Effect of beverages, denture cleanser and chlorhexidine gluconate on surface roughness of flexible denture base material: an in vitro study.

Purpose: The purpose of the study was to evaluate and compare the effect of beverages, denture cleanser and chlorhexidine gluconate solution on surface roughness of flexible denture base material. Materials and methods: Fifty flexible denture base resin specimens measuring 50±1mm in diameter and 0.5±0.05 mm in thickness were fabricated. The specimens were divided into five groups each containing ten specimens. The specimens were immersed in distilled water (Control group A); hot coffee (Group B); cold beverage (Group C); sodium perborate containing denture cleanser (Group D) and 2% chlorhexidine gluconate solution (Group E). The specimens were immersed for 10 min daily in mentioned solutions for up to 60 days. Surface roughness (Ra) was evaluated on the 1st, 20th and 60th day with the help of atomic force microscope. The statistical analysis was done using two-way ANOVA and Tukey's Post hoc test. Results: The two- way ANOVA revealed that the average Ra values varied significantly depending on the type of solution used for immersion (p<0.001) and the duration of immersion (p<0.001). Variation in surface roughness with cold beverage was highest (p=0.001). On the 60th day the surface roughness of flexible denture base resin material was higher with cold beverage (0.184 µm) and denture cleanser (0.203 µm) than that of distilled water (0.052 µm) hot coffee (0.030 µm) and 2% chlorhexidine gluconate (0.068 µm). Conclusion: Exposure to cold beverage, which was acidic in nature and peroxide containing denture cleanser, produces much rougher surface in the thermoplastic polyamide flexible denture base resin specimens.

Bonding Efficiency between Artificial Teeth and Denture Base in CAD/CAM and Conventional Complete Removable Dentures.

A common challenge encountered with both traditional and digitally produced dentures involves the extraction of artificial teeth from the denture base. This narrative review seeks to present an updated perspective on the adherence of synthetic teeth for denture base materials, employing diverse methods. Dental technicians often employ chemical approaches and mechanical techniques (including abrasion, laser treatment, and abrasive blasting) to augment the retention of denture teeth. However, the efficacy of these treatments remains uncertain. In certain instances, specific combinations of Denture Base Resin (DBR) materials and artificial teeth exhibit improved performance in conventional heat-cured dentures following these treatments. The primary reasons for failure are attributed to material incompatibility and inadequate copolymerization. As new denture fabrication techniques and materials continue to emerge, further research is imperative to identify optimal tooth-DBR combinations. Notably, 3D-printed tooth-DBR combinations have demonstrated reduced bond strength and less favorable failure patterns, while utilizing milled and traditional combinations appears to be a more prudent choice until advancements in additive manufacturing enhance the reliability of 3D-printing methods.

Accuracy of Mandibular Removable Partial Denture Frameworks Fabricated by 3D Printing and Conventional Techniques.

Herein, we used digital superimposition to evaluate the accuracy of metal frameworks for mandibular removable partial dentures fabricated using three techniques. Thirty master casts of a mandibular dentiform were categorized into three groups (n = 10) based on the framework manufacturing method: selective laser melting-based metal three-dimensional (3D) printing (SLM), digital light projection-based resin 3D printing and subsequent casting (RPC), and conventional casting (CON). The master casts were scanned twice, initially after preparation and subsequently after attaching silicone using the frameworks. These scan files were digitally superimposed to measure the silicone thickness. Statistical analysis was conducted using SPSS Statistics (Version 23.0, IBM Corp., Somers, NY, USA). One-way ANOVA and a post hoc Tukey's multiple comparison tests were performed to determine differences among the three groups (α = 0.05). The RPC group exhibited significantly higher overall and mean internal discrepancies at rest and tissue stops than the SLM and CON groups, which exhibited statistically insignificant differences. Thus, SLM fabrication resulted in comparable accuracy to that achieved by CON, whereas sequentially performing resin 3D printing and casting induced inferior accuracy. However, all frameworks across the three groups were clinically acceptable.

Effect of Different Surface Treatments as Methods of Improving the Mechanical Properties after Repairs of PMMA for Dentures.

