The Influence of Momentary Retention Forces on Patient Satisfaction and Quality of Life of Two-Implant–Retained Mandibular Overdenture Wearers Onur Geckili, PhD, DDS1/Altug Cilingir, PhD, DDS1/Ozge Erdogan, DDS2/ Aysun Coskun Kesoglu, DDS2/Caglar Bilmenoglu, DDS2/Arda Ozdiler, DDS2/Hakan Bilhan, PhD, DDS3 Purpose: The purpose of this study was to assess the influence of momentary retention forces on patient satisfaction and quality of life of two-implant–retained mandibular overdenture wearers. Materials and Methods: Edentulous patients who had been rehabilitated with two-implant–supported mandibular overdentures with single attachments and maxillary complete dentures at a university clinic were included in this study. The overdenture attachments were either ball or locator attachments. All the patients completed the Turkish version of the Oral Health Impact Profile-14 (OHIP-14) and the visual analog scale (VAS) satisfaction questionnaires. Momentary retention forces of the overdentures were measured using a custom-made dynamic testing machine. Results: Fifty-five patients were included in this study. No statistically significant association was detected between momentary retention forces and VAS scores (P > .05), but higher retention forces presented significantly better quality of life scores in the social disability and handicap domains of OHIP14 (P < .05). Conclusion: Within the limitations of this clinical study, it may be presumed that although higher instant retention force of an implant-retained overdenture provides better quality of life, it does not affect patient satisfaction. Int J Oral Maxillofac Implants 2015;30:397–402. doi: 10.11607/jomi.3774 Key words: interforaminal implants, mandibular overdenture, momentary retention forces, patient satisfaction, quality of life
B
eing edentulous is a handicap and negatively affects the quality of life of most patients.1 The traditional treatment of edentulism with conventional complete dentures is limited, mainly because of instability of the mandibular dentures, diminished chewing ability, and continuing bone resorption, particularly in the mandible.1–3 With the introduction of dental implants in the early 1980s, the compulsion to undergo conventional complete denture treatment has been eliminated for edentulous patients.1,2 It has been shown that the use of two to four implants to support a mandibular overdenture can be an effective treatment for edentulous patients who have persistent problems caused by a conventional mandibular denture.2,3 Furthermore, a 1 Associate
Professor, Istanbul University, Faculty of Dentistry, Department of Prosthodontics, Istanbul, Turkey. 2Doctoral Student, Istanbul University, Faculty of Dentistry, Department of Prosthodontics, Istanbul, Turkey. 3Associate Professor, Okan University, Faculty of Dentistry, Department of Prosthodontics, Istanbul, Turkey. Correspondence to: Associate Professor Dr Hakan Bilhan, Okan University, Faculty of Dentistry, Department of Prosthodontics, 34959 Tuzla-Istanbul, Turkey. Email: [email protected] ©2015 by Quintessence Publishing Co Inc.
panel of experts agreed that a two-implant–retained mandibular overdenture should become the first choice of treatment for the edentulous mandible in a symposium held at McGill University in 2002.3 It is well known that, compared to conventional mandibular complete dentures, two-implant–retained mandibular overdentures give rise to patient satisfaction and quality of life.2,4–6 Studies focusing on these measures often use visual analog scales (VAS), which measure perceptions of subjective phenomena for the evaluation of patient satisfaction,2,4–6 and an Oral Health Impact Profile (OHIP), which is a disease-specific measure of an individual’s perception of the social impact of oral disorders on their well-being for the evaluation of quality of life.2,7 A variety of attachment systems are used to connect implants to mandibular overdentures. Implants may be splinted or left unsplinted while connecting to the prosthesis.8 The selection of an attachment system is very important and plays a vital role in fulfilling the retention expectation of patients and minimizing postinsertion maintenance requirements.1,4 Therefore, evaluation of retention of the overdentures at the delivery of the prosthesis and after function could be beneficial for the clinicians because the attachment system could be adjusted according to the patients’ desires.9,10 The International Journal of Oral & Maxillofacial Implants 397
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Geckili et al
For the two-implant–retained mandibular overdentures, the most common attachment used has been the ball attachment.4,8 Some years ago, a new prefabricated self-aligning attachment system fitting most implant systems was introduced, the Locator attachments (Zest Anchors).11 The Locator system can be an alternative to ball attachments, especially when the interarch distance is insufficient for ball attachments’ matrices.4,11 Although patients report a strong preference for a more retentive prosthesis,9 the possible influence of momentary retention forces of two-implant–retained mandibular overdentures on patient satisfaction and quality of life has never been investigated to the authors’ knowledge. Therefore, this retrospective study was conducted to evaluate the potential influence of momentary retention forces on patient satisfaction and quality of life of two-implant–retained mandibular overdenture wearers.
