Review on regenerative endodontics: Past concepts, current protocols and future strategies

Till last few decades, a necrosed tooth with immature apex was an indication for apexogenesis. With advances in dentistry such as improved irrigation protocols, better visibility to the operating site and increased skills of endodontists, regenerative endodontic procedures have come into the limelight. The alongside research in tissue engineering also have been beneficial for researchers and endodontists to open new horizons in regenerative endodontics. This review paper involves the triad of tissue engineering, concepts of regenerative endodontics applied in past, current protocols according to American Association of Endodontists and future concepts of tooth tissue regenerations which are being researched.

miR-6807-5p Inhibited the Odontogenic Differentiation of Human Dental Pulp Stem Cells Through Directly Targeting METTL7A

Background: Tooth tissue regeneration mediated by mesenchymal stem cells (MSCs) has become the most ideal treatment. Although the known regulatory mechanism and some achievements have been discovered, directional differentiation cannot effectively induce regeneration of tooth tissue. In this study, we intended to explore the function and mechanism of miR-6807-5p and its target gene METTL7A in odontogenic differentiation.Methods: In this study, human dental pulp stem cells (DPSCs) were used. Alkaline phosphatase (ALP), Alizarin red staining (ARS), and calcium ion quantification were used to detect the odontogenic differentiation of miR-6807-5p and METTL7A. Real-time RT-PCR, western blot, dual-luciferase reporter assay, and pull-down assay with biotinylated miRNA were used to confirm that METTL7A was the downstream gene of miR-6807-5p. Protein mass spectrometry and co-immunoprecipitation (Co-IP) were used to detect that SNRNP200 was the co-binding protein of METTL7A.Results: After mineralized induction, the odontogenic differentiation was enhanced in the miR-6807-5p-knockdown group and weakened in the miR-6807-5p-overexpressed group compared with the control group. METTL7A was the downstream target of miR-6807-5p. After mineralized induction, the odontogenic differentiation was weakened in the METTL7A-knockdown group and enhanced in the METTL7A-overexpressed group compared with the control group. SNRNP200 was the co-binding protein of METTL7A. The knockdown of SNRNP200 inhibited the odontogenic differentiation of DPSCs.Conclusion: This study verified that miR-6807-5p inhibited the odontogenic differentiation of DPSCs. The binding site of miR-6807-5p was the 3′UTR region of METTL7A, which was silenced by miR-6807-5p. METTL7A promoted the odontogenic differentiation of DPSCs. SNRNP200, a co-binding protein of METTL7A, promoted the odontogenic differentiation of DPSCs.

Resistance fracture of minimally prepared endocrowns made by three types of restorative materials: a 3D finite element analysis

A thin endocrown restoration was often applied in endodontically treated teeth with vertical bite height loss or inadequate clinical crown length. A model of mandibular molars made by endocrown restoration with 1 mm thickness and 2 mm depth of pulp chamber was constructed and imported into FEA ANSYS v18.0 software. The three CAD/CAM materials, feldspathic (Mark2), lithium disilicate (EMAX), and lava ultimate (LU), were assigned, and the five load indenters were loaded on the full occlusal (FO), occlusal center (OC), central fossa (CF), buccal groove (BG), and mesiobuccal cusp (MC) of restoration in the model. The MinPS and MaxPS of the thin endocrown were significantly higher than those of tooth tissue in five types of loads except for the LU endocrown loaded in the FO group. The smaller the contact surface of the load was, the higher MaxPS and MinPS were. MaxPS and MinPS of the MC were the highest, followed by the BG and CF in the restoration. In the stress distribution of tooth tissue, MaxPS in the LU endocrown accumulated at the external edge of enamel and was significantly higher than MaxPS in Mark2 and EMAX endocrown concentrated on the chamber wall of dentin under OC, CF and BG loads. Within the limitations of this FEA study, the LU endocrown transferred more stress to tooth tissue than Mark2 and EMAX, and the maximum principal stress on endocrown restoration and tooth tissue at the mesiobuccal cusp load was higher than that at the central fossa and buccal groove load.

