Comparison of three-dimensional printed resin crowns and preformed stainless steel crowns for primary molar restorations: a randomized controlled trial.

The importance of aesthetics in children has increased over time. Therefore, this multicenter randomized clinical trial aimed to analyze and compare three-dimensional (3D)-printed resin crowns (RCs) as a potential alternative to stainless-steel crowns (SSCs) for restoring primary molars with extensive carious lesions. According to the null hypothesis, no statistically significant difference was observed in restoration failure between RC and SSC groups. A total of 56 primary molars after pulp treatment at two dental hospitals were included. After pulp treatment, the teeth were randomly divided into two groups: SSCs (n = 28) and RCs (n = 28). At 1 week and 3, 6 and 12 months, the Quigley-Hein plaque index (QHI), gingival index (GI), occlusal wear, and survival rate were assessed by examination, radiography and alginate impressions. No significant difference in QHI was observed between the two groups. However, the GI at 12 months and occlusal wear in the RC group were significantly higher than those in the SSC group (p < 0.05). The survival rates were 100% in the SSC group and 82.1% in the RC group (p = 0.047). Cracks and discoloration were also observed in the RCs. Within the limitations of this study, 3D-printed RCs are aesthetically superior to SSCs and clinically easy to repair. However, if clinical effectiveness and safety are improved, RCs could potentially become a viable aesthetic alternative in the future.

Determination of the range of intervention timing for supernumerary teeth using the Korean health insurance review and assessment service database.

This study aimed to identify the frequency of complications during the diagnosis, observation, and treatment of supernumerary teeth or odontomas and evaluate the relationship between complications and the timing of surgical intervention. This study was conducted based on data from the Korea Health Insurance Review and Assessment Service between January 2008 and December 2019. A 2-year washout period was applied, and a follow-up period of at least 2 years was also included. During the observation period, the age at diagnosis of supernumerary teeth and odontomas was analyzed using major diagnostic codes, and the treatment codes were used to determine the interval between diagnosis and surgical intervention. The incidence rates of supernumerary teeth (1.21%) and odontomas (0.36%) were comparable to that reported in previous studies. The frequency of supernumerary teeth was the highest in the anterior region, followed by the premolar and molar regions. The average ages at diagnosis according to the location of the supernumerary teeth were 7.25, 13.98, and 16.11 years in the anterior, premolar, and molar regions, respectively. The age at diagnosis correlated with the maturity period of the teeth at the corresponding location. For the supernumerary tooth group, surgical intervention was more likely to occur when malocclusion (p < 0.0001) or tooth eruption disturbances (p < 0.0001) were present or dentigerous cysts were absent (p = 0.006). For the odontoma group, malocclusion (p = 0.251) was not correlated with surgical intervention. When tooth eruption disturbances (p = 0.002) and dentigerous cysts (p < 0.0001) were present, surgical intervention was more likely to occur. Pediatric dentists should conduct timely clinical checks and periodic follow-ups to prevent complications and unnecessary orthodontic treatments in patients with supernumerary teeth or odontomas.

Differential Gene Expression Changes in Human Primary Dental Pulp Cells Treated with Biodentine and TheraCal LC Compared to MTA.

This study aimed to analyze the effects of pulp capping materials on gene expression changes in primary tooth-derived dental pulp cells using next-generation sequencing. Dental pulp cells were extracted and treated with mineral trioxide aggregate (MTA), Biodentine (BD), or TheraCal LC (TC). Cell viability assays were performed. Total RNA was extracted and analyzed through mRNA sequencing. Bioinformatic analysis of differential gene expression in dental pulp cells exposed to BD or TC versus MTA was performed. MTA, BD, and TC exposure had no significant effect on pulp cell viability (p > 0.05). Gene sets associated with inflammatory response (p = 2.94 × 10-5) and tumor necrosis factor alpha (TNF-α) signaling via the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway (p = 2.94 × 10-5) were enriched in all materials. In BD-treated cells, Wnt/ß-catenin signaling (p = 3.15 × 10-4) gene sets were enriched, whereas enrichment of interferon gamma (IFN-γ) response (p = 3 × 10-3) was observed in TC-treated cells. In gene plot analysis, marked increases in receptor activator of nuclear factor kappa-Β ligand (RANKL) expression were seen in TC-treated cells over time. Despite the similar cell viabilities exhibited among MTA-, BD-, and TC-treated cells, patterns of gene networks differed, suggesting that diverse functional gene differences may be associated with treatment using these materials.

Validation of a three-dimensional printed model for training of surgical extraction of supernumerary teeth.

