Reasons for Permanent Tooth Extractions in Taiwan

Introduction

Tooth loss is mostly a final consequence of oral disease and usually leads to impairment of oral health–related quality of life. ¹ Thus, understanding the patterns and the causes for tooth loss is important for oral health policy and disease prevention.

Surveys to investigate the reasons for tooth extractions have been performed in many countries or areas,^2-19 and the methods and criteria adopted were similar among these surveys. Some studies found that dental caries was the main reason for tooth extraction ^* ; others found that periodontal disease was more important^6,9,18 or equally frequent.^4,5,7 Generally speaking, dental caries and periodontal disease caused the majority of tooth extractions in these studies. Most of the studies found that orthodontics was the principle reason for extraction among young people younger than 20 years, ^† dental caries was the main reason among 20-to 50-year-old people, and the importance of periodontal disease increased with age.^{2-12,14,16-19} Some studies showed that dental caries was the main reason for extraction in both genders, but there was more dental caries in females than males and more periodontal disease in males than in females.^12,17,18 Some investigations of various tooth types showed that third molars or molars were the most frequently extracted.^{2,4,5,7,3,17,18} A likelihood that molars were more likely to be extracted because of dental caries was also found, and extractions of anterior teeth were mainly because of periodontal disease.^2,4,5,7,17

There has been no nationwide study in Taiwan on reasons for extraction of permanent teeth. This study aimed to perform a secondary data analysis based on the National Health Insurance Research Database (NHIRD) to determine the reasons for permanent teeth extraction in Taiwan.

Methods

Results

Proportion of Extractions Among All Dental Visits

Table 1 shows the number of dental visits and the visits with extraction according to age-group. The proportion of extractions among all dental visits was 3.78%. Children younger than 14 years had the smallest proportion of extractions (0.32%), and people older than 65 years showed the largest proportion of extractions (6.40%). There were 4811 patients’ records of dental visits with a coding of extraction in this sample, 3.0% of patients returned for more than 1 visit (Table 2).

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Table 1.

Proportion of Extraction Among All Dental Visits.

Age–group (Years)	No. of Dental Visits	No. of Visits With Extraction	%
5-14	20 297	64	0.32
15-24	18 566	708	3.81
25-34	22 200	882	3.97
35-44	19 677	704	3.58
45-54	21 713	963	4.44
55-64	15 161	773	5.10
65+	13 490	864	6.40
Total	131 104	4958	3.78

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Table 2.

Extractions According to Age and Gender. ^a

Age-Group (Years)	Male, n (%)	Female, n (%)	Total, n (%)
5-14	33 (1.3)	28 (1.2)	61 (1.3)
15-24	294 (12.0)	380 (16.1)	674 (14.0)
25-34	392 (15.9)	462 (19.6)	854 (17.8)
35-44	360 (14.6)	323 (13.7)	683 (14.2)
45-54	550 (22.4)	394 (16.7)	944 (19.6)
55-64	377 (15.3)	379 (16.1)	756 (15.7)
65+	452 (18.4)	387 (16.4)	839 (17.4)
Total	2458 (100.0)	2353 (100.0)	4811 (100.0)
No. of teeth	2536	2422	4958

a

χ² = 47.68, degrees of freedom = 6, P < .000.

Reasons for Tooth Extraction

There were 2662 patients who underwent tooth extraction because of dental caries (55.3%), 1064 patients because of periodontal disease (22.1%), 583 patients because of impaction (12.1%), and 502 patients because of other reasons (10.4%). Table 3 shows the differences between males and females (χ² = 45.19, df = 3, P < .000). The percentage of dental caries was 53.3% in males and 57.5% in females, and more teeth were extracted because of periodontal disease in males (25.5%) than in females (18.6%).

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Table 3.

Reasons for Tooth Extraction According to Gender. ^a

Reason	Male, n (%)	Female, n (%)	Total, n (%)
Dental caries	1310 (53.3)	1352 (57.5)	2662 (55.3)
Periodontal disease	626 (25.5)	438 (18.6)	1064 (22.1)
Impaction	252 (10.3)	331 (14.1)	583 (12.1)
Others	270 (11.0)	232 (9.9)	502 (10.4)
Total	2458 (100.0)	2353 (100.0)	4811 (100.0)
No. of teeth	2536	2422	4958

a

χ² = 45.19, degrees of freedom = 3, P < .000.

Figure 1 shows the reasons for tooth extraction according to age (χ² = 915.73, df = 18, P < .000). Extraction because of dental caries was the main reason in all age-groups, and the percentage of dental caries ranged from 48.33% to 62.50%. However, the percentage of impaction was also important in those younger than 34 years, and extraction because of periodontal disease increased in those older than 35 years.

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Figure 1.

Reasons for tooth extraction according to age.

