tooth width and arch dimensions in normal and malocclusion ... · 1 the journal of contemporary...

1The Journal of Contemporary Dental Practice, Volume 6, No. 2, May 15, 2005

Tooth Width and Arch Dimensions in Normal and Malocclusion Samples:

An Odontometric Study

The purpose of this study was to establish tooth width and arch dimensions in normal and malocclusion samples and to compare tooth width and arch dimensions between males and females in normal and malocclusion samples. A total of 120 pairs of orthodontic study casts were included in the study. An electronic digital caliper was used for the measurements. Descriptive statistics and the t-test were used for the statistical analysis of the data. Tooth width and arch dimensions were established in normal and malocclusion in the present study. Significant differences were found in tooth width between normal and malocclusion samples. However, no significant difference was observed in arch dimensions. Furthermore, there was statistical significant difference in tooth width between males and females where the males showed higher mean values. The same was true when arch dimensions were compared. The results of the current investigation are of great value to the anthropologist as well as to the orthodontist in understanding dimensional arch criteria and orthodontic arch wire selection. Furthermore, it helps the prosthodontist in the selection of the correct shape and size of stock impression trays and of suitable molds of artificial teeth for fixed and removable prostheses.

Keywords: Tooth width, dental arch dimensions, malocclusion, Dahlberg’s formula

Citation: Hashim HA, Al-Ghamdi SAF. Tooth Width and Arch Dimensions in Normal and Malocclusion Samples: An Odontometric Study. J Contemp Dent Pract 2005 May;(6)2:036-051.

Abstract

© Seer Publishing


IntroductionDental casts are still considered a vital diagnostic tool in orthodontic practice.1 The dental cast facilitates the analysis of tooth size and shape; alignment and rotations of the teeth; presence or absence of teeth; arch width, length, form and symmetry; and the occlusal relationship.2

A relative harmony in the mesiodistal dimension of the maxillary and mandibular teeth is a major factor in coordinating posterior interdigitation, overbite, and overjet in centric occlusion.3 Tooth size must also be in harmony with arch size to allow proper alignment.4

A significant variation in this harmony will lead to malocclusion and difficulties in obtaining an occlusion with optimal overjet, overbite, and class I canine and molar relationships. Although the natural teeth match very well in most individuals, approximately 5% of the population have some degree of discrepancy among the sizes of individual teeth.5

An anomaly in the size of the maxillary lateral incisors is the most common cause of tooth size discrepancy, but variation in premolars or other teeth may be present.5 These can be difficult to detect by inspection alone. However, comparing the size of upper and lower lateral incisors can provide a quick check for this discrepancy. Adiscrepancy almost surely exists unless the upper lateral incisor is 12-14% wider than the lower lateral incisor.6

Discrepancies in intermaxillary tooth size can be assessed using either a diagnostic setup or it can be predicted using a mathematical formula such as the Bolton analysis.7 If the discrepancy goes undetected, initially it may lead to delays in the completion of the treatment or to a compromised

result. Therefore, the ability to analyze the proportionality of the maxillary and mandibular teeth is an important diagnostic tool that would best be used at the initial diagnostic stage.

Mesiodistal tooth size is an important factor in orthodontic diagnosis and treatment planning.8

To achieve optimal occlusion, the maxillary and mandibular teeth must be proportional in size. If there is mismatch, there is no way to achieve optimal occlusion.9 This mismatch is defined as tooth size discrepancy.

At the beginning of this century, G.V. Black10

conducted one of the most classical investigations on the subject of tooth size. Although a large number of human teeth were measured, and tables of mean figures were established for each tooth in the dental arch, Black’s study was based upon a sample of unknown size and racial origin.

Review of the literature reveals variations in tooth size exist between different racial groups.11 Therefore, different diagnostic standards should be established for each racial group in order to provide an effective diagnostic standard.

Hashim and Murshid12-14 conducted a study on a Saudi sample with different types of malocclusion and found the first molars exhibited the least coefficient of variation in size, while the central and lateral incisors showed the most variation in size. They also indicated there was no significant statistical difference between the right and left sides. Thus, measurement of one side could


An equal distribution of male and female samples was maintained.

