- Email: [email protected]
Clinical performance and satisfaction of removable prostheses with self-adjusting magnetic attachments
Clinical performance and satisfaction of removable prostheses with self-adjusting magnetic attachments Tsung-Chieh Yang, PhD,a Yoshinobu Maeda, PhD,b and Tomoya Gonda, PhDc National Taiwan University, Taipei, Taiwan; Osaka University Graduate School of Dentistry, Osaka, Japan Statement of problem. Conventional magnetic attachments have rigid assemblies and are unable to compensate for the movement of the prosthesis under function, which may result in the deepening of periodontal pockets and an increase in the mobility of abutment teeth. Purpose. The purpose of this study was to evaluate the clinical performance and satisfaction of participants with removable prostheses with self-adjusting magnetic attachments that allow vertical and rotational movement. Material and methods. The clinical performance of 17 prostheses with 22 self-adjusting magnetic attachments in 16 participants was analyzed for a mean of 3.1 years. Periodontal indices, including probing pocket depth and tooth mobility, were measured at denture placement (baseline) and from 0.5 to 5 years after insertion. Control data were obtained from the remaining teeth, which were restored by resin or metal coping. Prosthetic parameters, including the reduction of retention in self-adjusting magnetic attachments, reline, or fracture of dentures, were also recorded. A visual analog scale questionnaire on participant satisfaction with stability, comfort, and cleaning of the prostheses was completed. The Wilcoxon signed rank test and 1-way analysis of variance (a¼.05) were performed on data collected at the time of prostheses placement and final follow-up evaluation. Results. No significant differences were found in terms of probing pocket depth and tooth mobility between the baseline and postinsertion data for self-adjusting magnetic attachments and control teeth. Retention in all prostheses was stable, without reduction. Higher visual analog scale scores for “easy cleaning” were noted. Conclusions. No significant difference between baseline and postinsertion was noted regarding the periodontal condition of self-adjusting magnetic attachments and control teeth with resin or metal coping materials. (J Prosthet Dent 2014;111:131-135)
Clinical Implications A self-adjusting magnetic attachment improves the retention of prostheses without damaging the periodontal tissue of the abutment teeth during long-term function. The use of a bar, ball, or magnetic attachment system on the remaining teeth can improve the retention and stability of removable prostheses. However, periodontal problems associated with abutment teeth may affect the success rate of treatment.1-5 a
Magnetic attachment is recommended because it enables easier cleaning.6 The assemblies of magnetic attachments, however, are rigid and unable to compensate for vertical and rotational movement when the prosthesis is under function, especially in a posterior distal
extension edentulous situation.7,8 With conventional magnetic attachments, the periodontal membrane compensates for the rigidity by allowing root movements. However, the deepening of periodontal pockets and increases in tooth mobility are usually observed.1
Assistant Professor, Department of Prosthodontics, School of Dentistry, National Taiwan University. Professor, Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry. c Assistant Professor, Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry. b
Yang et al
132
Volume 111 Issue 2 To overcome this problem, a new selfadjusting magnetic attachment (SA) system that allows vertical and rotational movement was designed. The objective of this study was to use periodontal, prosthodontic, and participant satisfaction measures to evaluate the long-term clinical performance of removable prostheses with SAs. The null hypothesis was that no difference would be noted regarding the periodontal condition of abutment teeth with SAs or retained roots without SAs at the recall examinations.
MATERIAL AND METHODS The ethics board of Osaka University Dental Hospital approved this study. Sixteen participants (7 men and 9 women; age range: 45 to 86 years; mean: 66.8 years) with 22 SAs in 17 prostheses (Magfit SX2; Aichi Steel
Table I.
