Crown forms and gingival phenotypes: Insights from a diverse Asian population.

Objective: This study aimed to classify the crowns of maxillary central incisors into distinct categories and to examine the associations between these crown forms and morphometric characteristics in an ethnically diverse Asian population. This is significant for the treatment planning and management of cases, especially for the anterior teeth, from the restorative and aesthetic points of view. Method and Materials: Clinical measurements and photographic data were collected from 160 participants, comprising students, staff, and patients of the Faculty of Dentistry, Universiti Kebangsaan Malaysia. The crown length, crown width, contact surface, papilla height, papilla fill, keratinized mucosa width, and gingival tissue thickness were measured. Cluster analyses were performed to identify the different crown form categories and corresponding characteristics. Results: The mean crown width measured 7.093 ± 0.637 mm, while the mean crown length was 10.209 ± 0.966 mm. Three crown-form clusters were identified: triangular (50 %), square/tapered (23.1 %), and square (26.9 %) shapes. The triangular cluster had a significantly higher mean papilla height (4.64 mm ± 0.818) and the highest incidence of incomplete papilla fill (17.5 %). The chi-squared test showed a significant difference in crown forms between the different ethnicities, χ2 (2, 160) = 0.033. Conclusion: Within this diverse Asian population, the crown form demonstrates three clusters: triangular, square/tapered, and square, characterized by a notably small average crown width and crown length. Most participants predominantly exhibited triangular crown forms with reduced crown width, crown length, and crown width/ crown length ratio. Furthermore, noticeable variations in crown forms and their morphometric attributes were observed among the three ethnic groups: Malays, Chinese, and Indians.

In Vitro and In Vivo Biological Assessments of 3D-Bioprinted Scaffolds for Dental Applications.

Three-dimensional (3D) bioprinting is a unique combination of technological advances in 3D printing and tissue engineering. It has emerged as a promising approach to address the dilemma in current dental treatments faced by clinicians in order to repair or replace injured and diseased tissues. The exploration of 3D bioprinting technology provides high reproducibility and precise control of the bioink containing the desired cells and biomaterial over the architectural and dimensional features of the scaffolds in fabricating functional tissue constructs that are specific to the patient treatment need. In recent years, the dental applications of different 3D bioprinting techniques, types of novel bioinks, and the types of cells used have been extensively explored. Most of the findings noted significant challenges compared to the non-biological 3D printing approach in constructing the bioscaffolds that mimic native tissues. Hence, this review focuses solely on the implementation of 3D bioprinting techniques and strategies based on cell-laden bioinks. It discusses the in vitro applications of 3D-bioprinted scaffolds on cell viabilities, cell functionalities, differentiation ability, and expression of the markers as well as the in vivo evaluations of the implanted bioscaffolds on the animal models for bone, periodontal, dentin, and pulp tissue regeneration. Finally, it outlines some perspectives for future developments in dental applications.

Contour Analysis of Three-Dimensional Peri-Implant Mucosal Model as an Endpoint Analysis of Photofunctionalization Effects on Implant Abutment Materials.

INTRODUCTION: The objective of this study was to examine the effect of photofunctionalization on the soft-tissue contour formed at the interface of various abutment materials using end-point analyses obtained from the three-dimensional oral mucosal model (3D-OMMs). METHODS: Commercially pure titanium (CPTi), alumina-toughened zirconia (ATZ), and yttria-stabilized zirconia (YSZ) made into discs shapes were classified into two groups: UV-treated (PTx) and non-treated (NTx). The materials in PTx groups were exposed to UV light for 12 min. Human gingival fibroblasts and TR146 epithelial cell lines co-cultured on the acellular dermal membrane were used to construct the 3D-OMM. After 4 days of culture, the discs were inserted into the holes prepared within the membrane of 3D-OMMs. The contour formed by the tissue was evaluated after 14 days of culture. RESULTS: The UV treatment of abutment materials resulted in the formation of more non-pocket-tissue types among the PTx group (p = 0.002). Of all materials tested, soft tissue contour around YSZ showed higher scores for the non-pocket type in both non- and UV-treated groups. CONCLUSIONS: The non-pocket type of tissue attachment was frequently found in all surfaces modified by photofunctionalization, particularly zirconia. The 3D-OMM can be used to evaluate the biological endpoints of implant surface modifications.

Expression of Interleukin-1ß and Histological Changes of the Three-Dimensional Oral Mucosal Model in Response to Yttria-Stabilized Nanozirconia.