Dental Study Cast MeasurementsMeasurements were made directly on the un-soaped plaster dental casts. One operator took all the measurements under natural and neon light. An electronic digital caliper (Digimatic caliper, Mitutoyo, UK) was used to measure the following variables (Figure1):

1. Mesiodistal tooth width2. Inter-canine width3. Inter-molar width4. Arch length

Mesiodistal tooth width: The procedure for measuring the mesiodistal tooth width was performed as described by Hunter and Priest.17 The caliper beaks were inserted from the facial aspect of the teeth and held perpendicular to the long axis of the tooth. The beaks were then closed until gentle contact with the predetermined contact points of the tooth was made. The measurements included the mesiodistal width of all the twelve maxillary and mandibular teeth from the right first permanent molar to the left first permanent molar on 90 pairs of casts (the malocclusion group), since the measurements of the remainder of the 30 pairs (the normal occlusion group) were obtained from a previous study.16 The dimensions are defined as follows:

• Inter-canine width: The horizontal dis-tance between cusp tips of the upper and lower permanent canines.18

• Inter-molar width: The horizontal distance between the right and left central fossae of the upper and lower first permanent molars.18

• Arch length: The distance from the distal

be representative when the corresponding measurement on the other side was unobtainable. Furthermore, the canines in both jaws exhibited significant differences between the sexes while the other teeth did not.

Detection of tooth size discrepancies is one of the important diagnostic aids which allow orthodontists to gain insight into the functional and esthetic outcome of a given case. However,there is little information regarding this issue among the Saudi population where there is a relatively large need for orthodontic treatment.15

The aims of the present study were to:

1. Establish mesiodistal tooth width and arch dimensions in a sample with normal occlu-sion (Class I) and malocclusion (i.e., Class II and Class III).

2. Compare mesiodistal tooth width and arch dimensions between normal occlusion and malocclusion.

3. Compare mesiodistal tooth width and arch dimensions between both sexes.

Materials and MethodsA total of 120 pairs of orthodontic study casts were included in this study. Ninety casts were selected randomly from the dental school at King Saud University in Riyadh and thirty were obtained from a previous study.16

The criteria for sample selection were as follows:

• Patient age ranged from 15 to 25 years• Presence of all permanent teeth from

central incisors to first molars in all four quadrants

• No evidence of bubbles or fractured teeth• No history of previous orthodontic treatment

The sample was selected according to Angle’s classification and contained the following:

• Thirty pairs of Class I normal occlusion designated as the normal occlusion group

• Thirty pairs of Class I• Thirty pairs of Class II and thirty pairs of

Class III malocclusion were combined and designated as malocclusion group

Figure 1: The Digimatic caliper.


surface of the second premolar to the distal surface of the lateral incisor and from there to the midline. This is repeated on both sides. These values are computed to determine the arch length in each dental arch.

Statistical AnalysisThe data of the present study was subjected to statistical analysis utilizing a computer program SPSS, “Statistical Package for the Social Science” version 10.0. The following tests were carried out:

Statistical Assessment of Measurement ErrorsAll measurements were repeated after one week by the same operator on five pairs of dental casts (120 teeth and 20 arch widths) to determine the error of the method using Dahlberg’s method.19

Dahlberg’s formula

Where (d) is the difference between the two readings and (n) is the number of duplicates.

Descriptive StatisticsThe following descriptive statistics were calculated for each variable:

1. Mean2. Standard deviation3. Standard error of the mean4. Coefficient of variance

Statistical Comparison between GroupsAn independent t-test was used for comparison between the groups.

The Level of SignificanceA level of significance of 5% was used for the rejection of the null hypothesis. One asterisk (*) represents p


Table 3. The mean, standard deviation, standard error of the mean and coefficient of variation of individual tooth in normal occlusion group for both sexes (n= 30)*.

Table 4. The mean, standard deviation, standard error of the mean and coefficient of variation of individual tooth in malocclusion group for both sexes (n= 90)*.

Table 2. Error of the method for arch dimensions by Dahlberg’s method (n= 5)*.


was found the upper right first molar showed the least variability, whereas the lower right second premolar showed the highest variability.

Tables 4 shows the descriptive statistics for mesiodistal tooth width in the malocclusion group. It showed when the variability of tooth width was studied by means of coefficient of variation, it was found the upper right first premolar showed the least variability, whereas the upper left lateral incisor showed the highest variability.