MATERIALS AND METHODS Patient Selection
The study sample comprised all edentulous patients who were rehabilitated with two-implant–retained mandibular overdentures and maxillary complete dentures at a university clinic between 2010 and 2011. All patients were personally invited by mail or telephone to participate in this clinical examination. The requirements of the Helsinki Declaration were fulfilled, and the patients provided informed consent (reference no. 2597). As a routine in the present clinic, all patients treated with dental implants were invited for a recall session at 6 months and each year after loading. The included patients had been wearing the two-implant– retained mandibular overdenture for exactly 2 years, and no maintenance procedures had been employed for their prosthesis. To prevent a misleading result and to ensure evaluation of a homogenous group, patients having had any maintenance procedures at the firstyear recall appointment (minority) were excluded. Patient overdentures were of two types: two single interforaminal implants with ball attachments (n = 22) or two single interforaminal implants with Locator attachments (n = 33). Surgery had been performed as suggested by the implant manufacturer (Astra Tech) by an experienced oral and maxillofacial surgeon using a single-stage surgical protocol. The overdentures were fabricated by five specialists in prosthodontics using a standard prosthetic method12 that included balanced articulation with anatomically shaped acrylic resin teeth (Enigma, Davis Schottlander & Davis) and maximal extension of the denture base using functional impression methods
and were delivered to the patients exactly 1½ months after insertion of the implants, consistent with the early loading protocol.1,4 The implants were connected to the overdentures either by ball or Locator attachments, decided randomly using a lottery method at the time of the treatment by the specialists. Among the three retention inserts in different colors representing altered retention forces, the pink inserts were used for Locator attachments and the yellow Preci Clix inserts (Preat Precision Attachments) were used for the ball attachments, both of which provide medium retention.11
Measurement of the Momentary Retention Forces
The momentary retention forces were measured for each patient using a custom-made dynamic testing machine designed for the present study and calibrated previously under both in vitro and in vivo conditions. The machine consisted of two units: a manual test stand (SLJ Manual Test Stand, Wenzhou Sundoo Instruments), which was manufactured for various testing purposes such as tension/compression tests, insertion/withdrawing tests, and fracture tests; and a push/ pull force gauge calibrated for measurements between 0 and 100 N (SN-50 Force Gauge, Wenzhou Sundoo Instruments), which was attached to the manual test stand. The force gauge had a metal holder at the bottom part, which was fabricated from an aluminum alloy and contained a hole for attaching the specimens to be tested. A thermoplastic impression compound (Impression Compound, Kerr) was softened using hot water and applied to a mandibular metal stock impression tray (Dentsply Caulk). The two-implant–retained mandibular overdenture was positioned into the impression tray; after the impression compound was set, the tray with the overdenture stabilized with the impression compound was inserted in the patient’s mouth. The selected patient was positioned in a chair with the impression tray and two-implant–retained mandibular overdenture in his or her mouth, and the tray was screwed to the metal holder of the force gauge using an apparatus (Fig 1). The cyclical arm of the testing machine was turned to apply a vertical pull-out force to the tray until the two-implant–retained mandibular overdenture was separated from the abutments. The peak vertical force was recorded as the momentary retention force value.
Patient Satisfaction and Quality of Life Measurements
A satisfaction questionnaire recording seven aspects of patient satisfaction with the use of two-implant– retained mandibular overdentures using a 100-mm
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VAS was prepared. The scales were anchored by the extremes of potential responses (eg, completely satisfied and completely dissatisfied).13 The patients used the scales to record their personal opinions about the twoimplant–retained mandibular overdentures based on the following factors, respectively: general comfort, retention, chewing, speech, ease of hygiene maintenance, esthetics, and pain. For the assessment of quality of life, instead of the original OHIP consisting of 49 questions,14 the Turkish-language OHIP-14,15 which is a shorter and more patient-friendly version that covers the same seven domains (functional limitation, physical pain, psychologic discomfort, physical disability, psychologic disability, social disability, and handicap) as the original OHIP, was used in the present study. The five response options for each item were never, hardly ever, occasionally, fairly often, and very often. Items were scored on a 5-point scale ranging from 0 = never to 4 = very often. Lower scores presented higher quality of life.13 All the patients completed the Turkish version of OHIP-14 together with the VAS satisfaction questionnaire.
Statistical Analyses
For the statistical analysis of the results, SPSS (Statistical Package for Social Sciences) (Version 15.0 for Windows, SPSS) was used. The relevance of the parameters to the normal distribution was analyzed using the Kolmogorov-Smirnov test. Aside from descriptive statistics (means and standard deviations), the MannWhitney U test was used for the comparison of two group parameters. The relations between the parameters were evaluated using Spearman’s rho correlation analyses. The results were assessed at the 95% confidence interval, at a significance level of P < .05.
RESULTS Among the 98 edentulous patients who were rehabilitated with two-implant–retained mandibular overdentures and maxillary complete dentures in the stated time interval, 55 patients (31 women, 24 men; average age, 64.40 years; range, 55 to 72 years) were included in the study group. For the evaluation of the effect of age, the patients were divided into two groups: the patients older than 65 years comprised one group (n = 30), whereas the patients younger than 65 years comprised the other group (n = 25). There was no statistically significant association between VAS scores and patient age (P > .05; Table 1); whereas OHIP-14 scores showed a statistically significant difference among patient age in the physical disability domain. The physical disability scores of patients older than 65 years were found to
Fig 1 Measurement of the momentary retention forces.
