A malocclusion, or improper bite, describes a situation where the upper and lower teeth do not align correctly. This can stem from various factors, such as tooth positioning or jaw relation. Crooked teeth or a bad bite can lead to numerous issues, including speech impediments and/or difficulties with eating or maintaining proper dental hygiene. However, many individuals overlook how a misaligned bite or crowded teeth might affect the health of their other oral structures.
Prior research has established correlations between certain types of malocclusion and tooth loss. Specifically, two forms of improper bite—crossbite and open bite—can alter how chewing forces are distributed across other teeth in the mouth, potentially impacting the risk of losing teeth.
To investigate the association between anterior crossbite or open bite and tooth loss in adults aged 40 and over, a research team from Tohoku University conducted an observational study. The findings of this research were published in the journal Clinical Oral Investigations.
The research unit compiled data from 17,349 adults aged 40 and older participating in the Tohoku Medical Megabank Project Community-Based Cohort Study. They categorized these participants into four groups—normal occlusion, anterior open bite, anterior crossbite, and combined malocclusion—based on intraoral measurements. Subsequently, the team determined whether patients possessed 19 or fewer remaining teeth and experienced posterior tooth loss to evaluate the potential impact of anterior crossbite and open bite relative to normal occlusion.
“Utilizing one of the largest datasets derived from a general population, this study demonstrates that anterior crossbite is associated with a higher prevalence of tooth loss in adults. Retaining fewer than 20 teeth compromises chewing, nutrition, resilience, and expected healthy life span; therefore, identifying this risk is significant for public health,” states Kento Numazaki, a co-author from Tohoku University’s Graduate School of Dentistry. “Our results suggest that bite alignment, separate from decay and gum disease, may be linked to long-term tooth retention. This underscores the importance of routine dental check-ups and appropriate orthodontic assessments.”
Notably, the research revealed that adults with an anterior crossbite (but not an anterior open bite) exhibited an increased likelihood of tooth loss, showing a 1.14 times higher risk of molar loss after adjusting for age, sex, oral hygiene, caries, periodontal disease, and lifestyle factors. Further analysis segmented by age groups indicated that the differences in molar retention among occlusion groups were more pronounced in older age brackets.
Conversely, adults with an anterior open bite in the study showed a lower incidence of posterior tooth loss, suggesting that different forms of anterior malocclusion might exert distinct effects on tooth preservation.
This study employed one of the largest population-based cohorts available (the Community-Based Cohort Study and Three-Generation Cohort Study) and provides, for the first time, clear, population-level evidence linking anterior crossbite to tooth loss. Building upon these initial findings, the research team plans to further explore the effects of anterior crossbite on tooth loss and oral health outside of Japan.
“The next step involves conducting longitudinal studies to better grasp the timeline of tooth loss development in individuals with an anterior crossbite,” Numazaki remarked. “In the long term, we hope to investigate whether the patterns observed in Japan are mirrored in other populations, potentially through future international collaborations.”
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