Indian Journal of Dental Sciences

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 11  |  Issue : 3  |  Page : 125--129

Orthodontic perspective in causing the severity of malocclusion in hypodontia patients: A clinical study


Deepankar Bhatnagar1, Tahira Bawa1, Rupinder Matharoo2, Dipti Bhatnagar3, Deepika Jhangu4,  
1 Department of Orthodontics and Dentofacial Orthopaedics, Rayat Bahra Dental College and Hospital, Mohali, Punjab, India
2 Department of Oral Medicine and Radiology, MNdav Dental College and Hospitals, Solan, Himachal Pradesh, India
3 Department of Orthodontics and Dentofacial Orthopaedics, Yamuna Institute of Dental Sciences and Research, Gadholi, Yamuna Nagar, Haryana, India
4 Department of Orthodontics, Yamuna Institute of Dental Sciences and Research, Gadholi, Yamuna Nagar, Haryana, India

Correspondence Address:
Deepankar Bhatnagar
H No. 3512, Sector 38-D, Sector 38, Chandigarh - 160 014
India

Abstract

Aim: This study was aimed to compare Bolton's ratio and the arch width of patients with hypodontia with that of the control group. Materials and Methods: Ten cases with congenitally missing teeth and 10 cases of the control group were grouped in this study. It was guided by Bolton's ratio and Ashley Howe's analysis considering the tooth material and comparing tooth material to jaw size in the latter. Tooth width measurements were compared using a t-test, statistically significant at P < 0.05. Results: Patients with hypodontia shows significantly lower Bolton's ratio as compared to the control group. However, the values when compared statistically were not significant (P > 0.05). Arch width analysis showed significantly reduced basal arch width dimensions in hypodontia patients (P < 0.05) with preponderance toward nonextraction. Conclusion: These findings suggest that the hypodontia patients have comparatively narrower mesiodistal tooth measurements (prominently in posterior segments), lower Bolton's ratio, and reduced basal arch width as compared to control population. The treatment of patients showed preponderance toward nonextraction methodology.



How to cite this article:
Bhatnagar D, Bawa T, Matharoo R, Bhatnagar D, Jhangu D. Orthodontic perspective in causing the severity of malocclusion in hypodontia patients: A clinical study.Indian J Dent Sci 2019;11:125-129


How to cite this URL:
Bhatnagar D, Bawa T, Matharoo R, Bhatnagar D, Jhangu D. Orthodontic perspective in causing the severity of malocclusion in hypodontia patients: A clinical study. Indian J Dent Sci [serial online] 2019 [cited 2019 Oct 17 ];11:125-129
Available from: http://www.ijds.in/text.asp?2019/11/3/125/261949


Full Text



 Introduction



The term hypodontia implies the congenital absence of only a few teeth. When the number of missing teeth exceeds six, it is termed as oligodontia and in case of the complete absence of teeth, it is referred to as anodontia, is the extreme form.[1],[2],[3]

Tooth agenesis arises during initial stages of tooth formation (during initiation and proliferation) when the tooth germ fails to develop or/and absent.[1],[2],[4] Hypodontia most frequently presents as an isolated developmental disturbance of teeth, but sometimes, it is also associated with certain conditions such as the delayed eruption of permanent teeth due to retained deciduous teeth, taurodontism, peg-shaped maxillary lateral incisors, and ectopic presence of maxillary canine.[4],[5],[6]

The etiological factors responsible for tooth agenesis are both environmental and genetic in origin. The environmental factors involve trauma, harmful radiations from chemotherapy, and the genetic factors includes mutations in certain genes or inherited.[5]

The prevalence varies according to the individual characteristics such as the gender, race, and diversity of a person.[7],[8] Hypodontia prevalence is seen more in females as compared to that of males and comparable in both maxilla and mandible.[9] A retrospective study done in India included 673 subjects, found the prevalence of tooth agenesis (16.3%) to be higher than that of other anomalies.[10] Another study reveals the prevalence of hypodontia in school children of the Indian population to be 0.32%.[11]

Hypodontia not only affects the esthetics but also functional abilities such as speech.[7],[12] The decrease in tooth measurements in the anterior regions can lead to retrognathic maxillary arch and prognathic mandibular arch, low mandibular angle, and change in the length of maxilla and mandible which is important for an orthodontist to keep in mind while fabricating an ideal treatment protocol to achieve ideal occlusal and functional balance and esthetic harmony.[12],[13]

The aim of this study is to calculate and compare Bolton's ratio and the arch width of patients with hypodontia and the control group.

 Materials and Methods



A sample consisting record of 20 patients was evaluated and divided into two groups. Group A (n = 10) with a mean age 16.75 ± 4.25 consisting of study models of patients with hypodontia (with congenitally missing one or more teeth). Group B (n = 10) with a mean age of 18.4 ± 2.29 consisting of patients with ideal/normal occlusion with full complement of teeth. The number of teeth and the presence or absence of missing teeth was confirmed by obtaining orthopantomographs for each patient.

The inclusion criteria for both the groups includes fully erupted all permanent dentition with the exclusion of 3rd molars, availability of dental casts and pretreatment orthopantomographs. The patients with any form of congenital or developmental syndromes, caries and ectopic erupted tooth were excluded from the study.