Corp) (Table I, Fig. 1) were enrolled in this study after giving informed consent. The predefined inclusion criteria were participants used their denture without problem, they experienced no disorder in their stomatognathic system or mucous membrane, and they were available for the periodic recall appointments. The design of the SA incorporates a movement allowance of up to 0.4 mm in vertical dimension and rotation up to 8 degrees. The SAs were placed on teeth with a healthy periodontal condition, and the crown to root ratio was reduced to avoid excessive occlusal force. In addition, to provide better support and stability for the removable dental prosthesis, the SA was placed on the tooth in the anterior or in the posterior part of the edentulous area. Posttreatment maintenance was scheduled every 3 months for up to 5 years (mean: 3.1 years). The same
operator measured the periodontal indices, recorded the prosthetic parameters, and completed the questionnaire of participant satisfaction with SAs throughout the study. Periodontal parameters such as probing depth (PD) with the CP11 probe and tooth mobility (TM) according to the Miller classification9 (scores from 1 to 3) were measured from the time of prostheses placement (baseline). Plaque accumulation on the SAs also was recorded. In addition, control data were collected from the remaining teeth, which were restored with resin or metal root coping (Fig. 2). Attrition, which is the surface wear of the SAs (without attrition: score 0; attrition area per total surface area of magnetic assemblies 25%: score 1; 50%: score 2; 75%: score 3; 100%: score 4), corrosion, loss of retention, and the
Data of study group
Participant No.
Observation Period (y)
Prosthesis* Agreed SR (n[17)
Sex
Age (y)
SA Abutment Teeth (n[22)
1
Man
77
Maxillary right canine, maxillary right first premolar
3
Overdenture
2
Man
65
Mandibular left canine, mandibular right canine
5
Overdenture
3
Woman
52
Maxillary left second molar, mandibular right second molar
4
Overdenture (maxilla and mandible)
4
Woman
64
Mandibular left central incisor, mandibular right central incisor
3
Overdenture
5
Woman
81
Mandibular right canine
4
Overdenture
6
Woman
67
Mandibular left first premolar, mandibular right canine
4
Overdenture
7
Man
71
Maxillary right canine
1
Overdenture
8
Man
58
Mandibular left second premolar
4
Class I partial RDP
9
Woman
76
Maxillary left second molar
3
Class I partial RDP
10
Woman
76
Maxillary left canine
1
Class I partial RDP
11
Man
55
Mandibular right second premolar
4
Class I partial RDP
12
Man
45
Mandibular right first premolar
5
Class I partial RDP
13
Woman
71
Mandibular right canine, mandibular right first premolar
0.5
Class I partial RDP
14
Woman
86
Mandibular right canine
1
15
Woman
66
Maxillary left central incisor
2
Class II partial RDP
16
Man
59
Maxillary right canine
5
Class IV partial RDP
Class I, modification 1 partial RDP
SA, self-adjusting magnetic attachment; Partial RDP, partial removable dental prosthesis. *Kennedy Classification
The Journal of Prosthetic Dentistry
Yang et al
February 2014
133 Movable assembly
Space: 0.4 mm Magnet Time of insertion
A
Movable assembly
Magnet Vertical movement
B Movable assembly
Magnet Rotation
C
1 Mechanics of self-adjusting magnetic attachment. A, Design incorporates movement allowance of up to 0.4 mm. B, In vertical dimension. C, Rotation up to 8 degrees.
participants regarding oral hygiene and the cleaning of the prosthesis. Toothbrushes, interdental brushes, dental floss, and denture-cleaning brushes were repeatedly provided during this study. Additional professional mechanical tooth cleaning was provided if required at the recall visit, and topical fluoride application also was performed during the follow-up period. Participants were asked to complete a questionnaire regarding the stability, comfort, and ease of cleaning their prostheses based on a visual analog scale (VAS). The Wilcoxon signed rank test was used to compare the change in the PD and TM of the SAs, and control teeth between the time of prostheses placement (baseline) and the last visit (after insertion) (a¼.05). One-way ANOVA was used to evaluate and compare the data from the VAS-based questionnaire on participant satisfaction (a¼.05). Software (SPSS 11.0; SPSS Inc) was used for the statistical analysis.
RESULTS Periodontal evaluation
2 Oral condition of self-adjusting magnetic attachments and control teeth in participant no. 2.
mobility allowance of the SAs were evaluated during clinical use. For corrosion assessment, the surface roughness and discoloration of the magnet in participants’ mouth were compared visually with a new magnetic attachment. For the retention assessment, the same operator assessed the resistance during the
Yang et al
insertion and the removal the denture. For the mobility assessment, the same operator assessed the capability of vertical and rotational movement in the magnetic assemblies. Prosthetic complications, such as fracture or repair, were also recorded during the period of follow-up. Instructions were provided for
Changes in the PD and TM of the SAs and the control teeth between baseline and after insertion are presented in Table II. No significant changes were noted in the PD of SA abutments (P¼.132) and control teeth (P¼.414). No significant change in TM was found in SA abutments (P¼.705) and control teeth (P¼.317), and no severe plaque accumulation that resulted in secondary caries on the SA abutments was found. One tooth was extracted because of a hopeless periapical lesion after 2 years of clinical use.