be significantly higher than those of younger patients (P < .05). There was no statistically significant association between OHIP-14 total scores or the other domain scores and patient age (P > .05; see Table 1). There was no statistically significant association between VAS and OHIP-14 scores and patient sex (P > .05) except for the first question of the VAS, which addressed the general comfort of the patients, and the physical disability domain of OHIP-14. Female patients showed higher scores on the first question of VAS and lower physical disability domain scores on the OHIP-14 (P < .05; Table 2). Attachment types did not affect the VAS scores significantly (P > .05), whereas significantly lower scores were reported for the social disability and handicap domains of the OHIP-14 for patients using Locator attachments (P =.031 and P =.032, respectively). No other significant difference was detected between the attachment types related to the other domains of the OHIP-14 or the OHIP-14 total scores (P > .05). The momentary retention forces ranged from 0 to 18 N (mean, 10.39 N) and are shown in Fig 2. No significant association was detected between momentary retention forces and VAS scores (P > .05). However, higher momentary retention forces were associated with significantly lower social disability and handicap domain scores on the OHIP-14 (P =.029 and P =.030, respectively). No other significant association was detected between momentary retention forces and the OHIP-14 total and the remaining domains of OHIP-14 (P > .05). The International Journal of Oral & Maxillofacial Implants 399
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Table 1 Association Between VAS and OHIP-14 Scores and Patient Age Age < 65 y (n = 30) Mean ± SD (Median)
> 65 y (n = 25) Mean ± SD (Median)
P
Question 1
88.07 ± 21.42 (95)
83.24 ± 23.75 (93)
.375
Question 2
84.77 ± 20.61 (90)
81.60 ± 29.77 (94)
.340
Question 3
86.83 ± 20.32 (92.5)
85.84 ± 23.71 (94)
.558
Question 4
87.03 ± 21.27 (96)
87.56 ± 17.10 (95)
.757
VAS
Question 5
80.83 ± 26.26 (90)
80.84 ± 26.84 (94)
.871
Question 6
84.80 ± 20.09 (94)
93.28 ± 9.06 (98)
.144
Question 7
84.23 ± 20.29 (94)
82.28 ± 27.73 (98)
.403
OHIP-14 OHIP total
3.40 ± 5.61 (2)
4.72 ± 5.98 (2)
.412
Functional limitation
0.17 ± 0.46 (0)
0.20 ± 0.41 (0)
.554
Physical pain
1.07 ± 1.39 (1)
1.44 ± 1.71 (1)
.477
Psychologic discomfort
1.07 ± 1.64 (0.5)
1.32 ± 1.97 (0)
.985
Physical disability
0.63 ± 1.67 (0)
1.44 ± 2.08 (1)
.028*
Psychologic disability
0.27 ± 1.14 (0)
0.20 ± 0.58 (0)
.542
Social disability
0.10 ± 0.40 (0)
0.08 ± 0.40 (0)
.683
Handicap
0.10 ± 0.40 (0)
0.04 ± 0.20 (0)
.652
*P < .05
Table 2 Association Between VAS and OHIP-14 Scores and Patient Sex Sex VAS
Women (n = 31) Mean ± SD (Median)
Men (n = 24) Mean ± SD (Median)
P
Question 1
89.48 ± 20.48 (95)
82.37 ± 23.05 (89.5)
.027*
Question 2
87.97 ± 20.25 (95)
83.17 ± 25.15 (93.5)
.416
Question 3
84.35 ± 24.61 (93)
82.00 ± 25.94 (90)
.227
Question 4
84.97 ± 23.79 (100)
90.25 ± 11.00 (93.5)
.375
Question 5
83.48 ± 26.45 (95)
77.42 ± 26.21 (89)
.077
Question 6
86.77 ± 20.56 (98)
91.08 ± 8.65 (92.5)
.706
Question 7
82.16 ± 22.56 (95)
84.87 ± 25.61 (96.5)
.401
OHIP-14 OHIP total
3.45 ± 5.53 (2)
4.71 ± 6.10 (2.5)
.531
Functional limitation
0.13 ± 0.43 (0)
0.25 ± 0.44 (0)
.153
Physical pain
1.19 ± 1.40 (1)
1.29 ± 1.73 (1)
.823
Psychologic discomfort
1.10 ± 1.70 (0)
1.29 ± 1.92 (0)
.904
Physical disability
0.58 ± 1.67 (0)
1.54 ± 2.06 (1)
.011*
Psychologic disability
0.26 ± 1.12 (0)
0.21 ± 0.59 (0)
.485
Social disability
0.10 ± 0.40 (0)
0.08 ± 0.41 (0)
.730
Handicap
0.10 ± 0.40 (0)
0.04 ± 0.20 (0)
.698
*P < .05
DISCUSSION The mandibular two-implant–retained mandibular overdenture is a cost-effective treatment modality for the edentulous patient, and as the popularity of this
treatment increases, it is valuable to analyze the factors affecting its success in the long term. Although the patients are routinely recalled every year for evaluation of their two-implant–retained mandibular overdentures, the patients who had received
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no maintenance for their overdentures for 2 years were selected for the present study to provide uniform standards for all patients. Metal impression trays were preferred over plastic trays when measuring the retention forces in the present study to avoid deformation of the plastic during the pull-out tests. The retention and stability of the overdentures have been publicized as the most important factors for improving patient satisfaction.16,17 However, although the two-implant–retained mandibular overdentures of 20 subjects provided no retention (see Fig 2), the results of the present study showed no relationship between patient satisfaction and momentary retention forces. This result is in accordance with the results of Burns and colleagues,18 who had reported of equal patient satisfaction results in a prospective clinical trial. It has been found that after 6 to 12 months of use, the retention force values decrease to approximately 10% to 30%,19 and sufficient stabilization of the overdentures occurs even if the attachment systems provide 5- to 7-N retention forces.10 It should be emphasized that initial retention influences patient acceptance of the prosthesis.6 Present results show that after an adaptation period, the patients were usually satisfied with their two-implant–retained mandibular overdentures even if the retention was lost. This may be due to the sense of security with their prostheses because of the initial retention,7 as well as the effect of the abutments on the stability of the two-implant– retained mandibular overdentures even if the retention was lost. On the other hand, it should be noted that higher momentary retention forces caused better quality of life scores in the social disability and handicap domains, indicating that the patients having more retentive overdentures had been less embarrassed and uncomfortable because of problems with their prostheses. It should also be noted that retention is not the only factor affecting patient satisfaction, as highlighted previously,17 and additional studies should be conducted to improve these points. An interesting finding of the present study was the effect of age on quality of life. Although there was no association between age and patient satisfaction, which is in accordance with other studies,20–24 the physical disability domain scores of patients older than 65 years were significantly higher than those of younger patients, corresponding to lower quality of life. The OHIP-14 physical disability domain covers questions about disruption of meals and poor diet because of the two-implant–retained mandibular overdenture’s retention and stability.18 This effect may be attributed to the higher degree of mandibular atrophy, especially in the posterior regions, leading to intolerance to loading forces by the mucosa and eating problems in older subjects25,26; two-implant–retained mandibular
Momentary retention forces (N)
Geckili et al
20 18 16 14 12 10 8 6 4 2 0 0
10
20
30 Subjects
40
50
60
Fig 2 Momentary retention forces in the included subjects.
