Denture Restoration Research Articles

Biomechanical behaviour of tilted abutment after fixed partial denture restoration of CAD/CAM materials

BackgroundFailure to restore missing teeth in time can easily lead to the mesial tilting of the distal abutment teeth. However, a fixed partial denture (FPD) can improve stress conduction and distribution and prevent periodontal injuries. In these more complex cases, it is necessary to consider various factors comprehensively to improve conventional treatment planning and achieve better results.MethodsWe selected a patient with a missing first molar and a mesial inclination of the second molar, leaving inadequate space or bone mass for implant denture restoration, necessitating an FPD for restoration. Three-dimensional finite element analysis (3D-FEA) combined with photoelastic analysis were used to explore how the inclination angle (0 ‒ 30°) and different dental restoration materials (zirconia, lithium disilicate, polymer-infiltrated ceramic network, and resin composite) affect the biomechanical behaviour of FPD‒abutments‒periodontal tissue complex.ResultsThe stress was easily concentrated in the FPD connectors, enamel shoulder collar, periapical area, and root bifurcation. The stress on FPD and the periodontal ligament (PDL) of the second premolar increased with an increase in the elastic modulus of FPD, with an opposite trend in the abutments, the alveolar bone, and the PDL of the second molar. The stress on the FPD and alveolar bone increased with increased inclination angle of the distal abutment. The stress on two abutments and their PDL were positively correlated with the inclination angle in two stages; however, when the inclination angle > 12°, the second premolar and its PDL showed a negative correlation.ConclusionsFPDs can be used for restoration within 24° of distal abutment inclination, but protecting the abutments (< 12° especially) and the periodontal tissue (> 12° especially) must be taken seriously. For this purpose, an FPD material with higher strength is recommended.

Research and development of intraoral scanning in edentulous soft tissue

During the complete denture restoration process, accurate impression making is a crucial step for achieving good denture retention. With the increasing popularity of intraoral scanning technology in fixed restoration, the use of intraoral scanning technology in complete denture restoration for edentulous Jaw has also been developed. This article systematically reviews the research progress and application of intraoral scanning of edentulous soft tissue, focusing on difficulties in intraoral scanning of edentulous jaws, scanning accuracy, clinical application effects, as well as precautions involved. The aim is to provide references for clinical application.

Copper nanoparticles incorporated visible light-curing chitosan-based hydrogel membrane for enhancement of bone repair

Alveolar bone defects caused by tumor, trauma and inflammation can lead to the loss of oral function and complicate denture restoration. Currently, guided bone regeneration (GBR) barrier membranes for repairing bone defect cannot effectively promote bone regeneration due to their unstable degradation rate and poor antibacterial properties. Furthermore, they require additional tailoring before implantation. Therefore, this study developed a visible light-curing hydrogel membrane (CF–Cu) comprising methacrylated carboxymethyl chitosan (CMCS-MA), silk fibroin (SF), and copper nanoparticles (Cu NPs) to address these shortcomings of commercial membranes. The CF-Cu hydrogel, characterized by scanning electron microscopy (SEM), a universal testing machine, and swelling and degradation tests, demonstrated a smooth porous network structure, suitable swelling ratio, biodegradability, and enhanced mechanical strength. Cytotoxicity and hemolysis tests in vitro demonstrated excellent cyto- and hemo-compatibility of the CF-Cu hydrogel extracts. Additionally, evaluation of antibacterial properties in vitro, including colony forming unit (CFU) counts, MTT assays, and live/dead fluorescence staining, showed that the CF-Cu hydrogel exhibited excellent antibacterial properties, inhibiting over 80% of S. aureus, S. mutans, and P. gingivalis with CF-1Cu hydrogel compared to the control group. Moreover, evaluation of osteogenic differentiation of rBMSCs in vitro suggested that the CF-1Cu hydrogel significantly improved alkaline phosphatase (ALP) activity and the mineralization of extracellular matrix, up-regulating the expressions of osteogenesis-related genes (Runx2, ALP, Col-1, OPN and BSP). In summary, these results indicated that CF-1Cu hydrogel exhibited excellent cytocompatibility, antibacterial and osteogenic properties in vitro. Therefore, the CF-1Cu hydrogel holds potential as a viable material for application in GBR procedures aimed at addressing bone defects.