Over the years, advancement in ceramic-based dental restorative materials has led to the development of monolithic zirconia with increased translucency. The monolithic zirconia fabricated from nano-sized zirconia powders is shown to be superior in physical properties and more translucent for anterior dental restorations. Most in vitro studies on monolithic zirconia have focused mainly on the effect of surface treatment or the wear of the material, while the nanotoxicity of this material is yet to be explored. Hence, this research aimed to assess the biocompatibility of yttria-stabilized nanozirconia (3-YZP) on the three-dimensional oral mucosal models (3D-OMM). The 3D-OMMs were constructed using human gingival fibroblast (HGF) and immortalized human oral keratinocyte cell line (OKF6/TERT-2), co-cultured on an acellular dermal matrix. On day 12, the tissue models were exposed to 3-YZP (test) and inCoris TZI (IC) (reference material). The growth media were collected at 24 and 48 h of exposure to materials and assessed for IL-1ß released. The 3D-OMMs were fixed with 10% formalin for the histopathological assessments. The concentration of the IL-1ß was not statistically different between the two materials for 24 and 48 h of exposure (p = 0.892). Histologically, stratification of epithelial cells was formed without evidence of cytotoxic damage and the epithelial thickness measured was the same for all model tissues. The excellent biocompatibility of nanozirconia, as evidenced by the multiple endpoint analyses of the 3D-OMM, may indicate the potential of its clinical application as a restorative material.

Assessment of gingival thickness in multi-ethnic subjects with different gingival pigmentation levels.

AIM: Assessment of the thickness of gingival tissues using the probe visibility test is regarded as the method of choice during routine examinations. However, the probe visibility test has not been validated for patients with gingival pigmentation and its accuracy in populations with physiological gingival pigmentation is yet unknown. This study aims to evaluate different methods for the clinical assessment of gingival thickness in participants with varying levels of gingival pigmentation. MATERIALS AND METHODS: Buccal mucosa of the maxillary right central incisor teeth of 171 participants was evaluated using four methods, which were direct measurements using calliper, transgingival probing method using an endodontic probe, and probe visibility method using Colorvue biotype probe (CBP) and UNC-15 probe. The pigmentation of the gingiva was assessed using the Dummett-Gupta oral pigmentation lesion index. RESULTS: The average gingival thickness of the selected population was 1.22 ± 0.38 mm with a distribution of 70% thick and 30% thin gingiva. Transgingival and calliper methods showed good agreement and significant correlation (r = 0.229; p = .003). Visual assessment using CBP and UNC-15 probe showed poor agreement with the direct measurement methods. Gingival pigmentation significantly affected the probe visibility assessment, reducing the visibility of both the CBP (odds ratio [OR] = 4.00; 95% confidence interval [CI], 1.83-8.74) and UNC-15 probe (OR = 1.84; 95% CI, 1.05-3.23) while controlling for thickness of the gingiva. CONCLUSION: The probe visibility method using either CBP or the UNC-15 probe is affected by the degree of gingival pigmentation. Direct measurements using either a calliper or transgingival probing are recommended as methods to measure the gingival thickness in populations with gingival pigmentation.

Current Advances of Three-Dimensional Bioprinting Application in Dentistry: A Scoping Review.

Three-dimensional (3D) bioprinting technology has emerged as an ideal approach to address the challenges in regenerative dentistry by fabricating 3D tissue constructs with customized complex architecture. The dilemma with current dental treatments has led to the exploration of this technology in restoring and maintaining the function of teeth. This scoping review aims to explore 3D bioprinting technology together with the type of biomaterials and cells used for dental applications. Based on PRISMA-ScR guidelines, this systematic search was conducted by using the following databases: Ovid, PubMed, EBSCOhost and Web of Science. The inclusion criteria were (i) cell-laden 3D-bioprinted construct; (ii) intervention to regenerate dental tissue using bioink, which incorporates living cells or in combination with biomaterial; and (iii) 3D bioprinting for dental applications. A total of 31 studies were included in this review. The main 3D bioprinting technique was extrusion-based approach. Novel bioinks in use consist of different types of natural and synthetic polymers, decellularized extracellular matrix and spheroids with encapsulated mesenchymal stem cells, and have shown promising results for periodontal ligament, dentin, dental pulp and bone regeneration application. However, 3D bioprinting in dental applications, regrettably, is not yet close to being a clinical reality. Therefore, further research in fabricating ideal bioinks with implantation into larger animal models in the oral environment is very much needed for clinical translation.

3D-Printed Hydroxyapatite and Tricalcium Phosphates-Based Scaffolds for Alveolar Bone Regeneration in Animal Models: A Scoping Review.

