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World J Meta-Anal. May 26, 2013; 1(1): 16-26
Published online May 26, 2013. doi: 10.13105/wjma.v1.i1.16
Smoking increases risk of tooth loss: A meta-analysis of the literature
Fumihito Sato, Masashi Sawamura, Miki Ojima, Keiko Tanaka, Takashi Hanioka, Hideo Tanaka, Keitaro Matsuo
Fumihito Sato, Masashi Sawamura, Hideo Tanaka, Keitaro Matsuo, Division of Epidemiology and Prevention, Aichi Cancer Center Research Institute, Nagoya, Aichi 464-8618, Japan
Miki Ojima, Department of Preventive Dentistry, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
Keiko Tanaka, Department of Public Health, Faculty of Medicine, Fukuoka University, Fukuoka 814-0180, Japan
Takashi Hanioka, Department of Preventive and Public Health Dentistry, Fukuoka Dental College, Fukuoka 814-0193, Japan
Hideo Tanaka, Keitaro Matsuo, Department of Epidemiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi 464-8601, Japan
Author contributions: Matsuo K designed the study, directed its conduct and finalized the manuscript; Sato F did analyses and drafted the manuscript; Sato F and Sawamura M extracted relevant information of the study; Ojima M, Tanaka K, Hanioka T and Tanaka H helped supervise the field activities and performed the literature review.
Supported by Grant-in-Aid for the Third Term Comprehensive 10-year Strategy for Cancer Control, No. H20-3rd-002; and Grant-in-Aid for Cancer Research, Grant No. 13-21-13-1 from the Japanese Ministry of Health, Labor and Welfare
Correspondence to: Keitaro Matsuo, MD, PhD, MSc, Division of Epidemiology and Prevention, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Chikusa-ku, Nagoya, Aichi 464-8618, Japan.
Telephone: +81-52-7626111 Fax: +81-52-7635233
Received: February 6, 2013
Revised: April 28, 2013
Accepted: May 7, 2013
Published online: May 26, 2013

AIM: To quantitatively evaluate the impact of smoking on tooth loss.

METHODS: We performed a PubMed search to identify published articles that investigated the risk of tooth loss by smoking, from which RRs and their variance with characteristics of each study were extracted. The random-effects models were used to derive a pooled effect across studies. Potential sources of heterogeneity on the characteristics of the study and their influence on the pooled effect size were investigated using meta-regression models.

RESULTS: We identified 24 studies containing a total of 95973 participants for analysis. The pooled RR of ever-smokers compared with never- smokers was 1.73 (95%CI: 1.60-1.86, P < 0.001). In meta-regression analysis, only the mean age of participants alone was identified as a statistically significant source of heterogeneity. The effect of smoking on tooth loss was stronger when the mean age of study participants was higher, indicating possible enhancement of tooth loss due to aging by smoking. RR was significantly lower in former smokers (1.49, 95%CI: 1.32-1.69, P < 0.001) than in current smokers (2.10, 95%CI: 1.87-2.35, P < 0.001), indicating the substantial benefit of smoking cessation for reducing the risk of tooth loss.

CONCLUSION: Smoking is an independent risk factor for tooth loss regardless of many other confounders. Smoking cessation may attenuate this effect.

Keywords: Meta-analysis, Oral health, Relative risk, Smoking, Tooth loss

Core tip: Smoking is known to be a major cause of tooth loss. However, it has never been known how it quantitatively attributes to tooth loss or whether smoking cessation counteracts or not. This study clarified that ever smoking increases risk of tooth loss by 73%. In addition, smoking cessation substantially attenuates this effect.