caries or proximal fillings. gram using a reflective scanner. With the aid of the 5. No crown and bridge restorations. mouse, widest mesiodistal dimensions were ob• tained by digitizing mesial and distal points for the 6. No supernumerary teeth or dental malforma• upper and lower 12 teeth (Right first permanent tions. molar to left first permanent molar). Figure: 1 The age range was 12 -17 years with a mean Bolton anterior ratio ( L of width of lower six age of 13.8 years. The sample consisted of 160 in• anterior teeth / L of width of upper six anterior dividuals was distributed as follows: Angle's Class teeth %) and overall ratio ( L of width of lower 12 I (36 males and 62 females); Angle's Class II, (18 teeth / L of width of upper 12 teeth %) were cal• males and 34 females); and Angle's Class III (8 culated according to Bolton,4 using the Ortho-l males and 2 females).Table 1. software program. With the ultimate aim of a 'paperless' or• Statistical analysis:
thodontic office and with the already existing pos• Data were saved on an Excel spreadsheet and sibilities of incorporating digital photos and radio• then transferred to SPSS software package (SPSS graphs into the electronic patient's file, the need for for Windows 98, version 10.0, SPSS Inc, Chicago, replacement of the plaster casts has emerged. Ill) for statistical analysis. After the measurements Measurements were done by the digital method us- corresponding to the sum of mesiodistal widths for the 6 maxillary and mandibular anterior teeth and Table 1. Sample distribution according to malocclusion the 12 maxillary and mandibular teeth were ob• and gender. tained, their distribution was evaluated using the 10160Females52982346298TotalMales 3662188 Class. Kolmogorov-Smirnov test to see whether the sam• TotalAngle'sAngle'sClassClassIIIIII ple came from a normally distributed population. The test indicated that the sample came from a nor• mally distributed population. Therefore, parametric tests were used.
To statistically compare the anterior and over• all tooth size ratios among the malocclusion
+- 0) M3X tt .• 0..)~)( t~1:h $IZ-!S .• !?y.)~ .• 0~M¥>dketh$'l!':" .• 1II:)~xtr .• D.)r<\Qxtransvf:fses¥l'fItI'iet,'1 .• O'..)t"<>nd .• O..Jr.taodtl~v~He")'TIY;~try .• EI~ M3x a .• 1iiI...'J l43x af\t{'Toposter..-$ syrrm<:t •. 1if..J M +- 0~ P;!ltiaJ .• 0.) P.,t,31 Soa:on .mat,~1$ .• 0'':'' Total! .• 0...) Tot3l6oli:oo.m.Sy~s .•=(~Upper .• EI.J Upper dent'..t)~ •...IC cOl">9luen .• liC.! lowel .• 113 Lower d!!fIt~b.Y..I(congruen .• O'.JM.axP :.- O.Jr>knPontan3lys1$ .• 1I.J1oe.s, + B.JIdea!.at'h .• 13.J ,,~X t. 0..1 I' groups, analysis of variance (ANOY A) was per• manzes the means, standard deviations and sta• formed. Statistical differences were determined at tistical comparisons of Bolton anterior and overall the 95% confidence level (P, .05). To determine if ratios observed in each group. It shows that t~ere is there is ~ny sexual dimorphism in the mean of in• no statistically significant difference between the termaxiliary tooth size ratios, a Student's Hest was three classes of malocclusion for both the anterior performed. and overall ratios. (P-value 0.753 & 0.217 re• Measurement error assessment: spectively) All measurements were done by the same in• Since there were no significant differences be• vestigator. For error assessment a total of 20 casts tween the groups of mal occlusion, all the casts were randomly selected from'the original sample, were combined and then separated into males and and all the procedures of analysis were repeated af• females. Student's Hest was performed to check ter one month. A paired Hest was applied to the for sexual dimorphism. Again, there were no sta• first and second measurements. No significant dif• tistically significant differences in both ratios be• ferences between the first and second measure• tween males and females. Table 3 summarizes the ments at the 95% confidence level. means, standard deviations and statistical compari• sons of Bolton anterior and overall ratios observed RESUL TS in each sex. It shows that there is no statistically There were no statistically significant differ• significant difference between the two genders for ences in Bolton anterior and overall ratios among both the anterior and overall ratios. (P-value 0.102 the different occlusal categories. Table 2 sum- & 0.353 respectively) Table 2. Analysis of Variance (ANOV A) of Anterior and Overall Bolton Ratios among Different Malocclusion Groups. Mean0.2]793.0696.308]0.75380.584.075.074.3]3.653.741.45SD.88 93.90Class81.] 