Evaluation of the Masticatory Part and the Habitual Chewing Side by Wax Cube and Bite Force Measuring System (Dental Prescale )

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1 J Jpn Prosthodont Soc 5:513-50, 008 ORIGINAL ARTICLE Evlution of the Mstictory Prt nd the Hitul Chewing Side y Wx Cue nd Bite Force Mesuring System (Dentl Prescle ) Mutsumi Tkhshi, DDS, Fumi Tkhshi, DDS, PhD, nd Osmi Morit, DDS, PhD Deprtment of Complete Denture, The Nippon Dentl University School of Life Dentistry t Niigt, Jpn Clinicl significnce The results of this study suggest tht the determintion of the mstictory prt y clenching the test food nd the evlution of the occlusl contct re, occlusl force, nd the center of the occlusl lnce y Dentl Prescle were useful to determine the hitul chewing side. Astrct Purpose: This study evluted the mstictory side s well s which side ws the hitul chewing side y the use of wx cues nd ite force mesuring system in norml dentte sujects (ND) nd complete denture werers (CD). Methods: Forty two ND sujects (9 mles, 13 femles; men ge,.8 ±. yers), nd 11 CD sujects ( mles, 7 femles; men ge, 7.8 ± 7.0 yers) prticipted in the study. The test food used in this study ws wx cues to determine the mstictory side. The difference in the occlusl contct re nd occlusl force etween the mstictory side nd the opposite side ws investigted using Dentl Prescle. ND ws clssified into groups: those whose greement on the mstictory prt ws high (ND-H) or low (ND-L). The distriution of the center of the occlusl lnce ws nlyzed y Dentl Prescle in ND-H, ND-L, nd CD. Results: The occlusl contct re nd occlusl force of the mstictory side ws greter thn the opposite one, nd the center of the occlusl lnce ws wide in ND-H. In ND-L nd CD, the occlusl contct re nd occlusl force did not differ etween the mstictory side nd the opposite one, nd the center of the occlusl lnce developed tendency to gther in the center. Conclusion: The results of this study suggested tht the evlution of the mstictory side nd the use of Dentl Prescle were helpful in determining the hitul chewing side. Key words: mstictory prt, hitul chewing side, Corresponding to: Dr Mutsumi Tkhshi Deprtment of Complete Denture, The Nippon Dentl University School of Life Dentistry t Niigt 1-8 Hmur-cho, Chuo-ku, Niigt , Jpn Tel: , Fx: E-mil: mutsumit@ngt.ndu.c.jp Received on Jnury 10, 008 /Accepted on My 1, 008 ite force mesuring system, wx cue Introduction Mstiction is series of the process of chewing food for swllowing nd digestion. There hve een mny methods to exmine the functions of ingestion, crunching, comminution, mixing, formtion of olus, nd swllowing. There re two types of methods to exmine the ility of mstiction. One of the methods to exmine the ility of mstiction is to msticte test food directly. The test food differs ccording to the type of ility of mstiction tht would e evluted. Regrding the ility of comminution, the test foods include penuts, rw rice etc. 1 Concerning the ility of mixing, the test foods include chewing gum, gummy jelly etc Also, the test food included temporry stopping to evlute the reltionship etween the occlusl contct re nd the min occluding re Other methods exmined the ility of mstiction from other fctors involved, such s muscle ctivity during mstiction, jw movement, food intke questionnire method, occlusl contct re, nd occlusl force. A pressure sensitive film, inspection of gnthic function, etc hve lso een used to exmine the ility of, 1 0 mstiction. It hs een reported tht the ility of mstiction is influenced y the introrl environment s well s other physiologicl ltertions such s the growth process. The hit to msticte t more useful side to crunch is developed through repeted dpttion. 1 There hve een vrious studies tht reported the relting fctors to the hitul chewing side, tht is, the hitul chewing side ws relted to the pth of mstictory movement, mstictory rhythm, occlusion, nd the dominnt hnd. In generl, the method to investigte the hitul chewing side is through medicl interview, however, there re some cses when the sujects 513