Prosthetic evaluation No corrosion was found on the assemblies of the SAs. The attrition of the SAs in the study was less than 25% (score 1) attrition area over the total contact surfaces of the magnet and keeper. This, however, did not influence the retention and movement allowance of the SA attachments. The bases of 6 prostheses
134
Volume 111 Issue 2 Periodontal evaluation of SA and control teeth (n¼22)
Table II.
After Baseline Insertion PD (mm) SA
3.05 0.72 3.27 0.77
Control
2.88 0.81 3.00 0.97
TM (score: 0-3) SA
0.36 0.49 0.32 0.48
Control
0.44 0.63 0.44 0.51
SA, self-adjusting magnetic attachment; PD, probing depth; TM, tooth mobility. There was no statistically significant difference between SAs and control teeth (P>.05).
were relined because of continuing alveolar bone resorption. Fracture lines were found over the SA area in 2 prostheses because of insufficient clearance of the antagonistic teeth.
Participant satisfaction with prostheses Although a high VAS score was noted for the “easy cleaning of the denture,” followed by “comfort of denture wear,” and “denture stability while using,” no significant difference was found in these factors (Fig. 3).
DISCUSSION After comparing SAs and control data collected from the remaining teeth, which were restored with resin or metal copping in the removal prostheses in this study,
Q1
the null hypothesis for the stability of the periodontal condition was not rejected; no significant difference was noted in the baseline and postinsertion PD and TM of SAs and control teeth. The occurrence of abutment tooth loss in participants with overdentures ranged from 1.5% to 14.3%,3,4 the causes being periodontal disease (29.3%), followed by periapical lesions (18.8%) and caries (16.5%) during long-term use.5 In this study, one of the abutments was lost because of a periapical lesion. A high VAS score with less deviation for satisfaction in easy cleaning was noted for the SAs, which may explain the stable periodontal condition and low frequency of secondary caries on abutment teeth. In this study, as indicated by Budtz-Jorgensen et al,10 regular maintenance, topical fluoride application, and oral hygiene instruction were considered important factors in the success rate. With overdentures with anterior teeth as abutments8 or removal prostheses with a posterior distal extension edentulous region, the prosthesis may rotate along the fulcrum line between the distal abutment teeth under functional loads. In this study, the attrition area of SAs was found to be less than 25% of the total contact surface, and there was no significant increase in PD and TM. The moveable assembly may have helped to compensate for the movement of the prostheses while the magnet and keeper of the SA were in constant contact. Due to the improvement of magnet attachment systems, Huang et al11 reported that the retentive force of the magnet did
Q2
Q3
VAS Score
100 80 60 40 20 0
3 Participant satisfaction with prostheses. No statistically significant differences (P>.05). Q1, denture stability while using; Q2, comfort of denture wear; and Q3, easy cleaning of the denture.
The Journal of Prosthetic Dentistry
not change significantly even after 9000 gliding cycles with clear abrasion. However, a low VAS score with a large deviation for denture stability may be explained by the vertical movement allowance of the SAs. Sufficient vertical space must be created to accommodate the keeper, the magnet, the denture space, and the prosthetic tooth.12 The fracture lines found in the 2 prostheses in this study also suggest the need for establishing indication criteria for SAs in relation to the clearance and reinforcement of the prosthesis. The location of natural teeth with SAs, which depended on the oral condition of the participants, may have limited this study. The sample size of this study was small, which also represents a limitation. Long-term observation is needed to evaluate the corrosion and attrition of SAs and their influence on retention. Further studies should enroll more participants with SAs.
CONCLUSIONS In spite of the limitations of this clinical study and with assuming regular dental maintenance, SAs can be used in prostheses without damaging the periodontal tissue of the abutment tooth.