INTRODUCTION: This study aimed to validate a three-dimensional (3D) printed model to provide training for supernumerary teeth (SNTs) extraction. MATERIALS AND METHODS: Each of the 30 participants, grouped as experienced and without experience, conducted two identically simulated surgeries on a 3D-printed replica of human mixed dentition with a SNT. The surgery time, area of bony window and volume of removed material were measured; subsequently, responses to a five-item questionnaire were recorded. The collected data were statistically analysed. RESULTS: The surgery time was 228.37 ± 141.53 seconds and 125.47 ± 53.03 seconds in the first and second surgery, respectively. The training significantly decreased the surgery time in the participants without experience (P = .000). However, there were no significant differences in the area of window opening (P = .271) and volume of removed material between the two surgeries (P = .075). The participants who perceived educational benefits accounted for more than 60% of the respondents for every question. Participants without experience in SNT extraction showed a tendency to rate a higher score than did those with experience. CONCLUSIONS: A 3D-printed model for surgical extraction of a SNT can improve surgical skill and, especially, shorten the learning curve in beginners.

The Use of Histidine-tryptophan-ketoglutarate Solution as a New Storage Medium for the Avulsed Tooth.

INTRODUCTION: Histidine-tryptophan-ketoglutarate (HTK) is a preservation solution used for organ transplantation. The physiological pH and osmolality of this solution are known to facilitate cell proliferation and cell membrane stabilization. The purpose of the present study was to investigate the efficacy of several concentrations of HTK solution as a storage medium for avulsed teeth. METHODS: Cultured human periodontal ligament cells were stored in different concentrations of HTK solutions. After 1, 3, 6, 12, 24, 48, and 72 hours, cell viability was assessed using the Cell-Counting Kit-8 (Dojindo Molecular Technologies, Kumamoto, Japan) and LIVE/DEAD (Invitrogen, Carlsbad, CA) assay. Cell response of the most effective concentrations of HTK solution were further analyzed by gene expression profiling, and their cell viability was compared with other storage media. RESULTS: The highest cell viability was observed in 50% HTK solution in various concentrations of HTK solution (P < .05). In periodontal ligament cells stored in 50% HTK solution for 3 hours, the expression of genes related to angiogenesis, the inflammatory response, and cell proliferation was increased compared with the control. Compared with other storage media, the highest cell viability was observed in 50% HTK solution. CONCLUSIONS: Our study suggests that 50% HTK solution containing cell culture medium represents a suitable storage medium for avulsed teeth.

Decellularized human periodontal ligament for periodontium regeneration.

Regenerating the periodontal ligament (PDL) is a crucial factor for periodontal tissue regeneration in the presence of traumatized and periodontally damaged teeth. Various methods have been applied for periodontal regeneration, including tissue substitutes, bioactive materials, and synthetic scaffolds. However, all of these treatments have had limited success in structural and functional periodontal tissue regeneration. To achieve the goal of complete periodontal regeneration, many studies have evaluated the effectiveness of decellularized scaffolds fabricated via tissue engineering. The aim of this study was to fabricate a decellularized periodontal scaffold of human tooth slices and determine its regeneration potential. We evaluated two different protocols applied to tooth slices obtained from human healthy third molars. The extracellular matrix scaffold decellularized using sodium dodecyl sulfate and Triton X-100, which are effective in removing nuclear components, was demonstrated to preserve an intact structure and composition. Furthermore, the decellularized scaffold could support repopulation of PDL stem cells near the cementum and expressed cementum and periodontal-ligament-related genes. These results show that decellularized PDL scaffolds of human teeth are capable of inducing the proliferation and differentiation of mesenchymal stem cells, thus having regeneration potential for use in future periodontal regenerative tissue engineering.

Simplified technique for easy extraction of impacted supernumerary teeth using guided surgery.

Most mesiodens remain impacted and can affect the growth and development of adjacent permanent teeth. Impacted mesiodens are usually located in an intraosseous position associated with complicated anatomical structures, necessitating minimally invasive surgical approaches. This article demonstrates a simple customized surgical stent for extraction of impacted mesiodens. Its use and advantages are described.

Prevalence of delayed tooth development and its relation to tooth agenesis in Korean children.

OBJECTIVE: The aim of this study was to investigate the epidemiology of delayed tooth development (DTD) and the link between DTD and tooth agenesis (TA). DESIGN: The dental maturity of all of the developing permanent teeth of 4611 children (2417 males and 2194 females) was evaluated from panoramic radiographs. The prevalence of DTD and TA was analyzed, and gender difference for DTS and TA was investigated. The correlation of DTD and TA was investigated in intra-fields and inter-fields. RESULTS: The total prevalence of DTD among the 4611 children was 3.40%. The maxillary second premolar was the most frequently delayed tooth (1.02%), followed by the maxillary second molar (0.88%) and the mandibular second premolar (0.74%). DTD significantly correlated with TA in both intra-fields and inter-fields (p<0.05). CONCLUSIONS: The field of delayed development exhibited a significant correlation with that of TA.