2 51 Tkhshi et l., J Jpn Prosthodont Soc 5 : , 008 cnnot recognize the chewing side. In these cses, there re some methods to evlute the chewing side ojectively nd esily in clinic, using cotton roll, 8,33,3 wx, 1 nd temporry stopping The prt tht these test foods were clenched ws defined s the mstictory prt, nd the side of the mstictory prt ws decided to e the hitul chewing side. However, the condition of the test food such s the si ze or the hrdness to decide the mstictory side in norml dentte sujects nd complete denture werers hs not een investigted. The im of this study ws to investigte the influence of the temperture conditions or the size of the wx cue s the test food to determine the mstictory prt. Additionlly, the reltions mong the mstictory prt, the hitul chewing side, nd occlusion ws investigted using ite force mesuring system. Mterils nd Methods 1. Experiment 1 1) Sujects The sujects of this study were 1 helthy dults ( mles, femles; men ge,.5 ±.5 yers), who hd norml occlusion. The study ws performed with the pprovl of the ethics committee of The Nippon Dentl University School of Life Dentistry t Niigt (#119), nd informed consent ws otined from ll of the sujects efore the strt of the study. ) Determining the mstictory prt nd method of nlysis In this study, we used wx cue (Inoue Attchment, Co., Tokyo, Jpn) s the test food to evlute the mstictory prt. The size of the test food ws 3.5-mm cue (out 0.0 g) nd 5.0-mm cue (out 0.10 g), nd the temperture conditions were 1,, nd 3 C. To investigte the mstictory prt, the wx cue ws positioned on the center of the tongue. Susequently, the sujects were instructed to clench the test food in 1 stroke where the sujects felt the esiest to clench the wx cue. The test ws repeted 3 times on ech size nd ech temperture condition. The clenched test food ws fitted into plster cst tht ws prepred efore the test (Fig. 1). The mstictory prt ws determined with plster cst with the conformed test food. c Fig. 1 : The test food positioned on the tongue, : Clenching the test food in 1 stroke, c: Clenched test food fitted into plster cst. Then, the numer of times tht ech suject clenched the test food t the sme cusp nd sme mrginl ridge ws counted, nd used for nlysis. The prt tht the suject clenched the test food most ws decided s the mstictory prt. The difference in the numer of greements of the mstictory prt ccording to the temperture conditions ws nlyzed y the Kruskl-Wllis test.. Experiment 1) Sujects The sujects were helthy dults (9 mles, 13 femles; men ge,.8 ±. yers), who hd norml occlusion (ND), nd 11 helthy dults ( mles, 7 femles; men ge, 7.8 ± 7.0 yers), nd who visited Niigt Hospitl nd wore complete dentures with no detriment (CD). The study ws performed with the pprovl of the ethics committee of The Nippon Dentl University School of Life Dentistry t Niigt (#119), nd informed consent ws otined from ll of the sujects efore the strt of the study. ) Determintion of the mstictory prt nd method of nlysis In experiment, we lso used wx cues s the test food. The size of the test cue ws 3.5 mm nd 5.0 mm in ND, nd 3.5 mm, 5.0 mm, nd 8.0 mm (out 0. g) in CD (Fig. ), t room temperture. The sujects clenched the test food in 1 stroke where the sujects felt the esiest to clench the cue. The test ws repeted 5 times in ND, nd 3 times in CD. The clenched test food ws fitted into plster cst tht ws previously prepred. The mstictory prt ws determined with plster cst with the conformed test food. Then, the numer of times tht ech suject clenched the test food

