Partial indirect restorations with deep margin elevation in the posterior region: long term results

Deep margin elevation (DME) relocates the cervical outline of large-sized cavity dimensions in the posterior area supragingivally, using a resin composite in a direct technique. The aim of this study is to evaluate the long-term clinical performance of partial indirect restorations with DME and compare the effects of selected baseline variables on the (quality of) survival of the restorations.
All teeth that were restored in combination with indirect restorations and DME between 2007 and 2016 were eligible for inclusion in this retrospective cohort study. Overall cumulative survival rates were calculated (Kaplan-Meier estimates) and compared among subsets of variables that were considered of influence over time (prior endodontic treatment, material used for the indirect restoration, quality of the emergence profile of the DME, cusp coverage, quality of the contact point; Log Rank Mantel-Cox).
Qualitative evaluation of all surviving restorations was performed using the modified United States Public Health Service (USPHS) criteria. The outcomes of the USPHS clusters were also compared among the potential influential factors, as well as in time (<3 years old, >3 years old) to evaluate if they impacted the quality and degradation behavior of the indirect restorations with DME (Chi-square tests).
A total of 197 indirect restorations in 120 patients could be included. Restorations or teeth presenting with secondary caries, fracture of the restoration / tooth, debonding of the indirect restoration, root caries, severe periodontal breakdown or pulpal necrosis were considered as absolute failures (n=8) to an overall cumulative survival rate of 95.9% (SE 2.9%) after more than 10 years, with an average evaluation time of 57.7 months.
Some indication of degradation of the restorations was seen over time (more: margin discoloration (X2(2)=9.02, p=0.01), fracture of restoration (X2(2)=42.03, p=0.000), fracture of tooth (X2(2)=23.18, p=0.000) and caries (X2(2)=9.02, p=0.000)). Composite restorations show more degradation (more: fracture of restoration (X2(2)=38.52, p=0.000), fracture of tooth (X2(2)=31.39, p=0.000), wear restoration (X2(2)=14.82, p=0.01). More wear of the antagonist is observed when they are opposed to ceramic restorations (X2(2)=6.62, p=0.04). Endodontic treatment negatively impacts the occurrence of fracture of restorations and teeth (X2(2)=38.52, p=0.000) and respectively X2(2)=20.67, p=0.000). All other predefined variables were not of statistically significant influence, either on survival or quality of survival of the restoration (p>0.05).
Indirect restorations with DME stand a good chance on long term survival. However, indications of degradation are seen in time. Ceramic indirect restorations exhibit less wear than composite resin restorations but are more abrasive to the antagonist. Composite resin indirect restorations and restorations on non-vital teeth are associated with a higher incidence of fractures of both restorations and teeth.

Long term survival rates with DME treated teeth. Better prognosis of indirect ceramic restorations in comparison to indirect composite restorations especially when taking degradation into account.

Initial, baseline, <3 years, >3 years of follow up, up to 10 years of follow up.

Deep margin elevation (DME) that relocates the cervical outline of large-sized cavity dimensions in the posterior area supragingivally, using a resin composite in a direct technique.