Three-dimensional-printed scaffolds have received greater attention as an attractive option compared to the conventional bone grafts for regeneration of alveolar bone defects. Hydroxyapatite and tricalcium phosphates have been used as biomaterials in the fabrication of 3D-printed scaffolds. This scoping review aimed to evaluate the potential of 3D-printed HA and calcium phosphates-based scaffolds on alveolar bone regeneration in animal models. The systematic search was conducted across four electronic databases: Ovid, Web of Science, PubMed and EBSCOHOST, based on PRISMA-ScR guidelines until November 2021. The inclusion criteria were: (i) animal models undergoing alveolar bone regenerative surgery, (ii) the intervention to regenerate or augment bone using 3D-printed hydroxyapatite or other calcium phosphate scaffolds and (iii) histological and microcomputed tomographic analyses of new bone formation and biological properties of 3D-printed hydroxyapatite or calcium phosphates. A total of ten studies were included in the review. All the studies showed promising results on new bone formation without any inflammatory reactions, regardless of the animal species. In conclusion, hydroxyapatite and tricalcium phosphates are feasible materials for 3D-printed scaffolds for alveolar bone regeneration and demonstrated bone regenerative potential in the oral cavity. However, further research is warranted to determine the scaffold material which mimics the gold standard of care for bone regeneration in the load-bearing areas, including the masticatory load of the oral cavity.

Clinical Efficacy of Repeated Applications of Local Drug Delivery and Adjunctive Agents in Nonsurgical Periodontal Therapy: A Systematic Review.

The aim of this systematic review is to compare the clinical efficacy of repeated applications of local drug delivery and adjunctive agents (LDAs) in nonsurgical periodontal therapy (NSPT) compared to subgingival mechanical debridement (SMD) alone. The Cochrane Central Register of Controlled Trials, MEDLINE, PubMed, EMBASE, Web of Science, hand-searched literature and grey literature databases were searched for randomized controlled clinical trials (RCTs) with a minimum of 6-month follow-up. The outcomes of interest were changes in probing pocket depth and clinical attachment level as well as patient-centred outcomes. Of 1094 studies identified, 16 RCTs were included in the qualitative analysis. Across 11 different adjuncts analysed, only two studies utilizing minocycline gel/ointment and antimicrobial photodynamic therapy (aPDT) with indocyanine green photosensitizer had statistically significant differences in primary outcomes when compared to their control groups. Only one study on aPDT methylene blue 0.005% had compared single versus multiple applications against its control group. A mean range of 0.27-3.82 mm PD reduction and -0.09-2.82 mm CAL gain were observed with repeated LDA application. Considerable clinical heterogeneity and methodological flaws in the included studies preclude any definitive conclusions regarding the clinical efficacy of repeated LDA applications. Future RCTs with a direct comparison between single and repeated applications should be conducted to confirm or refute the clinical advantages of repeated LDA application in the nonsurgical management of periodontitis.

An In-Vitro Analysis of Peri-Implant Mucosal Seal Following Photofunctionalization of Zirconia Abutment Materials.

The presence of epithelial and connective tissue attachment at the peri-implant-soft tissue region has been demonstrated to provide a biological barrier of the alveolar bone from the oral environment. This barrier can be improved via surface modification of implant abutment materials. The effect of photofunctionalization on creating a bioactive surface for the enhancement of the epithelial and connective tissue attachment of zirconia implant abutment's peri-implant mucosal interface using organotypic model has not been investigated. Therefore, this study aimed to evaluate the soft tissue seal around peri-implant mucosa and to understand the effect of photofunctionalization on the abutment materials. Three types of abutment materials were used in this study; yttria-stabilized zirconia (YSZ), alumina-toughened zirconia, and grade 2 commercially pure titanium (CPTi) which were divided into nontreated (N-Tx) and photofunctionalized group (UV-Tx). The three-dimensional peri-implant mucosal model was constructed using primary human gingival keratinocytes and fibroblasts co-cultured on the acellular dermal membrane. The biological seal was determined through the concentration of tritiated water permeating the material-soft tissue interface. The biological seal formed by the soft tissue in the N-Tx group was significantly reduced compared to the UV-treated group (p < 0.001), with YSZ exhibiting the lowest permeability among all materials. Photofunctionalization of implant abutment materials improved the biological seal of the surrounding soft tissue peri-implant interface.

Clinical Efficacy of Single Application Local Drug Delivery and Adjunctive Agents in Nonsurgical Periodontal Therapy: A Systematic Review and Network Meta-Analysis.

