The change of subjective and objective masticatory efficiency after implant prosthetic rehabilitation of unilateral missing molars

Abstract

The tooth loss may compromise the chewing function, ultimately leading to decreased quality of life. For this reason, restoration of a lost tooth has been considered an important field in dentistry. Recently, dental implant has become widely available, serving as an important option for replacement of a missing tooth. In this study, I explored a combination of subjective and objective evaluations of chewing efficiency as an alternative, more reliable quantitative means for the determination of the success of the dental implant for the lost molar tooth in one side. Specifically, I analyzed survey questionnaires on the Food Intake Ability (FIA) for 30 different food groups for subjective evaluation of chewing efficiencies, and then determined scores of the Key Food Intake Ability (KFIA) for chewing five hard foods. For objective evaluation of chewing efficiencies, the Mixing Ability Index was used. The participants were subject to dental examination before dental implant restoration. They were also asked to answer self-questionnaires and chew wax samples ten times before and after the completion of implant restoration treatment and I then collected the chewed wax samples for image analyses. The conclusions drawn in this study are the following:1. The dental implant treatment for the lost molar tooth in one side was found to improve both subjective and objective evaluation scores: the subjective evaluation scores, FIA and KFIA, increased by 7.4%** and 11.2%**, respectively, whereas the objective evaluation score did so by 8.6%. This improvement was statistically significant (**p<0.0001).2. I compared changes in chewing efficiency according to gender of patients. FIA, KFIA and MAI of male patients increased by 9.2%*, 13.6%* and 8.4%*, respectively. In comparison, FIA, KFIA and MAI increased by 7.3%*, 11.2%* and 8.4%*, respectively, for female patients. The statistical analyses indicate the lack of a significant difference in changes of chewing efficiency between male and female patients(*p<0.05, **p<0.0001).3. I compared FIA, KFIA and MAI scores according to age of patients. For patients at the age of 20-40, FIA and KFIA increased by 2.4%* and 6.2%**, respectively. The FIA and KFIA scores increased by 6.4%* and 10.0%**, respectively for patients at the age of 40-50. Similar statistical improvements were also found with patients over the age of 60 (i.e., 12.2%** and 16.2%* increases in FIA and KFIA, respectively). In contrast, a significant increase in the MAI score, which is an objective evaluation score of chewing efficiency, was found with only a patient group at the age of 40-50 (*p<0.005, **p<0.0001).4. I compared changes in chewing efficiency according to locations where tooth losses occurred. For other locations than upper left as principal sites of tooth losses, I found no significant improvement in subjective evaluation scores, FIA and KFIA, after the treatment. In comparison, FIA and KFIA significantly increased by 6.0%** and 9.2%**, respectively, after the treatment when the tooth loss occurred in upper left. An objective evaluation score, MAI, significantly increased by 7.4%* for upper right 13.4%* for lower right and 3.9%** for upper left. Changes in these scores after treatment for the loss of a tooth in lower left were found to be statistically insignificant (*p<0.005, **p<0.0001).5. I compared changes in chewing efficiency according to arch where the lost tooth belongs to. I found no significant differences in these scores for upper arch after treatment.6. I compared changes in chewing efficiency according to tested food groups and found that chewing efficiencies were improved by 10.6%* for food groups with high hardness, 5.6%* for those with medium hardness and 2.4%* for those with low hardness (*p<0.005).7. I compared changes in FIA, KFIA and MAI scores for patient groups having different chewing efficiencies judged based on baseline MAI scores prior to implantation. For patients with relatively low chewing efficiency prior to treatment, FIA, KFIA and MAI increased by 9.4%**, 12.4%** and 14.0%**, respectively. In contrast, relatively small improvements were observed with patients having relatively high chewing efficiency prior to treatment; FIA, KFIA and MAI scores increased by 5.6%**, 10.2%**, and 3.4%, respectively. Differences in chewing efficiency changes between these two patient groups were statistically significant (**p<0.0001).8. I explored correlations among chewing efficiencies evaluated subjectively and objectively through comparative analyses between FIA and MAI, and between KFIA and MAI. I found that FIA and KFIA (i.e., subjective evaluation scores) were inversely correlated with MAI (i.e., an objective evaluation score) (P<0.05).In short, results from my study described here demonstrate that changes in chewing efficiency after dental implant restoration treatment were directly reflected by statistical improvement in subjective evaluation scores, which may also be indicative of increased quality of life. In addition, I found that FIA measurements based on self-questionnaire survey and MAI measurements using wax cubes enabled facile, clinical assessment of chewing efficiency of patients, thus allowing for reliable evaluation of outcomes of treatment. Altogether, my study presented here suggests that reliable and accurate assessments of a patient''s condition based on the objective and subjective evaluation scores can provide an important guideline for future treatments and managements.