References from Steven Sadowsky’s ap presentation (5/2/09)



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References from Steven Sadowsky’s AP Presentation (5/2/09)


  1. Astrand P, Ahlqvist J, Gunne J, Nilson H. Clin Implant Dent Relat Res. 2008


Purpose: The aim was to investigate the outcome of implant treatment with fixed prostheses in edentulous jaws after 20 years, with special reference to survival rate of implants and prostheses and frequency of peri-implantitis. MATERIALS AND METHODS: The patient material was a group of patients treated in the early 1980s. The original patient group comprised the first 48 consecutive patients treated with implant-supported prostheses at Umeå University. All patients were edentulous in one or two jaws. The patients had a mean age at the implant insertion of 54.3 years (range 40-74). At the planning of this study 20 years after treatment, 19 of the 48 patients were found to be deceased. Of the 29 patients still alive, 21 patients with altogether 23 implant-supported prostheses could be examined clinically and radiographically. All patients were treated ad modum Brånemark (Nobel Biocare AB, Göteborg, Sweden) with a two-stage surgical procedure. The implants had a turned surface. Abutment connections were performed 3 to 4 months after fixture insertion in the mandible, and after a minimum of 6 months in the maxilla. The prostheses were fabricated with a framework of gold alloy and acrylic artificial teeth. RESULTS: The 21 patients (with 23 implant prostheses) examined had at the time of treatment got 123 implants (27 in the upper jaw and 96 in the lower jaw) inserted. Only one of these implants had been lost (about 2 years after loading) giving a survival rate of 99.2%. Very small changes occurred in the marginal bone level. Between the 1 and 20-year examinations, the mean bone loss was 0.53 mm and the mean bone level at the final examination was 2.33 mm below the reference point. CONCLUSIONS: This follow-up over two decades of implant-supported prostheses demonstrates a very good prognosis for the treatment performed. The frequencies of peri-implantitis, implant failures, or other complications were very small, and the original treatment concept with a two-stage surgery and a turned surface of the implants will obviously give very good results.

  1. Attard NJ, Zarb GA. 2004

  2. Jemt T, Johansson J. 2006 BACKGROUND: Few long-term follow-up studies are available on implant treatment based on patient level data related to time. PURPOSE: The aim of this study was to report 15-year patient-based data in relation to time of follow up after treatment with fixed prostheses supported by implants in the edentulous upper jaw. MATERIALS AND METHODS: Seventy-six edentulous consecutive patients, provided with 450 turned Brånemark implants, were followed up with regard to maintenance, complications, and radiographs taken during the follow-up period. RESULTS: Forty-four patients provided with 247 implants were lost to follow up. Patients followed up for 15 years showed as a group a trend of better implant survival than patients lost to follow up (p > .05). Altogether, 37 implants and 5 fixed prostheses failed during the follow-up period. Most implants were lost at abutment surgery (n- 15) and another nine during the first year of function. The 15-year implant and fixed prosthesis cumulative survival rate was 90.9 and 90.6%, respectively. Resin veneer fractures caused most problems, more frequent in the earlier stage while severe wear increased in the later stage of follow up. No implant fractures or loosening of abutment/bridge locking screws were noted. The mean marginal bone loss was 0.5 mm (SD 0.47) after 5 years, followed by only minimal average changes during the following years. No radiographic parameter showed any time-dependent relationship. The percentage of patients presenting at least one implant with more than 2.0-mm bone loss was 4.9% in the interval from 0 to 5 years and 4.0% between 10 and 15 years. Only 1.3% of implants showed >3.0 mm accumulated bone loss after 15 years. CONCLUSION: Implant treatment in the edentulous upper jaw functions well in a 15-year time perspective, but an insignificant trend of higher implant failures was observed for patients lost to follow up. Besides wear and fractures of veneers, no other parameter showed any time-related relationship, indicating an increased risk for more complications during later stages of follow up. However, accumulation of smaller amount of bone loss during the years resulted in an increasing number of implants and patients with bone levels below the third thread, which could be speculated to increase future maintenance after 15 years.

  3. Visser A, et al. IJP 2009;22:181-92. 10-y study on machined implants with 6-implant design for maxillary ioverdentures with 86% implant survival.

  4. Mericske-Stern R. JPD 1998;79:66-73. Joined a consensus with other authors recommending a minimum of 4 implants for a favorable palatelesss maxillary implant overdenture design.

  5. Eckert SE, Carr AB. DCNA 2004;48:585-601. Recommended 6 implants for a palateless design to insure against a catastrophic failure of the prosthesis, if there was an implant loss.

  6. Rodriquez, et al. Ann Periodontol 2000;5:101-8. 3-year study on bar retained maxillary implant overdentures with 94% implant survival, which included a minimum of 5-6 implants in their design criteria.

