We are pleased to introduce the collection Frontiers in Dental Medicine: Highlights in Reconstructive Dentistry 2021/22. This collection will welcome and showcase a selection of high impact articles authored by leaders in the field. The work presented here highlights the broad diversity of research performed across the Reconstructive Dentistry section, and aims to put a spotlight on the main areas of interest. This collection aims to further support Frontiers’ strong community by shining a spotlight on our authors' highly impactful research.

School of Life Dentistry, Nippon Dental University

Explore the wide-ranging studies in Reconstructive Dentistry and discover its influential research.

. This research topic presents a variety of techniques and materials for restoring and regenerating dental tissues: <ul> <li>A surgical technique as an alternative to implant removal for retrograde peri-implantitis, which was successful in restoring bone and retaining the implant.</li> <li>Bioactive materials available for enabling repair and regeneration of dental tissues, while preserving hard tissues and maintaining dental vitality.</li> <li>Marginal adaptation in enamel and dentin before and after aging of laser vs. bur-prepared mixed class V cavities restored by different restorative systems.</li> <li>Effect of two different access cavity designs on fracture strength of endodontically treated teeth and on cyclic fatigue resistance of Reciproc blue instruments.</li> </ul>

Frontiers in Dental Medicine

Reconstructive Dentistry

Frontiers in Dental Medicine: Highlights in Reconstructive Dentistry 2021/22

BackgroundRetrograde peri-implantitis is an infection at the apex of an implant, leading to progressive bone loss. We present a surgical technique that is an alternative to implant removal or “implantoplasty.”</sec>CaseA 47-year-old patient developed retrograde peri-implantitis 18 months after implant placement. As the infection was localized to the apex of the implant, an apicoectomy was performed on the implant. Post-operative serial periapical radiographs showed reparative tissue within 4 months, and a follow up radiograph showed complete bone restoration 2 years later.</sec>Practical ImplicationsThe findings of this case suggest a viable alternative to condemnation and removal of an implant with a periapical infection. It may be viable to resect the contaminated portion of the implant, graft the defect, and gain long term retention and service of the implant.</sec>

Background: Retrograde peri-implantitis is an infection at the apex of an implant, leading to progressive bone loss. We present a surgical technique that is an alternative to implant removal or “implantoplasty.”Case: A 47-year-old patient developed retrograde peri-implantitis 18 months after implant placement. As the infection was localized to the apex of the implant, an apicoectomy was performed on the implant. Post-operative serial periapical radiographs showed reparative tissue within 4 months, and a follow up radiograph showed complete bone restoration 2 years later.Practical Implications: The findings of this case suggest a viable alternative to condemnation and removal of an implant with a periapical infection. It may be viable to resect the contaminated portion of the implant, graft the defect, and gain long term retention and service of the implant.

Case Report: One alternative surgical treatment of retrograde peri-implantitis

Currently, minimally invasive restorations could be made in dentistry applying adhesive materials and adhesion principles to the dental structures. Following this philosophy, endodontic interventions have been avoided largely, preserving hard tissues, and maintaining dental vitality. Advances in biologically favorable bioactive materials enabled clinicans to induce repair and regeneration of dental tissues. Such materials are primarily used for pulp protection and cementation of indirect restorations. This review highlights current bioactive materials available, principles of bioactivity and their mechanisms of action.

Currently, minimally invasive restorations could be made in dentistry applying adhesive materials and adhesion principles to the dental structures. Following this philosophy, endodontic interventions have been avoided largely, preserving hard tissues, and maintaining dental vitality. Advances in biologically favorable bioactive materials enabled clinicans to induce repair and regeneration of dental tissues. Such materials are primarily used for pulp protection and cementation of indirect restorations. This review highlights current bioactive materials available, principles of bioactivity and their mechanisms of action.

Bioactive Materials for Direct and Indirect Restorations: Concepts and Applications

This study aimed to compare marginal adaptation in enamel and dentin before and after aging of laser vs. bur-prepared mixed class V cavities restored by different restorative systems. Seventy two caries-free human molars were distributed to nine experimental groups; cavities were prepared using two different lasers: a handpiece -integrated 2.94 μm Er:YAG laser at 4.5 W, 300 mJ, and 0.75 W, 50 mJ with 15 Hz (LiteTouch, Light Instruments, Israel) and a novel CO2 laser at 12.95 W, 19.3 mJ, and 4.1 W, 6.11 mJ with 671 Hz (Solea 9.3 μm, Convergent Dental, USA). Cavities prepared with conventional diamond burs (Intensiv, Switzerland) in a red contra angle at high speed under maximal water cooling served as control. Cavities were prepared under simulation of dentinal fluid and restored using three different self-etching universal adhesives in combination with three nanohybrid composites, applied in two layers: Scotchbond Universal with Filtek Supreme XTE (3M, USA), G-Premio BOND with Essentia Universal (GC, Japan), and OptiBond Universal with Harmonize Universal (Kerr, USA). After restorations' polishing and simultaneous thermal (5–50°C, 2 min each) and mechanical loading (max. 49 N; 200,000 cycles), replicas of restoration margins were examined under SEM at × 200 magnification. Percentages of continuous margins (CMs) were quantified before and after the fatigue test and statistically compared (two-way ANOVA with Fisher's least significant difference [LSD] post hoc test). Significant differences were found in almost all groups between the results before and after the fatigue test, as well as between the different preparation tools and restorative materials (p < 0.05). Traditional bur preparations are confirmed as gold standard in enamel and dentin, as all three tested restorative systems provide results of marginal adaptation of more than 80% CM after loading. Er:YAG laser preparations can be equally effective in combination with SBU/Filtek Supreme XTE. CO2 laser ablation could not provide convincing results with the tested self-etching restorative systems. Marginal adaptation has been highly dependent on the substrate and showed impaired adhesion, especially in enamel. Scotchbond Universal/Filtek Supreme XTE showed the highest and most stable values of CM. The other two restorative systems were highly dependent on the preparation device of the substrate.

