| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
RESEARCH REPORT |
1 Department of Head and Neck, Oral-Maxillofacial Surgery, Prosthodontics and Special Dental Care, University Medical Center Utrecht, Str. 4.115, PO Box 85.060, 3508 AB Utrecht, The Netherlands; and
2 Central Military Hospital, Utrecht, The Netherlands;
* corresponding author, a.vanderbilt{at}med.uu.nl
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
|---|
KEY WORDS: masticatory performance • swallowing threshold • oral implant • mandibular overdenture • attachment
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
|---|
The degree of mandibular overdenture support, 2 vs. 4 implants (Geertman et al., 1994), or fixed vs. removable prostheses (Feine et al., 1994; Tang et al., 1999) did not influence the masticatory performance. Nevertheless, the attachment type in implant-supported mandibular overdentures may influence the retention and the stability, and thus the oral function, of the prosthesis. This aspect has never been studied within the same subjects. Therefore, we designed a within-subject cross-over clinical trial to study the effects of 3 mandibular implant overdenture suprastructure modalities using magnet, bar-clip, and ball attachments. We demonstrated that maximum bite force nearly doubles after implant treatment with these 3 suprastructure modalities, while no significant differences in maximum bite force occur among the 3 attachment types (van Kampen et al., 2002). How this affects masticatory function remains unclear.
The aim of the present study was to test the hypothesis that mandibular conventional denture treatment, implant-supported overdenture treatment, and attachment type affects masticatory performance and efficiency as well as swallowing threshold. Therefore, we measured these variables in 18 subjects before and after treatment with 2 oral implants in the mandible using the 3 suprastructure modalities. These suprastructures were worn successively in a randomized order by all subjects, so we could make a within-subject comparison of the masticatory function obtained with the 3 attachment types.
|
MATERIALS & METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Surgical and Prosthetic Procedures
The subjects received 2 oral implants (Frialit-2, Friadent, Friedrichsfeld, Germany; diameter, 3.8 mm; length, 13 or 15 mm). The implants were placed in the region of the 2 former cuspids, according to a standardized two-stage surgical protocol. New conventional dentures in the maxilla and mandible were made following first-stage surgery. The dentures were made in centric occlusion with balanced articulation and anatomically shaped acrylic teeth (Bonartic, Ivoclar, Schaan, Liechtenstein). In each quadrant, 1 bicuspid and 2 molars were used. Subjects started to wear their new dentures without attachment 2 mos after first-stage surgery, for a three-month period. After second-stage surgery, 5 mos after implantation, the mandibular dentures were successively fitted with magnets (Dyna Magnet ES, Dyna Dental Engineering, Bergen op Zoom, the Netherlands), bar-clips (IMZ, Friadent Friedrichsfeld, Germany), or ball (Frialit-2, Friadent Friedrichsfeld, Germany) attachments. The sequence in which the 3 attachments were applied was randomized (van Kampen et al., 2002). All 6 possible sequences were used, so that possible cross-over effects could be studied. In that way, 6 groups of three subjects were formed, each group having a different sequence of successive attachments. Each attachment type was used during a three-month period.
Masticatory Function and Swallowing Threshold
We measured the masticatory function of all subjects by asking them to chew on cubes of a dental impression material. This material (Optosil plus, Bayer AG, Leverkusen, Germany) was specially prepared to make it more brittle, so that it could be fragmented by all participants (Fontijn-Tekamp et al., 2004). The subjects chewed on portions of 17 cubes with an edge size of 5.6 mm (approximately 3 cm3) for 15 and 30 chewing strokes. We determined the degree of fragmentation of the chewed food portions by sieving the food through a stack of 8 sieves, with square apertures between 5.6 and 0.5 mm and a bottom plate. The degree of fragmentation of the food (chewing performance) is given by the median particle size, X50, which is the aperture of a theoretical sieve through which 50% of the weight of the comminuted food could pass (van der Bilt et al., 1993). The number of chewing strokes needed to halve the initial median particle size (chewing efficiency), denoted as N1/2, was calculated from the initial size and the size after 15 and 30 chewing strokes (van der Bilt et al., 1987).
