Journal of Dental Research                            http://jdr.sagepub.com/        Biting and Chewing in Overdentures, F...
-I.F.A. Fontiin-Tekampl4*, A.P. Slagterl 4,A. Van Der BiMO, M.A. Van T Hof3,                                          Biti...
1520                                                                       Fontijn-Tekamp et al.                          ...
J Dent Res 79(7) 2000                                  Comparison of Objective Oral Function                              ...
1522                                                                        Fontijn-Tekamp et al.                         ...
J Dent Res 79(7) 2000                                  Comparison of Objective Oral Function                              ...
1 52,4                                                                   Fontiin-Tekamp et a/.                            ...
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Biting and chewing in overdentures, full dentures, and natural dentitions

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Biting and chewing in overdentures, full dentures, and natural dentitions

  1. 1. Journal of Dental Research http://jdr.sagepub.com/ Biting and Chewing in Overdentures, Full Dentures, and Natural DentitionsF.A. Fontijn-Tekamp, A.P. Slagter, A. Van Der Bilt, M.A. Van T Hof, D.J. Witter, W. Kalk and J.A. Jansen J DENT RES 2000 79: 1519 DOI: 10.1177/00220345000790071501 The online version of this article can be found at: http://jdr.sagepub.com/content/79/7/1519 Published by: http://www.sagepublications.com On behalf of: International and American Associations for Dental Research Additional services and information for Journal of Dental Research can be found at: Email Alerts: http://jdr.sagepub.com/cgi/alerts Subscriptions: http://jdr.sagepub.com/subscriptions Reprints: http://www.sagepub.com/journalsReprints.nav Permissions: http://www.sagepub.com/journalsPermissions.nav Citations: http://jdr.sagepub.com/content/79/7/1519.refs.html Downloaded from jdr.sagepub.com by guest on March 1, 2011 For personal use only. No other uses without permission. Copyright © 2000 SAGE Publications. All rights reserved.
  2. 2. -I.F.A. Fontiin-Tekampl4*, A.P. Slagterl 4,A. Van Der BiMO, M.A. Van T Hof3, Biting and Chewing inD.J. Witter1, W. Kalk1 5, and J.A. Jansen2Unit of Oral Function and Prosthetic Dentistry, Departments of Overdentures, Full Dentures,Occlusal Reconstruction and Oral Function and 2Biomaterials,3Department of Medical Statistics, University ofNijmegen;4Department of Oral-Maxillofacial Surgery, Prosthodontics and and Natural DentitionsSpecial Dental Care, University Medical Center Utrecht,P.O. Box 80.037, 3508 TA Utrecht; and 5Department of OralFunction, University of Groningen, The Netherlands;*corresponding author, F.A.Fontijn(med.uu.nlJ Dent Res 79(7): 1519-1524, 2000ABSTRACT INTRODUCTIONIt has been suggested that the provision of dental The provision of dental implants to subjects with severely resorbedimplants can improve the oral function of subjects I mandibles significantly improves subjective oral function. Subjects withwith severely resorbed mandibles, possibly dental implants have fewer complaints, feel more satisfied, and rate theirrestoring function to the level experienced by chewing comfort and ability more highly (Lindquist and Carlsson, 1985;satisfied wearers of conventional complete Boerrigter et al., 1995; Geertman et al., 1996a,b; Kapur et al., 1998; Meijerdentures. Nevertheless, a quantitative comparison et al., 1999). Also, objective oral function improves after treatment with oralhas never been made and can be drawn from the implants, as can be seen from an increased bite force and masticatoryliterature only with difficulty, since studies differ function (Lindquist and Carlsson, 1985; Haraldson et al., 1988; Geertman etgreatly in methodology. To make such a al., 1994; Fontijn-Tekamp et al., 1998; Pera et al., 1998). According tocomparison, we measured bite force and chewing Lindquist and Carlsson (1982, 1985) and Haraldson et al. (1988), theefficiency by using identical methods in subjects improvement in objective function seems to depend on the type of implantwith