Evaluation of Reasons for Extraction of Permanent Teeth in Ahvaz ( 2010 )

The prevention of tooth loss is the ultimate goal of dental care. Identification of reasons for tooth loss should help in the establishment of adequate preventive programs. The present study aims to investigate the reasons for extraction of permanent teeth and the demographic factors (age, gender, occupational status, educational status) associated with tooth loss. This study investigates the reasons for extraction of permanent teeth in 834 patients referred to department of dental faculty of Ahvaz university of medical sciences and 6 other center (two personal dental clinics, one government dental clinic, and three dental offices) in Ahvaz during February and March 2010. The study methodology has been descriptive-analytical and the data have been collected by questionnaire and clinical examination of patients. Data have been analyzed by Chi-square test and in SPSS software. A total of 1500 extracted teeth from 834 patients showed that caries (52.6%) and periodontal disease (23.4%) have been among the main causes of tooth extraction, followed by prosthetic reasons (10.2%), patient request (10%), failure of endodontic treatment (1%), trauma (0.9%), impaction (0.7%), orthodontic reasons (0.7%) and other reasons (0.4%). The most extracted tooth has been first molar of the lower jaw (396 extractions). Extraction due to caries has been commonly observed in all age groups under fifty years old, whereas periodontal disease has been predominant in the groups over fifty years old. No statistically significant difference was found between two genders in their mentioned causes for extraction, with periodontal disease and patient request being the main reasons for teeth extraction. The frequency of the extracted teeth has been inversely related with improvement of educational status of the patients. In addition, it has been observed that significant different pattern of tooth loss was seen when patients were classified according to the occupational status (67.2% employed, 32.8% unemployed). Permanent teeth have been mostly extracted due to caries and periodontal disease. Prevention and care for dental caries and periodontal disease are required for all age groups, and over middle age groups, respectively. In addition, for the purpose of oral health preservation and improvement of quality of everyday life, patients should be better informed and advised to maintain an adequate oral hygiene and pay regular visits to the dentist.


INTRODUCTION
State of tooth loss leads to lack of coordination and adaptation of the masticatory system that is often coupled with functional effects and beauty consequences that is perceived by patients to varying degrees.The majority of patients consider toothlessness as a disability.As the loss of all teeth to be considered similar to the loss of part of the body, its treatment involves taking a series of biomechanical problems dependent to a wide range of people's perception and tolerance, that is costly and time-consuming [1].So far, several studies have been conducted in several countries to investigate the causes for extraction of permanent teeth, in which caries has been the main cause for tooth extraction, and other factors such as periodontal disease, orthodontic considerations, preprosthetic treatments, radiation therapy, and trauma have been stated as the main reasons for tooth extraction [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].
Because of the important role of saliva in the control of oral flora and mineral content of teeth, saliva test should be performed in patients with high caries activity.At PH above 5.5, in the presence of calcium and phosphate ions, demineralization is reversed and remineralization takes place again.Fluoride ions greatly enhances the calcium and phosphate sediments causing the enamel to be remineralized and safer against the next caries attacks by accepting greater amounts of acidresistant fluorapatite compound [22].In addition, since dental pulp is protected by hard dental structure that is dentin, enamel, and cementum, and since caries causes the loss of enamel rods, dentin, and finally damaging the pulp over time if left untreated causes; it can be considered one of the tooth loss factors [22].Statistics has shown that higher social classes are exposed to higher levels of sucrose in their diet, having the greatest amount of caries [23].In addition, several studies have shown an increase of tooth loss among smokers [24].Diseases and syndromes such as histiocytosis X, Papillon Lefever syndrome and malignant tumors cause loosing of teeth and eventually pull them out due to the protective bone loss around teeth [25].
In some studies, periodontal disease has been mentioned as the most common cause of tooth extraction in the anterior teeth and premolars [8,15,17].In some studies, periodontal disease has been introduced as the most common cause of tooth extraction from the age of forty and higher [4,17,19].While this age has varied in other studies to 45 years [17] or 50 years [2,3,5,6].The results of this study show statistically significant differences in different countries, and even thees differences can be observed within a country from a region to another region.
Knowing the extraction of permanent teeth causes and the prevalence of each of these factors in terms of age, sex, educational level, occupational groups, and economic status of the people can be used for planning and policy making of the adequacy review of dental care, prevention programs, determining how to allocate the available resources to better effect, and delaying the tooth loss.Due to the limited number of such studies in Iran and lack of information in this context in Ahvaz, this study aims to investigate the cause of the extraction of permanent teeth in Ahvaz.