REFERENCES 1. Gonda T, Yang TC, Maeda Y. Five-year multicenter study of magnetic attachments used for natural overdenture abutments. J Oral Rehabil 2013;40:258-62. 2. Toolson LB, Smith DE, Phillips C. A 2-year longitudinal study of overdenture patients. Part II: Assessment of the periodontal health of overdenture abutments. J Prosthet Dent 1982;47:4-11. 3. Reitz PV, Weiner MG, Levin B. An overdenture survey: preliminary report. J Prosthet Dent 1977;37:246-58. 4. Toolson LB, Taylor TD. A 10-year report of a longitudinal recall of overdenture patients. J Prosthet Dent 1989;62:179-81. 5. Ettinger RL, Qian F. Abutment tooth loss in patients with overdentures. J Am Dent Assoc 2004;135:739-46. 6. van Kampen F, Cune M, van der Bilt A, Bosman F. Retention and postinsertion maintenance of bar-clip, ball and magnet attachments in mandibular implant overdenture treatment: an in vivo comparison after 3 months of function. Clin Oral Implants Res 2003;14:720-6.
Yang et al
February 2014
135
7. Maeda Y. Criteria for abutment selection for implant overdenture. In: Maeda Y, Walmesly AD, editors. Implant dentistry with new generation magnetic attachments. Chicago: Quintessence; 2005. p. 32-5. 8. Maeda Y. Treatment concepts classified with number and location of implant. In: Maeda Y, Walmesly AD, editors. Implant dentistry with new generation magnetic attachments. Chicago: Quintessence; 2005. p. 40-2. 9. Salvi GE, Lindhe J, Lang NP. Examination of patients with periodontal disease. In: Lindhe J, Lang NP, Karring T, editors. Clinical periodontology and implant dentistry. 5th ed. Oxford: Blackwell Munksgaard; 2008. p. 573-86.
10. Budtz-Jorgensen E. Prognosis of overdenture abutments in elderly patients with controlled oral hygiene: a 5 year study. J Oral Rehabil 1995;22:3-8. 11. Huang Y, Tawada Y, Hata Y, Watanabe F. The change in retentive force of magnetic attachment by abrasion. Odontology 2008;96:65-8. 12. Vere J, Deans RF. Tooth-supported, magnetretained overdentures: a review. Dent Update 2009;36:305-10.
Corresponding author: Dr Yoshinobu Maeda Department of Prosthodontics, Gerodontology and Oral Rehabilitation Osaka University Graduate School of Dentistry 1-8 Yamadaoka Suita, Osaka 565-0871 JAPAN E-mail: [email protected] Copyright ª 2014 by the Editorial Council for The Journal of Prosthetic Dentistry.
Receive Tables of Contents by E-mail To receive tables of contents by e-mail, sign up through our Web site at http://www.journals.elsevierhealth.com/periodicals/ympr. Instructions Log on and click “Register” in the upper right-hand corner. After completing the registration process, click on “My Alerts,” then “Add Table of Contents Alert.” Select the category “Mosby” or type The Journal of Prosthetic Dentistry in the search field and click on the Journal title. The title will then appear, and having already completed the Registration process, you may add tables of contents alerts by accessing an issue of the Journal and clicking on the “Add TOC Alert” link. You will receive an e-mail message confirming that you have been added to the mailing list. Note that tables of contents e-mails will be sent when a new issue is posted to the Web site.
Yang et al
Clinical Implications A self-adjusting magnetic attachment improves the retention of prostheses without damaging the periodontal tissue of the abutment teeth during long-term function. The use of a bar, ball, or magnetic attachment system on the remaining teeth can improve the retention and stability of removable prostheses. However, periodontal problems associated with abutment teeth may affect the success rate of treatment.1-5 a
Magnetic attachment is recommended because it enables easier cleaning.6 The assemblies of magnetic attachments, however, are rigid and unable to compensate for vertical and rotational movement when the prosthesis is under function, especially in a posterior distal
extension edentulous situation.7,8 With conventional magnetic attachments, the periodontal membrane compensates for the rigidity by allowing root movements. However, the deepening of periodontal pockets and increases in tooth mobility are usually observed.1
Assistant Professor, Department of Prosthodontics, School of Dentistry, National Taiwan University. Professor, Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry. c Assistant Professor, Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry. b
Yang et al
132
Volume 111 Issue 2 To overcome this problem, a new selfadjusting magnetic attachment (SA) system that allows vertical and rotational movement was designed. The objective of this study was to use periodontal, prosthodontic, and participant satisfaction measures to evaluate the long-term clinical performance of removable prostheses with SAs. The null hypothesis was that no difference would be noted regarding the periodontal condition of abutment teeth with SAs or retained roots without SAs at the recall examinations.