overdentures, complete full dentures, and support for the mandibular denture. However, more recent studies revealednatural dentitions. Our results indicated that bite no such differences, either for chewing efficiency (Geertman et al., 1994) orforces achieved with overdentures on dental for unilateral and bilateral bite force (Fontijn-Tekamp et al., 1998).implants were between those achieved with It has been suggested that the provision of dental implants to subjects withartificial and natural dentitions. Chewing severely resorbed mandibles can restore objective oral function to the levelefficiency was significantly greater than that of experienced by satisfied wearers of conventional full dentures (Geertman etsubjects with full dentures (low mandible), but al., 1994). We must emphasize, however, that a comparative quantification ofwas still lower than that of subjects with full such improvement has never been made and cannot be drawn from thedentures (high mandible) and overdentures on literature, since available studies are difficult to compare, because of variationsbare roots. Differences in the height of the in the study design (the age of the population studied, the male-to-femalemandible revealed significant differences in ratio), outcome measures used, clinical setting in which the implant therapychewing efficiency between the two full-denture was provided, oral status of subjects included, and the type of implant therapygroups. Furthermore, subjects with a shortened provided (Locker, 1998). To obtain outcome measures, chewing efficiencydental arch exerted bite forces similar to those of tests and bite force measurements are performed amongst other tests. In thesubjects with a complete-natural dentition, but chewing efficiency tests, the types of test foods (natural foods, e.g., peanuts,their chewing efficiency was limited due to the carrots, almonds, gummy bears, and gelatin, or artificial test foods such asreduced occlusal area. For all groups combined, a Optosil, Optocal, and Cutter Sil) vary, as do the amounts of test foods, thesignificant correlation was found between sieving method, and the methods for analysis of the results can be used (vanmaximum bite force and chewing efficiency. der Bilt et al., 1993a). For evaluating the bite force, several equipment designsNearly half of the variation in chewing efficiency can be used (see Fontijn-Tekamp et al., 1998).was explained by bite force alone. In view of the above, the aim of the current study was to compare, quantitatively, the oral function of three groups of subjects with (a)KEY WORDS: chewing efficiency, bite force, overdentures, (b) full dentures, and (c) natural dentitions. Furthermore, wedental implants, (over)dentures, dentate. investigated correlations between maximum bite forces and chewing efficiency. In addition, we inclusded a group of younger subjects with a complete-natural dentition to provide information about more optimal oral function. MATERIALS & METHODS Subjects Tests were performed in seven groups of female subjects: two overdentureReceived July 12, 1999; Last revision January 31, 2000; groups, two full-denture groups, and three groups with natural dentitions. AllAccepted February 8, 2000 edentulous subjects had a full maxillary denture and, in the mandible, either: (1) Downloaded from jdr.sagepub.com by guest on March 1, 2011 For personal use only. No other uses without permission. 1519 Copyright © 2000 SAGE Publications. All rights reserved.
  3. 3. 1520 Fontijn-Tekamp et al. J Dent Res 79(7) 2000Table. Characteristics of the treatment groups, numbers of chewing strokes needed to halve the food (N/2), and The ethics committee of thecorrelation coefficients (r) between maximum bite force and N1/2 Nijmegen University had given its approval for this Age Bone Number Occlusal study.Treatment Groups n (yrs) Heightab of Teeth Unitsa N1,2 r Unilateral Bite ForceOverdentures: Unilateral bite forces were Implants 40 58.3 (8.8) 13.6 (1.6) 56 0.17 measured with a miniature Root-overlay 19 59.7 (8.5) 28.7 (3.6) 32 -0.59** strain-gauge bite-forceFull dentures: transducer with a vertical Low bone height 13 59.0 (6.6) 14.1 (1.1) 106d -0.28 height of 