Regarding the tooth types, maxillary and mandibular third molar were removed most frequently (556 and 559, respectively, responsible for 33.64% of extractions), followed by upper and lower molars, and canine removal was the least frequent (Figure 2). A total of 41.5% of the mandibular third molars were removed because of impaction, 54.0% of mandibular central incisors because of periodontal disease, and all other tooth types were mainly extracted because of dental caries.

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Figure 2.

Distribution of the reasons for tooth extraction according to tooth type.

Discussion

This study used the NHIRD database as the research sample and performed a secondary data analysis to find the reasons for permanent tooth extractions in Taiwan. All previous studies in other countries used sampling methods and questionnaires to investigate the dentist/patient during several weeks or months, sometimes leading to a limitation of representativeness caused by a low response rate.^2,6,18 In the present study, the NHIRD database was sampled from all the records of dental visits in 2009, and hence without the potential problem of a low response rate.

On the contrary, the possible limitation of the present study was the definition of reasons for extractions that were slightly different from previous studies.^6,10,12 We compared the ICD-9-CM code with the criteria that have been used in the previous studies and defined 4 criteria as reasons for extraction: dental caries and its sequelae, periodontal disease, impaction, and other reasons. The other criteria such as orthodontic disease, prosthodontic disease, trauma, fracture, pericoronitis, and patient’s request, which have been used in other studies, were not included in our study. However, in our findings, dental caries, periodontal disease, and impaction were responsible for 89.3% of tooth extractions, and therefore this limitation could be considered not worth mentioning.

To our knowledge, this study represents the first available detailed information on the reasons for tooth extraction in Taiwan. Previous studies have already been published in different countries at different times. Variations such as the structure of population, prevalence of oral diseases, dental health service systems, and oral health attitude may influence the distribution of tooth extraction and necessitate caution when comparing the results of those studies.^5,17

Many of the results in this study were consistent with those previously reported. First, dental caries was the main reason for extraction and the prevalence was high in this study. Some studies showed a declination as age increased^{2,3,5,7,9,10,12,17}, but our findings showed a constantly high percentage of dental caries among all age-groups, indicating that the dental service and oral health system in Taiwan should give more importance to caries prevention. Unlike Korea or Japan and being a developed country in Asia, Taiwan has no systemic fluoridation such as water or salt fluoridation nor licensed dental nurses/hygienists/therapists to offer services to school students or people in the community. ²¹ In other countries in Asia such as Malaysia, the dental hygienist or dental therapist is ideally placed to play a key role in promoting oral health within the school setting. ²² In Thailand, there are community-based mobile dental clinics to serve schoolchildren. ²³ Poor oral health also influenced nutritional status among school children. ²⁴ There is an urgent need for policy makers in Taiwan to consider an effective oral health prevention/promotion system in the future.

Second, the percentage of periodontal disease increased in those older than 35 years, males reported more extractions because of periodontal disease, and males also reported more extractions than females older than 35 years. These findings support some epidemiological studies of periodontal disease concluding that men experience more periodontitis than women and that as age increases the prevalence of severe periodontitis increases. ²⁵ . Improving the preventive programs of periodontal disease among people older than 35 years in Taiwan must be an important task in the future.

Third, regarding tooth types, the present study also supported some previous findings that the third molar was the tooth most frequently extracted.^4,5,7,18 Some 56.8% of maxillary third molars were extracted because of dental caries, and 41.5% of mandibular third molars were extracted because of impaction. ⁵ It is noteworthy that the number of extractions of both maxillary and mandibular third molars was approximately double the number of first or second molars on the same side, significantly higher than all of the previous studies. In addition, most of the tooth types were extracted mainly because of dental caries, except for the third molar, which was extracted mainly because of impaction; and we also found that extractions because of impaction mostly centered on those younger than 34 years (87.12%). Those results indicated that there was obviously more tooth impaction of mandibular third molars among the Taiwanese population and suggest further research to investigate this issue.

Our research also found that people older than 65 years showed an increased proportion of dental visits with extraction. Among them, 57.82% of the extractions were because of dental caries and 26.93% because of periodontal disease, indicating that older people suffered from more tooth loss. The negative impact of poor oral conditions on daily life is particularly significant among edentulous people and sometimes leads to disability and mortality. ²⁶ In an aging population such as Taiwan, improving the oral health and quality of life of older adults is an important public health issue that must be addressed by policy makers. ²⁶

Conclusion

Both dental caries and periodontal disease were the main reasons for tooth extraction in Taiwan. Dental services and the oral health care delivery system in Taiwan should been shifted from a curative-oriented system to a preventive-oriented one in terms of prevention of caries and periodontal diseases, planning an effective oral health prevention/promotion system, and improving the oral health status and quality of life of older adults.