Comparison of Mesiodistal Tooth Width between Normal Occlusion and MalocclusionTable 5 (a) and 5 (b) shows statistical comparison of mesiodistal tooth width between the normal occlusion group and the malocclusion group. Inthe malocclusion group the mesiodistal tooth width of the upper and lower central incisors, lower left lateral incisor, and lower first molars were significantly higher than in the normal occlusion group.

Comparison of Mesiodistal Tooth Width between Males and FemalesTable 6 (a) and 6 (b) shows a statistical comparison of mesiodistal tooth width between the males and the females. It showed the

males have greater mesiodistal tooth width than the females in most of the upper and lower teeth. The maxillary and mandibular canines, maxillary left central incisor, mandibular left lateral incisor, and mandibular first molars demonstrated statistical significant differences when values for the males and females were compared. While insome teeth in which the females demonstrated greater readings, the difference was not statistically significant.

Arch DimensionsTable 7 shows the descriptive statistics for arch dimensions in the normal occlusion group. Both inter-canine and inter-molar widths and arch length in the maxilla showed less variability than in the mandible.

Table 8 shows the descriptive statistics for arch dimensions in the malocclusion group. Bothinter-molar width and arch length in the mandible showed less variability than the maxilla, whereas the opposite was found related to the inter-canine width.

Comparison of Arch Dimensions Between Normal Occlusion and MalocclusionTable 9 shows statistical comparison of arch dimensions between the normal occlusion

Table 5(a). Statistical comparison of mesiodistal tooth width between normal occlusion and malocclusion for both sexes in the upper jaw*.


Table 5(b). Statistical comparison of mesiodistal tooth width between normal occlusion and malocclusion for both sexes in the lower jaw*.

Table 6(a). Statistical comparison of mesiodistal tooth width between males and females in the upper jaw*.


Table 6(b). Statistical comparison of mesiodistal tooth width between males and females in the lower jaw*.

Table 7. The mean, standard deviation, standard error of the mean and coefficient of variation of individual tooth in normal occlusion group for both sexes (n= 30)*.

Table 8. The mean, standard deviation, standard error of the mean and coefficient of variation for arch dimensions in malocclusion group for both sexes (n= 90)*.


group and the malocclusion group. It shows no statistical significant difference was found in arch dimensions between the two groups.

Comparison of Arch Dimensions between Males and FemalesTable 10 shows statistical comparison of arch dimensions between the males and the females. It shows statistically significant sex differences in arch dimensions. The inter-canine and inter-molar widths and arch length in the maxilla and mandible were greater in the males than the females.

DiscussionThe mesiodistal tooth size of the maxillary and mandibular arch must relate to each other in order to obtain an optimal occlusion at the completion of the orthodontic treatment.20 If a patient has significant tooth size discrepancy, orthodontic alignment into optimal occlusion may not be possible.21 Crosby and Alexander22 and Freeman et al.23 reported a large percentage of orthodontic patients possess significant tooth size discrepancies. Therefore, orthodontists should be aware of the existence of these discrepancies before beginning orthodontic treatment. The treatment

Table 9. Statistical comparison for arch dimensions between normal occlusion and malocclusion for both sexes*.

Table 10. Statistical comparison of arch dimensions between males and females*.


alternatives for tooth size discrepancies include restoration of relatively small teeth, interproximal striping of relatively large teeth, modification of crown angulation or inclination, and extraction.24

The age range of the subjects in the present study was between 15 to 25 years “early adulthood.” Doris et al.25 indicated early permanent dentitions provide the best sample for tooth size measurements because early adulthood dentitions has less mutilation and less attrition in most individuals. Consequently, the effect of these factors on the actual mesiodistal tooth width will be minimum. Researchers, who studied growth changes in the arch widths, found inter-canine and inter-molar widths did not change after the age of thirteen years in females and sixteen years in males.26-28 Therefore, it was assumed inter-canine and inter-molar widths of the subjects selected in the present study were stable.