3.8 mm. Calibration Higher bone height 24 59.0 (8.7) and validation procedures 23.4 (5.2) 36 -0.34* were as described in aNatural dentitions: previous study by Fontijn- Shortened arch 14 58.1 (11.0) 21.1 (1.3) 3.6 (0.5) 32 -0.80** Tekamp et al. (1998). For the Completearch 14 54.1 (6.4) 28.2(1.1) 12.1 (1.2) 16 -0.67** dentate groups, we protected Complete arch 19 22.7 (1.5) 28.4 (2.8) 12.8 (2.2) 14 -0.52** teeth by covering both sides of the transducer with 1.5-Total group -0.62** mm-thick rubber plates (DrufosoftR, Oudheusden Data are presented as Mean (SD). Dental BV, Zeist, The Mandibular symphyseal bone height in mm as measured on a standardized lateral encephalogram Netherlands) attached by (Satow et al., 1998). double-sided adhesive tape.CNumbers of occluding pairs of teeth, with 1 premolar contact = 1 occlusal unit and 1 molar contact = 2 occlusal units Subjects were instructed (Witfer eta!., 1988). to bite on two force levels:dFor four subjects, N, was set at 200 strokes, since their calculated values were larger than 200 strokes. (1) one they thought to beeCorrelation coefficients were significant at * p < 0.005 and ** p < 0.001. equivalent to the force they use when chewing; and (2) their maximum force.an implant-retained overdenture (implant group) on either atransmandibular implant (n = 18) according to Bosker (1986) or on 150two permucosal, cylindrical IMZ implants (n = 22; Kirsch and -+implantsMentag, 1986); (2) an overdenture on at least 2 functional, natural *0* full dentures (low) a full dentures (high)bare roots in the mandible (root-overlay group); (3) a 125 root-overlayconventional, full denture with a mandibular symphyseal bone - 0- shortened archheight between 9 and 15 mm (full-denture group-low mandible); - A- complete arch (old) 100 - A- complete arch (young)or (4) a conventional, full denture with a mandibular symphysealbone height of 16 mm and over (full-denture group-high man- zdible). Subjects from the implant and full-denture groups (low 0i 2 75- 0mandible) were selected from a randomized clinical trial 5,(Geertman et al., 1994, 1996b). Subjects from the root-overlay andfull-denture groups (high mandible) were patients from the 50Nijmegen Dental School. Subjects in this full-denture group wereedentulous for a maximum period of 20 years and were includedonly if their mandibular bone height was 16 mm or more, as 25 ...measured on a standardized lateral cephalogram (Satow et al.,1998). 0- Subjects in the three natural-dentition groups had either: (1) a (pre) molars canines incisorsshortened dental arch with all anterior teeth present and 3 or 4occluding pairs of premolars (shortened-arch group); (2) a Figure 1. Unilateral bite forces at the force level as when chewing forcomplete-natural dentition and ages comparable with those of the the seven groups between central incisors, canines, and first molarsgroups described previously (complete-arch group-old); or (3) a (denture groups) and second premolars (dentate groups). Numbers ofcomplete-natural dentition group composed of dental students; subjects in each group are presented in the Table. For each data(complete-arch group-young). Subjects from the shortened-arch point, the standard error of the mean (SEM) is presented. Data points From corresponding groups are connected only for the sake of clarity.and complete-arch (old) groups were from a cohort study which For all 3 bitin positions, t tests on log-transformed data showed: (1)investigated subjective oral function in subjects with shortened implant vs. full denture with a low mandible (ns: p-values > 0.05); (2)dental arches (Witter et al., 1994). The Table presents the implant vs. root-overlay (ns); (3) implant vs. full denture with a highcharacteristics of all groups described above. Informed consent had mandible (p-values < 0.001); (4) full dentures low vs. high (ns); (5)been obtained from all participants prior to their entry into the study. complete arches old vs. young (ns); and (6) older complete vs. shortened arch (ns). Downloaded from jdr.sagepub.com by guest on March 1, 2011 For personal use only. No other uses without permission. Copyright © 2000 SAGE Publications. All rights reserved.
