- Email: [email protected]
Patient and tooth specific risk indicators for posterior tooth fracture are identified
HARM/ ETIOLOGY
A RTICLE A NALYSIS &
Patient and tooth specific risk indicators for posterior tooth fracture are identified
E VALUATION Original Article
Level of Evidence
Purpose
Source of Funding
Type of Study/Design
Bader JD, Shugars DA, Martin JA. Risk indicators for posterior tooth fracture. J Am Dent Assoc 2004;135(7):883-92.
3b
The purpose of this study was to quantify the odds of complete cusp fracture with specific tooth and patient-level clinical indicators, as well as patient-level behaviors and extraoral characteristics. US Government (NIDCR RO1)
Case-control study
Summary SUBJECTS A total of 200 patients with fractured cusps of premolars and molars and 252 patients without fractures were evaluated. The authors studied case and control subjects and comparison teeth in case subjects. The case and control teeth had to have been restored and noncarious at the time of the fracture. EXPOSURE Thirty-nine potential risk factors for cusp fracture were evaluated for both case and control subjects and teeth. Fracture risk–related symptoms included grinding when asleep, clenching or gritting of the teeth, ice
J Evid Base Dent Pract 2005;5:164-5 D 2005 Mosby, Inc. All rights reserved. doi:10.1016/j.jebdp.2005.06.004
164
chewing, chewing hard foods, and sensitivity to hot or cold. Tooth-specific factors included the presence of a fracture line at the postfracture examination of the tooth, subsurface discoloration, cross-sectional restoration area, relative volume proportion, minimum distance from restoration to cusp tip, mean isthmus width, pins present, occlusal restoration area, and intercuspal restoration width.
MAIN OUTCOME MEASURE The main outcome measure was cusp fracture in posterior teeth. MAIN RESULTS The presence of a fracture line and an increase in the proportion of the natural tooth crown occupied by the restoration substantially increased the odds of fracture (P b .001).
CONCLUSIONS Among posterior teeth with restorations, the presence of a fracture line in the enamel and proportional volume of the restoration (relative volume proportion [RVP]) were strongly associated with the risk of cusp fracture.
Commentary and Analysis The incidence of complete cusp fractures in general practices has been well documented.1,2 This study sought to address some of the tooth-specific and patient-centered risk factors associated with those fractures. The study confirmed clinical suspicion in the sense that the size of the restoration (RVP) and the presence of a fracture line in the tooth are the factors most likely associated with cusp failure. An interesting part of this study was that some of the suspected risk factors such as bruxism and guidance plane were not identified as risk factors for cusp failure. It is unclear how teeth with both a fractured cusp and lost restoration were handled. The RVP cannot be accurately calculated without a restoration in place. The authors reported in the discussion that the regression analyses produced some paradoxical results. For example, a recent blow to the face showed a reduced risk of fracture and an increase in the distance of the restorative margin to the cusp tip showed an increased risk for fracture. It is possible that regressions will produce results that cannot be logically interpreted depending on how the variables are set up and occasionally should be held lightly. Future case-control or cohort studies on the causal factors for cusp failure may further illuminate these issues.
Journal of Evidence-Based Dental Practice Volume 5, Number 3
Because the fracture line variable represented a postexamination finding, the assumption apparently was that the line also existed before the fracture. To lessen dependence of the overall findings on this assumption, the analysis was repeated excluding this variable. Excluding the fracture line variable did not change the other risk indicators in the model, therefore the fracture line was not masking other risk factors and was a risk factor itself. The authors offer no other support for the assumption that the fracture line existed prior to the fracture. This study confirms what dentists already hold to be true, namely that a tooth with a larger restoration is as prone to fracture as is a tooth that already contains a fracture line within it. However, other beliefs, such as the role of bruxism in cusp fractures, were not confirmed in the present study. Perhaps the take home lesson of this study is to preserve as much natural tooth structure as possible during restorative procedures to minimize the possibility of future cusp fracture. REFERENCES 1. Bader JD, Martin JA, Shugars DA. Incidence rates for complete cusp fracture. Community Dent Oral Epidemiol 2001;29(5): 346-53. 2. Fennis WM, Kuijs RH, Kreulen CM, Roeters FJ, Creugers NH, Burgersdijk RC. Int J Prosthodont 2002;15(6):559-63.