We examined the swallowing threshold by having the subjects chew on a piece of breakfast cake. The subjects chewed the breakfast cake (4 g; size 20 x 20 x 20 mm) normally and swallowed it. The examiner counted the number of chewing strokes needed until swallowing occurred. This measurement was performed twice, and the number of chewing strokes was averaged for each subject.
Procedure
We measured the masticatory performance and the swallowing threshold at 5 moments during the 14-month treatment period. The first measurement was performed with the old denture, just prior to the first-stage surgery. The second measurement was performed just prior to the second-stage surgery, after the newly made denture without attachments had been used for 3 mos. We performed the next 3 measurements at the end of each three-month period during which the various attachment types were incorporated into the dentures.
Statistical Analysis
We applied repeated-measures analysis of variance (ANOVA) to test the null hypothesis that there would be no statistical difference between the results obtained at the 5 occasions. Subsequently, post hoc tests (least significant difference multiple-comparison test) were used for pairwise comparisons of results. Pearson correlations were calculated between the change in masticatory performance due to the treatment and the masticatory performance with the old denture.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
|---|
). Repeated-measures ANOVA showed a significant effect (p < 0.001) of the 5 situations—old and new dentures, and dentures attached with a magnet, bar-clip, or ball attachment—on median particle size after 15 and 30 chewing cycles. Post hoc analysis showed that the median particle size obtained with the unsupported new denture was significantly larger than that for the old denture (p < 0.05). The masticatory performance significantly improved with the implant-supported new denture in comparison with that of the old and new dentures without implant support (p < 0.001). The masticatory performance obtained with the magnet attachment was less effective than that with the bar-clip and ball attachments (p < 0.05), whereas no differences were observed between performances with the bar-clip and ball attachment.
|
). The majority of the subjects had larger median particle sizes, thus poorer masticatory performance, with the unsupported new denture than with the old denture, whereas all subjects had smaller median particle sizes when the new denture was supported by the bar-clip attachment. Similar results were obtained for the magnet and ball attachments but are not shown so that congestion of data points can be avoided. A significant correlation between the change in median particle size and the median particle size, as obtained with the old denture, was observed when the new denture was supported by the bar-clip and ball attachment (r = –0.8; p < 0.001) and by the magnet attachment (r = –0.5; p < 0.05) for the measurements after 15 and 30 chewing cycles.
|
), which did not significantly change from old to new dentures. However, a significant decrease occurred after implant treatment: from 50 to 25 for the bar-clip and ball attachments (p < 0.001) and to 33 for the magnet attachment (p < 0.005).
Swallowing Threshold
The numbers of chewing strokes that subjects needed before they swallowed a piece of breakfast cake were tracked (Table). Repeated-measures ANOVA showed a significant effect (p < 0.05) for the 5 situations on the swallowing threshold. Post hoc analysis showed that the number of chewing cycles until swallowing with the old denture was slightly larger than with the supported new denture (p < 0.10 for all 3 attachments).
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
|---|
). The reduction in masticatory performance did not lead to a significant increase in the number of chewing cycles needed to halve the initial size, although some increase was observed (Table). In a previous study, we observed a reduction of about 20% in the maximum bite force after denture treatment (van Kampen et al., 2002). This bite force reduction may be caused by mucosal soreness above the submerged implants and adjustment of the subjects to new dentures. Significant correlations between maximum bite force and masticatory performance were reported (Fontijn-Tekamp et al., 2000). Thus, the reduced maximum bite force may partly explain the reduced masticatory performance. Deterioration of masticatory performance after denture treatment has been commonly observed (Lundquist et al., 1986; Garrett et al., 1996).
