Date of Graduation

2024

Document Type

Thesis

Degree Type

MS

College

School of Dentistry

Committee Chair

Samuel Dorn

Committee Co-Chair

Constance Wiener

Committee Member

Constance Wiener

Committee Member

Steven Whitaker

Abstract

Introduction: One objective of non-surgical endodontic therapy is the formation of a hermetic seal with elimination of any portal of entry of bacteria and their byproducts into the root canal space from periapical tissue. Extensive research has been conducted to determine ideal endodontic sealers. Bioceramic sealers have risen to prominence due to reported decreased shrinkage, less toxicity, and superior bond strength to root dentin compared to zinc oxide eugenol, calcium hydroxide, and resin-based sealers. GuttaFlow2®, a new sealer on the market, is composed of calcium silicate in combination with gutta-percha particles. Researchers from Coltene (Altstätten, Switzerland), the manufacturer of GuttaFlow2® report it has a tight seal due to its expansion and adhesive properties. Leakage studies have compared GuttaFlow2® to AH Plus Jet®, an epoxy-amine resin root canal sealer. No studies to date have compared shrinkage and bond strength of GuttaFlow2® with zinc oxide eugenol sealers such as Tubli-Seal®, manufactured by Kerr, or calcium silicate bioceramic sealers such as EndoSequence BC High Flow ®, manufactured by Brassler.

The research hypothesis being investigated in this study is that the calcium silicate/ gutta-percha endodontic sealer an endodontic sealer, GuttaFlow2®, will have with a high bond strength to dentin and will create an effective seal as compared with a selected zinc oxide-eugenol sealer (Tubli-Seal®), resin sealer (AH Plus Jet®), calcium hydroxide sealer (Sealapex®), and a similar calcium silicate sealer (EndoSequence BC High Flow®).

The null hypothesis, there is no difference in bond strength among GuttaFlow2®, EndoSequence BC High Flow®, Tubli-Seal®, Sealapex®, and AH Plus Jet® sealers. The alternative hypothesis is that GuttaFlow2® will have stronger adhesion to dentin and gutta-percha than the other four sealers being investigated.

Methods: One hundred extracted human mandibular first premolar teeth with fully formed apex and straight roots were collected, sterilized, and sectioned into 2 mm thick dentin sections. The canal space of each dentin slice was standardized at 1.5 mm. Samples were mounted on uniform epoxy resin blocks. The slices were randomly assigned to 5 groups: GuttaFlow2®, AH Plus Jet®, Tubli-Seal®, EndoSequence BC High Flow®, and Sealapex®. The push-out bond strength values were measured using a universal testing machine. A custom cylindrical stainless-steel plunger with a diameter of 1.5 mm was fabricated and delivered a downward pressure at a crosshead speed of 0.5 mm/min. The bond strength values and the nature of the failure were recorded for each specimen. The failure pattern was inspected under an endodontic surgical microscope with 6.4X magnification and by one operator. The data were analyzed using a robust linear mixed-effects model to compare the mean fracture resistance of the samples. Statistical significance was defined as p < 0.05.

II

Results: The mean push-out bond strength and standard deviation of each tested material from highest bond strength to lowest bond strength are:

  1. 1) AH Plus Jet® [45.45 MPa ± 45.45]

  2. 2) EndoSequence BC High Flow® [26.55 MPa ± 14.13]

  3. 3) Tubli-Seal® [12.39 MPa ± 8.58 ]

  4. 4) GuttaFlow2® [9.57 MPa ± 5.13]

Sealapex® was removed from statistical analysis due to inconsistency in material. GuttaFlow2® had significantly less mean push-out bond strength than EndoSequence BC High Flow® (p < .0001) and AH Plus Jet® (p < .0001).

Conclusion: In the context of this in-vitro research, there was great variation in push-out bond strengths of the sealers tested.

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