  7. Engquist B, et al. IJOMI 1988;3:129-34. 7-yr study on maxillary implant overdentures documenting 50% implant loss with 7mm machined implants and 30% loss with 10 mm machined implants.

  8. Narhi TO, et al. IJOMI 2001;16:259-66.

A 6-year study on maxillary implant overdentures with machined implants demonstrating a 90% implant survival with 12mm implants.

  1. Krennmair G, et al. IJOMI 2008;23:343-52. A 5-yr study on 13 mm textured implants either with 4 implants in anterior region with a cantilever milled bar or 6 implants posteriorly, augmenting sinuses bilaterally with a split milled bar, reporting 98% implant survival on anterior array and 97% implant survival when antra were grafted prior to implant placement.

  2. Ekfeldt A, Christiansson U, Eriksson T, Lindén U, Lundqvist S, Rundcrantz T, Johansson LA, Nilner K, Billström C. Clin Oral Implants Res 2001;12:462-7.

This retrospective study was designed to verify the factors that influence implant failures. Six prosthodontic clinics in Sweden participated in the study, and together they included a total of 54 patients treated between January 1988 and December 1996. All patients were completely edentulous in the maxilla, and received either a fixed prosthesis or an overdenture supported by at least 4 implants (Brånemark System). Half of the patients belonged to the study group, and an inclusion criterion for this group was that they had lost at least half of their implants. To reduce bias, the patients in the control group were matched to the study group, i.e. they were selected so that both groups were as identical as possible. The results of the study indicate that the control group had a better initial bone support than the study group. Furthermore, the patients in the study group suffered from circumstances that could induce implant failure, such as bruxism, personal grief, depression, as well as addictions to cigarettes, alcohol and/or narcotics. On the study form the clinicians were asked to give their own opinion of the reason for implant failure. The answers given could easily be grouped into 5 different topics, and this experience can be useful to improve patient selection. This study suggests that there are certain factors of importance to consider in preventing a cluster phenomenon of implant failures i.e. lack of bone support, heavy smoking habits and bruxism.

  1. Balshe AA, et al. IJOMI 2008;23:1117-22. A 5-yr. retrospective chart review demonstrating a difference in machined and oxidized implants as far as risk of implant failure(only machined) with smoking. He communicated to me that he has a follow-up study (which includes the edentulous population) on his data (in press) that shows a risk factor with implants 10 mm or less when machined, but no increase in failure rate with textured implants.

  2. Palmqvist S, et al. IJP 1994;9:184-90. Reported no relationship between implant survival and total length of implant array on maxillary implant overdentures, however, there was relationship with individual length and implant survival.

  3. Sadowsky SJ, Caputo AA. JPD 2000;84:327-34. Photoelastic study conducted at UCLA demonstrating inordinate stress transfer to terminal implant when a mandibular fixed implant complete denture was loaded on the cantilever. A similar magnified stress concentration on the distal implant was found when an overdenture was loaded on the first molar, if the extension base was not in intimate contact with the tissue.

  4. Fortin Y. Clin Implant Dent Relat Res 2002;4:69-77 Fortin offered a solution to the problem of anatomic limitations on the maxilla by recommending tilting terminal implants in a bar splinted array (Marius bridge) on the edentulous maxilla. He found 97% implant survival over 5 years. He offered that the terminal implants would be more optimally anchored if they were angled for more length. The additional advantage in this design would be minimizing the cantilevers, enhancing interfixture spread, while capitalizing on a longer terminal implant.

  5. Aparicio et al. Clin Oral Implants Res 2001;3:39-49. The authors compared angulated( >15 degrees) and axially placed implants during a 7-year follow-up study on the maxilla and found no difference in implant marginal bone height.

  6. Bellini CM, et al. Int J Prosthodont 2009;22:155-7.

Finite Element Analysis demonstrating biomechanical advantage of using tilted implants in edentulous maxilla compared to vertical implants.

  1. Trakas T, et al. Implant Dent 2006;15:24-34. Trankas and coauthors in their review article concluded that it appears there is no significant difference in mean bone loss between subjects restored with a ball or bar retained overdenture.

  2. Walton JN, Huizinga SC, Peck CC. Int J Prosthodont 1993;6:451-5.

Removable prostheses account for 78% of total repair vis avis fixed (4 to 1). Recommended divergent implants of more than 10 degrees should be splinted with a bar for an overdenture.

  1. Payne AG, et al. IJP 2000;13:246-53. Reported that bar designs offer the possibility of distalized support which can offer a stabilizing effect for a maxillary implant overdentures. Retrognathic patients would benefit from a cantilevered bar or attachment.