3 Evlution of the Mstictory Prt nd the Hitul Chewing Side mm Fig. Wx cues. The numer of greements of the mstictory prt (times) Fig. 3 The numer of greements of the mstictory prt (comprison y the temperture conditions of the test food). t the sme cusp nd sme mrginl ridge ws counted, nd used for nlysis. The prt tht the suject clenched the test food most ws decided s the mstictory prt. The difference in the numer of greements of the mstictory prt ccording to the size ws nlyzed y the Wilcoxon signedrnks test nd Kruskl-Wllis test. 3) Evlution of the hitul chewing side The hitul chewing side ws determined ccording to the sujectivity of ech suject tht ws found t the time of the medicl interview efore mstiction. The rte of greement etween the hitul chewing side nd the side contining the mstictory prt ws clculted. ) Mesurement of the occlusl contct re nd occlusl force The occlusl contct re nd occlusl force were mesured using pressure sensitive film (Dentl Prescle H-R type, Scimolex, Co., Ymnshi, Jpn), nd evluted using n Occluzr (Fuji Film, Co., Tokyo, Jpn). The sujects it down on the Dentl Prescle for 3 seconds with mximum occlusl force. The mesurement ws repeted 3 times, nd the verge of the occlusl contct re nd occlusl force ws used for nlysis. 5) Reltionship etween the mstictory prt, the occlusl contct re, nd occlusl force The ND sujects were divided into groups. The totl numer of clenching times of the wx cue in this study ws 10 times ( conditions y 5 times). One group consisted of sujects, who hd the sme mstictory prt more thn 8 times (ND-H). The other group consisted of 0 sujects, who hd the sme mstictory prt less thn 7 times (ND- L). The side tht contined the mstictory prt ws determined s the mstictory side, nd the other side ws determined s the opposite side. The totl of either side ws set t 100%, nd the percentge of the occlusl contct re nd occlusl force on the mstictory side nd the opposite side ws clculted. The difference of the occlusl contct re nd occlusl force etween the mstictory side nd the opposite side ws nlyzed y the t-test. In the sme wy, the difference of the occlusl contct re nd occlusl force etween the mstictory side nd opposite side ws nlyzed y the Wilcoxon signed-rnks test nd t-test in CD. ) The distriution of the center of the occlusl lnce The distriution of the center of the occlusl lnce ws nlyzed y the results of the Dentl Prescle test in ND-H, ND-L, nd CD. The differences of the distriution etween ND-H nd ND-L were nlyzed y the Mnn-Whitney s U test. Results 1. Experiment 1 The verge of the numer of greements of the mstictory prt t the temperture conditions of the wx cues of 1,, nd 3 C ws.33 ± 1.3 times,.5 ±.00 times, nd.33 ± 1.5 times, respectively. There ws no sttisticlly significnt difference mong the three temperture conditions of the wx cues (Fig. 3).. Experiment 1) Comprison y the size of the test food The verge of the numer of greements of the mstictory prt t the size of the wx cues of 3.5 mm nd 5.0 mm in ND ws 3.79 ± 1.00 times nd 3.91 ± 1.0 times, respectively. There ws no sttisticlly significnt difference etween the sizes

4 51 Tkhshi et l., J Jpn Prosthodont Soc 5 : , 008 The numer of greements of the mstictory prt (times) mm 5.0 mm mm 5.0 mm 8.0 mm Fig. : The numer of greements of the mstictory prt [comprison y the size of the test food in norml dentte sujects (ND)], : The numer of greements of the mstictory prt [comprison y the size of the test food in complete denture werers (CD)]. The percentge of the occlusl contct re (%) * *p < 0.05 c Mstictory side Opposite side Mstictory side Opposite side Mstictory side Opposite side Fig. 5 : The percentge of the occlusl contct re in norml dentte sujects who hd high greement regrding the mstictory prt (ND-H), : The percentge of the occlusl contct re in norml dentte sujects who hd low greement regrding the mstictory prt (ND-L), c: The percentge of the occlusl contct re in complete denture werers (CD). of the test food (Fig. -). Also the verge of the numer of greements of the mstictory prt t the size of the wx cues of 3.5 mm, 5.0 mm, nd 8.0 mm in CD ws 1. ± 1.9 times, 1.8 ± 1.5 times, nd 1.91 ± 1.0 times, respectively. There ws no sttisticlly significnt difference mong the three sizes of the wx cues (Fig. -). ) The rte of greement of the hitul chewing side nd the mstictory side The percentge of greement upon the hitul chewing side nd the mstictory side ws 95.