Effectiveness of Oral Care in Implant Denture Restoration in Chronic Periodontitis

Objective: To explore the effect of observation of oral care in implant denture restoration of chronic periodontitis. Methods: 80 patients with chronic periodontitis implant denture restoration admitted from March 2022 to March 2023 in the hospital were selected. They were randomly divided into an observation group and a control group, with 40 cases in each group. Both groups of patients received routine treatment and care. The patients in the control group used routine oral care methods to carry out oral care, the patients in the observation group carried out oral care on the basis of the control group, observation and analysis of the patients’ mastery of oral knowledge, as well as the depth of the probing and the level of clinical attachment. Results: The oral knowledge mastery of the observation group was 72.31 ± 6.98 after the nursing intervention, which was significantly higher than the score of 86.12 ± 7.36 of the patients in the control group who used conventional oral care, and the difference was statistically significant at P &lt; 0.05; the depth of probing and the clinical attachment level of the observation group were 2.43 ± 0.58 and 4.31 ± 0.86 respectively, which were significantly better than those of the control group. The depth of probing and clinical attachment level scores of the observation group were 2.99 ± 0.54 and 5.36 ± 1.02 respectively, and P &lt; 0.05 was considered statistically significant. Conclusion: The combination of conventional treatment and oral care can effectively improve the treatment effect of implant denture prosthesis for chronic periodontitis. However, it is necessary to pay attention to the psychological counseling of the patients in the specific clinical application to ensure that the patients can actively cooperate with the clinical treatment.

Implant-assisted removable partial denture restoration in small number of residual teeth in mandible: A case report

Implant-assisted removable partial denture restoration in small number of residual teeth in mandible: A case report

Efficient intraoral photogrammetry using self-identifying projective invariant marker.

The re-measurement of full-arch implant digital impressions is an important step in denture restoration. This paper provides an efficient oral photogrammetry technology using projective invariant marker, applied in the re-measurement of full-arch implant digital impressions. We have developed a self-recognizing marker with projection invariance, along with its detection code. The marker is installed on the scanning body and used for photogrammetric measurements. Triangulation is utilized to determine the 3D coordinates of the marker, followed by a series of post-processing steps to obtain more accurate 3D coordinates. The experimental data indicate that the optimal working distance is between 200 and 250mm, with a minimum measurement error of less than 0.05mm and an average measurement error of 0.10 mm. The measurement time is less than 2min. The experimental results show that the photogrammetric system can obtain reliable positions of full-arch implants with efficient photogrammetry, without the need to enter the patient's oral cavity, and has potential clinical application value.

Rehabilitation of complete edentulism and temporomandibular joint

Rehabilitation of complete edentulism is naturally related to temporomandibular joint (TMJ) since the proper functioning of complete denture depends on the normal movement of TMJ. This review briefly introduced the design of occlusion in complete denture, characteristic of different occlusal patterns, and key points in registration of maxillomandibular relationship and occlusal adjustment. This review emphasized the significance of complete denture restoration to the health of TMJ.

Symmetrical Midfacial Growth After Pediatric Mandibular Reconstruction With Free Fibula Flap