  4. 4. J Dent Res 79(7) 2000 Comparison of Objective Oral Function 1521Measurements involved 5 bitingpositions: between first molars(edentulous groups) or between second premolars (dentate groups) 450of the right and left sides of the jaw, between canines of both sides --implantsof the jaw, and between central incisors. Measurements were 400 - - full dentures (low) -C - - full dentures (high)started at the first right molar following the dentalarch toward the 3--6 root-overlayleft molar, with a one-minute rest between trials, and were repeated 350 -*- shortened arch X- - complete arch (old)once. To reduce the number of data for each subject, we calculated 300 --"--complete arch (young)the mean of 4 measurements on the (pre)molar as well as on thecanine position for 2 force levels. For the incisal position, we 250calcualted the mean of the 2 measurements. 0 200Chewing EfficiencyIn this study, "chewing efficiency" is defined as the number of t50strokes needed to achieve a certain particle size reduction (for -1 100instance, to half of the original particle size), whereas "masticatoryperformance" is defined as the particle size distribution of foodparticles after a given number of chewing strokes. 50 Chewing efficiency tests were performed with a standardizedartificial test food, Optocal Plus, based upon the silicone (pre) molars canines incisorscomponent OptosilR Plus (version 1997; Bayer Dental, Leverkusen,Germany). Food was offered in portions of 17 cubic particles (edge Figure 2. Maximum unilateral bite forces for the seven groups betweensize, 5.6 mm), totaling approximately 3 cm3. central incisors, canines, and first molars (denture groups) and second Particles were collected after 10, 20, 40, and 60 chewing premolars (dentate groups). Numbers of subjects in each group arestrokes for the edentulous groups and after 5, 10, 20, and 40 provided in the Table. For each data point, the standard error of the mean (SEM) is presented. Data points from corresponding groups arestrokes for the dentate groups. Tests were carried out twice, and connected only for the sake of clarity. For all 3 biting positions, t tests onparticles from corresponding numbers of chewing strokes were log-transformed data showed: (1) implant vs. full denture with a lowpooled. Collected particles were air-dried for at least 1 wk before mandible (p-values < 0.03); (2) implant vs. root-overlay (p-values <being sieved. Particles were sieved in a stack up to 10 sieves, with 0.004); (3) implant vs. full denture with a high mandible (p-values <square apertures decreasing from 5.6 to 0.5 mm and a bottom plate, 0.001); (4) full dentures low vs. high (p < 0.04, only for the canines); (5) complete arches old vs. young (p < 0.005, only for the premolars); andfor 20 min (Laboratory Sieving machine VS1000; F. Kurt Retsch (6) older complete vs. shortened arch (ns: p-values > 0.05).GmbH & Co. KG, Haan, Germany). For each number of chewing strokes, median particle sizes(X50) were determined (Vander Bilt et al., 1993a). Themedian particle size is theaperture of a theoretical sieve 6.0through which 50% of theparticles can pass by weight. 5.0The number of chewingstrokes (N.2) needed to obtaina median particle size of 2.8 4.0- kI6 implantsmm (half of the initial edge X 0 full dentures (low) --size) was estimated for each - -full dentures (high) - 0 3.0 - * --root-overlayindividual from the a -*- shortened archregression line of X50 and the - - -complete arch (old)number of chewing strokes c 2.0 - -complete arch (young) -(Slagter et al., 1993). Whensomeone is unable to Epulverize the test food, N,2 1.0 -will be very large. In a formerstudy (unpublished data), 0.0none of the subjects had used 0 10 20 30 40 50 60 70over 200 chewing strokes number of chewing strokesbefore swallowing.Therefore, we supposed that Figure 3. Mean median particle sizes (X50) are plotted as a function of thenumber of chewing strokes for thecalculated values over 200 seven groups. For each data point, the standard error of the mean (SEM) is presented. Numbers of subjects instrokes for N,,2 are not each group are provided in the Table. For all fixed numbers of chewing strokes, t tests on log-transformed dataphysiological. For further showed: (1) implant vs. full denture with a low mandible (p-values < 0.03); (2) implant vs. root-overlay (p-values < 0.001); (3) implant vs. full denture with a high mandible (p-values < 0.001); (4) full dentures low vs. high (p-calculations, these values values < 0.001); (5) complete arches old vs. young (ns: p-values > 0.05); and (6) older complete vs. shortenedwere set at 200 strokes. arch (p-values < 0.004). Downloaded from jdr.sagepub.com by guest on March 1, 2011 For personal use only. No other uses without permission. Copyright © 2000 SAGE Publications. All rights reserved.