MATERIAL AND METHODS The ethics board of Osaka University Dental Hospital approved this study. Sixteen participants (7 men and 9 women; age range: 45 to 86 years; mean: 66.8 years) with 22 SAs in 17 prostheses (Magfit SX2; Aichi Steel
Table I.
Corp) (Table I, Fig. 1) were enrolled in this study after giving informed consent. The predefined inclusion criteria were participants used their denture without problem, they experienced no disorder in their stomatognathic system or mucous membrane, and they were available for the periodic recall appointments. The design of the SA incorporates a movement allowance of up to 0.4 mm in vertical dimension and rotation up to 8 degrees. The SAs were placed on teeth with a healthy periodontal condition, and the crown to root ratio was reduced to avoid excessive occlusal force. In addition, to provide better support and stability for the removable dental prosthesis, the SA was placed on the tooth in the anterior or in the posterior part of the edentulous area. Posttreatment maintenance was scheduled every 3 months for up to 5 years (mean: 3.1 years). The same
operator measured the periodontal indices, recorded the prosthetic parameters, and completed the questionnaire of participant satisfaction with SAs throughout the study. Periodontal parameters such as probing depth (PD) with the CP11 probe and tooth mobility (TM) according to the Miller classification9 (scores from 1 to 3) were measured from the time of prostheses placement (baseline). Plaque accumulation on the SAs also was recorded. In addition, control data were collected from the remaining teeth, which were restored with resin or metal root coping (Fig. 2). Attrition, which is the surface wear of the SAs (without attrition: score 0; attrition area per total surface area of magnetic assemblies 25%: score 1; 50%: score 2; 75%: score 3; 100%: score 4), corrosion, loss of retention, and the
Data of study group
Participant No.
Observation Period (y)
Prosthesis* Agreed SR (n[17)
Sex
Age (y)
SA Abutment Teeth (n[22)
1
Man
77
Maxillary right canine, maxillary right first premolar
3
Overdenture
2
Man
65
Mandibular left canine, mandibular right canine
5
Overdenture
3
Woman
52
Maxillary left second molar, mandibular right second molar
4
Overdenture (maxilla and mandible)
4
Woman
64
Mandibular left central incisor, mandibular right central incisor
3
Overdenture
5
Woman
81
Mandibular right canine
4
Overdenture
6
Woman
67
Mandibular left first premolar, mandibular right canine
4
Overdenture
7
Man
71
Maxillary right canine
1
Overdenture
8
Man
58
Mandibular left second premolar
4
Class I partial RDP
9
Woman
76
Maxillary left second molar
3
Class I partial RDP
10
Woman
76
Maxillary left canine
1
Class I partial RDP
11
Man
55
Mandibular right second premolar
4
Class I partial RDP
12
Man
45
Mandibular right first premolar
5
Class I partial RDP
13
Woman
71
Mandibular right canine, mandibular right first premolar
0.5
Class I partial RDP
14
Woman
86
Mandibular right canine
1
15
Woman
66
Maxillary left central incisor
2
Class II partial RDP
16
Man
59
Maxillary right canine
5
Class IV partial RDP
Class I, modification 1 partial RDP
SA, self-adjusting magnetic attachment; Partial RDP, partial removable dental prosthesis. *Kennedy Classification
The Journal of Prosthetic Dentistry
Yang et al
February 2014
133 Movable assembly
Space: 0.4 mm Magnet Time of insertion
A
Movable assembly
Magnet Vertical movement
B Movable assembly
Magnet Rotation
C
1 Mechanics of self-adjusting magnetic attachment. A, Design incorporates movement allowance of up to 0.4 mm. B, In vertical dimension. C, Rotation up to 8 degrees.
participants regarding oral hygiene and the cleaning of the prosthesis. Toothbrushes, interdental brushes, dental floss, and denture-cleaning brushes were repeatedly provided during this study. Additional professional mechanical tooth cleaning was provided if required at the recall visit, and topical fluoride application also was performed during the follow-up period. Participants were asked to complete a questionnaire regarding the stability, comfort, and ease of cleaning their prostheses based on a visual analog scale (VAS). The Wilcoxon signed rank test was used to compare the change in the PD and TM of the SAs, and control teeth between the time of prostheses placement (baseline) and the last visit (after insertion) (a¼.05). One-way ANOVA was used to evaluate and compare the data from the VAS-based questionnaire on participant satisfaction (a¼.05). Software (SPSS 11.0; SPSS Inc) was used for the statistical analysis.