The antibacterial efficacy of photon-initiated photoacoustic streaming in root canals with different diameters or tapers

Background In recent years, the concept of minimally invasive endodontics has been proposed, which could be described as preventing or treating diseases by preserving more dental tissue and creating minimal damage. In the process of root canal preparation, it was recommended to use instruments with a smaller taper to preserve more tooth tissue and improve the preservation rate of the affected teeth. Photon-induced photoacoustic streaming (PIPS) was a new type of laser-activated irrigation technology, which was now widely used in endodontic treatment. The purpose of this article was to evaluate the bactericidal effect of PIPS with NaOCl in root canals with different widths or tapers. Methods Twenty-three maxillary first molars with three independent root canals were included in this study. The mesiobuccal (MB), distobuccal (DB), and palatal (P) root canals were prepared at sizes of #10/.02, #25/.02, and #25/.06, respectively. After being incubated with a bacterial suspension for 4 weeks, the specimen were irrigated with 2% NaOCl activated by conventional needle irrigation (CNI) (n = 10) or PIPS (n = 10). Three specimen were not treated (control group). Before and after irrigation, the presence of bacteria was assessed with an adenosine 5'-triphosphate (ATP) assay kit and biofilms were assessed using confocal laser scanning microscopy and scanning electron microscopy. Results In specimen prepared using PIPS irrigation, the ATP was reduced by more than 98%. When the root canal taper was 0.02, the size #25 root canals had a higher percentage of dead bacteria than the size #10 root canals in all regions (P < 0.05) in the PIPS group. When the root canal width was #25, the 0.02 taper group had a higher percentage of dead bacteria than the 0.06 taper group in the apical region (P < 0.05), except coronal and middle regions (P > 0.05). PIPS irrigation results in a greater percentage of dead bacteria and reduction of ATP in size #10/.02 root canals than CNI in size #25/.06 root canals in three regions (P < 0.05). Conclusion Increasing the width from #10 to #25 improves the bactericidal effect of PIPS in the root canal. Increasing the taper of the root canal from 0.02 to 0.06 at size #25 did not affect the bactericidal effects of PIPS. PIPS resulted in more dead bacteria in specimen with smaller tapers and root canal widths than CNI. PIPS can be used to clean the smear layer in the coronal region and open the dentin tubules. Clinical significance: Activation of irrigants with PIPS brought about significant bacterial reduction smaller tapers and width root canals compared to CNI, which was beneficial to prevent excessive loss of tooth tissue and conserve the structural integrity of teeth.

Assessment of the Potential Ability to Penetrate into the Hard Tissues of the Root of an Experimental Preparation with the Characteristics of a Dental Infiltrate, Enriched with an Antimicrobial Component—Preliminary Study

Infiltration is a method of penetration with a low viscosity resin that penetrates deep into demineralised tooth tissue and fills the intergranular spaces, hence reducing porosity. Carious lesions initially located at the enamel–cement junction are usually found in elderly patients. Those spots are predisposed to bacterial adhesion originating both from biofilm and from gingival pocket bacteria. The aim of this study was to evaluate the penetration of an experimental preparation, which has the characteristics of a dental infiltrant, enriched with an antibacterial component, into the decalcified root cement tissues of extracted human teeth in elderly patients. An experimental preparation with the characteristics of a dental infiltrant was prepared, applied, and polymerised on the surface of extracted, previously decalcified human teeth. The control sample was Icon (DMG, Hamburg, Germany). The ability of the preparations to penetrate deep into the root cement was evaluated using scanning electron and light microscopy. The study showed that an experimental preparation could potentially be used for treatment of early carious lesions within the tooth root in elderly patients, among others, as it penetrates deep into demineralised tissues. More research is needed.

Damage in Dentistry

Dentistry is one of the clinical disciplines that is closely related to medicine, but also to the technology of making various devices and placing artificial materials that compensate and/or upgrade lost teeth and surrounding structures. Dentistry is also medically responsible for the treatment of patients with diseases of the oral cavity. The main task of dentistry is healthy teeth and oral cavity, ie their preservation and treatment of damaged teeth. Caries is the most common dental disease, and is caused by the multiplication of bacteria inside the oral cavity due to lack of oral hygiene. If not treated in time, caries penetrates deeper tooth structures and destroys them which leading to tooth decay. The most common symptoms of caries are tooth sensitivity and toothache. If these symptoms occur, it is necessary to perform an examination at the dentist in order to prevent the disease immediately at the beginning and to avoid significant consequences for dental health. If caries is not treated in time, there is a high chance that irreparable damage will occur to the teeth and tooth tissue, which can ultimately result in the loss of one or more teeth.

CERAMIC LAMINATE VENEERS: A 3-YEAR CLINICAL FOLLOW-UP

Ceramic laminate veneers have been widely used in esthetic restorations, with advantages such as color stability, resistance to degradation, and excellent esthetic results, all of which contribute to long-term stability. The gold standard technique consists of bonding a thin ceramic laminate veneer to enamel. The present paper describes a clinical case with 3-year follow-up. Six ceramic laminate veneers were planned, fabricated and bonded to six sound anterior maxillary teeth showing diastema, thereby improving shape and size. The procedure followed a laminate veneer treatment protocol, using a mock-up, shade selection, and an adhesive system. The case was followed for 3 years. In conclusion, minimally invasive restorations with ceramic laminate veneers remained stable after 3 years of follow-up and are a good option for patients with diastema or microdontia and requires only a minimum amount of sound tooth tissue removal.