  5. 5. 1522 Fontijn-Tekamp et al. J Dent Res 79(7) 2000 groups. At the maximum bite force level, subjects with dental implants exerted, at all biting positions, forces significantly higher than those of the (1) full-denture group (low mandible; p- values < 0.03), (2) root-overlay group (p-values < 0.004), or (3) 1- 100 the full-denture group (high mandible; p-values < 0.001). z Nevertheless, maximum forces exerted by the implant group ,80- D were still lower than those of the dentate subjects. In agreement a) with the results from the as when chewing level, no differences 2 could be detected between the natural-dentition groups for the o 60- anterior biting positions. However, forces measured between the 0 (D 0 second premolars differed significantly: The maximum bite 40- force of the younger group was significantly larger than the 0 force of the older group, with 398 N (SD 103) and 292 N (SD E 94), respectively. The corresponding bite force of the subjects r_ 20- with a shortened dental arch was 246 N (SD 95). Chewing Efficiency 100 200 300 400 500 600 700 Fig. 3 shows mean median particle size (X50) as a function of the maximum bite force - (pre) molars (N) number of chewing strokes for the seven groups. Log- transformed data revealed a significantly higher reduction of X50Figure 4. Correlations between maximum bite force and the number of for the implant group compared with the full-denture group (lowchewing strokes needed to reduce the food to half of the original particle mandible) at all chewing strokes (t test, p-values < 0.03). Second,size (N12). For each subject, N,,2 is plotted against the maximum bite force subjects with natural roots under their overdentures performedmeasured between first molars (denture groups) or second premolars significantly better compared with subjects with dental implants(dentate groups). For each group, data points were curve-fitted by anexponential function. Numbers oF subjects in each group are provided in (all p-values < 0.001). Also, subjects from the full-denture groupthe Table. Except for the implant and full-denture (low mandible) groups, (high mandible) performed better than subjects with dentalsignificant correlations were observed (see Table). implants. Furthermore, subjects from the shortened-arch group had achieved significantly less particle-size reduction thanStatistical Procedures subjects from the complete-arch group (old), even at 5 chewing strokes (all p-values < 0.004). Finally, age did not influenceTo study effects on bite force and chewing efficiency, weperformed pure comparisons on log-transformed data by t tests. chewing efficiency, since no significant differences were found between the two complete-arch groups (all p-values > 0.20).First, we investigated the effects of implants by comparing (i) the The abovementioned differences among the seven groupsimplant group with the full-denture group (low mandible), (ii) the are reflected in NA/2. Subjects of the full-denture group (lowimplant group with the root-overlay group, and (iii) the implant-group with the full-denture group (high mandible). Second, we mandible) needed over 7 times more chewing strokes comparedstudied the effect of mandibular bone height by comparing two with subjects with a complete natural dentition to reduce the food to half of the original particle size (Table). The group withfull-denture groups. Third, we examined the effect of age by dental implants needed 50% fewer chewing strokes comparedcomparing two complete-arch groups. Fourth, we investigated the with the full-denture group with a low mandible (this is aeffect of reduced occlusal contact area by comparing the complete- reduction of ca. 60 strokes for Ny/2).arch (old) and the shortened-arch groups. Finally, we calculatedcorrelation coefficients between maximum bite force and chewing Correlationsefficiency values (N,,2) to explore their relationship. Fig. 4 illustrates the relationship between unilateral maximum bite force and chewing efficiency (N.) for the subjects of allRESULTS seven groups. From this Fig., it is evident that a larger maximumUnilateral Bite Force force accompanies a better chewing efficiency (lower N,/). TheGroups were compared with respect to the 3 biting positions, data points of each group were curve-fitted by an exponentialnamely, (pre)molars, canines, and central incisors. For the force function (lines in Fig. 4). All groups, except the implant grouplevel as when chewing (Fig. 1), forces exerted by subjects with and the full-denture groups (low mandible), showed significantdental implants were comparable, at all 3 biting positions, with correlations between the maximum bite force and N, (Table).those of the full-denture (with low mandible) (p-values > 0.08)and root-overlay groups (p-values > 0.08) but were significantly DISCUSSIONhigher than those of the full-denture group with a high mandible(p-values < 0.001). Nevertheless, no differences could be We conducted the present study to make quantitativeobserved between the two full-denture groups (p-values > 0.07). comparisons regarding two oral functions, viz. bite force andFurthermore, dentate subjects exerted similar bite forces for the chewing efficiency, between different states of natural and3 biting positions: p-values between the two complete-arch artificial dentition. While we attempted to carry out allgroups and between the complete-arch (old) and shortened-arch measurements with standardized and controlled equipment andgroups were not significant (all p-values > 0.40). procedures, some modifications were necessary. Fig. 2 shows the maximum bite forces for the different For the bite-force measurements, modifications were made Downloaded from jdr.sagepub.com by guest on March 1, 2011 For personal use only. No other uses without permission. Copyright © 2000 SAGE Publications. All rights reserved.