Free fibula is the workhorse flap for mandibular reconstruction and is increasingly being used in pediatric patients. However, craniomaxillofacial growth and development involve interdependent processes, and it remains unknown whether mandibular reconstruction with free fibula allows symmetric growth of the midface. The study evaluated midfacial symmetry after pediatric mandibular defect reconstruction. This retrospective cohort study included pediatric patients aged ≤14years who underwent mandibular reconstruction with free fibula flap. Postoperative computed tomography data were obtained at predefined follow-up time points. Midfacial symmetry was evaluated based on 3-dimensional (3D) cephalometry. The predictor variable was the side of the midface (affected or healthy side relative to the mandibular defect). The primary outcome variable was postoperative midfacial symmetry (at 1week, 6months, 1year, 2years, and >3years, or after the age of 18years), assessed in horizontal, vertical, and anteroposterior dimensions using 3D cephalometry. Another outcome variable was patient satisfaction based on a self-evaluation using visual analog scoring. Sex, age, diagnosis, and type of denture restoration. Paired t tests were performed to assess the relationship between the predictor and outcome variables, with the significance level of P<.05. A total of 13 patients were included in this study (9 males and 4 females; mean age: 12.23±2.39years). The average distance from upper first molar point (U6) to the horizontal plane on the affected side became greater than on the healthy side (difference: 0.7±0.5mm to 1.6±1.4mm, P<.05), while the average distance from pterygomaxillary fissure to coronal plane on affected side became shorter than that on the healthy side (difference: 0.6±0.6mm to 1.2±1.1mm, P<.05) from 1year after the surgery. There were no statistically significant differences in the remaining measurements between the 2 sides (P>.05). All the patients were satisfied with their postoperative facial symmetry. There were no severe midface deformities after pediatric mandibular reconstruction with free fibula flap. Meanwhile, pediatric mandibular reconstruction and proper occlusion could promote midfacial growth and symmetry.

Optical Impression Accuracy of Preparations for Fixed Prosthodontics: A Systematic Review.

This systematic review aimed to evaluate the accuracy of different optical impressions of tooth preparations. An electronic search in PubMed, Web of Science, Scopus, Medline Complete, and ScienceDirect was performed to identify articles comparing the accuracy of different optical impressions (OI) published up to the 1st of March 2022. The inclusion criteria enclosed the accuracy of optical impressions acquired for tooth-supported fixed prosthodontics. Exclusion criteria were defined as studies focused on orthodontic impressions and implant-supported restorations. This review was registered to Prospero; CRD42021287758. Eleven included studies had in vitro design and a low risk of bias. Considering scanned objects, 5 studies evaluated the accuracy based on a single preparation, 2 studies evaluated the accuracy of OIs based on fixed partial denture (FPD) restoration, 3 studies included both single preparation and preparations to receive FPD restorations, and 1 article included a fullarch scan. Mean values of the trueness and precision of OI systems varied according to methodological differences. Optical impression has certain advantages. However, stating a particular optical impression system as the most accurate or superior to conventional impression is not feasible because of the heterogeneity of the accuracy results presented in this systematic review.

3-step digital complete denture restoration using facial-scan: a case report

3-step digital complete denture restoration using facial-scan: a case report

Removable partial denture restoration using implant-supported surveyed crowns

Removable partial denture restoration using implant-supported surveyed crowns

Comparison of treatment outcomes and time efficiency between a digital complete denture and conventional complete denture: A pilot study

BackgroundThe authors of this study aimed to compare the treatment outcomes and time efficiency between digital and conventional complete denture restorations and propose suggestions for clinical use. MethodsThe authors used digital (functionally suitable digital complete denture [FSD]) and conventional complete denture restorations to make 2 dentures each for 10 edentulous patients. All the operations of both techniques before denture delivery were completed in the first 4 visits, and then 2 dentures were delivered successively for the patients. The clinical and laboratory times were recorded to evaluate the time efficiency; treatment outcomes were evaluated via scoring the denture satisfaction of the dentist and patients in a double-blind manner. ResultsThe satisfaction scores of FSDs (7.6-9.6 [dentist's scores], 8.4-10 [patients' scores]) were higher than those of conventional dentures (7.2-9.7 [dentist's score], 7.4-9.8 [patients' scores]), but there were no significant differences. The clinical and laboratory operation times of the FSD group were less than those of the conventional group, saving an average of 28.0 minutes and 64.3 minutes in the clinic and laboratory, respectively. ConclusionsFSD technology can improve the efficiency of clinical and laboratory operations and shorten the manufacturing cycle of dentures. The occlusion stability of FSDs was statistically better than that of traditional dentures, but there was no statistical difference in other clinical indicators. Practical ImplicationsFSD technology is low cost and easy to operate and has several applications. Compared with conventional complete denture restoration technology, FSDs can save time and have a comparable clinical effect.This clinical trial was registered at the Chinese Clinical Trial Registry. The registration number is ChiCTR1900021722.