After the new overdenture was attached to the oral implants, we observed a significant improvement in masticatory function. All subjects chewed the food better, and thus achieved smaller median particle sizes after 15 as well as 30 chewing cycles. This is reflected in negative values for the change in median particle size for the supported new denture (circles in Fig.). We observed a significant negative correlation between the change in median particle size due to implant treatment and the median particle size obtained with the old denture. This means that the improvement in masticatory performance that can be expected depends on the masticatory performance before treatment. Subjects with a relatively large median particle size before treatment (bad chewers) benefited more from the implant treatment than did subjects with a smaller median particle size (good chewers). The negative correlation could be attributed to a so-called ‘regression to the mean’, where relatively large values obtained in the first measurement have a larger chance to be smaller in the second measurement, and vice versa. However, in a study on 81 healthy dentate subjects, where we measured the median particle size on 2 occasions with a three-month time interval, there appeared to be no significant correlation between the change in median particle size and the median particle size at the first measurement (r = –0.19; p = 0.08, unpublished observation). In a study on the effect on oral function of optimizing a denture, the subjects with the poorest pre-treatment values also benefited the most (Lundquist et al., 1986).
The improvement in masticatory efficiency obtained with the magnet attachment was smaller than with the bar-clip and ball attachments. The number of chewing cycles needed to halve the initial size was 33 with the magnet vs. 25 with the bar-clip and ball attachments. We observed a similar trend in maximum bite force (van Kampen et al., 2002). The maximum bite force obtained with the magnet attachment was significantly smaller than the force obtained with the ball attachment. This lower force may be caused by the much smaller retention force of the denture with the magnet attachment (van Kampen et al., 2003). The lower retention of the mandible and the smaller resistance against horizontal movement (although the latter was not actually measured), in combination with the conventional maxillary denture, may lead to less denture stability during chewing and thus to a reduced masticatory performance. Indeed, subjects who received mandibular overdentures with magnet attachments preferred a more retentive solution because of the denture instability they experienced (Naert et al., 1999).
Swallowing Threshold
The effect of implant treatment on the swallowing threshold was limited. The number of chewing cycles needed to prepare the food for swallowing with the implant-supported overdenture was only slightly smaller than with the old denture (p < 0.10). Since the masticatory performance increased significantly (p < 0.001), and the number of chewing cycles until swallowing hardly changed, we may conclude that, after implant treatment, the food is better-chewed before it is swallowed. This may have a positive effect on the digestion of the food. Indeed, improvement of the nutritional state of edentulous people was observed after mandibular overdenture treatment (Morais et al., 2003). However, successful prosthetic treatment does not necessarily result in a satisfactory diet (Hamada et al., 2001; Allen and McMillan, 2002; Shinkai et al., 2002), so dietary advice will be needed if subjects are to take advantage of the improved masticatory performance.
We conclude that mandibular implant overdenture treatment, opposing conventional maxillary dentures, results in significantly better masticatory function. Only small differences in masticatory function were observed among the magnet, bar-clip, and ball attachments. The improved masticatory function after implant treatment resulted in food that was better-chewed when it was swallowed.
|
ACKNOWLEDGMENTS |
|---|
Received June 24, 2003; Last revision June 24, 2004; Accepted June 28, 2004
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Bakke M, Holm B, Gotfredsen K (2002). Masticatory function and patient satisfaction with implant-supported mandibular overdentures: a prospective 5-year study. Int J Prosthodont 15:575–581.[ISI][Medline]
Feine JS, Maskawi K, de Grandmont P, Donohue WB, Tanguay R, Lund JP (1994). Within-subject comparisons of implant-supported mandibular prostheses: evaluation of masticatory function. J Dent Res 73:1646–1656.
Fontijn-Tekamp FA, Slagter AP, van der Bilt A, van’t Hof MA, Witter DJ, Kalk W, et al. (2000). Biting and chewing in overdentures, full dentures, and natural dentitions. J Dent Res 79:1519–1524.
