Impact of haptic simulators in preclinical dental education: A systematic review.

BACKGROUND: Haptic technologies have opened a new avenue in preclinical dental education, with evidence that they can be used to improve student performance. The aim of this systematic review was to (1) determine the effect of haptic simulators on motor skill acquisition during preclinical dental training, (2) explore students' perception, and (3) explore the ability of haptic systems to distinguish users based on their initial level of manual dexterity. METHODS: A comprehensive search of articles published up to February 2023 was performed using five databases (i.e., PubMed/Medline, ScienceDirect, Web of Sciences, Scopus, and Cochrane Library) and specialized journals. The Preferred Reporting Items for Systematic Review and Meta-Analysis 2020 guidelines were followed, and the risk of bias was assessed. Only studies on the application of haptic simulators in dentistry preclinical training were included. Qualitative synthesis of data was performed, and the protocol was registered in PROSPERO (ID = CRD42022337177). RESULTS: Twenty-three clinical studies, including 1303 participants, were included. The authors observed a statistically significant improvement in dental students' motor skills in various dental specialties, such as restorative dentistry, pediatric, prosthodontics, periodontics, implantology, and dental surgery, after haptic training. Haptic technologies were perceived well by all participants, with encouraging data regarding their ability to differentiate users according to their initial level of manual dexterity. CONCLUSIONS: Our work suggests that haptic simulators can significantly improve motor skill acquisition in preclinical dental training. This new digital technology, which was well perceived by the participants, also showed encouraging results in discriminating users according to their level of experience.

Different Polymers for the Base of Removable Dentures? Part I: A Narrative Review of Mechanical and Physical Properties.

Even before considering their introduction into the mouth, the choice of materials for the optimization of the prosthesis depends on specific parameters such as their biocompatibility, solidity, resistance, and longevity. In the first part of this two-part review, we approach the various mechanical characteristics that affect this choice, which are closely related to the manufacturing process. Among the materials currently available, it is mainly polymers that are suitable for this use in this field. Historically, the most widely used polymer has been polymethyl methacrylate (PMMA), but more recently, polyamides (nylon) and polyether ether ketone (PEEK) have provided interesting advantages. The incorporation of certain molecules into these polymers will lead to modifications aimed at improving the mechanical properties of the prosthetic bases. In the second part of the review, the safety aspects of prostheses in the oral ecosystem (fragility of the undercuts of soft/hard tissues, neutral pH of saliva, and stability of the microbiota) are addressed. The microbial colonization of the prosthesis, in relation to the composition of the material used and its surface conditions (roughness, hydrophilicity), is of primary importance. Whatever the material and manufacturing process chosen, the coating or finishes dependent on the surface condition remain essential (polishing, non-stick coating) for limiting microbial colonization. The objective of this narrative review is to compile an inventory of the mechanical and physical properties as well as the clinical conditions likely to guide the choice between polymers for the base of removable prostheses.

Marginal and internal fit of five-unit zirconia-based fixed dental prostheses fabricated with digital scans and conventional impressions: A comparative in vitro study.

PURPOSE: This study aimed to compare the marginal and internal fit of five-unit zirconia-based fixed dental prostheses (FDPs) fabricated using digital scans and conventional impressions. MATERIALS AND METHODS: Nine master models with three zirconia abutments were scanned with an intraoral scanner (test group), and nine conventional impressions (control group) of these same models were also made. The stone casts from these impressions were scanned with a laboratory extraoral scanner (D700, 3Shape, Copenhagen, Denmark). A total of 18 five-unit zirconia-based FDP frameworks (test group, n = 9; control group, n = 9) were manufactured. Marginal and internal fit (in µm) were evaluated using the replica method under micro-computed tomography. Analysis of variance (one-way ANOVA) and Kruskal-Wallis tests were used to compare continuous variables across two groups. A level of p < 0.05 was accepted as statistically significant. RESULTS: The mean ± standard deviation of the marginal fit was 95.03 ± 12.74 µm in the test group and 106.02 ± 14.51 µm in the control group. The lowest marginal mean value was observed in the test group, with a statistically significant difference compared to the control group (F = 14.56, p < 0.05). The mean ± standard deviation of the internal fit was 103.61 ± 9.32 and 106.38 ± 7.64 µm, respectively, in the test and control groups, with no statistically significant difference (F = 1.56, p > 0.05). The mean values of both groups were clinically acceptable. CONCLUSIONS: The five-unit zirconia-based FDPs fabricated with digital scans showed better fit than those in the conventional impression group. Within the limitations of this study, these results are encouraging, and continued progress in the digital field should allow for more accurate long-span restorations.

Host's Immunity and Candida Species Associated with Denture Stomatitis: A Narrative Review.

