Imtiaz Ahmed 1 , Ayesha Wahaj 2 , Gul-e-Erum3
1 Incharge/ Head of Orthodontic Department, Dr. Ishrat-ul- Ebad Institute of Oral Health Sciences, Dow University, Karachi, Pakistan.
2 FCPS II Resident Department of Orthodontic, Dr Ishrat-ul- Ebad Institute of Oral Health Sciences, Karachi, Pakistan.
3 Assistant Professor, Department of Orthodontic, Dr Ishrat-ul- Ebad Institute of Oral Health Sciences, Karachi, Pakistan.
How to CITE:
Ahmed I, Wahaj A, Erum G. Comparison of intercanine and intermolarwidth among angle’s malocclusion groups. J Pak Dent Assoc. 2012;21(4):202-205.
To determine the difference between intercanine and intermolar width in class I,II&III malocclusion groups.
Initial orthodontic study casts of CLASS I, CLASS II DIV 1, CLASS II DIV 2 & CLASS III subjects coming to the Orthodontic Department of the Dr.Ishrat-Ul-Ebad Khan Institute Of Oral Health Sciences were selected. The sample included total 100 patients[25 in each group] including both male and female, with a mean age of 20years (17-25 years). The transverse widths of maxillary and mandibular dental casts was measured by universal digital calliper. Statistical analysis was done by using independent sample t-test for comparison among CLASS I, CLASS II DIV 1 and DIV 2 & CLASS III.
Maxillary arch was found to be narrower in CLASS II DIV1. In CLASS II DIV 2 intermolar width is widest overall. Whilst in CLASS III malocclusion intercanine and intermolar width is significantly wide in mandible. Also intermolar width in maxillary arch was found to be wide in CLASS III.
In our study, mean intercanine and intermolar width is significantly different in CLASS I ,CLASS II DIV1. CLASS II DIV2 & CLASS III groups.
Intercanine width, intermolar width, malocclusion.
In permanent dentition, dental alveolar arch either presented with wider arches ,narrow arches or no change in arch width. Although the dental arch dimensions changes till adulthood and is established at complete eruption of the canines and molars inspite of that the magnitude and direction does not necessarily outlines the justification for treatment. Consideration should be made to these limitations. Presently innovative inventions are constantly integrating knowledge related to an orientation, arrangement of dentition that allows the maxillary and mandibular arch form to establish. To this end, prefabricated maxillary and mandibular arch forms by many manufacturers are available , which are adapted to maintain the mandibular and maxillary relationship. The arch shapes of the maxilla and mandible results from a combination of genetic and environmental influences during development establishing intercanine width (ICW), and intermolar width (IMW) which varies from individual to individual. Both areequivalently necessary for case planning. The Directly proportional relationship between ICW, IMW and arch length has been demonstrated by Ricketts et al. and Adkins et al. . These considerations altogether, with the anteroposterior movements of the dentition determine the requirements for extraction or non extraction treatment. The size and shape of the dental arches could be affected by many factors such as heredity, growth of the bone, eruption & inclination of the teeth, racial back ground and environmental factors such as muscle forces and function .In post-treatment phase after retention arch dimensions typically decreases; whereas crowding increases in spite of maintenance of initial ICW width and expansion during treatment. Derya et al3reported decrease in IMW and arch size in extraction group. However, in non-extraction group, IMW decreased, without a change in arch size. Barbel et al showed in their study that postretention arch width relapse is more frequently found in the maxillary intermolar,intercanine region is (25.8%) and (13.8%) respectively while in mandibular intercanine and intermolar region (23.9%) and (19.0%) respectively. Considering pretreatment and posttreatment alignment and the amount of expansion to be influencing factors it is necessary to know the arch measurements of different malocclusions with respect to their dento-skeletal structures in order to produce a suitable plan with adequate mechanics and retention. Therefore, the aim of this study is to determine the difference between intercanine and intermolar width in class I,II&III malocclusion groups.
MATERIALS AND METHODS
The pretreatment orthodontic study casts of subjects CLASS I, CLASS II DIVI, CLASS II DIV2 & CLASS III malocclusions attending the Orthodontic Department of the Dr.Ishrat-Ul-Ebad Khan Institute Of Oral Health Sciences[Dow University Of Health Sciences Karachi- Pakistan]were selected. The sample included 100 patients both male and female, with a mean age of 20years (17-25 years). The inclusion criteria of the casts were fully erupted permanent teeth from first to first molar, goodquality casts, without tooth agenesis, anomalies, extractions and large restorations that could change the mesiodistal and buccolingual dimensions of the tooth. Exclusion criteria includes subjects with previous orthodontic treatment ,tooth agenesis, craniofacial anomalies, trauma,impaction and syndroms.