Fontijn-Tekamp FA, Slagter AP, van der Bilt A, van’t Hof MA, Kalk W, Jansen JA (2004). Swallowing thresholds of mandibular implant-retained overdentures with variable portion sizes. Clin Oral Implant Res 15:375–380.[ISI][Medline]
Garrett NR, Perez P, Elbert C, Kapur KK (1996). Effects of improvements of poorly fitting dentures and new dentures on masticatory performance. J Prosthet Dent 75:269–275.[ISI][Medline]
Garrett NR, Kapur KK, Hamada MO, Roumanas ED, Freymiller E, Han T, et al. (1998). A randomized clinical trial comparing the efficacy of mandibular implant-supported overdentures and conventional dentures in diabetic patients. Part II. Comparisons of masticatory performance. J Prosthet Dent 79:632–640.[ISI][Medline]
Geertman ME, Slagter AP, van Waas MAJ, Kalk W (1994). Comminution of food with mandibular implant-retained overdentures. J Dent Res 73:1858–1864.
Geertman ME, Slagter AP, van’t Hof MA, van Waas MAJ, Kalk W (1999). Masticatory performance and chewing experience with implant-retained mandibular overdentures. J Oral Rehabil 26:7–13.[ISI][Medline]
Hamada MO, Garrett NR, Roumanas ED, Kapur KK, Freymiller E, Han T, et al. (2001). A randomized clinical trial comparing the efficacy of mandibular implant-supported overdentures and conventional dentures in diabetic patients. Part IV: Comparison of dietary intake. J Prosthet Dent 85:53–60.[ISI][Medline]
Haraldson T, Jemt T, Stålblad P, Lekholm U (1988). Oral function in subjects with overdentures supported by osseointegrated implants. Scand J Dent Res 96:235–242.[ISI][Medline]
Lundquist LW, Carlsson GE, Hedegård B (1986). Changes in bite force and chewing efficiency after denture treatment in edentulous patients with denture adaptation difficulties. J Oral Rehabil 13:21–29.[ISI][Medline]
Morais JA, Heydecke G, Pawliuk J, Lund JP, Feine JS (2003). The effects of mandibular two-implant overdentures on nutrition in elderly edentulous individuals. J Dent Res 82:53–58.
Naert I, Gizani M, Vuylsteke M, van Steenberghe D (1999). A 5-year prospective randomized clinical trial on the influence of splinted and unsplinted oral implants retaining a mandibular overdenture: prosthetic aspects and patient satisfaction. J Oral Rehabil 26:195–202.[ISI][Medline]
Pera P, Bassi F, Schierano G, Appendino P, Preti G (1998). Implant anchored complete mandibular denture: evaluation of masticatory efficiency, oral function and degree of satisfaction. J Oral Rehabil 25:462–467.[ISI][Medline]
Shinkai RSA, Hatch JP, Rugh JD, Sakai S, Mobley CC, Saunders MJ (2002). Dietary intake in edentulous subjects with good and poor quality complete dentures. J Prosthet Dent 87:490–498.[ISI][Medline]
Slagter AP, Bosman F, van der Bilt A (1993). Comminution of two artificial test foods by dentate and edentulous subjects. J Oral Rehabil 20:159–176.[ISI][Medline]
Tang L, Lund JP, Taché R, Clokie CML, Feine JS (1999). A within-subject comparison of mandibular long-bar and hybrid implant-supported prostheses: evaluation of masticatory function. J Dent Res 78:1544–1553.
van der Bilt A, Olthoff LW, van der Glas HW, van der Weelen K, Bosman F (1987). A mathematical description of the comminution of food during mastication in man. Arch Oral Biol 32:579–586.[ISI][Medline]
van der Bilt A, Abbink JH, Mowlana F, Heath MR (1993). A comparison between data analysis methods concerning particle size distributions obtained by mastication in man. Arch Oral Biol 38:163–167.[ISI][Medline]
van Kampen FMC, van der Bilt A, Cune MS, Bosman F (2002). The influence of various attachment types in mandibular implant-retained overdentures on maximum bite force and EMG. J Dent Res 81:170–173.
van Kampen FMC, Cune MS, van der Bilt A, Bosman F (2003). Retention and post-insertion maintenance of bar-clip, ball, and magnet attachments in mandibular implant overdenture treatment; an in vivo comparison after three months of function. Clin Oral Implant Res 14:720–726.[ISI][Medline]
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| IADR Journals | Advances in Dental Research ® |
| Journal of Dental Research ® | Critical Reviews (1990-2004) |