Reviewer: Francis G. Serio, DMD, MS, MBA Chairman, Department of Periodontics and Preventive Medicine Professor of Periodontics and Preventive Sciences School of Dentistry University of Mississippi Medical Center Jackson, Mississippi
Bader et al 165
A RTICLE A NALYSIS &
Patient and tooth specific risk indicators for posterior tooth fracture are identified
E VALUATION Original Article
Level of Evidence
Purpose
Source of Funding
Type of Study/Design
Bader JD, Shugars DA, Martin JA. Risk indicators for posterior tooth fracture. J Am Dent Assoc 2004;135(7):883-92.
3b
The purpose of this study was to quantify the odds of complete cusp fracture with specific tooth and patient-level clinical indicators, as well as patient-level behaviors and extraoral characteristics. US Government (NIDCR RO1)
Case-control study
Summary SUBJECTS A total of 200 patients with fractured cusps of premolars and molars and 252 patients without fractures were evaluated. The authors studied case and control subjects and comparison teeth in case subjects. The case and control teeth had to have been restored and noncarious at the time of the fracture. EXPOSURE Thirty-nine potential risk factors for cusp fracture were evaluated for both case and control subjects and teeth. Fracture risk–related symptoms included grinding when asleep, clenching or gritting of the teeth, ice
J Evid Base Dent Pract 2005;5:164-5 D 2005 Mosby, Inc. All rights reserved. doi:10.1016/j.jebdp.2005.06.004
164
chewing, chewing hard foods, and sensitivity to hot or cold. Tooth-specific factors included the presence of a fracture line at the postfracture examination of the tooth, subsurface discoloration, cross-sectional restoration area, relative volume proportion, minimum distance from restoration to cusp tip, mean isthmus width, pins present, occlusal restoration area, and intercuspal restoration width.
MAIN OUTCOME MEASURE The main outcome measure was cusp fracture in posterior teeth. MAIN RESULTS The presence of a fracture line and an increase in the proportion of the natural tooth crown occupied by the restoration substantially increased the odds of fracture (P b .001).
CONCLUSIONS Among posterior teeth with restorations, the presence of a fracture line in the enamel and proportional volume of the restoration (relative volume proportion [RVP]) were strongly associated with the risk of cusp fracture.
Commentary and Analysis The incidence of complete cusp fractures in general practices has been well documented.1,2 This study sought to address some of the tooth-specific and patient-centered risk factors associated with those fractures. The study confirmed clinical suspicion in the sense that the size of the restoration (RVP) and the presence of a fracture line in the tooth are the factors most likely associated with cusp failure. An interesting part of this study was that some of the suspected risk factors such as bruxism and guidance plane were not identified as risk factors for cusp failure. It is unclear how teeth with both a fractured cusp and lost restoration were handled. The RVP cannot be accurately calculated without a restoration in place. The authors reported in the discussion that the regression analyses produced some paradoxical results. For example, a recent blow to the face showed a reduced risk of fracture and an increase in the distance of the restorative margin to the cusp tip showed an increased risk for fracture. It is possible that regressions will produce results that cannot be logically interpreted depending on how the variables are set up and occasionally should be held lightly. Future case-control or cohort studies on the causal factors for cusp failure may further illuminate these issues.
Journal of Evidence-Based Dental Practice Volume 5, Number 3
Because the fracture line variable represented a postexamination finding, the assumption apparently was that the line also existed before the fracture. To lessen dependence of the overall findings on this assumption, the analysis was repeated excluding this variable. Excluding the fracture line variable did not change the other risk indicators in the model, therefore the fracture line was not masking other risk factors and was a risk factor itself. The authors offer no other support for the assumption that the fracture line existed prior to the fracture. This study confirms what dentists already hold to be true, namely that a tooth with a larger restoration is as prone to fracture as is a tooth that already contains a fracture line within it. However, other beliefs, such as the role of bruxism in cusp fractures, were not confirmed in the present study. Perhaps the take home lesson of this study is to preserve as much natural tooth structure as possible during restorative procedures to minimize the possibility of future cusp fracture. REFERENCES 1. Bader JD, Martin JA, Shugars DA. Incidence rates for complete cusp fracture. Community Dent Oral Epidemiol 2001;29(5): 346-53. 2. Fennis WM, Kuijs RH, Kreulen CM, Roeters FJ, Creugers NH, Burgersdijk RC. Int J Prosthodont 2002;15(6):559-63.
Reviewer: Francis G. Serio, DMD, MS, MBA Chairman, Department of Periodontics and Preventive Medicine Professor of Periodontics and Preventive Sciences School of Dentistry University of Mississippi Medical Center Jackson, Mississippi
Bader et al 165