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Prosthetics May Not Affect the Survival or Complication Rates of Short Implants
PROGNOSIS
ARTICLE ANALYSIS
AND
EVALUATION
Prosthetics May Not Affect the Survival or Complication Rates of Short Implants ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION
SUMMARY Subjects
4
The study group consisted of 109 patients, 44 men and 65 women, with a mean age of 53.6 years (range 22 to 80 years), consecutively treated and followed since June 1994. All had limited bone height, mostly in the posterior areas of the jaws. All patients were rehabilitated with implantsupported fixed restorations. Two hundred sixty two machine-surfaced short implants (10 mm or shorter) supporting 123 fixed prostheses were included in this case series study. The majority of the short implants (88.5%) were in the mandible, and in premolar or molar sites (98.5%). All restorations were porcelain-fused-to-metal crowns/units. Seventy-eight restorations were screw-retained and 33 were cemented. The patients were followed for 12 to 108 months (mean 53 months).
PURPOSE/QUESTION
Exposure
Influence of prosthetic parameters on the survival and complication rates of short implants. Tawil G, Aboujaoude N, Younan R. Int J Oral Maxillofac Implants 2006;21(2): 275-82.
LEVEL OF EVIDENCE
To determine the influence of prosthetic factors on the survival and complication rates of short implants.
SOURCE OF FUNDING Information not available
TYPE OF STUDY/DESIGN Case series
The following prosthetic variables were assessed clinically: the buccolingual width of the occlusal table, the maxillo-mandibular occlusal relationship, the nature of the opposing dentition, and the presence of parafunction. Periapical radiographs were obtained using a noncustomized paralleling device to evaluate the following prosthetic parameters: the crown height (C), the implant length (I) and the crown/implant (C/I) ratio, the mesiodistal length of the prosthetic restoration (measured at both the crown level and the implant level), and the mesial or distal cantilever length.
Main Outcome Measure Peri-implant bone loss was assessed by comparing periapical radiographs at abutment connection and those at the last follow-up visit. Biomechanical complications (including screw loosening, component fracture, veneer fracture, fixation or abutment screw loosening, implant loss, or loss of osseointegration) were recorded.
Main Results Two implants failed (one was fractured and the other lost osseointegration after 7 years of function). Complications were observed in 15% of the patients. None of the measured factors had a significant impact on the complication rates. No statistically significant difference was found in peri-implant bone loss between different C/I ratio groups, occlusal table widths, occlusal relationships, bruxing habits, mesiodistal length of the restorations, as well as mesial and distal cantilevers. However, a higher incidence of complications was observed in the bruxer group. The bruxer group contained 22.6% of the patients but comprised 50% of the veneering fractures. The fractured implant was also in a patient with severe bruxism. J Evid Base Dent Pract 2007;7:123-124 1532-3382/$35.00 © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jebdp.2007.06.002
Conclusions Although more serious complications occurred in the bruxer group, there was no statistical difference in the rate of complications in the different
JOURNAL OF EVIDENCE-BASED DENTAL PRACTICE
bruxism groups examined. Neither did any of the other measured factors affect peri-implant bone loss or biomechanical failure.
