CAUSES FOR EXTRACTION OF PERMANENT TEETH IN GENERAL DENTAL PRACTICES IN YEMEN

The aim of this survey was to investigate the primary causes for extraction of permanent teeth, its correlations with age and gender, as well as identify the important predictors for dental caries in Sana'a University dental clinics in Sana'a city, Yemen. The study was conducted over a period of one year; its population consisted of 1,420 patients, aged 9–72 years, who underwent tooth extraction. There were 761(53.6%) male and 659 (46.4%) female patients. The frequency distribution was calculated using the ttest, ANOVA and t test for differences in mean number of extracted teeth and the logistic regression model to evaluate the variables associated with causes for tooth extraction. A total of 2,585 teeth were extracted from the 1,420 patients. The highest rate (23.1%) of extraction occurred for those 41–50 years old. Males comprised 53.6% of patients but had more teeth (1598, 61.8%) extracted than females (987, 38.2%).The rate of teeth extracted on the day of the survey per patient was 1.82±0.07 (2.1±0.1 in males and 1.5±0.05 in females). Tooth loss due to caries was 69%; periodontal disease was 28%; pre-prosthetic reasons were 1.9% and other reasons were 1.14%. There was a significant association between patient characteristics (age and gender) and number of teeth extracted in which the Mean±SD of extracted numbers were increase with increasing age and higher in male patients than in females (p<0.001). The most frequently extracted teeth were mandibular first and second molars (446, 17.3%), followed by maxillary premolars (415, 16.1%), while mandibular canines were least frequently extracted (87, 3.4%). In conclusion; dental caries and periodontal problems were the main causes for tooth extraction in Sana'a city, Yemen.


INTRODUCTION
Tooth extraction is one of the dental treatments which should be considered the last decision. A reduce in the number of teeth may result in poor dietary habit and decline of quality of life 1 . The number of extracted teeth can act as an indicator of socio-economic and oral hygiene level 2 . Extraction of permanent teeth is carried out for several causes including dental caries, periodontal disease, orthodontic causes, impacted teeth, failed dental treatment, prosthetic indications and other causes. An understanding of the causes why teeth are extracted is vital to enhance oral health outcomes. A large number of cross-sectional studies have investigated for tooth loss in different countries but no previous study to the current study was carried out to study the reasons for extraction teeth in Yemen except prevalence and pattern of Third Molar impaction in Sample of Yemeni Adults study which carried out last year 3 . Dental caries was the main cause for tooth loss worldwide 4-11 , but a few studies revealed that a greater proportion of tooth extractions were due to periodontal diseases [11][12][13] . Not enough data are available in Yemen and information on this topic is strongly required. By detecting the main causes and predictors for tooth loss, it may be feasible to limit future extractions and emphasize the crucial role of prevention. Consequently, the purpose of this study was to inspect the causes for extraction of permanent teeth, its associations to several characteristics such as age and gender; and the best analysts for dental caries in Sana'a city, Yemen.

SUBJECTS AND METHODS
This cross-sectional study of following sampling was prepared on dental clinics in the Faculty of Dentistry, Sana'a University during the period from January to December 2017. A predesigned questionnaire for the study was divided into two parts: first asked for the patient's gender, age, marital status, education level, history of smoking, Qat chewing and the time of last dental visit. This part was completed by the dental assistants. The second half was finished by dentists and documented the information on previous dental extractions, tooth type and the cause for each extraction that was to be performed on the day of survey. Dentists were asked to record the code of tooth type and the main cause for each extraction. All permanent teeth extracted, including third molars, during the 12-month study period (January to December 2017) were recorded. The causes for extraction were investigated for each tooth type in the upper and lower arch. Data were not separated into right and left quadrants as the prior surveys have revealed no differences in the rates of extraction for right and left sides of the oral cavity 1, 14 .
The data were entered and analyzed using the SPSS software (version 16.0). The extracted teeth data with normal distribution was expressed as mean and standard deviation (SD) for previous extraction and for extraction on the day of the survey. The relationships of the categorical background variables, such as age range and gender, with reasons for tooth extraction were analyzed by the 2 test, while differences in the mean number of extracted teeth per patient were analyzed with ANOVA and t test methods. A logistic regression model was used to evaluate the variables associated with reasons for tooth loss, considering tooth extraction due to caries and other causes such as caries and periodontal disease. A p value of less than 0.05 was considered to be statistically significant.

Ethical Consideration
Ethical clearance for the study was taken from the Faculty of Medicine and Health Sciences Research Review Committee. Informed Consent was taken from the volunteers before the denta NJJKl examinations.