Study on milling performances of 3Y-TZP ceramics using PCD and PCBN tools

ABSTRACT The 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) is regarded as a superior bioceramic being extensively used in modern denture restoration. However, the material possesses extremely poor machinability and are prone to serious cracking and failure formation due to its exceptionally high hardness and inherent brittleness. Hard milling is a feasible strategy to shape fully-sintered 3Y-TZP to desired quality and target dimensions. The present paper aims to study the milling behaviors and mechanisms of 3Y-TZP ceramics by using superhard PCD and PCBN tools. The fundamental milling responses, including cutting forces, temperatures, and surface morphologies, were all examined. The parametric effects on the 3Y-TZP machinability outputs were addressed. A particular focus is placed on comparing the cutting performances of different tools in milling 3Y-TZP. It is found that the PCD tool outperforms the PCBN tool from the perspective of reducing cutting forces, specific cutting energy consumption, and milling temperatures. To get smooth surface morphologies with minimal damage, the spindle speed lower than 5000 rpm and the feed per tooth lower than 9 μm/z should be adopted for the PCD tools. However, under large milling parameters, the PCBN tools show advantages in ensuring the stability of machined surface quality for 3Y-TZP ceramics over the PCD ones.

Complications related to axial orientation of implants and their research progress

The ideal axial orientation of implant is the key to the success of implant denture restoration. According to the restoration-oriented concept of implant, the implant axis direction should be consistent with the long axis direction of the suprastructure. In clinical practice, implant axial deviation leads to related complications, such as implant fracture, periimplant inflammation, and poor esthetic outcome of implant restoration, resulting in implant treatment failure. In this paper, complications related to improper implant axial orientation, their causes and treatment strategies are reviewed.

Study on Overdenture of Immediate Implant Placement and Function.

This study aims to investigate the bone remodelling and resorption in immediate implantation and restoration of clinical implant-supported overdentures. Six adult domestic dogs were divided into 2 groups: In the experimental group, 6 implants were immediately placed in each mandible, the distal end implants were inclined distal to the long axis of the tooth at an angle of 30 degrees, and restored immediately. As the control group, the animals underwent immediate implant placement with single denture restoration, respectively, nontilting and tilting at 30 degrees in the long axis of the tooth. The osseointegration index (OI) and rate of bone ingrowth fraction were measured, and the peri-implant bone remodelling was observed. The marginal bone loss was measured in the slices of bone-implant and analyzed. New bone regenerated and had remodelled in each group. The experimental group had no statistically significant differences, when compared with other groups, except the tilted implant control group, in terms of the OI and bone ingrowth fraction. Obvious bone absorption did not statistically significantly occur in implant-supported overdenture of immediate implant placement and function with satisfactory new bone and OI.

A novel visible light-curing chitosan-based hydrogel membrane for guided tissue regeneration

Inflammation and trauma destroy the tooth-supporting tissue, leading to the loss of oral function and the difficulty of denture restoration. Guided tissue regeneration (GTR) is a technique based on a barrier membrane designed to restrict soft tissue invasion and maintain the space for bone regeneration. This study examined a new formulation to prepare methacrylated carboxymethyl chitosan (CMCS-MA) hydrogel as a barrier membrane that could be crosslinked under visible-light irradiation. This new CMCS-MA hydrogel showed fast light-curing, good biocompatibility, and could be degraded by lysozyme. Further, the physicochemical property, cytotoxicity and antibacterial activity of the CMCS-MA hydrogels can be adjusted by varying the degree of substitution of methacrylic acid (DS) in a certain range. Thus, the biocompatible and biodegradable CMCS-MA hydrogels may have a promising application in periodontal tissue regeneration with convenience and flexibility.