This study aimed to compare marginal adaptation in enamel and dentin before and after aging of laser vs. bur-prepared mixed class V cavities restored by different restorative systems. Seventy two caries-free human molars were distributed to nine experimental groups; cavities were prepared using two different lasers: a handpiece -integrated 2.94 μm Er:YAG laser at 4.5 W, 300 mJ, and 0.75 W, 50 mJ with 15 Hz (LiteTouch, Light Instruments, Israel) and a novel CO2 laser at 12.95 W, 19.3 mJ, and 4.1 W, 6.11 mJ with 671 Hz (Solea 9.3 μm, Convergent Dental, USA). Cavities prepared with conventional diamond burs (Intensiv, Switzerland) in a red contra angle at high speed under maximal water cooling served as control. Cavities were prepared under simulation of dentinal fluid and restored using three different self-etching universal adhesives in combination with three nanohybrid composites, applied in two layers: Scotchbond Universal with Filtek Supreme XTE (3M, USA), G-Premio BOND with Essentia Universal (GC, Japan), and OptiBond Universal with Harmonize Universal (Kerr, USA). After restorations' polishing and simultaneous thermal (5–50°C, 2 min each) and mechanical loading (max. 49 N; 200,000 cycles), replicas of restoration margins were examined under SEM at × 200 magnification. Percentages of continuous margins (CMs) were quantified before and after the fatigue test and statistically compared (two-way ANOVA with Fisher's least significant difference [LSD] post hoc test). Significant differences were found in almost all groups between the results before and after the fatigue test, as well as between the different preparation tools and restorative materials (p &lt; 0.05). Traditional bur preparations are confirmed as gold standard in enamel and dentin, as all three tested restorative systems provide results of marginal adaptation of more than 80% CM after loading. Er:YAG laser preparations can be equally effective in combination with SBU/Filtek Supreme XTE. CO2 laser ablation could not provide convincing results with the tested self-etching restorative systems. Marginal adaptation has been highly dependent on the substrate and showed impaired adhesion, especially in enamel. Scotchbond Universal/Filtek Supreme XTE showed the highest and most stable values of CM. The other two restorative systems were highly dependent on the preparation device of the substrate.

Effect of 9.3 μm CO2 and 2.94 μm Er:YAG Laser vs. Bur Preparations on Marginal Adaptation in Enamel and Dentin of Mixed Class V Cavities Restored With Different Restorative Systems

Introduction: The aim of this study was to compare the effect of two different access cavity designs on fracture strength of endodontically treated teeth and on cyclic fatigue resistance of Reciproc blue instruments.Methods: Forty (40) maxillary central incisor teeth and forty (40) upper first premolars were selected and divided into 4 groups (n = 20/group): Group 1A, incisors prepared with conservative access cavity (CEC); group 1B, incisors prepared with traditional access cavity (TEC); group 2A, premolars prepared with CEC; group 2B, premolars prepared with TEC. After access cavity preparation, all teeth were endodontically treated, restored, and then loaded to fracture. A total of 80 Reciproc blue R25 files were used for root canal shaping and then tested for cyclic fatigue. Normality of data distribution was evaluated by Kolmogorov-Smirnov test. Data were statistically analyzed by Independent T-test and the significance level was set at p < 0.05.Results: No statistically significant differences in fracture strength were found between the two tested access cavities both for incisors (P = 0.70) and premolars (0.422). Cyclic fatigue resistance of Reciproc blue R25 was significantly reduced in endodontically treated teeth with CEC (P < 0.001).Conclusions: Within the limits of the present in vitro study, CEC does not increase fracture strength of endodontically treated teeth in comparison to TEC. Conservative Endodontic Cavity causes more cyclic fatigue of Reciproc blue R25 than Traditional Endodontic Cavity.

Introduction: The aim of this study was to compare the effect of two different access cavity designs on fracture strength of endodontically treated teeth and on cyclic fatigue resistance of Reciproc blue instruments.Methods: Forty (40) maxillary central incisor teeth and forty (40) upper first premolars were selected and divided into 4 groups (n = 20/group): Group 1A, incisors prepared with conservative access cavity (CEC); group 1B, incisors prepared with traditional access cavity (TEC); group 2A, premolars prepared with CEC; group 2B, premolars prepared with TEC. After access cavity preparation, all teeth were endodontically treated, restored, and then loaded to fracture. A total of 80 Reciproc blue R25 files were used for root canal shaping and then tested for cyclic fatigue. Normality of data distribution was evaluated by Kolmogorov-Smirnov test. Data were statistically analyzed by Independent T-test and the significance level was set at p &lt; 0.05.Results: No statistically significant differences in fracture strength were found between the two tested access cavities both for incisors (P = 0.70) and premolars (0.422). Cyclic fatigue resistance of Reciproc blue R25 was significantly reduced in endodontically treated teeth with CEC (P &lt; 0.001).Conclusions: Within the limits of the present in vitro study, CEC does not increase fracture strength of endodontically treated teeth in comparison to TEC. Conservative Endodontic Cavity causes more cyclic fatigue of Reciproc blue R25 than Traditional Endodontic Cavity.

Influence of Endodontic Access Cavity Design on Fracture Strength of Maxillary Incisors and Premolars and on Fatigue Resistance of Reciprocating Instruments