Denture fractures are a common problem in dental practice, and their repair is considered a first option to restore their functional properties. However, the inter-material resistance may become compromised. Typically, the bond between these materials weakens. Therefore, various surface treatment methods may be considered to enhance their mechanical properties. Poly(methyl methacrylate) (PMMA) heat-polymerized resin (HPR) was used as the repaired material, cold-polymerized material (CPR) for the repairs, and different variants of alumina abrasive blasting (AB), methyl methacrylate (M), ethyl acetate (EA), methylene chloride (CH), and isopropyl alcohol (IA) treatments were applied. Finally, combined surface treatments were chosen and analyzed. Surface morphologies after treatments were observed by scanning electron microscopy and the flexural, shear, and impact strengths were tested. AB and chemical treatment with CH, M, and EA was used to improve all mechanical properties, and further improvement of the properties could be achieved by combining both types of treatments. Varied changes in surface morphologies were observed. Treatment with IA yielded less favorable results due to the low impact strength. The best results were achieved for the combination of AB and CH, but during the application of CH it was necessary to strictly control the exposure time.

Accuracy and time efficiency of conventional and digital outlining of extensions of denture foundation on preliminary casts.

PURPOSE: The purpose of this diagnostic study was to assess the accuracy and time efficiency of a digital method to draw the denture foundation extension outline on preliminary casts compared with the conventional technique. MATERIALS AND METHODS: A total of 28 preliminary edentulous casts with no anatomical landmarks were digitized using a laboratory scanner. The outlining of the entire basal seat of the denture was performed on preliminary casts and digitized. Casts with no extension outline were digitized and outlines were drawn using software (DWOS, Straumann). The accuracy of the extension outlined between both techniques was evaluated in the software (GOM Inspect; GOM GmbH) by file superimposition. Specificity and sensitivity tests were applied to measure accuracy. The paired t-test (95% CI) was used to compare the mean total area and the working time. RESULTS: The accuracy ranged from 0.57 to 0.92. The buccal and labial frenulum showed a lower value in the maxilla (0.57); while the area between the retromolar pad and buccal frenulum (0.64) showed a lower score in the mandible. The maxillary denture foundation and the working time for both arches were significantly longer for the digital method (P < .001). CONCLUSION: The denture foundation extension outline exhibited a sufficiently excellent accuracy for the digital method, except for the maxillary anterior region. However, the digital method required a longer working time.

Comparison of perceived masticatory ability in completely edentulous patients treated with thermoplastic complete denture versus single implant-retained mandibular overdenture: a single-center prospective observational study.

Background: This study aimed to compare the perceived masticatory ability (PrMA) in completely edentulous patients (EDPs) with thermoplastic conventional complete dentures (CDs) versus single implant-retained mandibular overdentures. Methods: The current study was conducted in the outpatient Prosthodontic Clinic, Faculty of Dental Medicine, Al-Azhar University, Cairo, Egypt. PrMA was evaluated in 45 completely edentulous patients (46% males, mean age 50.4 ± 4.7 years). Each patient received a thermoplastic PMMA complete denture (Polyan IC TM Bredent GmbH & Co.KG, Germany). The PrMA was evaluated at one-month and six-month intervals of denture use. An immediate loading single implant was placed into the mid-symphyseal for each patient, and the denture was adjusted. Subsequently, the PrMA was reevaluated after one month and six months. The data were collected and statistically analyzed using the SPSS@V25 to assess the changes in PrMA. Results: The PrMA demonstrated improvement after six months of thermoplastic conventional denture use. However, this improvement was not statistically significant (p = 0.405). In addition, the PrMA showed a substantial increase following a single implant placement at one and six months (p < 0.001) of the overdenture use compared to the conventional denture. The PrMA insignificantly improved (p = 0.397) after six months of the single implant retained overdenture use. Discussion: The study's findings indicate that using immediate loading single implant-retained mandibular overdentures significantly improved PrMA in completely edentulous patients.

A cross-sectional study on dental anxiety and state anxiety related to removal of fixed partial dentures.