MATERIALS AND METHODS
The present study is a cross-sectional descriptive epidemiological study that evaluates the causes of the extraction of permanent teeth in Ahvaz.In this study, patients referred to a social welfare center, Faculty of Dentistry of Jundishapur University of Medical Sciences, two private clinics, and three public dental offices have been investigated on the reasons for tooth extraction.
Stratified sampling has been used to choose the centers and the samples, and statistical tests of chi-square test and T-test have been used based on central and dispersion parameters.The statistical data has been described by tables and charts.At least 100 samples and in total 1500 samples have been collected from each of these centers.For data collection, a checklist including demographic data (age, sex, educational level, employment status), the tooth number and the reason for the tooth extraction according to the patient's treating dentist has been prepared.
For patients who had more than one extracted tooth, a separate questionnaire has been completed for each of the teeth.Only the wisdom teeth in occlusion have been entered in the study and pericoronitis and impaction of the wisdom teeth have been excluded.The collected data has been analyzed using SPSS 15 software.The relationship between variables has been analyzed using Chisquare test.In addition, P <0.05 has been considered a significant difference.

RESULTS
834 patients 1,500 cases of tooth extraction participated in this study (an average of 1.8 teeth per person).Frequency distribution of referred patients by age and gender is shown in Table 1.
As it can be seen, male patients were fewer than female patients, while their average extraction of teeth has been higher.
In the frequency distribution of the dental groups (molars, premolars, canines, incisors) mandibular first molar, and then maxillary first molar have been the most teeth extracted, and mandibular canine has been the least tooth extracted by 30 cases (see Table 2).
No significant difference has been observed in evaluating the relationship between the reasons for tooth extraction and sex in men and women.But caries and periodontal disease in both genders have been the most common causes of tooth extraction (Table 3).
In the distribution of the causes of tooth extraction in the total sample, caries has been the most common reason for tooth extraction and other causes in order of frequency have been: Periodontal disease, prosthetic reasons, the patient's request, endodontic treatment failure, trauma, orthodontic reasons, impaction (   5).
Periodontal disease increases with age increase.In the meantime, from 40 years old and higher, this upward process has had an significant ascending increase.While in the case of caries, this process showed a significant decrease from 40 years old and higher.
In investigating the relationship between the frequency of tooth extraction with patients' education, most people have been the patients with high school degree, followed by the patients diploma and higher education diplomas (Table 6).
Caries, periodontal disease, and prosthetic reasons have been the most common reasons for tooth extraction in patients with high school education, respectively.In the patients with diploma and higher, caries, periodontal disease, and the patient's request have been the main reasons for tooth extraction (Table 7).
Statistically, no significant difference has been observed between the causes of tooth extraction and the education (pvalue> 0.05).
In evaluating the reasons for tooth extraction in connection with the employment status of patients, a higher percentage of patients have been unemployed (Table 8).
In addition, the relationship between the main reasons for tooth extraction such as caries and periodontal disease have been investigated between the employed and unemployed patients (Table 9).
In the evaluation of frequency distribution of type of the tooth extracted due to the reason for teeth extraction, molars have been the most extracted teeth.From 712 extracted molars, caries and periodontal disease have been the most common reasons for teeth extraction.In premolars, caries and periodontal disease have been the main  2).No statistically significant difference has been observed between the reason for tooth extraction in the mandibular left quadrant and mandibular right quadrant, as well as teeth extraction in the upper jaw with the lower jaw.Most teeth extracted due to periodontal disease have been anterior teeth, molars, and premolars; while the most extracted teeth due to caries have been molars, premolars, and anterior teeth, respectively (Fig. 5 and 6).
The obtained results indicated that cells that the first molar and incisors has been the most extracted tooth due to caries and periodontal disease, respectively.In addition, in evaluating the reasons for extraction of permanent teeth in terms of the tooth number, the most teeth have been extracted due to caries of mandibular first molar, and the most teeth extracted due to periodontal disease have been maxillary first molar and mandibular incisors (Table 2).Among the teeth extracted due to caries, molars, premolars, and anterior teeth have had the most frequency and this order has been maintained among all age groups.In ages more than 60 years and in the ages of 60 and lower, incisors and molars have been the most teeth extracted due to periodontal disease.