The question of the accuracy of plaster casts made from alginate impressions as a representation of the actual mesiodistal tooth width was investigated by Hampson29, Beresford30,Miller31, and Coleman32 et al. The outcome of these studies indicated alginate impressions produce the most accurate dental casts when poured immediately. Furthermore, Hunter and Priest17 indicated there was considerable advantage in the measurement of teeth on the dental cast rather than measuring teeth directly in the mouth. Therefore, it should not be assumed the clinical measurements are necessarily more accurate than those obtained from plaster models.

Previous studies calculated the error of the method of an individual tooth width by Dahlberg’s method. The error of the individual tooth width found by various studies were as follows: LundstrÖm33, 34 were in the range of 0.06 mm-0.25 mm; Sanin and Savara35 were0.05 mm-0.11 mm; Towsend and Brown36 were 0.09 mm- 0.18 mm, while those by Hashim and Murshid37, 38, 12 were 0.02 mm-0.30 mm. In the present study the error of the individual tooth width ranged from 0.02 mm-0.37 mm. These disagreements could be due to the different types of measuring devices and methodology used.

Variability in the size of the teeth was studied by means of coefficient of variation. The result of

the current study showed the first molars in both jaws had the least variability, whereas the lower right second premolar had the highest. This is in partial agreement with the results obtained by earlier investigators.39 Lunt40 noticed the first molars of both jaws showed the lowest variability, while the third molar and lateral incisor of both jaws had the highest degree of variability in size. However, in the present study third molars were not included. Moreover, the results of the present study were in agreement with the findings of Hashim and Murshid38 who reported that first molars exhibited the least variability in mesiodistal tooth width in a Saudi sample.

Sex differences in mesiodistal tooth width have been of interest to several earlier investigators. In the present study the males had larger teeth than females, and the canines in both jaws displayed a statistically significant sexual dimorphism in mesiodistal tooth size. This was in agreement with the results of Moorrees41, Stahle42, Mack43,Kellam44, Bishara et al.45, Hashim and Murshid13, and Hattab et al.46 In addition to the canine, lower first molars also showed a statistically significant sexual dimorphism in mesiodistal tooth size. Selmer-Oslen47 found the greatest sex differences were in the canines and the premolars. No significant difference was observed in premolars in the present study.

The results of the present study show the inter-canine and inter-molar widths were greater in males than in females. This is in agreement with the result obtained by Tavas48 in a British sample, Younes49, and Diwan and Elahi50 in a Saudisample, but in disagreement with the finding of Sarhan and Diwan51 in a Egyptian sample. Theresult of the arch length measurements showed the males had significantly greater arch length than the females. However, no statistical significance was noted between both sexes in a study carried out by Hashim and Ghamdi52

in a Saudi sample collected from the AL-Baha area. This was not consistent with the results of the current study. On the other hand, when comparing the arch width and length between the malocclusion group and the normal occlusion group, no statistical significant difference was observed. The mean values of the upper inter-canine and inter-molar widths of the present study were lower than those reported by Younes49


and Diwan and Elahi50 in Saudi subjects. This difference in the measurements could be attributed to the variability of the reference points of the measurements and the methods of recording the arch dimensions. However, in the present study the central fossae were used as reference points, whereas the distobuccal cusps were used in both other studies. Hence, meaningful comparisons are not always possible and firm conclusions are difficult to draw.

The results of the current investigation are of great value to the anthropologist as well as to the orthodontist in understanding dimensional arch criteria. For the orthodontist, this can also assist

with orthodontic arch wire selection. Further, it would be helpful to the prosthodontist in the selection of the correct shape and size of stock impression trays and of suitable molds of artificial teeth for fixed and removable prostheses.

ConclusionThe results of the present study led to the following conclusions:

1. Mesiodistal tooth width and arch dimen-sions were established in normal occlusion and malocclusion groups for the sample of the present study.

2. A significant difference was found between normal occlusion and malocclusion groups in mesiodistal tooth width. However, no significant difference was observed in arch dimensions.

3. There was a statistical significant difference in mesiodistal tooth width between males and females where the males showed high-er mean values. The same was noticed when arch dimensions were compared.