  2. Naert I, et al. JPD 1994;71:486-92.

In vivo demonstration of higher retention values with bar as compared to ball anchors when submitted to vertical and oblique forces.

  1. Petropolous VC, et al. IJOMI 1997;12:176-85.

In vitro demonstation of higher retention values with a bar versus ball anchors when submitted to vertical and oblique forces.

  1. Chung KH, et al. J Prosthodont 2004:13:221-6.

Implant angulation may compromise the retention of solitary anchors. However, with the parallel orientation of implants, Chung demonstrated that solitary attachment syatems such as ERA grey or the Locator white may match or exceed the Hader bar and metal clip which is in the range of 5 lbs. A laboratory study, by Williams BH, et al. (JPD 2001;86:603-7.) simulating an edentulous maxilla with 4 implants has also demonstrated improved retention of bar overdentures with distal ERA attachments rather than cantilevered bar with Hader clips.

  1. Ambard AJ, et al. J Am Dent Assoc 2002;133:1237-42. Found no differences in periimplant health between bar and ball design, if diligent homecare regimens followed and robust recall schedules are instituted.

  2. Keiner P, et al. Int J Prosthodont 2001;14:133-40.

Keiner and others have shown that most of the adjustments are required are in the first year and half of the adjustments were found in 1/5 of the patients.

  1. Goodacre CJ, et al. JPD 2003;90:121-32.

The authors found highest incidence of both implant failure (81%) and maintenance burden (30%) after his quasi meta analysis (pooled raw data). This is due to higher loading forces from the antagonist arch (natural teeth or fixed reconstruction) and limitations in vertical space often leading to compromises in the contour of the matrix, in an attempt to meet the demands of patient comfort and phonetics.

  1. Davis DM, et al. Eur J Prosthodont Restor Dent 2000;8:131-4. Bergendal T et al. 1998;13:253-62. Both researchers found that the most prevalent mechanical complication was the looseness or fracture of the attachment system.

  2. Ekfeldt A. et al. IJP 1997;10:366-74. The authors found that 62% of fractured retention systems were in bruxers.

  3. Jemt T, et al IJOMI 1995;10:303-11. The authors noted 24% of patients with maxillary implant overdentures needed a reline within the first year and 17% of the retention devices required adjustment and 22% experienced clip fractures.

  4. Smedberg JI, et al. Eur J Prosthodont Restor Dent 1999;7:51-6. The authors found 40% of max. overdentures required a reline before the 3 year mark.

  5. AbuJamra NF, et al. J Prosthodont 2000;9:102-5. The authors recommended a technique using silicone putty to mount the maxillary denture and mandibular denture and measure the vertical space available for the components and matrix of a maxillary implant overdenture.

  6. Phillips K, Wong KM. Compend Cont Educ Dent 2001;22:516-8. The vertical space of 8-9 mm for Locator/ ball attachment assembly and 12 mm for the bar/clip has been identified.

  7. Sadowsky SJ. J Calif Dent Assoc 1992;20:59-62. The fluid wax technique using Adaptol wax is elucidated in this article using 10 drops of vegetable oil per Adaptol stick for capturing the relationship of attachments and tissue relief.

  8. Bryant SR, et al. IJOMI 2007;(Suppl):117-39. Given task to determine if the prosthesis type is related to implant survival or aftercare burden. Concluded little evidence to support the contention that a fixed or removable prosthetic design could contribute to implant loss. However, exclusion criteria only allowed 3 overdenture articles. Bryant et al did allow for different maintenance demands.

  9. Ferrigno N, et al. Clin Oral Implants Res 2002;13:260-73. A prospective 10-year study comparing 4-implant Dolder bar design with 6-implant milled bar design and found 87% implant survival with Dolder bar design and 92% implant survival with milled bar. No report on maintenance differences.

  10. Jemt T, Carlsson L, Boss A, Jörneús L. IJOMI 1991;6:413-7.

In vivo load measurements on osseointegrated implants supporting fixed or removable prostheses: a comparative pilot study. Load was measured in vivo on a single terminal abutment cylinder by means of a strain gauge technique. The clinical measurements were made on one female patient (age 62) provided with six implants in the edentulous maxilla. A fixed prosthesis was tested initially, followed by an overdenture supported by a bar connected to the implants. The results indicated that a significant force could be introduced when connecting the framework. Furthermore, measurements showed that compression/tension forces were lower in the overdenture situation. However, the preliminary data also indicated relatively higher bending moments on the implant when the overdenture was loaded.

  1. Sadowsky SJ, Caputo A. J Prosthet Dent 2000;84:327-34. Photoelastic study which demonstrated the reduced bending moment on the terminal abutment under cantilever load with a milled bar as opposed to a Dolder bar.