overdentures’ retention and stability are provided by both the mucosa and implants.18 In the present study, it was also demonstrated that women reported better physical disability scores on the OHIP-14 and higher satisfaction scores related to the overall treatment outcomes. This result supports the findings of Awad and Feine,20 who emphasized that patient satisfaction is highly dependent on gender, and women, in general, have a more positive view of removable dentures. However, it should be emphasized that when the samples were divided into two groups, the small sample size and unequal percentage of genders restricted comparison between men and women in the present study. The lower scores detected on the social disability and handicap domain scores of the OHIP-14 of the patients using Locator attachments, which corresponds to a better quality of life, are in accordance with a previous study.4 When the vertical space for placing ball attachments in a two-implant–retained mandibular overdenture was inadequate, the lingual part of the overdenture had to be overcontoured in the present study, and the tongue space may have been restricted, as stated previously.4 This might be the reason for the poorer quality of life results for those with ball attachments. However, it should be emphasized that the outcomes may have been affected by the quality of the dentures made by different operators, although all were qualified prosthodontists, rather than by the attachment system only. It should also be noted that because a validated Turkish version of the OHIP-EDENT was not available;,the Turkish OHIP-14 had to be used for assessing the quality of life in the present study, which may be regarded as a limitation. OHIP-EDENT is the shortened version of OHIP prepared for edentulous patients and has proven to be more appropriate for use in edentulism than OHIP-14.27 The International Journal of Oral & Maxillofacial Implants 401
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Geckili et al
CONCLUSIONS Within the limitations of this study, one may conclude that momentary retention of two-implant–retained mandibular overdentures does not affect patient satisfaction but provides better quality of life.
ACKNOWLEDGMENTS The authors would like to thank Enishan Ozcan, working as a PhD student in Istanbul Technical University Faculty of Mechanical Engineering, for his efforts in the production of the custom-made device for measuring the retention forces of the overdentures. The authors reported no conflicts of interest related to this study.
REFERENCES 1. Mericske-Stern RD, Taylor TD, Belser U. Management of the edentulous patient. Clin Oral Implants Res 2000;1:108–125. 2. Geckili O, Bilhan H, Mumcu E, Dayan C, Yabul A, Tuncer N. Comparison of patient satisfaction, quality of life, and bite force between elderly edentulous patients wearing mandibular two implantsupported overdentures and conventional complete dentures after 4 years. Spec Care Dentist 2012;32:136–141. 3. Feine JS, Carlsson GE, Awad MA, et al. The McGill consensus statement on overdentures. Mandibular two-implant overdentures as first choice standard of care for edentulous patients. Int J Oral Maxillofac Implants 2002;17:601–602. 4. Bilhan H, Geckili O, Sulun T, Bilgin T. A quality-of-life comparison between self-aligning and ball attachment systems for 2-implant-retained mandibular overdentures. J Oral Implantol 2011;37:167–173. 5. Allen PF, McMillan AS, Walshaw D. A patient-based assessment of implant-stabilized and conventional complete dentures. J Prosthet Dent 2001;85:141–147. 6. Awad MA, Lund JP, Dufresne E, Feine JS. Comparing the efficacy of mandibular implant-retained overdentures and conventional dentures among middle aged edentulous patients: Satisfaction and functional assessment. Int J Prosthodont 2003;16:117–122. 7. Cune M, van Kampen F, van der Bilt A, Bosman F. Patient satisfaction and preference with magnet, bar-clip, and ball-socket retained mandibular implant overdentures: A cross-over clinical trial. Int J Prosthodont 2005;18:99–105. 8. Krennmair G, Weinländer M, Krainhöfner M, Piehslinger E. Implantsupported mandibular overdentures retained with ball or telescopic crown attachments: A 3-year prospective study. Int J Prosthodont 2006;19:164–170. 9. Chung KH, Chung CY, Cagna DR, Cronin RJ. Retention characteristics of attachment systems for implant overdentures. J Prosthodont 2004;13:221–226.
10. Lehmann KM, Arnim Fv. Studies on the retention capability of push-button attachments [in German]. SSO Schweiz Monatsschr Zahnheilkd 1976;86:521–530. 11. Geckili O, Bilhan H, Bilgin T. Locator attachments as an alternative to ball attachments in 2-implant retained mandibular overdentures. J Can Dent Assoc 2007;73:679–682. 12. Zarb CA, Bolender C, Carlsson GE. Boucher’s Prosthodontic Treatment for Edentulous Patients, ed 11. St Louis: Mosby-Year Book, 1997. 13. Mumcu E, Bilhan H, Geckili O. The effect of attachment type and implant number on satisfaction and quality of life of mandibular implant-retained overdenture wearers. Gerodontology 2012;29: 618–623. 14. Slade GD, Spencer AJ. Development and evaluation of the Oral Health Impact Profile. Community Dent Health 1994;11:3–11. 15. Mumcu G, Inanc N, Ergun T, et al. Oral health related quality of life is affected by disease activity in Behcet’s disease. Oral Dis 2006;12: 145–151. 16. Burns DR, Unger JW, Elswick RK Jr, Giglio JA. Prospective clinical evaluation of mandibular implant overdentures. Part II: Patient satisfaction and preference. J Prosthet Dent 1995;73:364–369. 17. Naert I, Quirynen M, Theuniers G, van Steenberghe D. Prosthetic aspects of osseointegrated fixtures supporting overdentures. A 4-year report. J Prosthet Dent 1991;65:671–680. 