Immediate dentin sealing

Immediate dentin sealing improves bond strength of indirect restorations
Pascal Magne, DMD, PhD,a Tae Hyung Kim, DDS,b Domenico Cascione, CDT,c and Terence E. Donovan, DDSd Division of Primary Oral Health Care, University of Southern California, School of Dentistry, Los Angeles, Calif Statement of problem. Delayed dentin sealing is traditionally performed with indirect restorations. With thistechnique, dentin is sealed after the provisional phase at the cementation appointment. It was demonstrated that this chronology does not provide optimal conditions for bonding procedures. Immediate dentin sealing (IDS) is a new approach in which dentin is sealed immediately following tooth preparation, before making the impression. Purpose. The purpose of this study was to determine whether therewere differences in microtensile bond strength to human dentin using IDS technique compared to delayed dentin sealing (DDS). Material and methods. Fifteen freshly extracted human molars were obtained and divided into 3 groups of 5 teeth. A 3-step etch-and-rinse dentin bonding agent (DBA) (OptiBond FL) was used for all groups. The control (C) specimens were prepared using a direct immediate bondingtechnique. The DDS specimens were prepared using an indirect approach with DDS. Preparation of the IDS specimens also used an indirect approach with IDS immediately following preparation. All teeth were prepared for a nontrimming microtensile bond strength test. Specimens were stored in water for 24 hours. Eleven beams (0.9 3 0.9 3 11 mm) from each tooth were selected for testing. Bond strengthdata (MPa) were analyzed with a Kruskal-Wallis test, and post hoc comparison was done using the Mann-Whitney U test (a=.05). Specimens were also evaluated for mode of fracture using scanning electron microscope (SEM) analysis. Results. The mean microtensile bond strengths of C and IDS groups were not statistically different from one another at 55.06 and 58.25 MPa, respectively. The bond strengthfor DDS specimens, at 11.58 MPa, was statistically different (P=.0081) from the other 2 groups. Microscopic evaluation of failure modes indicated that most failures in the DDS group were interfacial, whereas failures in the C and IDS groups were both cohesive and interfacial. SEM analysis indicated that for C and IDS specimens, failure was mixed within the adhesive and cohesively failed dentin. ForDDS specimens, failure was generally at the top of the hybrid layer in the adhesive. SEM analysis of intact slabs demonstrated a well-organized hybrid layer 3 to 5 mm thick for the C and IDS groups. For DDS specimens the hybrid layer presented a marked disruption with the overlying resin. Conclusions. When preparing teeth for indirect bonded restorations, IDS with a 3-step etch-and-rinse filledDBA, prior to impression making, results in improved microtensile bond strength compared to DDS. This technique also eliminates any concerns regarding the film thickness of the dentin sealant. (J Prosthet Dent 2005;94:511-9.)

CLINICAL IMPLICATIONS
Tooth preparation for indirect bonded restorations such as composite/ceramic inlays, onlays, and veneers can generate significant dentin exposure. Theresults of this study indicate that freshly cut dentin surfaces may be sealed with a dentin bonding agent immediately following tooth preparation, prior to impression making. A 3-step etch-and-rinse dentin bonding agent with a filled adhesive resin is recommended for this purpose.

I
a

f a considerable area of dentin has been exposed during tooth preparation for indirect bonded restorations, itis suggested that a dentin adhesive be applied strictly according to the manufacturer’s instructions.

Associate Professor, Don and Sybil Harrington Foundation Chair of Esthetic Dentistry. b Assistant Professor. c Dental Technologist. d Professor and Co-Chair, Director of Advanced Education in Prosthodontics.

Successful dentin bonding is of particular clinical importance for inlays,...