  6. 6. J Dent Res 79(7) 2000 Comparison of Objective Oral Function 1 523with regard to (1) the thickness of the device and (2) the biting were capable of exerting relatively high bite forces but were unableposition in the (pre) molar area. Of course, teeth of dentate subjects to comminute food properly.had to be protected during measurements. The rubber material, Significant differences in bite force between the implant andDrufosoftO, leads to an increase in vertical dimension, which is root-overlay groups existed only for the maximum force level.known to have a negative effect on bite force (Waltimo and This is in contrast to results from a study by Mericske-Stem et al.Kononen, 1993, 1995). Nevertheless, this increase was limited, (1993). They observed a tendency for higher maximum bite forcessince teeth can easily compress Drufosoft. Furthermore, the only in subjects with dental implants compared with a group withsubjects mouth-openings did not exceed an incisal separation over natural roots. In their study, overdentures were attached by gold28 mm, which is within the range of the most favorable opening for copings. Perhaps differences between the two groups in our studybite-force measurements (Paphangkorakit and Osbom, 1997). would have been smaller if overdentures in the root-overlay group Bite force measurements were carried out with the had been retained by precision attachments.transducer between first molars (edentulous groups) and between The full-denture group (high mandible) needed 50% fewersecond premolars (dentate groups). All full (over)dentures in this strokes to halve the test food than did the other full-denturestudy had been prepared according to the lingualized occlusion group with a lower mandibular bone height. Differences in biteconcept, with one premolar and two molars in each segment force existed only for the maximum level in frontal regions.(Becker et al., 1977; Lang and Razzoog, 1992). Consequently, These regions are not particularly loaded during chewing, sincethe position of the first molar in these dentures corresponded to food is predominantly chewed between the (pre)molars. Forthat of a second premolar in the natural dentition. chewing efficiency, the full-denture group (high mandible) may A final remark deals with the age of the complete-arch have benefited from a more favorable bone height of 23.4 + 5.2group (old). The mean age of this group is 4 years younger than mm (vs. 14.1 ± 1.1 mm in the CD-low group). At the samethose of the implant, the root-overlay, the two full-denture, and time, this bone height is more often associated with a knife-the shortened-arch groups. It can be assumed that this difference edge ridge form with its inherent painful stimuli when loaded.influenced oral function. However, comparisons between the This may have particularly limited this groups ability to exerttwo complete-arch groups revealed that age affected only the bite forces. More advanced stages of resorption-as, for instance,maximum bite force between the second premolars. The in the full-denture group (low mandible)-are infrequentlyobservation that an age difference of over nearly three decades accompanied by such a painful, knife-edge ridge.hardly affected bite force and chewing efficiency allows for the Edentulous groups were clearly less efficient than subjectscomparison of the slightly younger complete-arch group (old) from the natural-dentition groups in breaking down the testwith the other groups without the need for an age correction. food. Although the edentulous groups had not chewed the food It appeared that maximum bite forces in the implant group for 5 strokes, reductions in particle size after 10 chewingwere between those of the artificial- and natural-dentition groups. strokes were still so limited that one can infer that the dentateObviously, the improved retention and support of the mandibular groups were already way ahead in comminuting their food afterdenture by dental implants allowed subjects to exert higher forces. 5 chewing strokes. Limitations in bite force, as well as stabilityIn subjects from the two full-denture groups, bite forces may have and retention problems of the denture, may explain the poorbeen limited, due to the mandibular denture-bearing tissues being selection process in the denture wearers compared with themore subject to compression, denture shifting, and resultant painful dentate subjects (Slagter et al., 1993).irritation. In addition, subjects in the root-overlay group may have Chewing efficiency of the shortened-arch group wasreceived negative feedback from periodontal receptors as well as significantly less than that of the two groups with a completepainful compression of the marginal gingiva of the remaining roots. natural dentition, although bite forces (maximum as well as during