OBJECTIVES: This study aimed to evaluate the effect of the clinical removal of fixed partial dentures (FPDs) on oral health-related quality of life (OHRQoL) and the anxiety values of individuals and to determine the clinical factors of high anxiety levels. METHOD AND MATERIALS: In total, 300 participants were included in this study. Six different reasons for the clinical removal of FPDs (oral examination, denture renewal, endodontic treatment, tooth extraction, periodontal treatment, and composite filling restoration) were defined. The United Kingdom Oral Health-Related Quality-of-Life Measure (OHRQoL-UK), the Modified Dental Anxiety Scale (MDAS), and the Spielberger State-Trait Anxiety Inventory- State (STAI-S) and Trait (STAI-T) were answered. The reason groups were compared using one-way analyses of variance (ANOVA). Binary logistic regression analyses were performed to evaluate the risk factors for high anxiety. RESULTS: There was no significant difference in OHRQoL-UK scores (P=.279) among the reason groups, but there were significant differences in MDAS, STAI-S, and STAI-T scores (P=.004, P<.001, P=.018 respectively) among the reason groups. Endodontic treatment, tooth extraction, and gender were determined to be risk factors, considering the anxiety scales. CONCLUSIONS: Females are 2.2 times more likely to have trait anxiety than men. Although the effect of the reason for the clinical removal of FPDs on OHRQoL was similar among the groups, it is concluded that endodontic treatment and tooth extraction reasons for the clinical removal of FPDs could be risk factors for high anxiety regardless of FPD usage time.

Clinical use of duplicate complete dentures: A narrative review.

Most reports on duplicate dentures are introduction to fabrication methods or clinical case reports. Only a few studies have verified their clinical effectiveness; hence, evidence to construct useful clinical guidelines for duplicate denture use is lacking. This review aimed to comprehensively investigate reports on duplicate dentures to accumulate evidences that will contribute to the formulation of clinical practice guidelines. Duplicate dentures are effectively used for impression making and bite registration when fabricating new dentures, thereby reducing the number of clinic visits and treatment time. Duplicate denture can also be used as temporary or new dentures. Older people in whom various adaptive abilities have declined, may find it difficult to adjust to new dentures and experience stress, even if the shape is appropriate. Duplicate dentures, which reproduces the shape of old dentures that they are used to, have the advantage of being more familiar to older people and less stressful. When manufacturing duplicate dentures, digital methods such as milling and three-dimensional printing are superior to conventional methods regarding working time and cost. A notable advantage of the digital method is that the denture shape can be saved as digital data, and the denture can be easily duplicated if lost.

Ingested Foreign Bodies in the Sigmoid Colon Requiring Earlier Intervention in Patients With Prior Hysterectomy.

The use of dentures and dental plates is widespread in the adult population. Accidental ingestion of these foreign objects is not uncommon, with the majority of patients having an uneventful passage of the object through the gastrointestinal tract. Of those patients requiring intervention, endoscopy is the most common, followed by surgical removal. We discuss a case of a patient with prior pelvic surgery and diverticulosis causing severe angulation of the bowel, resulting in non-passage of the foreign object requiring surgical intervention.

Biofilm inhibition of denture cleaning tablets and carvacrol on denture bases produced with different techniques.

OBJECTIVES: This study compares the biofilm inhibition effects of denture cleaning tablets, carvacrol, and their combined use against Candida albicans on denture bases produced with different techniques. Additionally, the surface roughness and contact angles of these denture bases were evaluated. MATERIALS AND METHODS: Test samples were prepared from four different denture base materials (cold-polymerized, heat-polymerized, CAD/CAM milling, and 3D-printed). The surface roughness and contact angles of the test samples were measured using a profilometer and goniometer, respectively. For the evaluation of biofilm inhibition, samples were divided into 5 subgroups: Corega and carvacrol, separately and combined treatments, positive (inoculated with C. albicans) and negative control (non-inoculated with C. albicans, only medium). Biofilm mass was determined using the crystal violet method. An additional prepared test sample for each subgroup was examined under scanning electron microscopy (SEM). RESULTS: The surface roughness values of the 3D-printed test samples were found to be statistically higher than the other groups (P < .001). The water contact angle of all test materials was not statistically different from each other (P > .001). Corega and carvacrol, separately and combined, significantly decreased the amount of biofilm on all surfaces (P < .0001). Treatment of corega alone and in combination with carvacrol to the 3D-printed material caused less C. albicans inhibition than the other groups (P < .001; P < .05). CONCLUSIONS: The surface roughness values of all test groups were within the clinically acceptable threshold. Although Corega and carvacrol inhibited C. albicans biofilms, their combined use did not show a synergistic effect. CLINICAL RELEVANCE: Carvacrol may be used as one of the disinfectant agents for denture cleaning due to its biofilm inhibition property.

Simulating the Entire Clinical Process for an Implant-Supported Fixed Prosthesis: In Vitro Study on the Vertical Implications of Implant-Abutment Connections and Rotational Freedom.

