Minimally invasive treatment for esthetic enhancement of white spot lesion in adjacent tooth
A 22-year-old woman who lost her maxillary right central and lateral incisor prosthesis presented to the Gangneung-Wonju National University Dental Hospital for treatment (). The prosthesis was lost with severe secondary caries around the metal post. Each root canal was incompletely filled with a radiopaque resinous hard material, and the right lateral incisor root had apical rarefying osteitis (). Extraction was necessary due to the large extent of secondary caries and the nonremovable canal filling material. A white spot was found in the maxillary left central incisor with poor oral hygienic control.\nBecause the patient refused tooth preparation, restoring the teeth with an implant prosthesis was planned. A diagnostic waxing of the teeth determined the installing site of implants to meet the esthetic needs and to fabricate a radiographic stent and a surgical stent. Six weeks after extraction, severe bone loss of the buccal plate was confirmed (). In view of the insufficient implant primary stability, guided bone regeneration was performed as defects were filled with a xenograft material (Bioss; Geistlich Pharma AG, Wolhusen, Switzerland) and covered with a resorbable bilayer collagen membrane (Bio-gide; Geistlich Pharma AG) (). Four months after guided bone regeneration, sufficient hard and soft tissue volume was acquired. A tapered internal hex titanium implants (Implantium; Dentium, Seoul, Korea) were installed, oriented by a surgical guide. An acrylic resin RPD was fabricated to replace the missing tooth during the healing period.\nSix month after implant placement, a tissue-punch technique was used to place a screw-retained provisional restoration with a provisional plastic abutment (Plastic temporary abutment, Dentium). The treatment for the white spot of the left maxillary central incisor was also needed. Diagnosis for the white spot was performed with visual-tactile inspection evaluating change of the surface gloss and color after dessication. The lesion surface was hard and shiny, it was diagnosed as an inactive ICDAS (International Caries Detection and Assessment System) code 2 which requires esthetic improvement only. Regenerating the white spot on the prosthesis was not esthetic and removal of the white spot lesion was thus required. Gingival recession after a surgical procedure highlights the white spot in the cervical area (). Furthermore, bandlike whitish discoloration along the perikymata in the middle third coronal area also needed esthetic enhancement. The proposed minimally invasive technique is based on a combined approach of bleaching, resin infiltration and composite resin bonding. In-office bleaching treatment was applied according to the manufacturer's (Lumawhite; Luma Lite, Spring Valley, CA, USA) recommendations. After gingival tissues were isolated using a light-polymerized resin dam (Opal Dam; Ultradent Products Inc., South Jardan, UT, USA), 35% hydrogen peroxide (Lumawhite) was applied onto the left maxillary incisor with consistent coverage of 2 to 3 mm thickness for 8 minutes, for a total of 3 times (). Two weeks after treatment, the white spot lesion was still apparent though bleaching became effective on the normal tooth structure, requiring more effective treatment ().\nConsequently, the decision was made to conduct the resin infiltration technique as it was more preservative than microabrasion or macroabrasion. On the enamel surface, careful application of 15% hydrochloric acid gel (ICON-Etch; DMG, Hamburg, Germany) was performed for 120 seconds to remove the surface layer less than 30 to 40 µm (). The acid gel was suctioned and washed away thoroughly. The lesions were desiccated using ethanol (ICON-Dry; DMG) for 30 seconds. At the moment of applying ethanol, the color change in the white spot lesion was confirmed with ethanol penetration. After thorough dessication with ethanol, an infiltrant resin (ICON-Infiltrant; DMG) was placed on the tooth surface for 3 minutes for inside penetration. Excessive resin was wiped away from the surface and the proximal spaces. Light polymerizing was performed for 40 seconds. Applying the infiltrant resin was repeated to compensate for the shrinkage after polymerization. The tooth surface was polished with polishing discs (Sof-lex disk; 3M ESPE, Saint Paul, MN, USA). After resin infiltration, some of the cervical white spot and bandlike whitish discoloration along the perikymata in the middle third coronal area disappeared (). However, resin infiltration in some parts of the cervical white spot lesion was ineffective, requiring an advanced approach.\nThe limited, unchanged white spot lesion was removed with a carbide bur (Carbide Burs Round; Mani Inc., Tochigi, Japan). The tooth structure was etched with 38% phosphoric acid (Scotchbond Etchant; 3M ESPE) for 15 seconds. The etching gel was washed away and dried. A bonding agent (Adper Single Bond Plus adhesive, 3M ESPE) was applied to the preparation area and light polymerized for 10 seconds. Composite resin (Filtek Supreme XT; 3M ESPE) was placed and polymerized for 40 seconds. Finally, polishing the restoration surface was performed with polishing discs (Sof-lex disk; 3M ESPE) ().\nA complete maxillary arch impression was made with a silicone impression material (Exafine, GC, Tokyo, Japan). A customized abutment (Direct Casting Abutment; Dentium) was fabricated. Shade information was transferred to the dental laboratory after taking clinical photos with a shade guide (VitaLumin shade guide; VidentInc, Brea, CA, USA) and a detailed shade map (). A metal ceramic fixed dental prosthesis was cemented with implant cement (Premier Implant Cement; Premier Products Co., Plymouth Meeting, PA, USA) ().\nThe patient was followed for oral hygiene instruction and no complications were found after 6 months (). However, due to insufficient long term clinical research on color stability for resin infiltration treatment, continuous post-treatment monitoring should be followed. It is also important to monitor the maintenance of proper surface gloss, oral hygiene and health of peri-implant soft and hard tissue.