18. Burns DR, Unger JW, Coffey JP, Waldrop TC, Elswick RK Jr. Randomized, prospective, clinical evaluation of prosthodontic modalities for mandibular implant overdenture treatment. J Prosthet Dent 2011;106:12–22. 19. Bayer S, Komor N, Kramer A, Albrecht D, Mericske-Stern R, Enkling N. Retention force of plastic clips on implant bars: A randomized controlled trial. Clin Oral Implants Res 2012;23:1377–1384. 20. Awad MA, Feine JS. Measuring patient satisfaction with mandibular prostheses. Community Dent Oral Epidemiol 1998;26:400–405. 21. van Waas MA. Determinants of dissatisfaction with dentures: A multiple regression analysis. J Prosthet Dent 1990;64:569–572. 22. MacEntee MI, Walton JN, Glick N. A clinical trial of patient satisfaction and prosthodontic needs with ball and bar attachments for implant-retained complete overdentures: Three-year results. J Prosthet Dent 2005;93:28–37. 23. Naert IE, Alsaadi G, Quirynen M. Prosthetic aspects and patient satisfaction with two-implant-retained mandibular overdentures: A 10-year randomized clinical study. Int J Prosthodont 2004;17:401–410. 24. Torres BL, Costa FO, Modena CM, Cota LO, Côrtes MI, Seraidarian PI. Association between personality traits and quality of life in patients treated with conventional mandibular dentures or implant-supported overdentures. J Oral Rehabil 2011;38:454–461. 25. Stellingsma C, Vissink A, Meijer HJ, Kuiper C, Raghoebar GM. Implantology and the severely resorbed edentulous mandible. Crit Rev Oral Biol Med 2004;15:240–248. 26. Oetterli M, Kiener P, Mericske-Stern R. A longitudinal study on mandibular implants supporting an overdenture: The influence of retention mechanism and anatomic-prosthetic variables on peri implant parameters. Int J Prosthodont 2001;14:536–542. 27. Allen F, Locker D. A modified short version of the oral health impact profile for assessing health-related quality of life in edentulous adults. Int J Prosthodont 2002;15:446–450.
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B
eing edentulous is a handicap and negatively affects the quality of life of most patients.1 The traditional treatment of edentulism with conventional complete dentures is limited, mainly because of instability of the mandibular dentures, diminished chewing ability, and continuing bone resorption, particularly in the mandible.1–3 With the introduction of dental implants in the early 1980s, the compulsion to undergo conventional complete denture treatment has been eliminated for edentulous patients.1,2 It has been shown that the use of two to four implants to support a mandibular overdenture can be an effective treatment for edentulous patients who have persistent problems caused by a conventional mandibular denture.2,3 Furthermore, a 1 Associate
Professor, Istanbul University, Faculty of Dentistry, Department of Prosthodontics, Istanbul, Turkey. 2Doctoral Student, Istanbul University, Faculty of Dentistry, Department of Prosthodontics, Istanbul, Turkey. 3Associate Professor, Okan University, Faculty of Dentistry, Department of Prosthodontics, Istanbul, Turkey. Correspondence to: Associate Professor Dr Hakan Bilhan, Okan University, Faculty of Dentistry, Department of Prosthodontics, 34959 Tuzla-Istanbul, Turkey. Email: [email protected] ©2015 by Quintessence Publishing Co Inc.
panel of experts agreed that a two-implant–retained mandibular overdenture should become the first choice of treatment for the edentulous mandible in a symposium held at McGill University in 2002.3 It is well known that, compared to conventional mandibular complete dentures, two-implant–retained mandibular overdentures give rise to patient satisfaction and quality of life.2,4–6 Studies focusing on these measures often use visual analog scales (VAS), which measure perceptions of subjective phenomena for the evaluation of patient satisfaction,2,4–6 and an Oral Health Impact Profile (OHIP), which is a disease-specific measure of an individual’s perception of the social impact of oral disorders on their well-being for the evaluation of quality of life.2,7 A variety of attachment systems are used to connect implants to mandibular overdentures. Implants may be splinted or left unsplinted while connecting to the prosthesis.8 The selection of an attachment system is very important and plays a vital role in fulfilling the retention expectation of patients and minimizing postinsertion maintenance requirements.1,4 Therefore, evaluation of retention of the overdentures at the delivery of the prosthesis and after function could be beneficial for the clinicians because the attachment system could be adjusted according to the patients’ desires.9,10 The International Journal of Oral & Maxillofacial Implants 397
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Geckili et al
For the two-implant–retained mandibular overdentures, the most common attachment used has been the ball attachment.4,8 Some years ago, a new prefabricated self-aligning attachment system fitting most implant systems was introduced, the Locator attachments (Zest Anchors).11 The Locator system can be an alternative to ball attachments, especially when the interarch distance is insufficient for ball attachments’ matrices.4,11 Although patients report a strong preference for a more retentive prosthesis,9 the possible influence of momentary retention forces of two-implant–retained mandibular overdentures on patient satisfaction and quality of life has never been investigated to the authors’ knowledge. Therefore, this retrospective study was conducted to evaluate the potential influence of momentary retention forces on patient satisfaction and quality of life of two-implant–retained mandibular overdenture wearers.