Denture-related Candida stomatitis, which has been described clinically in the literature, is either localized or generalized inflammation of the oral mucosa in connection with a removable prosthesis. During this inflammatory process, the mycobacterial biofilm and the host's immune response play an essential role. Among microorganisms of this mixed biofilm, the Candida species proliferates easily and changes from a commensal to an opportunistic pathogen. In this situation, the relationship between the Candida spp. and the host is influenced by the presence of the denture and conditioned both by the immune response and the oral microbiota. Specifically, this fungus is able to hijack the innate immune system of its host to cause infection. Additionally, older edentulous wearers of dentures may experience an imbalanced and decreased oral microbiome diversity. Under these conditions, the immune deficiency of these aging patients often promotes the spread of commensals and pathogens. The present narrative review aimed to analyze the innate and adaptive immune responses of patients with denture stomatitis and more particularly the involvement of Candida albicans sp. associated with this pathology.

Implant-supported removable partial dentures compared to conventional dentures: A systematic review and meta-analysis of quality of life, patient satisfaction, and biomechanical complications.

OBJECTIVES: The purpose of this systematic review and meta-analysis was to compare implant-supported removable partial dentures (ISRPDs) with distal extension removable partial dentures (DERPDs) in terms of patient-reported outcome measures (PROMs: patients' quality of life and satisfaction) and to determine mechanical and biological complications associated with ISRPDs. MATERIAL AND METHODS: An electronic search was performed on four databases to identify studies treating Kennedy class I or II edentulous patients and which compared ISRPDs with DERPDs in terms of PROMS and studies, which evaluated mechanical and biological complications associated ISRPDs. Two authors independently extracted data on quality of life, patient satisfaction, and biomechanical complications from these studies. The risk of bias was assessed for each study, and for PROMs, the authors performed a meta-analysis by using a random-effects model. RESULTS: Thirteen articles were included based on the selection criteria. The difference in mean scores for quality of life (30.5 ± 1.8; 95% confidence interval [CI], 24.9-36.1) and patient satisfaction (-20.8 ± 0.2; 95% CI, -23.7 to -17.8) between treatments with conventional and implant-supported removable dentures was statistically significant (p < .05). Implant-supported removable dentures improved patients' overall quality of life and satisfaction. Some mechanical and biological complications, such as clasp adjustment, abutment or implant loosening, marginal bone resorption, and peri-implant mucositis, were noted in ISRPDs during patient follow-up. Studies assessing PROMs were very heterogeneous (I2 = 65%, p = .85; I2 = 75%, p = .88). CONCLUSIONS: ISRPDs significantly improved quality of life and patient satisfaction. Some mechanical and biological complications have been associated with ISRPDs treatment, requiring regular monitoring of patients to avoid the occurrence of these complications.

In vitro and in vivo biocompatibility of calcium-phosphate scaffolds three-dimensional printed by stereolithography for bone regeneration.

Stereolithography (SLA) is an interesting manufacturing technology to overcome limitations of commercially available particulated biomaterials dedicated to intra-oral bone regeneration applications. The purpose of this study was to evaluate the in vitro and in vivo biocompatibility and osteoinductive properties of two calcium-phosphate (CaP)-based scaffolds manufactured by SLA three-dimensional (3D) printing. Pellets and macro-porous scaffolds were manufactured in pure hydroxyapatite (HA) and in biphasic CaP (HA:60-TCP:40). Physico-chemical characterization was performed using micro X-ray fluorescence, scanning electron microscopy (SEM), optical interferometry, and microtomography (µCT) analyses. Osteoblast-like MG-63 cells were used to evaluate the biocompatibility of the pellets in vitro with MTS assay and the cell morphology and growth characterized by SEM and DAPI-actin staining showed similar early behavior. For in vivo biocompatibility, newly formed bone and biodegradability of the experimental scaffolds were evaluated in a subperiosteal cranial rat model using µCT and descriptive histology. The histological analysis has not indicated evidences of inflammation but highlighted close contacts between newly formed bone and the experimental biomaterials revealing an excellent scaffold osseointegration. This study emphasizes the relevance of SLA 3D printing of CaP-based biomaterials for intra-oral bone regeneration even if manufacturing accuracy has to be improved and further experiments using biomimetic scaffolds should be conducted.

Evaluation of a hydrogel membrane on bone regeneration in furcation periodontal defects in dogs.

