Title In a Healthy Adult, The Incomplete Removal of Caries When Compared to The Complete Removal of Caries May Result in Reduced Fracture Resistance of Restored Posterior Teeth
Clinical Question In a healthy adult, would the incomplete excavation of caries in comparison to the complete removal of caries affect the fracture resistance of restored posterior teeth?
Clinical Bottom Line Incomplete caries removal of restored teeth when compared to complete excavation of restored teeth could possibly affect the fracture resistance and strength of the tooth and/or restoration. Based on the conflicting results of the two in vitro studies cited, utilization of this information to a clinical scenario needs to be approached carefully because several clinical factors can influence the longevity of incompletely excavated restored teeth including lesion depth, environment, and caries extent.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
24333956Schwendicke/201348 human upper second premolars.Laboratory study
Key resultsIn this lab study, artificial deep and shallow lesions were created on pulpo-axial walls with standardized mesial-distal-occlusal cavities. The 48 premolars were randomly assigned to two groups, one with an EDTA solution that created deep lesions and one with acetic acid that created shallow lesions. Demineralized dentin was either removed or left behind before restoring the tooth. All specimens were subjected to thermo-mechanical cycling at loads of 200 N and 400 N. Teeth were submitted to occlusal-perpendicular loading until fracturing occurred. Fracture resistance of restorations was not significantly different between teeth with and without demineralized dentin remaining under the restoration regardless of the lesion depth (p> 0.30; t-test). Regardless of the caries removal technique, teeth with deeper lesions had a significantly lower fracture resistance (p<0.001). If fractures occurred, there was no difference in the fracture mode between teeth with or without demineralized dentin remaining (p> 0.05; Fisher’s Test). Teeth with deep lesions commonly showed bulk fractures of proximal boxes or small enamel chipping adjacent to the restoration. Teeth in the shallow lesion group repeatedly showed vertical or oblique-vertical fractures. This study concluded that incomplete removal of caries when compared to complete caries removal will not significantly affect the fracture resistance of restored teeth. However, there was a trend of decreased fracture resistance (-13%) in teeth with dentin remaining regardless of the lesion depth.
20858783Hevinga/2010Fourteen pairs of human molars.Laboratory study
Key resultsIn this double blind lab study, fourteen pairs of un-restored molars that had visual and radiographic evidence of occlusal caries lesions were randomly assigned to an experimental (incomplete excavation) group and control (complete excavation) group. Restored teeth in the incomplete excavation group resulted in a reduced fracture strength (p <0.001) when compared to the control group. All specimens were subjected to cyclic loading of 5 Hz frequency and 350 N that was applied vertically to the restored molar with a stainless steel cylindrical ball stylus placed centrally on the restoration. Statistical analysis revealed a significant difference in failure strength between teeth in both groups (p <0.001; 95% CI [1084 N … 1901 N]). The mean failure load was 2768 N (SD =710 N) for the complete caries excavation group, and for the experimental group the mean failure load was 1276 N (SD= 626 N). According to regression analysis, there was no statistically significant effect of the size of the molar on the fracture strength (p=0.25; effect=17 mm2 …47 N/ mm2). The restored molars in the control group showed vertical root fractures below the cementoenamel junction and those in the experimental group showed cracks that were characterized as “ice-cracks” in the restorations. The study concluded that the fracture strength of teeth restored over incomplete caries excavation was significantly lower than those teeth with complete caries excavation which could result in long-term clinical failure.
Evidence Search (incomplete[All Fields] AND ("dental caries"[MeSH Terms] OR ("dental"[All Fields] AND "caries"[All Fields]) OR "dental caries"[All Fields] OR "caries"[All Fields])) AND (restored[All Fields] AND ("tooth"[MeSH Terms] OR "tooth"[All Fields] OR "teeth"[All Fields]))
Comments on
The Evidence
The study by Schwendicke (2013) tested 48 upper second premolars by placing artificial deep or shallow multi surface lesions on the surfaces of non-restored teeth. The groups were similar at the start with a high compliance rate. Groups were treated the same and recall bias was unlikely. There were no conflicting interests found and the results would be feasible in a clinical setting. The study by Hevinga (2010) tested fourteen pairs of molars with existing single surface occlusal caries lesions with the groups similar at start and with a high compliance rate. Groups were treated the same and recall bias was unlikely. There were no conflicting interests found and results would apply to a clinical setting. When comparing the study testing artificial lesions versus the study testing existing lesions, the study experimenting with existing lesions would be more representative of what dentists would encounter in the clinical setting.
Applicability Dentists on a daily basis confront the clinical scenario of risk to benefit of complete versus incomplete excavation of caries in deep lesions. Clinical providers must balance the potential for future fracture of the tooth/restoration versus preserving the vitality of the tooth.
Specialty (General Dentistry) (Restorative Dentistry)
Keywords caries, incomplete excavation
ID# 2675
Date of submission 03/13/2014
E-mail ghazvini@livemail.uthscsa.edu
Author Aida Ghazvini
Co-author(s) e-mail
Faculty mentor Joseph Bartoloni, DMD
Faculty mentor e-mail Bartoloni@uthscsa.edu
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
None available
Comments and Evidence-Based Updates on the CAT
None available