MATERIALS AND METHODS Patient Selection
The study sample comprised all edentulous patients who were rehabilitated with two-implant–retained mandibular overdentures and maxillary complete dentures at a university clinic between 2010 and 2011. All patients were personally invited by mail or telephone to participate in this clinical examination. The requirements of the Helsinki Declaration were fulfilled, and the patients provided informed consent (reference no. 2597). As a routine in the present clinic, all patients treated with dental implants were invited for a recall session at 6 months and each year after loading. The included patients had been wearing the two-implant– retained mandibular overdenture for exactly 2 years, and no maintenance procedures had been employed for their prosthesis. To prevent a misleading result and to ensure evaluation of a homogenous group, patients having had any maintenance procedures at the firstyear recall appointment (minority) were excluded. Patient overdentures were of two types: two single interforaminal implants with ball attachments (n = 22) or two single interforaminal implants with Locator attachments (n = 33). Surgery had been performed as suggested by the implant manufacturer (Astra Tech) by an experienced oral and maxillofacial surgeon using a single-stage surgical protocol. The overdentures were fabricated by five specialists in prosthodontics using a standard prosthetic method12 that included balanced articulation with anatomically shaped acrylic resin teeth (Enigma, Davis Schottlander & Davis) and maximal extension of the denture base using functional impression methods
and were delivered to the patients exactly 1½ months after insertion of the implants, consistent with the early loading protocol.1,4 The implants were connected to the overdentures either by ball or Locator attachments, decided randomly using a lottery method at the time of the treatment by the specialists. Among the three retention inserts in different colors representing altered retention forces, the pink inserts were used for Locator attachments and the yellow Preci Clix inserts (Preat Precision Attachments) were used for the ball attachments, both of which provide medium retention.11
Measurement of the Momentary Retention Forces
The momentary retention forces were measured for each patient using a custom-made dynamic testing machine designed for the present study and calibrated previously under both in vitro and in vivo conditions. The machine consisted of two units: a manual test stand (SLJ Manual Test Stand, Wenzhou Sundoo Instruments), which was manufactured for various testing purposes such as tension/compression tests, insertion/withdrawing tests, and fracture tests; and a push/ pull force gauge calibrated for measurements between 0 and 100 N (SN-50 Force Gauge, Wenzhou Sundoo Instruments), which was attached to the manual test stand. The force gauge had a metal holder at the bottom part, which was fabricated from an aluminum alloy and contained a hole for attaching the specimens to be tested. A thermoplastic impression compound (Impression Compound, Kerr) was softened using hot water and applied to a mandibular metal stock impression tray (Dentsply Caulk). The two-implant–retained mandibular overdenture was positioned into the impression tray; after the impression compound was set, the tray with the overdenture stabilized with the impression compound was inserted in the patient’s mouth. The selected patient was positioned in a chair with the impression tray and two-implant–retained mandibular overdenture in his or her mouth, and the tray was screwed to the metal holder of the force gauge using an apparatus (Fig 1). The cyclical arm of the testing machine was turned to apply a vertical pull-out force to the tray until the two-implant–retained mandibular overdenture was separated from the abutments. The peak vertical force was recorded as the momentary retention force value.
Patient Satisfaction and Quality of Life Measurements
A satisfaction questionnaire recording seven aspects of patient satisfaction with the use of two-implant– retained mandibular overdentures using a 100-mm
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Geckili et al
VAS was prepared. The scales were anchored by the extremes of potential responses (eg, completely satisfied and completely dissatisfied).13 The patients used the scales to record their personal opinions about the twoimplant–retained mandibular overdentures based on the following factors, respectively: general comfort, retention, chewing, speech, ease of hygiene maintenance, esthetics, and pain. For the assessment of quality of life, instead of the original OHIP consisting of 49 questions,14 the Turkish-language OHIP-14,15 which is a shorter and more patient-friendly version that covers the same seven domains (functional limitation, physical pain, psychologic discomfort, physical disability, psychologic disability, social disability, and handicap) as the original OHIP, was used in the present study. The five response options for each item were never, hardly ever, occasionally, fairly often, and very often. Items were scored on a 5-point scale ranging from 0 = never to 4 = very often. Lower scores presented higher quality of life.13 All the patients completed the Turkish version of OHIP-14 together with the VAS satisfaction questionnaire.
Statistical Analyses
For the statistical analysis of the results, SPSS (Statistical Package for Social Sciences) (Version 15.0 for Windows, SPSS) was used. The relevance of the parameters to the normal distribution was analyzed using the Kolmogorov-Smirnov test. Aside from descriptive statistics (means and standard deviations), the MannWhitney U test was used for the comparison of two group parameters. The relations between the parameters were evaluated using Spearman’s rho correlation analyses. The results were assessed at the 95% confidence interval, at a significance level of P < .05.
RESULTS Among the 98 edentulous patients who were rehabilitated with two-implant–retained mandibular overdentures and maxillary complete dentures in the stated time interval, 55 patients (31 women, 24 men; average age, 64.40 years; range, 55 to 72 years) were included in the study group. For the evaluation of the effect of age, the patients were divided into two groups: the patients older than 65 years comprised one group (n = 30), whereas the patients younger than 65 years comprised the other group (n = 25). There was no statistically significant association between VAS scores and patient age (P > .05; Table 1); whereas OHIP-14 scores showed a statistically significant difference among patient age in the physical disability domain. The physical disability scores of patients older than 65 years were found to
Fig 1 Measurement of the momentary retention forces.