OBJECTIVES: The aim of this in vitro study was to investigate whether and to what extent different scenarios of rotational freedom in different IAC designs affect the vertical dimension of a three-part fixed partial denture (FPD). At the same time, the experimental setup should simulate all clinical and laboratory steps of the implementation of such an FPD as accurately as possible. MATERIAL AND METHODS: Twenty identical pairs of jaw models were fabricated from aluminum, each lower-jaw model holding two implants with conical or flat IACs. Three impressions of each model were taken to fabricate stone casts and three-unit FPDs. Three assembly scenarios were compared for the vertical position stability they offered for these FPDs, differing by how the sequential implant components (impression posts > laboratory analogs > abutments 1 > abutments 2) were aligned with the positional index of the IAC. In this way, a total of 60 stone casts and FPDs were fabricated and statistically analyzed for changes in vertical dimension (p < 0.05). RESULTS: Regardless of whether a conical/flat IAC was used (p > 0.05), significantly greater mean changes in vertical dimension were consistently (all comparisons p < 0.0001) found in a "worst-case scenario" of component alignment alternating between the left- and right-limit stop of the positional index (0.286/0.350 mm) than in a "random scenario" of 10 dentists and 10 technicians with varying levels of experience freely selecting the alignment (0.003/0.014 mm) or in a "best-case scenario" of all components being aligned with the right-limit stop (-0.019/0.005 mm). CONCLUSIONS: The likelihood of integrating a superstructure correctly in terms of vertical dimension appears to vary considerably more with assembly strategies than with IAC designs. Specifically, our findings warrant a recommendation that all implant components should be aligned with the right-limit stop of the positioning index.

Biological interaction, esthetics, handling, and loss rate of temporary luting cements - a clinical single-blind randomized controlled trial.

OBJECTIVES: To evaluate three temporary luting cements in terms of their restoration loss rates, biological interactions, esthetic properties, and handling characteristics. MATERIALS AND METHODS: 75 adults requiring fixed prosthodontics voluntarily participated in a single-blind, randomized controlled trial. After preparation, temporary restorations were luted with a randomly selected temporary luting cement (either Provicol QM Plus (PQP), Bifix Temp (BT), or Provicol QM Aesthetic (PQA)). Clinical examinations were performed one to two weeks after cementation. The following criteria were evaluated: tooth vitality, percussion, hypersensitivity, gingival bleeding, odor formation, esthetics, cement handling, removability, cleanability, and retention loss. Antagonistic teeth served as controls. Statistical analysis was performed using the paired t-test, one-way ANOVA, Pearson's chi-square and Fisher's exact test, where appropriate. RESULTS: The overall loss rate of temporary restorations was 16.0%, showing no cement-specific differences. Postoperative hypersensitivity occurred in 8% of cases regardless of cement type. Esthetic impairment was reported by 31% of the PQP-fixed restorations, compared with 4.0% and 4.2% of the BT and PQA-bonded restorations. Cement application was reported to be easy in 100% of cases, excess removal in 88-96%, depending on the cement used. CONCLUSIONS: The choice of luting material affects the esthetic appearance of a temporary restoration and should be considered, particularly in restorations in esthetically demanding areas. No significant differences between the cements were identified regarding biocompatibility, handling, and loss rate. CLINICAL RELEVANCE: Translucent cements can help to reduce color interferences, resulting in a more appealing appearance of the temporary restoration.

Relationship between tooth loss and progression of frailty: Findings from the English longitudinal study of aging.

OBJECTIVE: The objective of the present study was to investigate the relationship between indicators of oral health status (number of teeth; denture use) and the progression of frailty amongst adults in England. METHODS: The subjects were participants of the English Longitudinal Study of Aging [ELSA] aged 50 years and older. We used panel data from three waves of the study (Waves 7-9). Indicators of oral health comprised the number of teeth (≥20; 10-19; 1-9; 0) and combination of removable denture usage and the number of teeth. Frailty was assessed by the 32-item Frailty Index (FI). Covariates were age, sex, education, marital status, smoking, alcohol, and physical activity. The longitudinal relationship between oral health indicators and change in FI were investigated using linear mixed-effect models considering frailty as a time-varying variable. RESULTS: Among the 7,557 participants, compared to those people with 20 or more teeth, change in frailty over time was significantly higher among those with less than 20 teeth: 10-19 teeth (ß: 0.249, 95 %CI: 0.116 to 0.382), and 1-9 teeth (ß: 0.238, 95 %CI: 0.053 to 0.423) and being edentate (ß: 0.286, 95 %CI: 0.106 to 0.465) when adjusting for co-variates. The rise in frailty over time was significantly higher among those with fewer teeth (<20 teeth), including those using dentures. CONCLUSIONS AND IMPLICATIONS: This longitudinal analysis suggests that tooth loss is associated with accelerated progression of frailty and utilizing dentures did not reduce the trend in frailty. Thus, maintaining a functional natural dentition is important in healthy ageing.

