#8 Longitudinal Study of Magnetic Attachments ーInvestigation of Probing Depth on Abutment teeth ー

R.Ito , K.Hoshiai , Y.Tanaka , T.Ishigami^＊, K.Ishibasi^＊＊ , E.Bando^＊＊＊ , H.Sasaki^＊＊＊＊
	Department of Removable Prosthodontics , School of Dentistry, Aichi-Gakuin University Department of Partial Denture Prosthodontics , Nihon University School of Dentistry^＊ , Department of Fixed Prosthodontics , School of Dentistry ,Iwate Medical University^＊＊ , 　 Department of Fixed Prosthodontics , Institute of Health Biosciences Graduate School The University of Tokushima^＊＊＊ , Sasaki Dental clinic^＊＊＊＊

Introduction

At present, magnetic attachments have been applied clinically in various cases. It’s useful to carry out postoperative investigations and to confirm results, as it shows the criterion of the clinical application1). Thus , magnetic attachments can be used safely. Prospective investigation of magnetic attachments has been carried out since 2003 at the Japanese Society of Magnetic Applications in Dentistry. （JSMAD）

Methods

The transition of probing depth (PD) of the abutment teeth was measured and the changes of the conditions of periodontal tissue were evaluated. Immediately after cementation, oral conditions were recorded by use of an original questionnaire, and PD were measured by the 6 points method. After 5 years , the patients were recalled and PD was measured. This time, 5 departments of the JSMAD showed in the title participated in this study. At the beginning of the study, 44 patients were participate in the study. However, 12 patients were censored so 29 patients were able to participate in the study.

Results

Table. 1 details the cases which were able to participate in the study. The dentures were 6 maxillary plates and 19 mandibular plates . The abutment teeth were 12 incisor teeth, 24 cuspid teeth, 17 premolar teeth and 9 molar teeth. The materials of the dentures were 21 resin plates and 14 metal plates. The results were statistically analyzed using Willcoxon signed rank test. The significance level was set at 0.05 ( SPSS Ver. 17.0 ; SPSS Japan Inc. ).



Fig.1 shows the cases by removable partial denture classifications. The Figure shows that missing distal extension (Kennedy’s classifications class1 and 2) were about 90%, and that lost occlusal support cases (Eichner’s Classifications class B-4 and C ) were about 70%.


Fig 2 shows the transition with Median value and quartile deviation of PD of surviving teeth for 5 years. For this study, only max point of 6 points counted as PD of the abutment teeth. A significant difference was found between initial PD and PD after 5 years . The right side of the graph shows PD of the extracted teeth which were measured after cementation.


Fig 3 shows the transition of PD of maxillary and mandibular plates. Significant differences were found in maxillary plates.


Fig 4 shows the transition of PD of gender. Significant differences were found for females. The PD of females significantly deteriorated.


Fig 5 shows the transitions of PD by abutment teeth. No significant differences were found .


Fig 6 shows the transitions of PD of materials of plates Significant differences were found for resin plates.

Discussion

The null hypothesis that PD (Probing depth) of the abutment teeth would not deteriorate was rejected, as significant difference was found between initial PD and PD after 5 years . We reported a retrospective cohort study that the survival rate of resin plates was worse than that of metal plates2). The result that a significant difference was found in resin plates, corresponds with this study. The major connector of metal plates is solid, so flexure of metal plates are less than that of resin plates. Therefore the abutment teeth of metal plate were not moved. So, PD of metal plates was less than that of resin plates. With respects to the significant differences found in maxillary plates and for women, further study is required.

Conclusion

The results of prospective observation of magnetic attachments from the point of the transition of PD for 5 years are below.
・ PD of the abutment teeth were increased over 5 year period.
・ Significant differences were found between initial PD and PD of 5 years later for maxillary plates , resin plates, and for females.

References

1. K.Hoshiai, Y.Tanaka, M.Kawakita, W.Fujinami, K.Wakayama, Y.Imaizumi, T.Matumoto and M.Sakane; Longitudinal Study on Metal Plate Denture with Magnetic Attachments-Part 4, J J Mag Dent, 13(2), 26-29, 2004.
2. R.Ito, K.Hoshiai, N.Hasegawa, N.Muraji, T.Kawaguchi, K.Noda, K.Watanabe and Y. Tanaka; Longitudinal Study on Metal Plate Denture with Magnetic Attachments, J J Mag Dent, 18(2), 8-14, 2009.

Discussion Board