1ITIII P-Value Class I Mean Overal1 ratioAnterior ratio * P ~ .05 ** p ~ .0] *** p ~ .001 Table 3. Student's Hest of Anterior and Overall Bolton Ratios between two Genders. Mean0.3530.]0294.]082.024.604.50SD4.783.34SD 93.2780.24 Females P-Value NlaJcs Mean Overal1 ratio Anterior ratio * P ~ .05 ** P ~ .0] **", p ~ .001 E.D.J. Vat. 52. No. 2 BOLTON ANALYSIS IN DIFFERENT CLASSES OF MALOCCLUSION 1123 DISCUSSION gle Class I and Class III malocclusions show sig• Tooth size discrepancies in orthodontic di• nificantly greater prevalence of tooth size dis• agnosis has been widely reported in the literature crepancies than do individuals with. Class n mal• occlusions; and the mean anterior tooth size and accepted in the orthodontic field as the re• discrepancy for Angle Class III subjects was sig• lationship between the upper and lower anterior nificantly greater than for Class I and Class n sub• and posterior dentitions is related to proper or• jects. Again Nie and Lin 11found a significant dif• thodontic finishing. 16in this study Bolton anterior ference for all the anterior and overall ratios and overall ratios in the three classes of malocclu• between the groups, the ratios showing that Class sions in a Saudi Arabian sample were studied. The III the highest followed by Class I and then Class sample size (160 subjects) was relatively small be• n. He further added that intermaxillary tooth size cause we restricted the selection upon a young age discrepancy may be one of the important factors in group to minimize the possibility of alterations in mesiodistal tooth dimensions due to factors such as the cause of malocclusions, especially in Class n and Class III malocclusions and that Bolton analy• attrition, proximal restoration or caries. sis should be taken into consideration during .or• In this study, the statistical analysis of Bolton thodontic diagnosis and therapy. anterior and overall ratios calculated in the three This study demonstrated that there were no classes of malocclusion studied showed no sig• sex differences in both anterior and overall· Bolton nificant differences. This finding was in agreement ratios, a finding which is in agreement with other with earlier studies done by other researchers. investigators. Nie and Lin II found no statistically Crosby and Alexander 9 found that there was no significant sex differences in his Chinese sample. significant difference among Class I; Class n, divi• Nourallah et aI., 15 also obtained the same results sion 1; Class n, division 2; and Class n surgery concerning the gender difference when he applied groups. However, they did not include Class III pa• tients. the Bolton standards upon the Syrian population. Crosby and Alexander 9 did not differentiate be• Also Qiong and Jiuxiang [7 compared five dif• tween sexes for any gender differences. ferent mal occlusion groups and reported that there Lavelle 13demonstrated sexual dimorphism in were no statistically significant differences be• the ratio of upper to lower arch tooth size, this is in tween these groups. a disagreement with the conclusions of this current The results obtained here in this study confirm study. Also in the study done by Bernabe et al.,19 also those of Laino et al.,19 when they used three when they studied the tooth-width ratio in a sample malocclusion groups based on the values of Steiner of Peruvian adolescents mean total tooth-width ra• cephalometric analysis. Bolton's anterior and total tios between male and female samples were sta• indices were calculated. They concluded that there tistically different but the anterior tooth-width ra• is no evidence of any predisposition for a tooth-size tios between male and female samples were not discrepancy in any of the malocclusion groups. statistically significantly different. In a disagreement with our results Lavelle13 Again in conflict with the results obtained by found that Class III individuals had dis• Ta et al.,12 Then they found a statistically sig• proportionally smaller maxillary teeth than Class I nificant difference between the Bolton standard and Class n subjects did when maxillary and man• and the Class In occlusion group. For the overall dibular dentition sizes were compared. Also Araujo ratio, a statistically significant differences were and Souki 16 concluded that individuals with An- found between the Bolton standard and the Class n 1124 Fahad F. H. Ai Suiaimani & Ahmed Rami Afify E.D.J. Vo/. 52. No. 2 occlusion group, and between the Class II and the REFERENCES Class III occlusion groups. 1. Neff CW. Tailored occlusion with the anterior coeffici'ent. As regard to the method of measuring the Am J Orthod. 1949;35:309-313. tooth size for the analysis it could be perforn1ed 2. Lundstrom A. 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