RESULTS Periodontal evaluation
2 Oral condition of self-adjusting magnetic attachments and control teeth in participant no. 2.
mobility allowance of the SAs were evaluated during clinical use. For corrosion assessment, the surface roughness and discoloration of the magnet in participants’ mouth were compared visually with a new magnetic attachment. For the retention assessment, the same operator assessed the resistance during the
Yang et al
insertion and the removal the denture. For the mobility assessment, the same operator assessed the capability of vertical and rotational movement in the magnetic assemblies. Prosthetic complications, such as fracture or repair, were also recorded during the period of follow-up. Instructions were provided for
Changes in the PD and TM of the SAs and the control teeth between baseline and after insertion are presented in Table II. No significant changes were noted in the PD of SA abutments (P¼.132) and control teeth (P¼.414). No significant change in TM was found in SA abutments (P¼.705) and control teeth (P¼.317), and no severe plaque accumulation that resulted in secondary caries on the SA abutments was found. One tooth was extracted because of a hopeless periapical lesion after 2 years of clinical use.
Prosthetic evaluation No corrosion was found on the assemblies of the SAs. The attrition of the SAs in the study was less than 25% (score 1) attrition area over the total contact surfaces of the magnet and keeper. This, however, did not influence the retention and movement allowance of the SA attachments. The bases of 6 prostheses
134
Volume 111 Issue 2 Periodontal evaluation of SA and control teeth (n¼22)
Table II.
After Baseline Insertion PD (mm) SA
3.05 0.72 3.27 0.77
Control
2.88 0.81 3.00 0.97
TM (score: 0-3) SA
0.36 0.49 0.32 0.48
Control
0.44 0.63 0.44 0.51
SA, self-adjusting magnetic attachment; PD, probing depth; TM, tooth mobility. There was no statistically significant difference between SAs and control teeth (P>.05).
were relined because of continuing alveolar bone resorption. Fracture lines were found over the SA area in 2 prostheses because of insufficient clearance of the antagonistic teeth.
Participant satisfaction with prostheses Although a high VAS score was noted for the “easy cleaning of the denture,” followed by “comfort of denture wear,” and “denture stability while using,” no significant difference was found in these factors (Fig. 3).
DISCUSSION After comparing SAs and control data collected from the remaining teeth, which were restored with resin or metal copping in the removal prostheses in this study,
Q1
the null hypothesis for the stability of the periodontal condition was not rejected; no significant difference was noted in the baseline and postinsertion PD and TM of SAs and control teeth. The occurrence of abutment tooth loss in participants with overdentures ranged from 1.5% to 14.3%,3,4 the causes being periodontal disease (29.3%), followed by periapical lesions (18.8%) and caries (16.5%) during long-term use.5 In this study, one of the abutments was lost because of a periapical lesion. A high VAS score with less deviation for satisfaction in easy cleaning was noted for the SAs, which may explain the stable periodontal condition and low frequency of secondary caries on abutment teeth. In this study, as indicated by Budtz-Jorgensen et al,10 regular maintenance, topical fluoride application, and oral hygiene instruction were considered important factors in the success rate. With overdentures with anterior teeth as abutments8 or removal prostheses with a posterior distal extension edentulous region, the prosthesis may rotate along the fulcrum line between the distal abutment teeth under functional loads. In this study, the attrition area of SAs was found to be less than 25% of the total contact surface, and there was no significant increase in PD and TM. The moveable assembly may have helped to compensate for the movement of the prostheses while the magnet and keeper of the SA were in constant contact. Due to the improvement of magnet attachment systems, Huang et al11 reported that the retentive force of the magnet did
Q2
Q3
VAS Score
100 80 60 40 20 0
3 Participant satisfaction with prostheses. No statistically significant differences (P>.05). Q1, denture stability while using; Q2, comfort of denture wear; and Q3, easy cleaning of the denture.