COMMENTARY AND ANALYSIS The lack of adequate bone height to place dental implants is a common clinical occurrence. One approach in such circumstances is to place short implants, and more information on the factors determining success for such short implants has the potential to significantly impact clinician decision making. The authors concluded that prosthetic parameters (such as C/I ratio, mesiodistal dimension of the prostheses, cantilever, occlusal table width, occlusion pattern, bruxism) had no effect on periimplant bone loss or complication rates, although more severe complications were observed grouping the implants placed in individuals with bruxism. A limitation in the present study is the potential for lack of power. With few implant failures (2 based on the description in the text), inadequate power was available to reliably answer the many questions that were raised. There were more biomechanical complications, but still, power may have been lacking to address several important questions. In addition, the short follow-up further compromised the ability to provide reliable answers. It is indeed valuable to see how well the short implants performed over a relatively long (mean 53 months) period of time. However, this overall high success rate decreased power. In addition, one should also be aware that a significant number of patients (29 of 109) and implants (63 of 262) were not followed in the last recall visit. Therefore, the strength of the data is compromised. Since the majority of the patients (96.6%) in this study received single or splinted crowns as their final restorations, it is more appropriate to apply the conclusions for single or splinted crowns (verses fixed partial dentures) on short implants. The occlusal considerations, such as cantilever and bruxism, have been controversial topics in dental implan-
124
tology. Clinical practice guideline is mainly based on case reports, nonsystematic reviews, or experts’ opinions, rather than evidence generated from high-quality studies and systematic reviews. Bruxism has been suggested as being related to higher implant failure rates and complication rates.1-3 However, a definitive cause-and-effect relationship between bruxism and implant failure has not yet been proved. In line with previously published papers, in this study more severe complications occurred among individuals with signs of bruxism (veneering porcelain fracture and implant fracture) although statistical analysis failed to show significant difference. Nevertheless, a careful approach has been recommended by various authors when treating patients with bruxism.4-6
REFERENCES 1. Engel E, Weber H. Treatment of edentulous patients with temporomandibular disorders with implant-supported overdentures. Int J Oral Maxillofac Implants 1995;10:759-64. 2. Gittelson G. Occlusion, bruxism, and dental implants: diagnosis and treatment for success. Dent Implantol Update 2005;16:17-24. 3. Williamson R. Postoperative care for patients with implant prostheses. J Am Dent Assoc 2000;131:523-4. 4. Kim Y, Oh TJ, Misch CE, Wang HL. Occlusal considerations in implant therapy: clinical guidelines with biomechanical rationale. Clin Oral Implants Res 2005;16(1):26-35. 5. Misch CE. The effect of bruxism on treatment planning for dental implants. Dent Today 2002;21(9):76-81. 6. Lobbezoo F, Brouwers JEIG, Cune MS, Naeije M. Dental implants in patients with bruxing habits. J Oral Rehabil 2006;32:152-9.
REVIEWER Hai Zhang, DMD, PhD Department of Restorative Dentistry University of Washington NE Pacific Street Box 357456 Seattle, WA 98195-7456 [email protected]
September 2007
ARTICLE ANALYSIS
AND
EVALUATION
Prosthetics May Not Affect the Survival or Complication Rates of Short Implants ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION
SUMMARY Subjects
4
The study group consisted of 109 patients, 44 men and 65 women, with a mean age of 53.6 years (range 22 to 80 years), consecutively treated and followed since June 1994. All had limited bone height, mostly in the posterior areas of the jaws. All patients were rehabilitated with implantsupported fixed restorations. Two hundred sixty two machine-surfaced short implants (10 mm or shorter) supporting 123 fixed prostheses were included in this case series study. The majority of the short implants (88.5%) were in the mandible, and in premolar or molar sites (98.5%). All restorations were porcelain-fused-to-metal crowns/units. Seventy-eight restorations were screw-retained and 33 were cemented. The patients were followed for 12 to 108 months (mean 53 months).
PURPOSE/QUESTION
Exposure
Influence of prosthetic parameters on the survival and complication rates of short implants. Tawil G, Aboujaoude N, Younan R. Int J Oral Maxillofac Implants 2006;21(2): 275-82.
LEVEL OF EVIDENCE
To determine the influence of prosthetic factors on the survival and complication rates of short implants.
SOURCE OF FUNDING Information not available
TYPE OF STUDY/DESIGN Case series
The following prosthetic variables were assessed clinically: the buccolingual width of the occlusal table, the maxillo-mandibular occlusal relationship, the nature of the opposing dentition, and the presence of parafunction. Periapical radiographs were obtained using a noncustomized paralleling device to evaluate the following prosthetic parameters: the crown height (C), the implant length (I) and the crown/implant (C/I) ratio, the mesiodistal length of the prosthetic restoration (measured at both the crown level and the implant level), and the mesial or distal cantilever length.
Main Outcome Measure Peri-implant bone loss was assessed by comparing periapical radiographs at abutment connection and those at the last follow-up visit. Biomechanical complications (including screw loosening, component fracture, veneer fracture, fixation or abutment screw loosening, implant loss, or loss of osseointegration) were recorded.