Dental Cast Measurements:
The transverse width of dental casts was measured with the help of digital calliper to the nearest of 0.01 mm. The intermolar and intercanine width was measured according to Staley etal . It was the distance between mesiobuccal cusp tips of the maxillary first molars , buccal grooves of the mandibular first molars and between cusp tips of the canines in both arches respectively.
SPSS 16 software was used in this study. Descriptive statistical analysis was done to calculate the mean difference and Independent sample t-test used for comparison among CLASS I, CLASS II DIV 1 and DIV 2 & CLASS III. Mean differences with standard deviation and p value(<0.05) was calculated.
In our study the mean intercanine and intermolar width was calculated as shown in bar graph 1& 2. Maxillary arch was found to be narrower in CLASS II DIV1. In CLASS II DIV 2 intermolar width was widest overall. Whilst in CLASSIII malocclusion intercanine and intermolar width was significantly wide in mandible. Also intermolar width in maxillary arch found to be wide in CLASS III. Mean values are shown in table below:
Previously various researches interpreted the difference between intercanine and intermolar width in different malocclusion groups. Frohlich compared intercanine and intermolar widths of both arches of 51 subjects with Class II malocclusion and normal occlusion and reported no difference. Sayin and Turkkahraman7 compared dimensions of patients with Class II division1 malocclusion and subjects with Class I ideal occlusion in the permanent dentition. They reported a significantly increased mandibular ICW in the Class II division 1 group, although maxillary intermolar widths were larger in the normal occlusion sample. Our study shows that maxillary intercanine width was significantly decreased in Class II DIV 1 & 2 while mandibular intercanine & intermolar width both in maxilla and mandible was increased in Class II DIV 2 malocclusion group. Enlow and Hans8 explained Class II dentoskeletal features and facial growth without differentiating Class II sub-divisions and reported that Class II patients have long, narrow anterior cranial bases that affect the nasomaxillary complex and result in long, narrow palates and maxillary arches. Mandibular intercanine width changes during orthodontic phase remains debatable in orthodontics. Recently studies have shown that expansion during treatment is significantly relapsed later in post retention phase. Bishara et al9 studied maxillary and mandibular dental arch widths and lengths in conjunction with growth between Class II DIV1 malocclusions and normal subjects and did not report difference in maxillary and mandibular ICW. This was in contrast with Sayin and Turkkahraman. In this study, molar reference points were taken from Staley et al explained that in normal centric occlusion, the mesiobuccal cusp tips of the maxillary molars are positioned near the buccal grooves of the mandibular molars. Staley et al and Sayin and Turkkahraman emphasize upon the narrow widths of the dental arch in Class II division 1 patients appeared to be caused both by palatally tipped teeth and narrower bony bases of the dental arch. Arch widths changes with age, but these changes are variable amongst samples It is possible that many factors have influenced such as the degree of crowding, amount of overjet, presence of displaced canines, and the variability in arch shape. Local factors and arch wire type may also play a role. Also treatment outcome depends upon variations in the arch form and length of retention. These factors may affect intercanine stability, but the specifics of treatment and retention warrents it to be. The findings of our study corresponds with that of Uysal etal10 in relation with that of maxillary intercanine and intermolar width in Class II DIV 1 .He concluded from his study that the Maxillary interpremolar width, all maxillary alveolar widths, and mandibular premolar and molar alveolar widths were significantly narrower in the Class II division1 group. Also in Class III significant difference was found when compared to Class I in our study. Kuntz etal11 showed that the growth and etiology are the basic factors of Class I crowded malocclusions and Class III malocclusion. His study shows narrower than normal intermolar and alveolar arch widths in maxillary and mandibular arches in Class I. While narrower than normal maxillary intermolar and alveolar arch widths in Class III; but our study did not find this instead it shows increase in intermolar width in Class III group.
In our study mean intercanine and intermolar width is significantly different in CLASS I ,CLASS II DIV1. CLASS II DIV2 & CLASS III groups. Mean intercanine and intermolar width of maxillary arch was found to be narrower in CLASS II DIV1. In CLASS II DIV 2 intermolar width was widest overall While in mandible it is significantly wide in CLASS III malooclusion group. There is no gender difference between groups.
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