The Journal of Prosthetic Dentistry
not change significantly even after 9000 gliding cycles with clear abrasion. However, a low VAS score with a large deviation for denture stability may be explained by the vertical movement allowance of the SAs. Sufficient vertical space must be created to accommodate the keeper, the magnet, the denture space, and the prosthetic tooth.12 The fracture lines found in the 2 prostheses in this study also suggest the need for establishing indication criteria for SAs in relation to the clearance and reinforcement of the prosthesis. The location of natural teeth with SAs, which depended on the oral condition of the participants, may have limited this study. The sample size of this study was small, which also represents a limitation. Long-term observation is needed to evaluate the corrosion and attrition of SAs and their influence on retention. Further studies should enroll more participants with SAs.
CONCLUSIONS In spite of the limitations of this clinical study and with assuming regular dental maintenance, SAs can be used in prostheses without damaging the periodontal tissue of the abutment tooth.
REFERENCES 1. Gonda T, Yang TC, Maeda Y. Five-year multicenter study of magnetic attachments used for natural overdenture abutments. J Oral Rehabil 2013;40:258-62. 2. Toolson LB, Smith DE, Phillips C. A 2-year longitudinal study of overdenture patients. Part II: Assessment of the periodontal health of overdenture abutments. J Prosthet Dent 1982;47:4-11. 3. Reitz PV, Weiner MG, Levin B. An overdenture survey: preliminary report. J Prosthet Dent 1977;37:246-58. 4. Toolson LB, Taylor TD. A 10-year report of a longitudinal recall of overdenture patients. J Prosthet Dent 1989;62:179-81. 5. Ettinger RL, Qian F. Abutment tooth loss in patients with overdentures. J Am Dent Assoc 2004;135:739-46. 6. van Kampen F, Cune M, van der Bilt A, Bosman F. Retention and postinsertion maintenance of bar-clip, ball and magnet attachments in mandibular implant overdenture treatment: an in vivo comparison after 3 months of function. Clin Oral Implants Res 2003;14:720-6.
Yang et al
February 2014
135
7. Maeda Y. Criteria for abutment selection for implant overdenture. In: Maeda Y, Walmesly AD, editors. Implant dentistry with new generation magnetic attachments. Chicago: Quintessence; 2005. p. 32-5. 8. Maeda Y. Treatment concepts classified with number and location of implant. In: Maeda Y, Walmesly AD, editors. Implant dentistry with new generation magnetic attachments. Chicago: Quintessence; 2005. p. 40-2. 9. Salvi GE, Lindhe J, Lang NP. Examination of patients with periodontal disease. In: Lindhe J, Lang NP, Karring T, editors. Clinical periodontology and implant dentistry. 5th ed. Oxford: Blackwell Munksgaard; 2008. p. 573-86.
10. Budtz-Jorgensen E. Prognosis of overdenture abutments in elderly patients with controlled oral hygiene: a 5 year study. J Oral Rehabil 1995;22:3-8. 11. Huang Y, Tawada Y, Hata Y, Watanabe F. The change in retentive force of magnetic attachment by abrasion. Odontology 2008;96:65-8. 12. Vere J, Deans RF. Tooth-supported, magnetretained overdentures: a review. Dent Update 2009;36:305-10.
Corresponding author: Dr Yoshinobu Maeda Department of Prosthodontics, Gerodontology and Oral Rehabilitation Osaka University Graduate School of Dentistry 1-8 Yamadaoka Suita, Osaka 565-0871 JAPAN E-mail: [email protected] Copyright ª 2014 by the Editorial Council for The Journal of Prosthetic Dentistry.
Receive Tables of Contents by E-mail To receive tables of contents by e-mail, sign up through our Web site at http://www.journals.elsevierhealth.com/periodicals/ympr. Instructions Log on and click “Register” in the upper right-hand corner. After completing the registration process, click on “My Alerts,” then “Add Table of Contents Alert.” Select the category “Mosby” or type The Journal of Prosthetic Dentistry in the search field and click on the Journal title. The title will then appear, and having already completed the Registration process, you may add tables of contents alerts by accessing an issue of the Journal and clicking on the “Add TOC Alert” link. You will receive an e-mail message confirming that you have been added to the mailing list. Note that tables of contents e-mails will be sent when a new issue is posted to the Web site.
Yang et al