% (/ sujects) in ND nd 90.9% (10/11 sujects) in CD. 3) Comprison of the occlusl contct re nd occlusl force on the mstictory side nd opposite side (1) The occlusl contct re The results of the evlution y the Dentl Prescle test ws tht the percentge of the occlusl contct re of the mstictory side ws greter thn the opposite one in ND-H (p < 0.05), the verge of the percentge of the occlusl contct re of the mstictory side nd the opposite one ws. ± 8.5% nd.8 ± 8.%, respectively (Fig. 5-). The verge of the percentge of the occlusl contct re of the mstictory side nd the opposite one in ND-L ws 51.0 ± 7.0% nd 9.0 ± 7.0%, respectively. There ws no significnt difference etween the mstictory side nd the opposite one (Fig. 5-). Also, the verge of the percentge of the occlusl contct re of the mstictory side nd the opposite one in CD ws. ± 9.% nd 9. ± 9.7%, respectively. There ws no significnt difference etween the mstictory side nd the opposite one (Fig. 5-c). () The occlusl force The results of the evlution y Dentl Prescle ws tht the percentge of the occlusl force of the mstictory side ws greter thn the opposite one in ND-H (p < 0.05), the verge of the percent

5 Evlution of the Mstictory Prt nd the Hitul Chewing Side 517 The percentge of the occlusl force (%) Mstictory side * *p < 0.05 Opposite side Mstictory side Opposite side Mstictory side Opposite side Fig. : The percentge of the occlusl force in norml dentte sujects who hd high greement regrding the mstictory prt (ND-H), : The percentge of the occlusl force in norml dentte sujects who hd low greement regrding the mstictory prt (ND-L), c: The percentge of the occlusl force in complete denture werers (CD). c Forwrd Opposite side Mstictory side Forwrd Opposite side Mstictory side Opposite side Mstictory side Fig. 7 : The distriution of the center of the occlusl lnce in norml dentte sujects who hd high greement regrding the mstictory prt (ND-H), : The distriution of the center of the occlusl lnce in norml dentte sujects who hd low greement regrding the mstictory prt (ND-L), c: The distriution of the center of the occlusl lnce in complete denture werers (CD). c Forwrd ge of the occlusl force of the mstictory side nd the opposite one ws 5.0 ± 7.% nd.0 ± 7.%, respectively (Fig. -). The verge of the percentge of the occlusl force of the mstictory side nd the opposite one in ND-L ws.7 ±.8% nd 9.3 ±.8%, respectively. There ws no significnt difference etween the mstictory side nd the opposite one (Fig. -). Also, the verge of the percentge of the occlusl force of the mstictory side nd the opposite one in CD ws 51. ± 9.0% nd 8.8 ± 9.0%, respectively. There ws no significnt difference etween the mstictory side nd the opposite one (Fig. -c). ) The distriution of the center of the occlusl lnce The distriution of the center of the occlusl lnce in ND-H, ND-L, nd CD is shown in Fig. 7. The distriution of the center of the occlusl lnce in ND-H ws wider thn ND-L in ilterl distriution (p < 0.05). Discussion 1. The test food In the present study, we selected wx cues s the test food to evlute the mstictory prt. Kto et l. 11,1 nd Tokud et l. 13 used temporry stopping for norml dentte sujects. However, the temporry stopping ws too difficult to clench for complete denture werers. Ichikw et l. 37 used clernce wx (Syofu Inc., Kyoto, Jpn) for complete denture werers. The wx cue used in this study ws mde y mixing prffin wx with Hi- Mic-10 wx.,3,38 1 It cn e used widely for norml dentte sujects nd complete denture werers, ecuse it does not stick to the teeth or dentures. The wx cue cn e fricted in ny size nd the temperture conditions cn vry; therefore, the complete denture werers proly clenched the wx cue esily. Therefore it cn evlute ojective dt in short time, nd the sujects were not urdened with this evlution.