This review aimed to rank the clinical efficacy of commercially available single-application local drug delivery and adjunctive agents (LDAs) compared with subgingival mechanical debridement (SMD) in nonsurgical periodontal therapy (NSPT). Randomized controlled clinical trials that compared LDAs against SMD alone or with placebo in adults (aged at least 18 years) diagnosed with periodontitis with a minimum of 6 months follow-up were included. A frequentist approach to random-effects network meta-analysis was implemented. The efficacies of the LDAs measured by probing pocket depth (PPD) reduction and clinical attachment level (CAL) gain were reported as mean difference (MD) with 95% confidence intervals (CIs). The treatments were ranked according to their P-score. Four network meta-analyses suggested that sulfonic/sulfuric acid gel (PPD MD -1.13 mm, 95% CI -1.74 to -0.53, P-score 0.91; CAL MD -1.09 mm, 95% CI -1.58 to -0.61, P-score 0.95) and doxycycline hyclate gel (PPD MD -0.90 mm, 95% CI -1.50 to -0.30, P-score 0.93; CAL MD -0.84 mm, 95% CI -1.40 to -0.28, P-score 0.92) were the most effective in reducing PPD and gaining CAL in split-mouth and parallel studies, respectively (moderate certainty of evidence). LDAs have differing efficacies, but they present with possible clinical significance over SMD alone in NSPT.

Influence of alloying elements on cellular response and in-vitro corrosion behavior of titanium-molybdenum-chromium alloys for implant materials.

PURPOSE: Not all elements with ß-stabilizing properties in titanium alloys are suitable for biomaterial applications, because corrosion and wear processes release the alloying elements to the surrounding tissue. Chromium and molybdenum were selected as the alloying element in this work as to find balance between the strength and modulus of elasticity of ß-titanium alloys. This study aimed to investigate the effect of Titanium-10Molybdenum-10Chromium (Ti-10Mo-10Cr), Titanium-10Chromium (Ti-10Cr) and Titanium-10Molybdenum (Ti-10Mo) on the elemental leachability in tissue culture environment and their effect on the viability of human gingival fibroblasts (HGFs). METHODS: Each alloy was immersed in growth medium for 0-21 days, and the elution was analyzed to detect the released metals. The elution was further used as the treatment medium and exposed to seeded HGFs overnight. The HGFs were also cultured directly to the titanium alloy for 1, 3 and 7 days. Cell viability was then determined. RESULTS: Six metal elements were detected in the immersion of titanium alloys. Among these elements, molybdenum released from Ti-10Mo-10Cr had the highest concentration throughout the immersion period. Significant difference in the viability of fibroblast cells treated with growth medium containing metals and with direct exposure technique was not observed. The duration of immersion did not significantly affect cell viability. Nevertheless, cell viability was significantly affected after 1 and 7 days of exposure, when the cells were grown directly onto the alloy surfaces. CONCLUSIONS: Within the limitation of this study, the newly developed ß-titanium alloys are non-cytotoxic to human gingival fibroblasts.

Commercial Local Pharmacotherapeutics and Adjunctive Agents for Nonsurgical Treatment of Periodontitis: A Contemporary Review of Clinical Efficacies and Challenges.

Periodontal infections tend to be site-specific, mostly confined to the periodontal pocket. With the surge of antibiotic-resistant bacteria, the trend is shifting towards other therapeutic modalities, especially locally delivered approaches that include other pharmacotherapeutic drugs and medical devices. This narrative review aimed to provide insights into the clinical efficacy of local drug delivery and adjunctive agents used in nonsurgical management of periodontitis. Electronic (PubMed/MEDLINE, CENTRAL, and EMBASE) and bibliographic searches of past systematic reviews were carried out to identify previous publications on the topic. Only relevant literature and randomized controlled trials published in English were selected. In addition, a literature review was developed based on the selected articles. Experimental drugs or agents were excluded. This review highlights the clinically proven and commercially available therapeutic agents related to the management of periodontal disease with comparisons of their clinical efficacies and challenges. A vast array of commercial local pharmacotherapeutic agents had been clinically tested, but the methodologies and clinical results varied within and between each agent used, causing difficulty in drawing conclusions and providing support to the superiority of one agent over another. Considering the benefit-cost ratio with the modest clinical results, the long-term usefulness of these agents remains debatable.

Autotransplantation of maxillary canine following removal of compound odontome: a case report.

Obstruction remains as an important cause of failure in the eruption of a tooth. In this article, a 15-year-old girl was presented with retained upper left primary canine (63) and first primary molar (64), while the contralateral permanent canine (13) and premolars (14 and 15) have erupted. Upon radiographic examination, a mass which was diagnosed later to be compound odontome was detected. The treatment consisted of surgical removal of the odontome, extraction of the primary canine (63) and left permanent canine (23), and transplantation of the permanent canine (23). The management of this case and the literature related to autotransplantation are discussed.