Clinical evaluation of a one-piece polyetheretherketone removable partial denture fabricated using a novel digital workflow: A self-controlled clinical trial.

PURPOSE: To explore the clinical application of one-piece polyetheretherketone (PEEK) removable partial dentures (RPDs) fabricated using a novel digital workflow and to evaluate their weights and fits in vivo and patient satisfaction. MATERIALS AND METHODS: Fifteen cases with posterior partially edentulous situations were selected, and each patient received two types of RPDs, including a novel digital workflow (test group) and a conventional workflow (control group). For the test group, one-piece RPDs were designed through three-dimensional (3D) methods by scanning stone casts and fabricated by milling PEEK discs. Each RPD was weighed. The gaps between the oral tissue and RPDs in each group were duplicated using a polyvinylsiloxane (PVS) replica and measured by 3D analysis. A visual analog scale (VAS) was used to evaluate the patient's satisfaction. Paired t-tests were used to compare the differences in the weight, the gaps of each RPD, and VAS values between the two groups. One-way analysis of variance tests was used to compare the differences in the gap among different components in each group. RESULTS: The RPD in the test group weighed less than that in the control group (p < 0.01). No statistically significant differences in the gaps of denture bases and rests (p > 0.05) were found between the two groups, but the gaps of major connectors in the test group were significantly smaller than in the control group (p < 0.05). The VAS scores for comfortableness and masticatory efficiency were not significantly different between the two groups (p > 0.05) but the scores for the aesthetic appearance of the clasps in the test group were significantly higher than that in the control group (p < 0.05). CONCLUSIONS: One-piece PEEK RPDs manufactured using a novel digital workflow weighed less than conventional RPDs and exhibited a clinically acceptable internal fit. Although the aesthetic appearance of the PEEK clasps was superior to the control, there is still room for improvement.

Accuracy of virtual articulation in maximal intercuspal position in direct and indirect digital workflows for fixed partial denture fabrication.

PURPOSE: To assess the accuracy of virtual articulation in direct digital workflow (DDW) and indirect digital workflow (IDW) in arches prepared for fixed partial dentures (FPDs). MATERIALS AND METHODS: Five pairs of master models were used in this study representing different clinical scenarios of full dentate (FD), and prepared arches for fixed partial dentures as follows: FD group, short span posterior (SSP group), long span posterior (LSP group), short span anterior (SSA group), and long span anterior (LSA). Fourteen pairs of interarch reference points were added to each set of master models to measure linear interarch distance with a caliper (reference measurements). The direct digital workflow included digital scans and virtual articulation with buccal scan images using an intraoral scanner. The indirect digital workflow included conventional polyvinylsiloxane impressions and bites followed by pouring, mounting, and scanning the stone models in a laboratory scanner. The scanned stone models were virtually articulated with buccal scanning in the laboratory scanner. Digital linear interarch measurements on all virtually-articulated models were compared with reference measurements. The absolute mean differences in linear interarch distances were calculated. The Mann-Whitney test was used for statistical analysis (α = .05). RESULTS: The direct digital workflow produced significantly less linear interarch deviations in the virtually articulated models compared to the indirect digital workflow for all study groups (P < .05). However, the direct digital workflow had significantly less accuracy for virtual articulation in long span posterior, long span anterior, and short span anterior groups compared to the full dentate group.  CONCLUSIONS: Both workflows produced virtually-articulated models with acceptable accuracy. However, the direct digital workflow had significantly better accuracy in all assessed clinical scenarios.

In vitro analysis of monomer leaching in modern dental materials: CAD milled, printed, traditional heat-processed, and auto-polymerizing denture base resins.