References1. Saatci P, Yukay F. The effect of premolar extraction on tooth-size discrepancy. Am J Orthod

Dentofacial Orthop. 1997 Apr; 111(4):428-34.2. Moyers R.E. (1983a) Handbook of Orthodontics. 3rd edition Chicago. London. Year book medical

publisher. Page # 352.3. Sperry TP, Worms FW, Isaacson RJ, et al. Tooth-size discrepancy in mandibular prognathism. Am J

Orthod. 1977 Aug;72(2):183-90.4. Moorees C.F.A, Reed R.B (1964) Correlation among crown diameters of human teeth. Arch. Oral

Biol. 9: 685-697.5. Proffit W.R, Fields H.W, Ackerman J.L, Sinclair P.M, Thomas P.M and Tulloch J.F (1993)

Contemporary Orthodontics. (Second Ed.) Mosby- Year book, Inc, Page 158.6. Binder R.E, and Cohen S.M (1998) Clinical evaluation of tooth size discrepancy.7. Bolton W.A. (1952) Thesis for master degree. University of Washington, Seattle. U.S.A.8. Thilander B, and Rönning O (1985b) Introduction to Orthodontics. (5th edition) Tandläkarförlaget,

Stockholm. P # 57.9. Shellhart WC, Lang DW, Kluemper GT, Hick EP, Kaplan AL. (1995) Realability of the Bolton tooth

size analysis when applied to crowded dentitions. Angle Othod 65: 327-34.10. Black G. V. (1902) Descriptive anatomy of the human teeth, ed. 4, Philadelphia, S. S. White Dental

Mfg. Co.11. Smith S. S, Buschang P. H and Watanabe E. (2000) Interarch tooth size relationships of 3

populations: “Does Bolton’s analysis apply?” Am. J. Dentofacial Orthop. 117: 167-74.12. Hashim H.A., Murshid Z. (1994) Intermaxillary tooth width ratio in a Saudi sample with different

malocclusions. Alexandria. Dent. J 19:45-52.


13. Hashim H.A. and Murshid Z. (1993b) Mesiodistal tooth width. A comparison between males and females. Part 1, Egyptian Dent J. 39: 343-345.

14. Hashim H.A. and Murshid Z. (1993b) Mesiodistal tooth width in a Saudi population sample comparing right and left sides. Part 2, Egyptian Dent J. 39: 343-345.

15. Al-Emran S, Wisth P and Böe E. (1990) Prevalence of malocclusion and need for orthodontic treatment in Saudi Arabia. Community Dent Oral Epidemiol. 18: 253-5.

16. Al-Tamimi T. S. (2000) An odontometric study of tooth size and arch dimensions in a Saudi sample with normal occlusion.

17. Hunter WS, Priest WR. (1960) Error and discrepancies in measurement of tooth size. J. Dent. Res. 39: 405-14.

18. Merz M.L, Isaacson R.J, Germane N and Rubenstein L.K (1991) Tooth diameter and arch perimeter in black and white population. Am J Orthod 100: 53-8.

19. Dahlberg (1940) A. Statistical methods for medical and biological students. New York interscience publications.

20. Bolton W.A. (1958) Disharmony in tooth size and its relation to the analysis and treatment of malocclusion. Angle Orthod 28: 113-30.

21. Rudolph DJ, Dominguez PD, Ahn K and Thinh T. (1998) The use of tooth thickness in predicting intermaxillary tooth size discrepancies. Angle Orthod 68:133-8; discussion 139-40.

22. Crosby DR, Alexander CG. (1989) The occurrence of tooth size discrepancies among different malocclusion groups. Am. J. Orthod Dentofacial Orthop. 95: 457-61.

23. Freeman JE Maskeroni AJ, Lorton L. (1996) Frequency of Bolton tooth size discrepancies among orthodontic patients. Am. J. Orthod Dentofacial Orthop. 110: 24-27.

24. Fields H.W. (1981) Orthodontic-restorative treatment for relative mandibular anterior excess tooth-size problems. Am. J. Orthod Dentofacial Orthop. 79: 176-183.

25. Doris J.M, Bernard B.W, and Kuftinec M.M (1981) A biometric study of tooth size and dental crowding. Am. J. Orthod Dentofacial Orthop. 79: 326-336.

26. Moorrees C.F.A (1959) The dentition of the growing child a longitudinal study of dental development between 3 and 18 years age. Cambridge, Mass: Harvard University Press, P.87-110 and 230.

27. Sillman J.H (1964) Dimensional changes of the dental arches: Longitudinal study from birth to 25 years. Am. J. Orthod. 50:824-842.

