Tooth loss in patients undergoing long-term maintenance at a private dental clinic 1 in Japan: A retrospective study 2

20 Background: Tooth loss is generally considered the final outcome of oral disease. This 21 retrospective study was performed to identify risk factors for tooth loss in patients 22 undergoing long-term maintenance therapy. 23 Methods: We surveyed 1145 adult patients who underwent maintenance therapy for ≥5 24 years after they had undergone active treatment from January 2015 to December 2016 25 and established a baseline status. The study variables were patient compliance, sex, 26 number of teeth lost, cause of tooth loss, age at start of maintenance, number of remaining 27 teeth at start of maintenance, duration of maintenance, smoking status, use of salivary 28 secretion inhibitors, and diabetes mellitus. Additionally, 57 patients who did not undergo 29 maintenance therapy were surveyed to examine and compare the effects of maintenance 30 therapy. Statistical analyses were performed to assess the correlation of each variable with 31 tooth loss. 32 Results: The average number of teeth lost under maintenance therapy was 0.07/year. 33 Significantly fewer teeth were lost in the maintenance than non-maintenance group. Most 34 of the teeth lost were non-vital teeth, and the most common cause of tooth loss was tooth 35 fracture. Patient age, number of remaining teeth at start of maintenance, use of salivary 36 secretion inhibitors, and diabetes mellitus were related to tooth loss. 37 Conclusions: To the best of our knowledge, this is first large-scale study of tooth loss in 38 patients undergoing long-term maintenance therapy within a general dental clinic. Our 39 findings demonstrate that starting maintenance therapy when patients are younger and 40 possess more teeth may prevent future tooth loss. 41


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Background 46 Dental studies have shown that dental caries and periodontal disease are the most 47 common pathological conditions affecting the oral cavity. More specifically, several 48 studies have shown that the most common cause of tooth loss (TL) is dental caries, 49 followed by periodontal disease. 1-5 Thus, control of dental caries and periodontal disease 50 is critical for prevention of TL.

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A major etiological factor underlying the pathogenesis of dental caries and periodontal 52 disease is the formation of a biofilm on the tooth surface. Removal of dental plaque is 53 critical in preventing dental caries and periodontal disease. Axelsson and Lindhe 6 and 54 Axelsson et al. 7 found that regular maintenance therapy reduced the incidence of dental  Therefore, to verify these prior findings derived from specific or small patient 69 5 populations, we conducted a retrospective analysis in a private general clinic at a primary 70 medical institution in Japan. More than 11,000 local residents utilize this clinic for their 71 family dentistry needs. We investigated the effectiveness of long-term maintenance on TL 72 as well as the various causes of TL (both with and without maintenance) to identify 73 optimal prevention strategies. Using this approach, we aimed to determine the most 74 convenient and effective methods for preventing TL in this population and thus improve 75 the clinical dental care of our patients.

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The present survey was conducted at a private dental clinic (Kawahara Dental Clinic) in 79 Mima, Tokushima, Japan. The population of Mima is approximately 30,000. This dental 80 clinic was selected because it is a general dental clinic and not a university hospital or 81 specialist clinic. Dental examinations were performed and associated records were 82 obtained by one of the authors (H.K., a general dentist) with the assistance of several 83 trained dental hygienists. All patients were required to meet the following five criteria established by Miyamoto et 96 al. 37 before the end of active treatment and entry into periodontal maintenance therapy: 97 1) <10% of sites with bleeding on probing, 2) an overall plaque score of <15%, 3) <10% 98 of sites with a probing depth of ≥4 mm, 4) no defective restorations, and 5) no active 99 dental caries. The maintenance period and the contents of maintenance were determined 100 with reference to the study by Miyamoto et al. 37 Evaluation of the maintenance interval 101 was conducted by a dental hygienist at 3 or 6 months and was based on the patient's   The cause of any TL was determined by the dentist (H.K.) during extraction. These 113 causes included dental caries, periodontal disease, root fracture, and others (e.g., an apical 114 lesion, trauma, tooth transposition, or tooth extraction for convenience). The extraction 115 of wisdom and deciduous teeth was excluded from the analysis. Tooth extraction for 116 which the patient's consent was not obtained before the BL was also excluded. Patient       The results of the analysis according to number of teeth lost are shown in    Their study also suggested a beneficial effect of maintenance on TL. In addition, their 265 study was conducted in a general dental clinic, demonstrating the broad effectiveness of 266 maintenance for TL.

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In the present study, root fractures were the most common cause of TL, followed by 268 caries and periodontal disease. These results are similar to those from a study in a general 269 dental clinic by Axelsson et al. 7 In another study showing that the primary cause of TL 270 was periodontal disease, data samples were obtained from three periodontists' private 271 offices. 30 In another study, patient data were obtained after treatment by a periodontist. 31

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In these studies, most patients were considered to be at high risk of periodontal disease.

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In the present study, the status of periodontal disease at BL was as follows: healthy or