The results of the chewing efficiency tests in subjects with chewing) in these three groups were comparable. The shortened-mandibular implant-retained overdentures did not quite parallel the arch groups chewing efficiency data were in the same range asbite-force data. Their chewing efficiency was even less than that of those from the full-denture (high mandible) and the root-overlaysubjects in the full-denture (high mandible) or root-overlay groups. groups. The impaired chewing efficiency of the shortened-archThey probably had more problems with the process of particle group should be explained by the reduced occlusal contact area,selection, since food comminution is the combined process of which reduces the quantity of food particles trapped between theselection and breakage (van der Bilt et al., 1987; van der Glas et al., teeth. The loss of opposing posterior teeth significantly reduces 1987). This selection process may be disturbed by the depth of the chewing efficiency in a linear relationship to the number ofvestibular folds combined with the presence of a large bulky occlusal units (Van der Bilt et al. 1993b).denture to compensate for the alveolar bone loss and restore the For the total group (all seven groups combined), chewingvertical dimension of occlusion. Upon re-collection of the test food, efficiency significantly increased when higher bite forces wereparticles were often retrieved from the mandibular buccal folds in exerted. A higher bite force leads to a better fragmentation ofthe molar area. These particles may have escaped buccally from the the food particles trapped between the posterior teeth. Theocclusal surface during the chewing process to migrate further into correlation between maximum bite force and chewing efficiencythe depths of the buccal folds beyond control of the tongue. After (N 2) was significant for all groups combined. In the total group,being chewed, particles were also found to remain labially under nearly half of the variation in chewing efficiency can bethe border of the mandibular denture and in the "dead space" that explained by bite force alone. In the separate groups, thisaccommodates the bar-clip attachment. Furthermore, the efficiency correlation cannot be found for the implant and the full-dentureof subjects with mandibular implant-retained overdentures can also (low mandible) groups. In the implant group, a large variationbe limited by retention and stability problems of the maxillary exists in chewing efficiency as well as bite force (Fig. 4). Mostdenture. This phenomenon was observed in several subjects who of the implant subjects have enough force to pulverize the food, Downloaded from jdr.sagepub.com by guest on March 1, 2011 For personal use only. No other uses without permission. Copyright © 2000 SAGE Publications. All rights reserved.
  7. 7. 1 52,4 Fontiin-Tekamp et a/. J Dent Res 79(7) 2000but are unable to manipulate it adequately between posterior an occlusal scheme for edentulous implant patients. Implant Dentteeth, which leads to poor chewing efficiency. In the full- 1:204-211.denture group (low mandible), the correlation was weak, Lindquist LW, Carlsson GE (1982). Changes in masticatory function inprobably due to the small number of subjects and the fact that, complete denture wearers after insertion of bridges onfor four subjects, values of N½ were set at 200 chewing strokes. osseointegrated implants in the lower jaw. In: Clinical applications of From the present study, we conclude that the provision of biomaterials. Lee AJC, Albrektsson T, Branemark PI, editors.dental implants cannot restore objective oral function of Chichester: John Wiley and Sons Ltd., pp. 151-155.subjects with persistent problems wearing conventional Lindquist LW, Carlsson GE (1985). Long-term effects on chewing withcomplete dentures to the level enjoyed by satisfied complete- mandibular fixed prostheses on osseointegrated implants. Actadenture-wearers, as has been suggested. Unilateral bite forces Odontol Scand 43:39-45.of subjects with overdentures on dental implants are between Locker D (1998). Patient-based assessment of the outcomes of implantthose of subjects with natural and artificial dentitions; chewing therapy: a review of the literature. Int JProsthodont 11:453-461.efficiency is improved but not to the same level. Meijer HJ, Raghoebar GM, Vant Hof MA, Geertman ME, Van Oort RP (1999). Implant-retained mandibular overdentures compared withACKNOWLEDGMENTS complete dentures; a 5-years follow-up study of clinical aspects andThis work was supported by the Faculty of Medical Sciences patient satisfaction. Clin Oral Implants Res 10:238-244.of the University of Nijmegen and The Netherlands Institute Mericske-Stern R, Hoflnann J, Wedig A, Geering AH (1993). 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