6 518 Tkhshi et l., J Jpn Prosthodont Soc 5 : , 008 For these resons, the wx cue ws selected s the test food in this study. In experiment 1, the proper temperture conditions of the test food to determine the mstictory prt ws investigted in norml dentte sujects. According to the results of questions to the sujects, the sujects could clench the test food the esiest t the temperture condition of C. There ws no reltionship etween the sujectivity of esily clenching nd the determintion of the mstictory prt. This study suggested tht the hrdness of the test food did not influence the determintion of the mstictory prt, ecuse there ws no difference in the numer of greements of the mstictory prt mong the temperture conditions. Therefore, it ws suggested tht controlling the temperture conditions of the test food ws not necessry.. The mstictory prt In experiment, the test ws repeted 5 times in ND, nd 3 times in CD, ecuse the importnce of one tril ws lrge t the cse of the comprison y sizes of the test food on 3 trils in ND. The sujects clenched the test food with the size of 3.5 mm more esily thn 5.0 mm in ND, ut there ws no reltionship etween the sujectivity of esily clenching nd the determintion of the mstictory prt. On the other hnd, the sujects felt tht it ws most difficult to clench the test food with the size of 3.5 mm in CD, nd some of them clenched the test food using the nterior teeth or the test food fell from the occlusl surfce. Therefore, it ws suggested tht the test food with the size of 3.5 mm ws not suitle to determine the mstictory prt in CD. According to the results of questions to the sujects, the sujects clenched the test food esily with the size of 5.0-mm nd 8.0-mm cues in CD, ut there ws no reltionship etween the sujectivity of esily clenching nd determintion of the mstictory prt. These results suggested tht the size of the test food did not influence the determintion of the mstictory prt. 3. Reltionship etween the sujectivity of the hitul chewing side nd the mstictory side Regrding the frequency of the sujectivity of the hitul chewing side, Ued et l. reported tht out hlf of the sujects were conscious of their hitul chewing side, nd Kurchi et l. 31 reported tht out three-qurters of the sujects were conscious of their hitul chewing side, nd this ws discovered t the medicl interview. Ogimito et l. 33 compred the reliility of the sujectivity of the hitul chewing side efore nd fter mstiction, nd the results suggested tht the medicl interview fter mstiction ws more relile nd more detectle thn the one efore. The hitul chewing side in this study ws found t the time of the medicl interview efore mstiction, nd the rte of greement with the mstictory side ws 95.% in ND nd 90.9% in CD. These findings suggested tht clenching the test food ws useful nd esy method to determine the hitul chewing side.. The occlusl contct re nd occlusl force Concerning the evlution of Dentl Prescle, it ws reported tht the occlusl contct re nd occlusl force t the hitul chewing side ws greter thn the opposite one. 3 In the present study, the numer of greements on the mstictory prt ws evluted, nd the ND were divided into ND-H nd ND-L groups. CD ws lso exmined. The occlusl contct re nd occlusl force t the mstictory side ws greter thn the opposite one in ND-H, however, there were no differences in ND-L nd CD. These results suggested tht the sujects who did not hve regulr mstictory prt did not hve right or left difference regrding the occlusl contct re nd occlusl force. And on the sujects who hd regulr mstictory prt, the occlusl contct re nd occlusl force were greter thn the opposite one. 5. The center of the occlusl lnce The center of the occlusl lnce ws clculted from the distriution of the occlusl contct re nd occlusl force. In ND-H, the center of the occlusl lnce tended to e towrd the mstictory side. This finding ws sed on the ide tht the chewing side would incline to the right or left, nd the mstictory prt could e esily decided in ND-H. On the other hnd, the center of the occlusl lnce converged towrd the center in ND- L nd CD. This finding indicted tht it is difficult to determine whether the chewing side is on the right or left, nd the mstictory prt won t develop tendency either wy. Nmely, these results suggested tht there ws reltionship mong the numer of greements on the mstictory prt, the center of the occlusl lnce, the occlusl contct re, nd occlusl force.