Resistance Fracture of Minimally Prepared Endocrowns Made By Three Types of Restorative Materials: A 3D Finite Element Analysis

A thin endocrown restoration was often applied in endodontically treated teeth with vertical bite height loss or inadequate clinical crown length. A model of mandibular molars made by endocrown restoration with 1 mm thickness and 2 mm depth of pulp chamber was constructed and imported into FEA ANSYS v18.0 software. The three CAD/CAM materials, feldspathic (Mark2), lithium disilicate (EMAX) and lava ultimate (LU), were assigned, and the five load indenters were loaded on the full occlusal (FO), occlusal center (OC), central fossa (CF), buccal groove (BG) and mesiobuccal cusp (MC) of restoration in the model. The MinPS and MaxPS of the thin endocrown were significantly higher than those of tooth tissue in five types of loads except for the LU endocrown loaded in the FO group. The smaller the contact surface of the load was, the higher MaxPS and MinPS were. MaxPS and MinPS of the MC were the highest, followed by the BG and CF in the restoration. In the stress distribution of tooth tissue, MaxPS in the LU endocrown accumulated at the external edge of enamel and was significantly higher than MaxPS in Mark2 and EMAX endocrown concentrated on the chamber wall of dentin under OC, CF and BG loads. Within the limitations of this FEA study, the LU endocrown transferred more stress to tooth tissue than Mark2 and EMAX, and the maximum principal stress on endocrown restoration and tooth tissue at the mesiobuccal cusp load was higher than that at the central fossa and buccal groove load.

Chosen applications and approaches to modeling lasers in dentistry

Historically, although the first indications for the use of lasers in general were in dentistry, coming as a relief from the sound of the drill and mechanical contacts, it still seems somewhat that the entry in various ways of lasers in dentistry has been slower. This is somewhat true for the situation at the continents (e.g. USA much later approved the application relative to Europe). This paper analyzes the potential and existing applications of lasers in dentistry in a wide range of existing types, including interaction with dental tissues, in terms of surgical applications, on living tissue, the prosthetic area of applications and therapeutic doses. There is another special feature that can be recognized is the precise determination of the color of the material (teeth and prosthetics) and in general the determination of the composition of the material including classic, but also modern laser techniques (LIBS, complimentary techniques, tooth tissue, bone) and especially in the case of the first Q switch systems related to pain reduction, because the short pulse favors the intervention rate (ns, ps and fs). Special attention should be paid to modeling of interaction and analysis with the appropriate software support.

Evaluation of the Effects of Different Rapid Maxillary Expansion Appliances on Obstructive Sleep Apnea: A randomized clinical trial

Purpose The aim of this randomized clinical trial was to evaluate the effects of tooth tissue-borne (TTB), tooth-borne (TB), and bone-borne (BB) rapid maxillary expansion appliances on obstructive sleep apnea (OSA) severity. Trial design Three-arm parallel randomized controlled trial. Methods This study was designed in parallel with an allocation ratio of 1:1:1. Forty six patients with narrow maxilla and diagnosis of OSA recruited from the Department of Orthodontics, ### University were randomly assigned to three groups according to appliance used: tooth tissue-borne, tooth-borne and bone-borne expanders. The primary outcome of this study included polygraphic change in sleep parameters. Secondary outcome was the correction of posterior crossbite. Each subject underwent overnight sleep test with polygraphy at baseline and 3 month-follow-up of treatment. Randomization was performed using a computer-generated randomization program The outcome assessor was blinded to group assignment. For the statistical analysis, Kruskal-Wallis analysis and Dunn-Bonferroni tests were used for inter-group comparisons and Wilcoxon analysis was used for intra-group evalaution. p<0.05 was accepted statistically significant. Results The amount of expansion in maxillary width and upper intermolar width were similar in all goups (95% confidence interval [CI], p>0.05). The groups were similar in terms of apnea-hypopnea index (AHI) and oxygen saturation parameters at baseline (95% [CI], p>0.05). After 3 months of treatment, there was no significant decrease in AHI and oxygen desaturation index, and no increase in minimum and mean oxygen saturations (95% [CI], p>0.05). Supine AHI values were decreased by the tooth tissue-borne and tooth-borne appliances, but these changes were not significant (95% [CI], p>0.05). Harms No serious harm ocurred except mild gingivitis. Conclusions Similar skeletal and dental expansion of maxilla were observed after RME with all expanders. Although the decrease in AHI was not significant, RME can be used as an adjunct to the primary treatment in OSA patients.