Expression of inflammatory cytokines and MMPs on replanted teeth at different extra-alveolar time: an ex vivo and in vivo study.

BACKGROUND: Immediately after the avulsed tooth is replanted, a complex inflammatory response ensues. As part of the periodontium healing process, the extracellular matrix macromolecules are essential to create the cellular environment required during healing and morphogenesis. AIM: This study was designed to evaluate the correlation between different extra-alveolar dry times and inflammatory cytokines and matrix metalloproteinases (MMPs) as part of the periodontal ligament (PDL) gene expression. DESIGN: The first phase of the study aimed testing human PDL cells ex vivo. Extracted teeth were dried for 15 and 30 min. The PDL cells were extracted and analyzed by qRT-PCR. The second phase was performed in vivo, and 36 Sprague Dawley rat first maxillary molars were extracted and replanted after 15, 30, and 60 min extra-alveolar time. We tested the levels of inflammatory cytokines and MMPS in periodontal tissue at 3, 7, and 28 days after tooth replantation. The replanted area was dissected, grounded, and analyzed by RT-PCR. RESULTS: Expressions of IL-1ß, IL-6, TNF-α, and MMP-3 and MMP-9 were significantly higher in the replanted teeth. Extended dry time had a direct correlation with induction of pro-inflammatory cytokine and MMPs in PDL cells. CONCLUSION: Our study showed that pro-inflammatory cytokines were more significantly expressed in the tissues surrounding the replanted teeth. Future research must be undertaken to additionally confirm the release of these cytokines and be focused on the inhibition of these cytokines to reduce inflammation of replanted teeth.

Complication After Extraction of Natal Teeth with Continued Growth of a Dental Papilla.

The purposes of this case report were to describe a growing two-cm gingival mass that developed after natal teeth were extracted in a four-month-old female patient, present a review of the literature on the growth of a gingival mass after the extraction of natal teeth, and illustrate the clinical and histological features that differentiate this condition from other types of gingival masses in infants. Histological examination of the excised mass revealed that it contained tooth-like hard tissue (regular and irregular dentin) that intermingled with bone, dental pulp, and fibrous tissue. We found eight cases from 1962 to 2009 in which a soft-tissue mass with dentin-like hard tissue or a tooth-like structure had developed after the extraction of natal teeth. Based on clinical and histological findings, we deduced that the mass was the result of abnormal growth of a residual dental papilla, including mesenchymal stem cells. Consequently, dentists, obstetricians, gynecologists, and pediatricians should be aware of this potential complication and observe caution before they extract natal teeth.

Recent advances in topical anesthesia.

Topical anesthetics act on the peripheral nerves and reduce the sensation of pain at the site of application. In dentistry, they are used to control local pain caused by needling, placement of orthodontic bands, the vomiting reflex, oral mucositis, and rubber-dam clamp placement. Traditional topical anesthetics contain lidocaine or benzocaine as active ingredients and are used in the form of solutions, creams, gels, and sprays. Eutectic mixtures of local anesthesia cream, a mixture of various topical anesthetics, has been reported to be more potent than other anesthetics. Recently, new products with modified ingredients and application methods have been introduced into the market. These products may be used for mild pain during periodontal treatment, such as scaling. Dentists should be aware that topical anesthetics, although rare, might induce allergic reactions or side effects as a result of an overdose. Topical anesthetics are useful aids during dental treatment, as they reduce dental phobia, especially in children, by mitigating discomfort and pain.

Characteristics of stem cells from human exfoliated deciduous teeth (SHED) from intact cryopreserved deciduous teeth.

The aim of this study is to compare the characteristics of stem cells derived from human exfoliated deciduous teeth (SHED) from cryopreserved intact deciduous teeth with those of fresh SHED. In total, 20 exfoliated deciduous teeth were randomly divided into a fresh group (f-SHED; n = 11) and cryopreserved group (c-SHED; n = 9; stored for 1-8 months). Following thawing and separation of the pulp, the SHED cells were cultured, and the characteristics as mesenchymal stem cells were investigated using proliferation assays, cell-cycle analysis, colony-forming unit-fibroblast (CFU-F) assays, and flow cytometry analyses. Furthermore, differentiation into adipogenic and osteogenic lineages was investigated in vitro as well as in vivo via transplantation in mice. We found no significant differences between the two groups in the proliferation analyses, in the expression of mesenchymal stem cell markers, or in the adipogenic and osteogenic differentiation in vitro (p < 0.05). Furthermore, the in vivo transplantation results showed no significant differences in the quantity of bone tissue that formed or in histochemistry performance (p < 0.05). In conclusion, cryopreservation of intact exfoliated deciduous teeth appears to be a useful method for preserving SHED.

Effects of In Vitro Osteogenic Induction on In Vivo Tissue Regeneration by Dental Pulp and Periodontal Ligament Stem Cells.