  1. Benzing UR, et al. Int J Oral Maxillofac Implants 1995;10:188-98. A broadly distributed array of implants from ant./premolar region to tuberosity is more ideal than a concentrated array in anterior supporting a cantilever. Kramer [ ]has indicated 3X less stress on terminal abutment.

  2. Krennmair G. Int J Oral Maxillofac Implants 2008;23:343-52. Completed a 5-year retrospective study using 13 mm implants either in an anterior array(4 implants) with a continuous milled bar or posteriorly (6 implants total) with a split milled bar after sinus grafting. Results were encouraging-98% implant survival with anterior continuous bar, 97% with split bar on grafted region. The researchers also reported low maintenance.

  3. Dudic A, et al. Clin Implant Dent Relat Res 2002;4:212-9.

Seventy-five patients had a resilient retention device (ball anchors or a round clip bar); 44 patients had a rigid bar with or without distal extensions. The incidence and rate of complications were calculated for the overall- and for the 2- and 5-year observation periods. Comparisons were made between the three categories of maintenance and the two types of retention. A Kaplan-Meier analysis was applied for calculations of changes of the retention mechanism. RESULTS: The mean number of complications per overdenture during the entire observation period was 3.5; this did not differ statistically between the two retention groups. Some significant differences were found only for the 2- and 5- year period. Broken, loose, or lost female parts were more frequently observed with resilient devices, as were repairs and relining of the resin denture base, whereas tightening of bar retainers was more typical with rigid bars. A change from a resilient retention device to a rigid bar was performed more often than vice versa but not at a statistically significant level. CONCLUSION: Although these long-term results do not indicate a significant difference between the retention groups, a slight superiority of the rigid bar is suggested

  1. Krennmair G, Krainhöfner M, Piehslinger E. Int J Prosthodont. 2008 Nov-Dec;21(6):514-20. The aim of the present study was to evaluate the prosthodontic maintenance required for mandibular overdentures supported by 4 implants and splinted with either a round bar and resilient overdenture anchorage or a milled bar with rigid anchorage over a 5-year period. MATERIALS AND METHODS: In a randomized prospective trial, 51 edentulous patients received 4 mandibular interforaminal implants to support an overdenture and maxillary complete dentures. For the implant-supported overdentures (IODs), bar architecture and denture stabilization were chosen randomly; 25 patients received round bars (group 1) and resilient anchorage and 26 patients received milled bars (group 2) and rigid anchorage. The prosthodontic maintenance required for the IODs and opposing dentures were evaluated during a 5-year follow-up period and compared between the 2 retention modalities used for IODs. RESULTS: Forty-six patients (22 in group 1, 24 in group 2) were available for a 5-year follow-up (dropout rate: 9.8%). Prosthodontic maintenance efforts were significantly greater (P < .01) with the round bar design (group 1) than with the overdentures stabilized with milled bars (group 2). In group 1, prosthodontic maintenance efforts were more frequent in the early phase of use (1 to 2 years), as compared with an evenly distributed incidence over the 5-year period with the rigid milled bar system. Major prosthetic complications (IOD remaking, bar fracture) were only seen in cases without metal-reinforced frameworks (group 1). CONCLUSION: When 4 interforaminal implants are used to anchor mandibular overdentures, the design of the anchorage system will significantly affect prosthodontic maintenance efforts and complication rates. Rigid anchorage using milled bars and a metal-reinforced denture framework required less prosthodontic maintenance, ie, for clip activation/fracture, than resilient denture stabilization using multiple round bars without a rigid denture framework.

  2. Hahnel S, et al. J Prosthet Dent 2009;101:269-78. Researchers found differences in simulated wear of PMMA;IPN, DCL acrylic resin teeth, and filler modified composite resin depending on the material of the antagonist arch. Recommended also using more than one setting on the chewing simulators to mirror the in vivo condition.

  3. Heydecke G, et al. Clin Oral Implants Res 2003;14:125-30.

The authors used a crossover study to show preferences between fixed and removable implant prostheses on the maxilla. The overdenture design was favored 2 to 1 in 13 patients because of speech competency and hygiene access.

  1. de Albuquerque RF, et al. Clin Oral Implants Res 2000;11:555-65.

Authors conducted a crossover study that evaluated new complete dentures with implant overdentures with and without a palate. No differences in stability, retention, mastication, esthetics, and speech were reported for patients that had experience with dentures for 5 years, using a VAS to assess satisfaction (16 patients).

45. Henry PJ. JPD 1998;79:100-6. He noted only 7% of patients recruited for a study of maxillary implant overdentures were inclined to participate because of satisfaction with conventional maxillary dentures.


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