7 Evlution of the Mstictory Prt nd the Hitul Chewing Side 519 Conclusion This study investigted the mstictory prt nd the hitul chewing side using wx cue nd Dentl Prescle in norml dentte sujects nd complete denture werers, nd the following conclusions were otined: 1. The temperture conditions of the test food did not influence the determintion of the mstictory prt.. The size of the test food did not influence the determintion of the mstictory prt. 3. The percentge of greement concerning the hitul chewing side nd the mstictory prt ws 95.% in norml dentte sujects nd 90.9% in complete denture werers.. The occlusl contct re nd occlusl force of the mstictory side ws greter thn the opposite one in norml dentte sujects who hd high greement regrding the mstictory prt (p < 0.05). The occlusl contct re nd occlusl force did not differ etween the mstictory side nd the opposite one in norml dentte sujects who hd low greement concerning the mstictory prt nd complete denture werers. 5. The center of the occlusl lnce vried widely in norml dentte sujects who hd high greement regrding the mstictory prt, nd it converged towrd the center in norml dentte sujects who hd low greement concerning the mstictory prt nd complete denture werers. In this study, it ws suggested tht the center of the occlusl lnce ws relevnt to the hitul chewing side nd the mstictory prt. The determintion of the mstictory prt y clenching the test food nd the evlution of the occlusl contct re, occlusl force, nd the center of the occlusl lnce y Dentl Prescle were useful to determine the hitul chewing side. References 1. Mnly RS, Brley LC. Mstictory performnce nd efficiency. J Dent Res 19; 9: 8.. Hiri T, Ishijim T, Koshino H et l. Age-relted chnge of mstictory function in complete denture werers. Int J Prosthodont 199; 7:. 3. Ishijim T, Hiri T, Koshino H et l. The reltionship etween slivry secretion rte nd mstictory efficiency. J Orl Rehil 003; 31: 3.. Ishiwr T. Mstictory efficiency nd prticle size distriution of msticted rw rice. J Stomtol Soc Jpn 1995; : 07. (in Jpnese) 5. Tnk A, Shig H, Koyshi Y. Quntittive evlution of mndiulr movement nd mstictory musculr ctivities y nlyzing the mount of glucose dischrge during gummy jelly chewing. J Jpn Prosthodont Soc 199; 38: Liederg B, Öwll B. Orl olus kneding nd shping mesured with chewing gum. Dysphgi 1995; 10: Hykw I, Wtne I, Hirno S et l. A simple method for evluting mstictory performnce using color chngele chewing gum. Int J Prosthodont 1998; 11: Prinz JF. Quntittive evlution of the effect of olus size nd numer of chewing strokes on the introrl mixing of two-color chewing gum. J Orl Rehil 1999; : Ikee K. Reproduciility nd ccurcy in mesuring mstictory performnce using test gummy jelly. Prosthodont Res Prct 005; : Koyshi Y, Shig H, Arkw I et l. The effectiveness of mesuring glucose extrction for estimting mstictory performnce. Prosthodont Res Prct 00; 5: Kto H, Furuki Y, Hsegw S. Oservtions on the min occluding re in mstiction. J Jpn Soc Stomtognth Funct 199; : (in Jpnese) 1. Kto H, Hsegw S, Yoshid K et l. Oservtions on the min occluding re in mstiction-continution The reltion with food impction. J Jpn Soc Stomtognth Funct 1999; 5: (in Jpnese) 13. Tokud A, Kto H, Miur H et l. The min occluding re in considertion of the occlusl reltion. J Jpn Soc Stomtognth Funct 00; 13: (in Jpnese) 1. Peyron MA, Mioche L, Renon P et l. Mstictory jw movement recordings A new method to investigte food texture. Food Qul Pref 199; 7: Peyron MA, Lssuzy C, Wod A. Effects of incresed hrdness on jw movement nd muscle ctivity during chewing of visco-elstic model foods. Exp Brin Res 00; 1: Morit M, Kuroe K, Diniz P et l. Reltionship etween the mstictory jw movement nd the occlusl contct re, the mximum occlusl force nd the lveolr one minerl contct t the mndiulr first molr region Study with the unilterl mstiction. Orthod Wves 00; 1:. (in Jpnese) 17. Miyzki J, Shig H, Koyshi Y. The reliility of evluting mstictory function y mstictory movement nlysis. Dent Jpn 003; 39: Nkshim M, Okimoto K, Mtsuo K et l. A study of mstictory ility in the elderly -A comprison etween dentulous sujects nd denture werers-.

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