28. Knott V.B. (1972) Longitudinal study of dental arch widths at four stages of dentition. Angle Orthod. 42: 387-394.

29. Hampson EL. (1955) The effects of environment on the dimensional stability of reversible and irreversible hydrocolloid impression materials. Br Dent J 90:371-80.

30. Beresford I.S (1969) Tooth size and class distinction. Dent Practit 20: 113-20.31. Miller M. (1975) Syneresis of alginate impression materials. Br Dent J 139:425-30.32. Coleman RM, Hembree JH, Weber FN. (1979) Dimensional stability of irreversible hydrocolloid

impression material. Am. J. Orthod. 75:438-46.33. Lundström A. (1964) Size of the teeth and jaw in the twins. Br Dent J. 117: 321-6.34. Lundström A. (1967) A genetic aspect of variation in tooth width based on asymmetry and twin

studies. Hereditas. 57: 403.35. Sanin C. and Savara B.S. (1971) An analysis of permanent mesiodistal crown size. Am. J. Orthod.

59: 488-500.36. Towsend GC and Brown T. (1978b) Inheritance of tooth size in Australian aborigines. Am J Phys

Anthropol 48: 305-31.37. Hashim H.A. and Murshid Z. (1992) Comparative study of Saudi and British populations on

mesiodistal tooth width: A pilot study. Alexandria Dent J.17: 55-58.38. Hashim H.A. and Murshid Z. (1993a) Mesiodistal tooth width in a Saudi population: A preliminary

report. Saudi. Dent. J 5: 68-72.39. Lundström A (1948) Tooth size and occlusion in twins. Thesis (Uppsala) Karger, Basle.40. Lunt D. A (1969) An odontometric study of medieval Danes. Acta Odont. Scand. 27: 55.41. Moorrees C.F.A (1957) The Aleut dentition. Cambridge, Harvard University Press, P. 257.


42. Stahle H. (1959) The determination of mesiodistal crown width of unerupted permanent cuspids and bicuspids. Helv. Odont. Acta. 3: 14.

43. Mack P.J (1981) Maxillary arch and central incisors dimensions in Nigerian and British population sample. J. Dent. 9: 67-70.

44. Kellam GA. (1982) Tooth size and arch perimeter – their relation to crowding of the dentition: a comparison between Navajo Indian and American Caucasian [MS Thesis] Iowa City, Iowa: University of Iowa.

45. Bishara S.E, Jakobsen J.R, Abdullah E.M and Garcia A.F (1989) Comparison of mesiodistal and buccolingual crown dimensions of the permanent teeth in three populations from Egypt, Mexico and United states. Am. J. Orthod Dentofacial Orthop 96: 416-422.

46. Hattab F.N, Al-Kateeb S. and Sultan I. (1996) Mesiodistal diameters of permanent teeth in Jordanians. Arch oral Biol. 41: 641-5.

47. Selmer-Oslen R (1949) An odontometrical study on the Norwegian Lapps. Thesis published by Det. Norske Videnskaps-Akadem, Jacop, Dybuad (cited lundström 1954).

48. Tavas, A. Group findings analysis of population dentofacial patterns from the lateral skull cephalostat radiograph. M.Sc. Thesis 1976. University of Manchester UK.

49. Younes S. A (1984) Maxillary arch dimensions in Saudi and Egyptian population sample. Am. J. Orthod Dentofacial Orthop. 85: 83-88.

50. Diwan R.R. and Elahi, J.M. A coparative study between three ethnic groups to derive some standards for maxillary arch dimensions. J Oral Rehab, 1990, 17, 43.

51. Sarhan, O.A. and Diwan, R.R. Maxillary arch dimensions in Egyptian and British children. Tropical Dental Journal, 1987, 2, 101.

52. Hashim H.A. and Ghamdi H.S. (2002) Arch dimensions in Class I, II and III malocclusion. Pakjopcod. 01: 21-26.

About the Authors

AcknowledgmentsThe authors would like to thank Dr. S. Barakati for her help in providing the digital caliper and Dr. N. Khan for carrying out the statistical analysis of the present study.

tooth width and arch dimensions in normal and malocclusion ... · 1 the journal of contemporary...

Documents