be significantly higher than those of younger patients (P < .05). There was no statistically significant association between OHIP-14 total scores or the other domain scores and patient age (P > .05; see Table 1). There was no statistically significant association between VAS and OHIP-14 scores and patient sex (P > .05) except for the first question of the VAS, which addressed the general comfort of the patients, and the physical disability domain of OHIP-14. Female patients showed higher scores on the first question of VAS and lower physical disability domain scores on the OHIP-14 (P < .05; Table 2). Attachment types did not affect the VAS scores significantly (P > .05), whereas significantly lower scores were reported for the social disability and handicap domains of the OHIP-14 for patients using Locator attachments (P =.031 and P =.032, respectively). No other significant difference was detected between the attachment types related to the other domains of the OHIP-14 or the OHIP-14 total scores (P > .05). The momentary retention forces ranged from 0 to 18 N (mean, 10.39 N) and are shown in Fig 2. No significant association was detected between momentary retention forces and VAS scores (P > .05). However, higher momentary retention forces were associated with significantly lower social disability and handicap domain scores on the OHIP-14 (P =.029 and P =.030, respectively). No other significant association was detected between momentary retention forces and the OHIP-14 total and the remaining domains of OHIP-14 (P > .05). The International Journal of Oral & Maxillofacial Implants 399
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Geckili et al
Table 1 Association Between VAS and OHIP-14 Scores and Patient Age Age < 65 y (n = 30) Mean ± SD (Median)
> 65 y (n = 25) Mean ± SD (Median)
P
Question 1
88.07 ± 21.42 (95)
83.24 ± 23.75 (93)
.375
Question 2
84.77 ± 20.61 (90)
81.60 ± 29.77 (94)
.340
Question 3
86.83 ± 20.32 (92.5)
85.84 ± 23.71 (94)
.558
Question 4
87.03 ± 21.27 (96)
87.56 ± 17.10 (95)
.757
VAS
Question 5
80.83 ± 26.26 (90)
80.84 ± 26.84 (94)
.871
Question 6
84.80 ± 20.09 (94)
93.28 ± 9.06 (98)
.144
Question 7
84.23 ± 20.29 (94)
82.28 ± 27.73 (98)
.403
OHIP-14 OHIP total
3.40 ± 5.61 (2)
4.72 ± 5.98 (2)
.412
Functional limitation
0.17 ± 0.46 (0)
0.20 ± 0.41 (0)
.554
Physical pain
1.07 ± 1.39 (1)
1.44 ± 1.71 (1)
.477
Psychologic discomfort
1.07 ± 1.64 (0.5)
1.32 ± 1.97 (0)
.985
Physical disability
0.63 ± 1.67 (0)
1.44 ± 2.08 (1)
.028*
Psychologic disability
0.27 ± 1.14 (0)
0.20 ± 0.58 (0)
.542
Social disability
0.10 ± 0.40 (0)
0.08 ± 0.40 (0)
.683
Handicap
0.10 ± 0.40 (0)
0.04 ± 0.20 (0)
.652
*P < .05
Table 2 Association Between VAS and OHIP-14 Scores and Patient Sex Sex VAS
Women (n = 31) Mean ± SD (Median)
Men (n = 24) Mean ± SD (Median)
P
Question 1
89.48 ± 20.48 (95)
82.37 ± 23.05 (89.5)
.027*
Question 2
87.97 ± 20.25 (95)
83.17 ± 25.15 (93.5)
.416
Question 3
84.35 ± 24.61 (93)
82.00 ± 25.94 (90)
.227
Question 4
84.97 ± 23.79 (100)
90.25 ± 11.00 (93.5)
.375
Question 5
83.48 ± 26.45 (95)
77.42 ± 26.21 (89)
.077
Question 6
86.77 ± 20.56 (98)
91.08 ± 8.65 (92.5)
.706
Question 7
82.16 ± 22.56 (95)
84.87 ± 25.61 (96.5)
.401
OHIP-14 OHIP total
3.45 ± 5.53 (2)
4.71 ± 6.10 (2.5)
.531
Functional limitation
0.13 ± 0.43 (0)
0.25 ± 0.44 (0)
.153
Physical pain
1.19 ± 1.40 (1)
1.29 ± 1.73 (1)
.823
Psychologic discomfort
1.10 ± 1.70 (0)
1.29 ± 1.92 (0)
.904
Physical disability
0.58 ± 1.67 (0)
1.54 ± 2.06 (1)
.011*
Psychologic disability
0.26 ± 1.12 (0)
0.21 ± 0.59 (0)
.485
Social disability
0.10 ± 0.40 (0)
0.08 ± 0.41 (0)
.730
Handicap
0.10 ± 0.40 (0)
0.04 ± 0.20 (0)
.698
*P < .05
DISCUSSION The mandibular two-implant–retained mandibular overdenture is a cost-effective treatment modality for the edentulous patient, and as the popularity of this
treatment increases, it is valuable to analyze the factors affecting its success in the long term. Although the patients are routinely recalled every year for evaluation of their two-implant–retained mandibular overdentures, the patients who had received
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no maintenance for their overdentures for 2 years were selected for the present study to provide uniform standards for all patients. Metal impression trays were preferred over plastic trays when measuring the retention forces in the present study to avoid deformation of the plastic during the pull-out tests. The retention and stability of the overdentures have been publicized as the most important factors for improving patient satisfaction.16,17 However, although the two-implant–retained mandibular overdentures of 20 subjects provided no retention (see Fig 2), the results of the present study showed no relationship between patient satisfaction and momentary retention forces. This result is in accordance with the results of Burns and colleagues,18 who had reported of equal patient satisfaction results in a prospective clinical trial. It has been found that after 6 to 12 months of use, the retention force values decrease to approximately 10% to 30%,19 and sufficient stabilization of the overdentures occurs even if the attachment systems provide 5- to 7-N retention forces.10 It should be emphasized that initial retention influences patient acceptance of the prosthesis.6 Present results show that after an adaptation period, the patients were usually satisfied with their two-implant–retained mandibular overdentures even if the retention was lost. This may be due to the sense of security with their prostheses because of the initial retention,7 as well as the effect of the abutments on the stability of the two-implant– retained mandibular overdentures even if the retention was lost. On the other hand, it should be noted that higher momentary retention forces caused better quality of life scores in the social disability and handicap domains, indicating that the patients having more retentive overdentures had been less embarrassed and uncomfortable because of problems with their prostheses. It should also be noted that retention is not the only factor affecting patient satisfaction, as highlighted previously,17 and additional studies should be conducted to improve these points. An interesting finding of the present study was the effect of age on quality of life. Although there was no association between age and patient satisfaction, which is in accordance with other studies,20–24 the physical disability domain scores of patients older than 65 years were significantly higher than those of younger patients, corresponding to lower quality of life. The OHIP-14 physical disability domain covers questions about disruption of meals and poor diet because of the two-implant–retained mandibular overdenture’s retention and stability.18 This effect may be attributed to the higher degree of mandibular atrophy, especially in the posterior regions, leading to intolerance to loading forces by the mucosa and eating problems in older subjects25,26; two-implant–retained mandibular
Momentary retention forces (N)
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20 18 16 14 12 10 8 6 4 2 0 0
10
20
30 Subjects
40
50
60
Fig 2 Momentary retention forces in the included subjects.