The aim of the study was to evaluate bone regeneration using a canine model with surgically created periodontal defects filled for 12 weeks using a stratified biomaterial consisting in a biphasic calcium phosphate (BCP) covered with a crosslinking hydrogel acting as polymer membrane of silated hydroxypropyl methylcellulose (Si-HPMC) as the tested new concept. Bilateral, critical-sized, defects were surgically created at the mandibular premolar teeth of six adult beagle dogs. The defects were randomly allocated and: (i) left empty for spontaneous healing or filled with: (ii) BCP and a collagen membrane; (iii) BCP and hydrogel Si-HPMC membrane. At 12 weeks, the experimental conditions resulted in significantly enhanced bone regeneration in the test BCP/Si-HPMC group. Within the limits of this study, we suggest that the hydrogel Si-HPMC may act as an occlusive barrier to protect bone area from soft connective tissue invasion and then effectively contribute to enhance bone regeneration.

[Orthodontic tooth displacement: histology, biology and iatrogenic effects]. / Le déplacement dentaire orthodontique : histologie, biologie et effets iatrogènes.

Iatrogenic effects of orthodontic forces, in particular root resorption, are described in the literature. However, our knowledge on the risk of osseous defects induced by orthodontic treatment is still scarce. After an overview of histological and biological principles of orthodontically-induced tooth movement, this study focuses on the recent data concerning the occurrence and the treatment of bone resorption associated with orthodontic treatment.

Histomorphometric analysis of the osseointegration of four different implant surfaces in the femoral epiphyses of rabbits.

OBJECTIVES: The surface properties of titanium dental implants are key parameters for rapid and intimate bone-implant contact. The osseointegration of four implant surfaces was studied in the femoral epiphyses of rabbits. MATERIAL AND METHODS: Titanium implants were either grit-blasted with alumina or biphasic calcium phosphate (BCP) ceramic particles, coated with a thin octacalcium phosphate (OCP) layer, or prepared by large-grit sand blasting and acid-etched (SLA). After 2 and 8 weeks of implantation, the bone-implant contact and bone growth inside the chambers were compared. Scanning electron microscopy (SEM) and profilometry showed distinct microtopographies. RESULTS: The alumina-Ti, BCP-Ti and OCP-Ti groups had similar average surface roughness in the 1-2 mum range whereas the SLA surface was significantly higher with a roughness averaging 4.5 microm. Concerning the osseointegration, the study demonstrated a significantly greater bone-to-implant contact for both the SLA and OCP-Ti surfaces as compared with the grit-blasted surfaces, alumina- and BCP-Ti at both 2 and 8 weeks of healing. CONCLUSION: In this animal model, a biomimetic calcium phosphate coating gave similar osseointegration to the SLA surface. This biomimetic coating method may enhance the apposition of bone onto titanium dental implants.

Osteoblastic cell behavior on nanostructured metal implants.

AIMS: Surface modifications at the nanometric scale may promote protein adsorption, cell adhesion and thus favor the osseointegration of metal implants. The behavior of osteoblastic cells was studied on mirror-polished (Smooth-SS) and nanostructured (Nano-SS) stainless steel surfaces. MATERIALS & METHODS: The nanostructuration was obtained by anodization. The surfaces were characterized by scanning electron, atomic force microscopy (AFM) and X-ray photoelectron specytoscopy. Osteoblastic cells were cultured on these surfaces. RESULTS & DISCUSSION: AFM showed a regular array of pores on the Nano-SS. Osteoblastic cells spread more rapidly on Nano-SS surfaces than on Smooth-SS surfaces. Cell viability was similar on Smooth-SS and Nano-SS. Alkaline phosphatase activity increased with culture time whatever the substrate but was better enhanced at 21 days on the Nano-SS than on the Smooth-SS. CONCLUSION: This study shows that the nanostructuration of metal implants may improve the adhesion and differentiation of osteoblastic cells.

Osteoblastic cell behaviour on different titanium implant surfaces.

The osseointegration of oral implants is related to the early interactions between osteoblastic cells and titanium surfaces. The behaviour of osteoblastic MC3T3-E1 cells was compared on four different titanium surfaces: mirror-polished (Smooth-Ti), alumina grit-blasted (Alumina-Ti) or biphasic calcium phosphate ceramic grit-blasted (BCP-Ti) and a commercially available implant surface (SLA). Scanning electron microscopy and profilometry showed distinct microtopographies. The BCP-Ti group had higher average surface roughness (Ra=2.5 microm) than the other grit-blasted groups. Hydrophilicity and surfaces energies were determined on the different substrates by dynamic contact angle measurements. The most hydrophilic surface was the Alumina-Ti discs, while SLA was the most hydrophobic. The titanium surfaces were all oxidized as TiO2 and polluted by carbon contaminants, as determined by X-ray photoelectron spectroscopy. Alumina-Ti samples also exhibited aluminium peaks as a result of the blasting. The BCP-Ti discs contained traces of calcium and phosphorus. MC3T3-E1 cells attached, spread and proliferated on the substrates. For both the SLA and BCP-Ti groups, the entire surface was covered with a layer of osteoblastic cells after 2 days. At high magnification, the cells exhibited cytoplasmic extensions and filopodia. Compared with plastic, cell viability was similar with the Smooth-Ti, slightly lower with the Alumina-Ti and superior with the SLA and BCP-Ti groups. Alkaline phosphatase activity increased with the culture time whatever the substrate. This study shows that BCP-blasting produces rough titanium implants without surface contaminants.