Main Results Two implants failed (one was fractured and the other lost osseointegration after 7 years of function). Complications were observed in 15% of the patients. None of the measured factors had a significant impact on the complication rates. No statistically significant difference was found in peri-implant bone loss between different C/I ratio groups, occlusal table widths, occlusal relationships, bruxing habits, mesiodistal length of the restorations, as well as mesial and distal cantilevers. However, a higher incidence of complications was observed in the bruxer group. The bruxer group contained 22.6% of the patients but comprised 50% of the veneering fractures. The fractured implant was also in a patient with severe bruxism. J Evid Base Dent Pract 2007;7:123-124 1532-3382/$35.00 © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jebdp.2007.06.002
Conclusions Although more serious complications occurred in the bruxer group, there was no statistical difference in the rate of complications in the different
JOURNAL OF EVIDENCE-BASED DENTAL PRACTICE
bruxism groups examined. Neither did any of the other measured factors affect peri-implant bone loss or biomechanical failure.
COMMENTARY AND ANALYSIS The lack of adequate bone height to place dental implants is a common clinical occurrence. One approach in such circumstances is to place short implants, and more information on the factors determining success for such short implants has the potential to significantly impact clinician decision making. The authors concluded that prosthetic parameters (such as C/I ratio, mesiodistal dimension of the prostheses, cantilever, occlusal table width, occlusion pattern, bruxism) had no effect on periimplant bone loss or complication rates, although more severe complications were observed grouping the implants placed in individuals with bruxism. A limitation in the present study is the potential for lack of power. With few implant failures (2 based on the description in the text), inadequate power was available to reliably answer the many questions that were raised. There were more biomechanical complications, but still, power may have been lacking to address several important questions. In addition, the short follow-up further compromised the ability to provide reliable answers. It is indeed valuable to see how well the short implants performed over a relatively long (mean 53 months) period of time. However, this overall high success rate decreased power. In addition, one should also be aware that a significant number of patients (29 of 109) and implants (63 of 262) were not followed in the last recall visit. Therefore, the strength of the data is compromised. Since the majority of the patients (96.6%) in this study received single or splinted crowns as their final restorations, it is more appropriate to apply the conclusions for single or splinted crowns (verses fixed partial dentures) on short implants. The occlusal considerations, such as cantilever and bruxism, have been controversial topics in dental implan-
124
tology. Clinical practice guideline is mainly based on case reports, nonsystematic reviews, or experts’ opinions, rather than evidence generated from high-quality studies and systematic reviews. Bruxism has been suggested as being related to higher implant failure rates and complication rates.1-3 However, a definitive cause-and-effect relationship between bruxism and implant failure has not yet been proved. In line with previously published papers, in this study more severe complications occurred among individuals with signs of bruxism (veneering porcelain fracture and implant fracture) although statistical analysis failed to show significant difference. Nevertheless, a careful approach has been recommended by various authors when treating patients with bruxism.4-6
REFERENCES 1. Engel E, Weber H. Treatment of edentulous patients with temporomandibular disorders with implant-supported overdentures. Int J Oral Maxillofac Implants 1995;10:759-64. 2. Gittelson G. Occlusion, bruxism, and dental implants: diagnosis and treatment for success. Dent Implantol Update 2005;16:17-24. 3. Williamson R. Postoperative care for patients with implant prostheses. J Am Dent Assoc 2000;131:523-4. 4. Kim Y, Oh TJ, Misch CE, Wang HL. Occlusal considerations in implant therapy: clinical guidelines with biomechanical rationale. Clin Oral Implants Res 2005;16(1):26-35. 5. Misch CE. The effect of bruxism on treatment planning for dental implants. Dent Today 2002;21(9):76-81. 6. Lobbezoo F, Brouwers JEIG, Cune MS, Naeije M. Dental implants in patients with bruxing habits. J Oral Rehabil 2006;32:152-9.
REVIEWER Hai Zhang, DMD, PhD Department of Restorative Dentistry University of Washington NE Pacific Street Box 357456 Seattle, WA 98195-7456 [email protected]
September 2007