RESULTS
Males comprised 53.6% of patients and they had more teeth extracted (61.8%) than females (p<0.001). According to Table 1 Table 2). Although dental caries was responsible for most extractions in both genders, caries and periodontal disease were more common in males than females ( Table 2). While caries was the leading cause for tooth extraction among young patients in ≤ 20 years of age (85.9%) and patients in 21-30 years of age (85.4%). Periodontal causes were the common causes for tooth loss in patients older than 51years (45.7% in age group 51-60 years and 49% in age group≥61 years) (p<0.001) ( Table 2). The most frequently extracted teeth were mandibular first and second molars (446, 17.3%), followed by maxillary premolars (415, 16.1%), while mandibular canines were least frequently extracted (87, 3.4%) ( Table 3). Premolars, first and second molars of both jaws were the most frequently extracted teeth due to dental caries (Table 3).
Additionally, periodontal problems were the main cause for the loss of all incisors in upper and lower jaws (p< 0.001) ( Table 3).

DISCUSSION
The current study indicated that in Sana'a city-Yemen, dental caries and its complications were the leading cause for extraction (69%). Periodontal disease was the next most common reason of teeth extraction in Sana'a city in which it counted 28% of the causes (  In the current study, most patients whose teeth were extracted were 21-61 years old age groups, while extraction in younger patients (≤20 years) accounted for only 6% of all teeth loss. Even if, 45.7% and 49.7% of teeth extracted for periodontal disease were in patients over 50 years of age (Table 2); caries was still the major cause for extraction even in elderly patients, but to a less degree than in younger ones. This result was also reported by Thomas and Al-Maqdassy 21 . Nevertheless, current study, as previously mentioned, is not in agreement with studies where periodontal disease was the major cause of extraction in patients over 40 years old 2,5,13,16,17 . It may be that extractions caused by caries are occurring later in the disease process, possibly following initial efforts to treat the tooth. In other words, if more teeth are restored rather than extracted, then extractions would be postponed to an older age group. Consequently, the continuing high frequency of extraction for caries may indicate an increase in restorations prior to extraction rather than high incidence of caries in older people.
In this survey, the mean number of teeth extracted per patient was 1.82, higher than the 1.26 reported by Angelillo et al., 16 in Italy and the 1.3 found by Corbet and Davies 8 in Hong Kong, but lower than the 2.42 reported by Chrysanthakopoulos 2 in a study in Greece and the 2.3 found by Murray et al., 13 in Canada. These dissimilarities are at least in part attributed to different response rates, methodological differences plus the age of the population sample. Therefore, comparison of tooth extraction data between different countries is loaded with difficulty. When considering all the teeth patients had extracted until the day of examination, the mean number of tooth loss in patients over 60 was 8.4, the highest among all age groups. This finding substantiated the evidence for increasing prevalence of tooth loss with increasing age 16, 22 . In the current study, the most repeatedly extracted teeth were mandibular first and second molars (446, 17.3%), followed by maxillary premolars (415, 16.1%) (  14 in Scotland in which first and second premolars and teeth extracted for the same reasons were mainly first and second premolars. A likely reason for the high periodontal extraction in anterior teeth is that they are less susceptible to caries, preserved longer in the mouth, and then may be subjected to the risk of periodontal diseases 2,5,17, 19 . In the current study, males comprised 53.6% of patients and they had more teeth extracted (61.8%) than females (p < 0.001). According to Table 1, the rate of teeth extracted on the day of the survey was 2.1±0.1 in males higher than that of 1.5±0.05 in females. Multiple tooth loss was higher in men might be due to their lack of interest in spending more time on complicated restorative treatments rather than extractions as it has been confirmed by the finding of Da'ameh in Afghanistan 9 . There was proportionally more extraction for caries in women than in men in the current study (77.2% Versus 63.9% respectively) ( Table 2), this finding which is in disagreement with other studies 10,14,19,23 While caries in the current study were the main causes of tooth loss in females, males lost more teeth due to caries and periodontal disease. The second finding was similar to previous investigations 2,5,24,25 . What is more, male gender has been reported as a risk indicator for periodontal disease severity 2,5,26 . Finally; studies on tooth loss have generally discussed very few factors associated with missing teeth 10,27, 28 . In this study, several predictors for tooth loss due to caries were considered. Patients' age had a significant association with dental caries, while a study by Jovino-Silveria et al., in Brazil 10 showed age as the best predictor for tooth loss due to periodontal disease.

CONCLUSION
The outcomes of this survey revealed that dental caries and periodontal diseases were the most important causes for tooth extraction in Sana'a city, Yemen. The best predictors for tooth loss due to caries were age and gender, tooth type and having had a previous extraction. What's more, strategies for efficient ways of screening for periodontal disease, in particular for middle aged people, might be requisite. Future studies could be alert on changes in causes for dental extraction in a time trend to determine whether or not their relative importance has changed. Intervention studies could also be conducted with the available data and more surveys could be carried out to compare extraction patterns between public and private dental practices.