The study models of 20 patients were evaluated for individual mesiodistal widths using digital Vernier caliper-Mitutoyo [Figure 1]. The mesiodistal diameter of individual tooth for both the groups was calculated on the casts. The maximum distance between the contact points on the two proximal surfaces was measured with accuracy of 0.01 mm using a digital caliper.{Figure 1}

All measurements were calculated by one investigator and the given data were subjected first to Bolton's analysis to determine the optimum inter-arch relationship by calculating the overall ratio (ideal-91.3%) and anterior ratio (ideal-77.2%) and to determine whether the discrepancy lies in the mandibular or maxillary teeth in millimeters [Table 1] and [Table 2]. Second, Ashley-Howe's analysis was performed to determine whether hypodontia had an effect on the arch width for which the premolar diameter and premolar basal arch width was calculated and inter-molar and inter-canine widths were also calculated additionally [Table 3] and [Table 4]. Two-sample t-test was used to find the statistical variables between the two groups. The statistical significance level was determined at P < 0.05.{Table 1}{Table 2}{Table 3}{Table 4}

Intra-operator reliability was evaluated on five random study casts from each group and variables were measured again at 1-month interval.

 Results



On comparing Bolton's ratio in both Groups A and B showed difference in anterior and the overall tooth material excess ratio. Patients with hypodontia show significantly lower Bolton's ratio as compared to the control group. However, the values when compared statistically were not significant (P > 0.05).

On subjecting the sample to Ashley-Howe Analysis, indicated that Group A (patients with hypodontia) had significantly smaller basal arch width percentage (premolar basal ach width [PMBAW] %) when compared to control group with P < 0.05.

The inter-canine and inter-molar widths were reduced in Group A when compared to that of Group B. However, the values when compared statistically were not significant (P > 0.05). Similarly, the inter-molar and inter-canine widths were reduced in hypodontia patients, whereas these findings were not statistically significant.

 Discussion



The treatment of anodontia or severe hypodontia is complex and by early detection of missing teeth, alternative treatment modalities can be planned and performed with a multidisciplinary team approach. Hence, the present study was carried out to analyze the effect of one or missing teeth on the extent of malocclusion in hypodontia patients.

For this study, models of patients with hypodontia were obtained and mesiodistal dimensions for individual teeth were calculated. The values were subjected to Bolton's ratio analysis, Ashley-Howe analysis and inter-molar and inter-canine widths were calculated, which are routinely done model analysis during treatment planning in orthodontics to assess the need for expansions or extractions in patients and to find out the extent of discrepancy when compared to a control population comprising individuals with full complement permanent dentition.

Patients with missing one or two permanent teeth showed narrower mesiodistal width of individual tooth when compared to the control group. These findings were in agreement with those of previous studies,[14],[15],[16],[17],[18],[19],[20],[21] hence indicating an association between hypodontia and smaller tooth size in the remaining dentition. However, Wisth et al.[22] did not find any statistical difference in mesiodistal diameter of the teeth between the hypodontia group and control group with full complement of teeth. Furthermore, Chung et al.[23] found that hypodontia is not associated with reduced tooth size.

Several authors have also assessed the craniofacial morphology of patients with hypodontia. Ben-Bassat et al. (AJODO 2003)[24] concluded that patients with multiple congenitally missing teeth demonstrate a characteristic skeleton-dental pattern, especially those with missing incisors. Karmani et al. (ajodo2002)[25] concluded that patients which showed tooth agenesis had significantly reduced the maxillary size and to a small extent reduced mandibular size. However, these above-mentioned studies evaluated the hypodontia patients craniofacially through two-dimensional cephalometric radiographs. The present study instead used study models to evaluate the effect of hypodontia on the dento-alveolar structure of the affected individuals.

Bolton's analysis is important and taken into consideration for diagnosis, specific treatment planning to achieve proper occlusion with an optimal overjet and overbite. In the present study, Groups A and B showed a difference in anterior and the overall tooth material excess ratio. However, the values when compared statistically were not significant (P > 0.05) which is in concrescence with a study by Han et al.[12] who investigated that the application of Bolton's ratio is important for the proper diagnosis and treatment planning for the Chinese patients with missing mandibular incisors and concluded that it is clinically beneficial for optimal treatment outcomes. However, Smith [26] evaluated the inter-arch relationships and tooth sizes in three different populations, and the results showed differences based on ethnicity and gender. Furthermore, Laino et al.[27] proved that the relationship between the sizes of the upper and lower teeth depends on the ethnicity of the population studies and the gender suggesting that Bolton's ratio is not universally applicable across all population.

Ashley-Howe Analysis, indicated that Group A (patients with hypodontia) had significantly smaller basal arch width percentage (PMBAW %) when compared to control group with P < 0.05 indicating the greater need for expansion in patients with hypodontia and the lesser need for extractions. The intercanine and intermolar width was also reduced in Group A when compared to Group B. However, values when compared statistically were not significant (P > 0.05). This was in accordance with a study by Wisth et al. (acta scandol 1974)[22] who concluded that neither the dental arch width nor the mesiodistal diameter of the teeth were significantly different in the hypodontia group compared to a control group without hypodontia.

Hence, when orthodontic treatment is performed on patients with hypodontia, not only the number but also the distribution of missing teeth should be taken into consideration. It must be notified that the treatment planning employed for patients with hypodontia must be considered for diagnosis, including profile, growth pattern, and esthetics of the patient. Depending on the proper diagnostic analysis, various treatment plans, namely stripping upper teeth, flaring of incisors, and slight increasing the overjet or overbite must take into consideration.[12]

 Conclusion



These findings suggest that the hypodontia patients have comparatively narrower mesiodistal tooth measurements (prominently in posterior segments) and reduced basal arch width as compared to control population. This indicates the greater need for expansion in patients with hypodontia and preponderance toward nonextraction methodology.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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