INTRODUCTION: The aim of this study was to determine the effects of in vitro odontogenic/cementogenic differentiation on the in vivo tissue regeneration of dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs). METHODS: DPSCs and PDLSCs were predifferentiated for 0, 4, or 8 days with an odontogenic/cementogenic medium and then transplanted into subcutaneous pockets in immunocompromised mice. The transplants were harvested 9 weeks after transplantation, and the characteristics of the newly formed tissues in vivo were analyzed by histologic staining; examining alkaline phosphate activity; immunohistochemical staining for osteocalcin, dentin sialoprotein, and type XII collagen; and quantitative real-time polymerase chain reaction to analyze the expression patterns of the following genes: RUNX2, OC, DMP1, DSPP, POSTN, CP23, and Col XII. RESULTS: In DPSC transplants, the amount of new tissues was similar in all groups, whereas in predifferentiated transplants the OC and DSPP expression were higher than undifferentiated transplants. Predifferentiated PDLSC transplants generated more hard tissue and expressed higher alkaline phosphatase activity than undifferentiated transplants. In particular, 8-day predifferentiated PDLSC transplants formed tissue closer to the cementum/PDL complex in vivo as confirmed by the higher expression levels of POSTN, CP23, and Col XII. CONCLUSIONS: Although there was no significant increase in tissue-forming ability among DPSCs after predifferentiation, predifferentiated DPSCs generated hard tissue closer to dentin. Also, predifferentiated PDLSCs appeared to be able to generate higher-quality and greater amounts of tissue for dental regeneration than undifferentiated PDLSCs.

Microscopic analysis of molar--incisor malformation.

OBJECTIVE: Molar-incisor malformation (MIM) is a newly discovered type of dental anomaly that involves a characteristic root malformation of the permanent first molars. The aim of this study was to reveal the microstructure of MIM teeth in order to determine their origin. STUDY DESIGN: Four MIM teeth were extracted from a 9-year-old girl due to severe mobility. The detailed microstructure of the teeth was determined by examinations with micro-computed tomography (micro-CT), hematoxylin and eosin (H&E) staining, immunohistochemical staining, and scanning electron microscopy to reveal the detailed microstructure. RESULTS: Micro-CT and H&E staining revealed the pulpal floor comprising three layers: upper, middle, and lower. Amorphous hard tissues and hyperactive cells were observed in the middle layer of the pulpal floor, and the cells stained positively for dentin sialoprotein and osteocalcin, but not for collagen XII. CONCLUSION: The results of the present study imply that MIM-affected molars probably result from inappropriate differentiation of the apical pulp and dental follicle.

A new type of dental anomaly: molar-incisor malformation (MIM).

A molar-incisor malformation (MIM) is a newly discovered type of dental anomaly of the permanent first molars, deciduous second molars, and permanent maxillary central incisors. MIM anomalies of the permanent first molars and deciduous second molars may include normal crowns with a constricted cervical region and thin, narrow, and short roots, whereas the affected maxillary central incisors may exhibit a hypoplastic enamel notch near the cervical third of the clinical crown. Although the etiology of MIM remains to be determined, it is thought to be attributable to an epigenetic factor linked to brain- and central nervous system-related systemic diseases at around age 1 to 2 years. MIM teeth are associated with clinical problems such as impaction, early exfoliation, space loss, spontaneous pain, periapical abscess, and poor incisor esthetics. Children with MIM teeth should be observed closely with respect to their medical history, and dentists should formulate a wider-ranging treatment plan.

Comparative gene-expression analysis of the dental follicle and periodontal ligament in humans.

The human dental follicle partially differentiates into the periodontal ligament (PDL), but their biological functions are different. The gene-expression profiles of the dental follicle and PDL were compared using the cDNA microarray technique. Microarray analysis identified 490 genes with a twofold or greater difference in expression, 365 and 125 of which were more abundant in the dental follicle and PDL, respectively. The most strongly expressed genes in the dental follicle were those related to bone development and remodeling (EGFL6, MMP8, FRZB, and NELL1), apoptosis and chemotaxis (Nox4, CXCL13, and CCL2), and tooth and embryo development (WNT2, PAX3, FGF7, AMBN, AMTN, and SLC4A4), while in the PDL it was the tumor-suppressor gene WIF1. Genes related to bone development and remodeling (STMN2, IBSP, BMP8A, BGLAP, ACP5, OPN, BMP3, and TM7SF4) and wound healing (IL1, IL8, MMP3, and MMP9) were also more strongly expressed in the PDL than in the dental follicle. In selected genes, a comparison among cDNA microarray, real-time reverse-transcription polymerase chain reaction, and immunohistochemical staining confirmed similar relative gene expressions. The gene-expression profiles presented here identify candidate genes that may enable differentiation between the dental follicle and PDL.