Influence of calcium chloride and aprotinin in the in vivo biological performance of a composite combining biphasic calcium phosphate granules and fibrin sealant.

Highly bioactive biomaterials have been developed to replace bone grafts in orthopedic revision and maxillofacial surgery for bone augmentation. A mouldable, self-hardening material can be obtained by combining TricOs Biphasic Calcium Phosphate Granules and Tissucol Fibrin Sealant. Two components, calcium chloride and antifibrinolytic agents (aprotinin), are essential for the stability of the fibrin clot. The ingrowth of cells in composites combining sealants without calcium chloride or with a low concentration of aprotinin was evaluated in vivo in an experiment on rabbits. Bone colonization was compared using TricOs alone or with the composite made from TricOs and the standard fibrin sealant. Without the addition of calcium chloride, the calcium ions released by the ceramic component interacted with the components of the sealant too late to stabilize the clot. With a low concentration of aprotinin, the degradation of the clot occurred more quickly, leading to the absence of a scaffold on which the bone cells could colonize the composite. Our results indicate that a stable fibrin scaffold is crucial for bone colonization. The low calcium chloride and low aprotinin groups have shown lower bone growth. Further studies will be necessary to determine the minimal amount of antifibrinolytic agent (aprotinin) necessary to allow the same level of osteogenic activity as the TricOs-fibrin glue composite.

Osteointegration of femoral stem prostheses with a bilayered calcium phosphate coating.

Our purpose was to evaluate the osteointegration of bilayered calcium phosphate (CaP)-coated femoral hip stems in a canine model. A first layer of hydroxyapatite (HA) 20 microm thick and a superficial layer of Biphasic Calcium Phosphate (BCP) 30 microm thick were plasma-sprayed on to the proximal region of sandblasted Ti6Al4V prostheses. Bilayered CaP-coated and non-coated canine femoral stems were implanted bilaterally under general anesthesia in 6 adult female Beagle dogs. After 6 and 12 months, a significant degradation of the bilayered coating occurred with a remainder of 33.1+/-12.4 and 23.6+/-9.2 microm in thickness, respectively. Lamellar bone apposition was observed on bilayered coated implants while fibrous tissue encapsulation was observed on non-coated femoral stems. The bone-implant contacts (BIC) were 91+/-3% and 81+/-8% for coated and 7+/-8% and 8+/-12% for non-coated implants, at 6 and 12 months, respectively. Our study supports the concept of a direct relationship between the biodegradation of CaP coating and the enhanced osteointegration of titanium prostheses. A bilayered CaP coating might therefore enhance bone apposition in the early stages because of the superior bioactivity of the BCP layer while the more stable HA layer might sustain bone bonding over long periods.

MBCP biphasic calcium phosphate granules and tissucol fibrin sealant in rabbit femoral defects: the effect of fibrin on bone ingrowth.

An ageing population implies an increase in bone and dental diseases, which are in turn a source of numerous handicaps. These pathologies are an expensive burden for the European health system. As no specific bioactive materials are efficient enough to cope with this burden, we have to develop an injectable, mouldable, self-hardening bone substitute to support bone tissue reconstruction and augmentation. New, highly bioactive and suitable biomaterials have been developed to replace bone grafts in orthopedic revision and maxillofacial surgery for bone augmentation. These mouldable, self-hardening materials are based on the association of MBCP Biphasic Calcium Phosphate Granules and Tissucol Fibrin Sealant. The in vivo evaluation of ingrowth in relation to the composite was made in an experiment on rabbits. The results indicate that in the presence of fibrin sealant, newly-formed bone developed at a small distance from the surface of the calcium phosphate ceramic. Two different bone apposition processes were identified. Without the fibrin component (MBCP group), bone rested directly on the surface of the granules. This observation is commonly described as osteoconduction in calcium phosphate materials. On the contrary, the presence of the fibrinogen component seemed to modify this standard osteoconduction phenomenon: the newly-formed bone essentially grew at a distance from the surface of the granules, on the fibrillar network, and could be considered as an inductive phenomenon for osteogenic cell differentiation from mesenchymal stem cells.