DISCUSSION AND CONCLUSION
The results showed that caries and periodontal disease have been the main reasons for tooth extraction in dental offices and dentistry service centers in Ahvaz, consistent with studies conducted in Iran and other countries [2,13,17,19].Periodontal disease increases with age increase, among them the age of 40 and higher this trend has been increasing; this finding can also be observed in the previous studies in this area [2,13,17,19].
In the present study, in ages 50 and below caries and periodontal disease have been the main reasons for extraction of permanent teeth, and in ages above 50 the periodontal disease became the most common cause of tooth extraction that is consistent with some studies in this area [2,3,5,6,13].While in some other studies, periodontal disease at the age of 40 years and higher has been considered as the main cause of tooth extraction [12,16,17,19].This difference could be due to differences in implementing methods of the project and differences in methodology of the research, as well as the dentist and the patient's desire to maintain the teeth [17,26].It can also be due to differences in susceptibility to periodontal disease, since based on the results of the conducted studies, the destructive type of periodontal disease has been higher in some ethnic groups [27][28][29][30][31]. Smoking by patients can also influence the incidence of periodontal disease [32,33].In addition, differences in the implementing methodology of the project can also be among the other factors influencing the study findings.For example, in the present study the prosthetics reasons include 10% of tooth extraction cases, while in the study conducted in Kuwait by AL-Shammary et al. ( 2004) [17], this variable has not been considered and its related items have been included in the other variables, especially the variable of periodontal diseases.In addition, the tooth extraction cases due to endodontic treatment failure has been included in cases related to periodontal diseases.
In several studies, the most anterior teeth have been the most tooth extracted due to periodontal disease [5,10,17,19,34].One explanation could be that the mandibular anterior teeth is less susceptible to caries than other teeth, therefore these teeth remain in the people's dentition.Thus, in older ages that periodontal disease has become a more effective factor in the tooth loss, these tooth would be removed from the dentition by the disease [17,35,36].In addition, the mandibular first molar has been the most extracted tooth due to caries.It could be due to the specific morphology of the teeth, as well as early growth of this tooth in the mouth, demanding more care of it [10,19,37,38].The results show the high rate of teeth extraction due to periodontal disease in men that is consistent to the research conducted in this field [10,17,18,29,32,33,39].
Finally, the results of this study showed that caries has been the most common reason for teeth extraction in the ages of 50 and lower, while periodontal disease has been the most common cause of tooth extraction in the ages over 50 years.In addition, there is a significant relationship between the educational level and employment status of people with the extraction of permanent teeth.So that people with higher education and employed, the level of teeth extraction is lower.First molars have been the most teeth extracted due to caries, while anterior teeth have been the most common teeth extracted due to periodontal disease.
It is suggested that due to the high prevalence rate of the extraction of the first molar teeth due to caries in the age groups of 21-30 and 31-40, the implementation of preventive programs and dental care is more recommended to preserve these teeth as the occlusion key in the patients.

Fig. 5 :Fig. 6 :
Fig. 5: Distribution of the causes of caries and periodontal according to the type of tooth and jaw

Table 4 )
.By other division of the reasons for tooth extraction in terms of age, caries and periodontal disease have been the first and second reasons for tooth extraction in ages less than 50 years old.While in ages over 50, periodontal disease and dental caries have been the first and the second leading cause of tooth extraction.Reasons for tooth extraction between different age groups have been separately investigated based on the most common cause of tooth extraction for each age group.In addition, the highest frequency of the tooth extraction have been

Table 2 : Frequency distribution of the causes of tooth extraction based on the jaws in
age groups of 41-50 and 31-40 years old, respectively (Table