Masticatory muscle disorders and treatment from the perspective of prosthodontics

Masticatory muscle disorders (MMD) is the biggest subtype of temporomandibular disorders (TMD). Among them, local fibromyalgia and myofascial pain are localized lesions, manifested as masticatory muscle pain, which can be aggravated with jaw function. MMD is caused by a combination of multiple factors. Occlusal disharmony such as occlusal trauma, occlusal interference, and decreased vertical dimension of occlusion have the potential risk of inducing or aggravating the MMD. During prosthodontic treatment, iatrogenic occlusal interference should be avoided. Most patients with MMD can be relieved by comprehensive treatment, and occlusal therapy or prosthodontic treatment is used as an auxiliary means of diagnosis and treatment. By means of occlusal splint, occlusal adjustment and denture restoration, the goal of relieving masticatory muscle tension, stabilizing occlusal support, eliminating occlusal interference and adjusting jaw position can be achieved, so as to eliminate some risk factors of MMD and relief the pain faster.

Access to denture restoration services under removable dentures subsidy program for adults aged 65\xa0years and older in Taiwan- an interpretive approach

BackgroundAccess is an important issue in health equality. Availability of dental services and cost subsidies is an important factor affecting access to denture restoration for the elderly. This study aims to explore access to denture restoration services in the elderly removable denture’s subsidy program of Taiwan.MethodsAccess to the elderly removable dentures subsidy program was measured from two aspects, that is, availability of subsidies and payment for these services and the characteristics of patients and their treatment needs. The first aspect included reimbursements and the number and location of subsidy clinics, and the second aspect included the age and gender distribution of patients and denture types. Information on reimbursement regulations and the number and location of dental clinics providing subsidized services were obtained from the website of the Taoyuan City Public Health Bureau, Taoyuan Hospital, Department of Statistics and Ministry of Health and Welfare. Data on patient characteristics and denture type were obtained through a retrospective survey. We selected individuals who participated in the elderly removable denture’s subsidy program from 2015 to 2018 at the Geriatric Dentistry Department of Taoyuan Hospital. We conducted data analysis using an interpretive approach.ResultsThis study found that reimbursement amounts are inadequate, and the availability of subsidized services is low. Moreover, the proportion of male applications is slightly higher than that of females. In addition, among the applicants, removable partial dentures for single or two arches are the most common.ConclusionsProblems of insufficient numbers of contracted hospitals and low reimbursement amounts are observed in the subsidy program, which are the key factors affecting access to denture restoration services among the elderly. Policymakers should exclude wealthy individuals and offer subsidy only to low-income elderly individuals with missing teeth who are in dire need of financial support to improve their dental health.

The modification of split pontic as non-rigid connector in the management of pier abutment

In long-span fixed partial denture restoration, especially when pier abutment is present, a non-rigid connector as a stress breaker is indicated. The Non-rigid connector is classified into a dovetail, loop connector, split pontic, cross-pin, and wing. Split pontic is an attachment placed entirely inside the pontic, particularly indicated in the tilted abutment case, to prevent the box preparation of distal pier abutment. This case report presents A pier abutment case treated with long span porcelain fused to the metal fixed movable bridge using dovetail shaped attachment, assembling the split pontic as a non-rigid connector. Split pontic acts as the stress breaker to prevent the pier abutment acts as a fulcrum. Split pontic also transfers the shear stress to the alveolar bone, minimalizes the mesiodistal torquing of the abutment teeth, and enables individual tooth movement. The advantages of this design are preparation with minimal reduction and better esthetic outcome as the porcelain build up can be done. Thus, there is no metal exposure of the restoration. Longevity and success of fixed partial denture restoration depend on the size, shape, type, and connector position. In pier abutment cases, a non-rigid connector must be considered one of the treatment choices to restore the missing teeth and preserve the abutments.KEYWORDS: pier abutment, split pontic, non-rigid connector

A case of removable partial denture restoration using implant supported surveyed crown in a maxillary edentulous patient

A case of removable partial denture restoration using implant supported surveyed crown in a maxillary edentulous patient