overdentures’ retention and stability are provided by both the mucosa and implants.18 In the present study, it was also demonstrated that women reported better physical disability scores on the OHIP-14 and higher satisfaction scores related to the overall treatment outcomes. This result supports the findings of Awad and Feine,20 who emphasized that patient satisfaction is highly dependent on gender, and women, in general, have a more positive view of removable dentures. However, it should be emphasized that when the samples were divided into two groups, the small sample size and unequal percentage of genders restricted comparison between men and women in the present study. The lower scores detected on the social disability and handicap domain scores of the OHIP-14 of the patients using Locator attachments, which corresponds to a better quality of life, are in accordance with a previous study.4 When the vertical space for placing ball attachments in a two-implant–retained mandibular overdenture was inadequate, the lingual part of the overdenture had to be overcontoured in the present study, and the tongue space may have been restricted, as stated previously.4 This might be the reason for the poorer quality of life results for those with ball attachments. However, it should be emphasized that the outcomes may have been affected by the quality of the dentures made by different operators, although all were qualified prosthodontists, rather than by the attachment system only. It should also be noted that because a validated Turkish version of the OHIP-EDENT was not available;,the Turkish OHIP-14 had to be used for assessing the quality of life in the present study, which may be regarded as a limitation. OHIP-EDENT is the shortened version of OHIP prepared for edentulous patients and has proven to be more appropriate for use in edentulism than OHIP-14.27 The International Journal of Oral & Maxillofacial Implants 401
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Geckili et al
CONCLUSIONS Within the limitations of this study, one may conclude that momentary retention of two-implant–retained mandibular overdentures does not affect patient satisfaction but provides better quality of life.
ACKNOWLEDGMENTS The authors would like to thank Enishan Ozcan, working as a PhD student in Istanbul Technical University Faculty of Mechanical Engineering, for his efforts in the production of the custom-made device for measuring the retention forces of the overdentures. The authors reported no conflicts of interest related to this study.
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10. Lehmann KM, Arnim Fv. Studies on the retention capability of push-button attachments [in German]. SSO Schweiz Monatsschr Zahnheilkd 1976;86:521–530. 11. Geckili O, Bilhan H, Bilgin T. Locator attachments as an alternative to ball attachments in 2-implant retained mandibular overdentures. J Can Dent Assoc 2007;73:679–682. 12. Zarb CA, Bolender C, Carlsson GE. Boucher’s Prosthodontic Treatment for Edentulous Patients, ed 11. St Louis: Mosby-Year Book, 1997. 13. Mumcu E, Bilhan H, Geckili O. The effect of attachment type and implant number on satisfaction and quality of life of mandibular implant-retained overdenture wearers. Gerodontology 2012;29: 618–623. 14. Slade GD, Spencer AJ. Development and evaluation of the Oral Health Impact Profile. Community Dent Health 1994;11:3–11. 15. Mumcu G, Inanc N, Ergun T, et al. Oral health related quality of life is affected by disease activity in Behcet’s disease. Oral Dis 2006;12: 145–151. 16. Burns DR, Unger JW, Elswick RK Jr, Giglio JA. Prospective clinical evaluation of mandibular implant overdentures. Part II: Patient satisfaction and preference. J Prosthet Dent 1995;73:364–369. 17. Naert I, Quirynen M, Theuniers G, van Steenberghe D. Prosthetic aspects of osseointegrated fixtures supporting overdentures. A 4-year report. J Prosthet Dent 1991;65:671–680. 18. Burns DR, Unger JW, Coffey JP, Waldrop TC, Elswick RK Jr. Randomized, prospective, clinical evaluation of prosthodontic modalities for mandibular implant overdenture treatment. J Prosthet Dent 2011;106:12–22. 19. Bayer S, Komor N, Kramer A, Albrecht D, Mericske-Stern R, Enkling N. Retention force of plastic clips on implant bars: A randomized controlled trial. Clin Oral Implants Res 2012;23:1377–1384. 20. Awad MA, Feine JS. Measuring patient satisfaction with mandibular prostheses. Community Dent Oral Epidemiol 1998;26:400–405. 21. van Waas MA. Determinants of dissatisfaction with dentures: A multiple regression analysis. J Prosthet Dent 1990;64:569–572. 22. MacEntee MI, Walton JN, Glick N. A clinical trial of patient satisfaction and prosthodontic needs with ball and bar attachments for implant-retained complete overdentures: Three-year results. J Prosthet Dent 2005;93:28–37. 23. Naert IE, Alsaadi G, Quirynen M. Prosthetic aspects and patient satisfaction with two-implant-retained mandibular overdentures: A 10-year randomized clinical study. Int J Prosthodont 2004;17:401–410. 24. Torres BL, Costa FO, Modena CM, Cota LO, Côrtes MI, Seraidarian PI. Association between personality traits and quality of life in patients treated with conventional mandibular dentures or implant-supported overdentures. J Oral Rehabil 2011;38:454–461. 25. Stellingsma C, Vissink A, Meijer HJ, Kuiper C, Raghoebar GM. Implantology and the severely resorbed edentulous mandible. Crit Rev Oral Biol Med 2004;15:240–248. 26. Oetterli M, Kiener P, Mericske-Stern R. A longitudinal study on mandibular implants supporting an overdenture: The influence of retention mechanism and anatomic-prosthetic variables on peri implant parameters. Int J Prosthodont 2001;14:536–542. 27. Allen F, Locker D. A modified short version of the oral health impact profile for assessing health-related quality of life in edentulous adults. Int J Prosthodont 2002;15:446–450.
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