SEM Evaluation of Tooth Surface after a Composite Filling Removal Using Er:YAG Laser, Drills with and without Curettes, and Optional EDTA or NaOCl Conditioning.

Jan Kiryk,Maciej Dobrzyński,Piotr Kuropka,Jacek Matys,Marzena Dominiak,Małgorzata Małecka,Rafał J Wiglusz,Kinga Grzech-Leśniak

doi:10.3390/ma14164469

Abstract

(1) Background: This study aimed to evaluate the microporosity of the tooth surface structure adjacent to the cemento-enamel junction (CEJ) after the removal of composite fillings with a drill in comparison with removal by an Er:YAG laser and after cleaning with a periodontal curette, chemical EDTA and NaOCl (sodium hypochlorite) conditioning. (2) Methods: The research material consisted of 30 extracted premolars with cervical composite fillings. The teeth were divided into six groups according to the method of tooth preparation: group G1 (n = 5)—a diamond drill; group G2 (n = 5)—a diamond drill + curette; group G3 (n = 5)—a diamond drill + 24% EDTA (PrefGel, Straumann, Switzerland); group G4 (n = 5)—an Er:YAG laser (LightWalker, Fotona, Ljubljana, Slovenia) set with the following parameters: power: 1.65 W (composite removal, CR), 1.2 (tooth conditioning, TC), energy: 110 mJ (CR), 80 mJ (TC), frequency: 15 Hz, pulse duration: 50 μs, tip diameter: 1 mm, air/fluid cooling: 4, distance 1.5 mm, energy density: 14.01 J/cm2 (CR), 10.19 J/cm2 (TC); group G5 (n = 5)—an Er:YAG laser + 2% sodium hypochlorite (NaOCl); group G6 (n = 5)—an Er:YAG laser + 5.25% NaOCl. In each tooth, three cavities were made and subjected to analysis. The dentin surface was evaluated using a scanning electron microscope (SEM). (3) Results: Groups G1 and G2 exhibited mechanical damage to the tooth surface structure caused by the rotary motion of a diamond drill. The SEM image showed a smear layer that could only be removed chemically using 24% EDTA gel (group G3). The tooth surfaces prepared with the Er:YAG laser (groups G4–G6) revealed a homogeneous structure without damage along with open dentinal tubules (without smear layer) and visible denaturation of collagen fibers. The sodium hypochlorite (NaOCl) conditioning did not increase the visibility of dentinal tubules. (4) Conclusions: Dentin surfaces have open dentinal tubules after removal of the composite filling using the Er:YAG laser and therefore do not require additional NaOCl conditioning.

Highlights

Dental filling removal in the cervical region of the tooth is a procedure that is performed before gingival recession coverage [1]
This study aimed to evaluate, by means of a scanning electron microscope (SEM), the microporosity of the tooth surface structure after removal of a composite filling from the cervical region of the tooth (CEJ) when using an Er:YAG laser with additional conditioning of the dentin surface with sodium hypochlorite (NaOCl) compared to that when using a traditional filling removal method with a diamond dental drill and periodontal curette or chemical EDTA conditioning in order to determine their usefulness in procedures for gingival recession coverage
Open dentinal tubules on the tooth surface are among the critical elements that determine the quality of fibroblast adhesion to the dental root surface [26]

Summary

Introduction

Dental filling removal in the cervical region of the tooth is a procedure that is performed before gingival recession coverage [1]. The presence of the filling in the cementoenamel junction (CEJ) or on the dental root surface impairs the connection of fibroblasts with dental tissues and, prevents successful gingival recession coverage [2]. Gingival recession can be found in people with very good oral hygiene where it mainly affects labial surface [3,4,5]. Gingival recession can occur among individuals who exhibit negligence in oral hygiene; in such cases, it affects all tooth surfaces [5]. To perform the procedure of gingival recession coverage, the root surface needs to be free of caries and cannot be covered with any dental material or smear layer, as the connective tissue attachment can only be formed properly in contact with the dental tissue [8] Restoration of hard-tissue defects in the labial and buccal regions of the teeth without gum regenerative procedures may cause other problems, such as dentin hypersensitivity, root caries and patient discomfort for aesthetic reasons [6,7].

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