PURPOSE: Denture fabrication has shifted from traditional heat-processed and auto-polymerizing materials to computer-aided design and computer-aided manufacturing (CAD-CAM) milled and printed materials. The monomer in traditional materials can induce an allergic reaction in some patients. With the rise in the edentulous population and increasing demand for the fabrication of dentures, these newer materials should be studied for monomer leaching. The purpose of this study was to evaluate the ratio of residual monomer in materials being used for denture bases: CAD-milled polymethylmethacrylate (PMMA), printed denture base resin, heat-processed PMMA, and auto-polymerizing PMMA comparatively. MATERIALS AND METHODS: Milled, printed, heat-activated, and auto-polymerizing denture base specimens (n = 3 for each group, each test run three times) were fabricated according to manufacturer recommendations. Specimens were first immersed in deuterated chloroform (CDCl3), a deuterated organic solvent, to evaluate monomer leaching and to observe physical properties of the materials. NMR spectroscopy was used to evaluate the dissolution of materials and residual monomer to crosslinked polymer ratios at 1, 4, and 9 days. A second group of specimens was then immersed in deuterium oxide (D2O) to evaluate if the residual monomers would leach out of the system. The solution was then analyzed using nuclear magnetic resonance (NMR) spectroscopy for 1 month. The deuterated forms of chloroform (CDCl3) and water (D2O) were used to enable sample characterization by NMR. RESULTS: While the heat-processed, auto-polymerizing, and milled specimens possessed residual monomers, no significant monomer leaching was noted in the printed specimen, while immersed in CDCl3. Similarly, the printed specimen was most resistant to dissolution, as compared to the rest; dissolution of the specimen is indicative of little to no cross-linking. No detectable dissolution of monomer was seen when all specimens were immersed in D2O for up to 1 month. CONCLUSIONS: Residual monomers were not found in the printed denture material in this study in either CDCl3 or D2O, whereas CAD-milled and traditionally processed denture bases still have residual monomers within their respective systems when immersed in organic solvent. None of the specimens tested leached monomers into D2O.

Four-year assessment of masticatory function in mandibular overdenture wearers: A randomised clinical trial comparing two to four implants to retain the prosthesis.

BACKGROUND: Limited data exist on the mid- to long-term masticatory capacity of mandibular overdenture (IOD) wearers, particularly regarding the use of posterior implants to retention. OBJECTIVES: To periodically evaluate mastication of IOD wearers, comparing the effectiveness of two to four implants to retain the prosthesis. METHODS: In a randomised controlled clinical trial, 20 complete edentulous patients (14 women), aged 51-84 years (mean age 69.1 ± 9.6), received new bimaxillary complete dentures (CD). After adaptation, baseline measurements of masticatory performance (X50) and swallowing threshold were conducted using the sieving method. Patients were then randomly assigned to groups: control (two intra-foraminal regular implants) and experimental (two intra-foraminal regular implants and two extra-short posterior implants) (n = 10 each). After 4 months, implants were splinted, and a new mandibular IOD was fabricated with bar/clip retention. Mastication was reassessed after 6, 12, and 48 months, and data analysed with repeated measures ANOVA and Sidak's post hoc (α = 0.05). RESULTS: Despite a loss of two patients per group, masticatory performance significantly improved after mandibular IOD installation (p = .031) in both groups (p = .670). A second improvement was observed after 6 months (p = .027), with no subsequent changes (p > .05). Swallowing threshold improvements were noted with IOD, and no discernible differences between groups were observed (p > .05). CONCLUSION: Masticatory function significantly improved after mandibular IOD installation, with the number of implants demonstrating minimal influence. CLINICAL TRIAL REGISTRATION: The present study was not registered in a public database, as mandated. It is important to note that the recommendation for registration was initiated in 2017 by the Committee of Medical Journal Editors, while patient inclusion in the research took place in 2016. Given that the data presented in this manuscript cover a follow-up period of up to 4 years post-surgical intervention, delayed registration was not feasible.

Sapindus Mukurossi - An Effective Biocleanser for Removable Dental Prostheses? An In vitro Study.

This study aims to determine the efficient concentration of Sapindus mukorossi that can be used as a denture cleanser. 60 heat cure denture base resin specimens of dimensions 10*10*2 mm were fabricated. Among these, 30 were fabricated by compression moulding technique and the remaining 30 by an injection moulding technique. The samples inoculated with Candida albicans and Streptococcus mutans were subjected to denture cleansing protocols using a medicinal herbal extract from the Sapindus mukorossi, at various concentrations [15%, 20%, and 25%]. The colony-forming unit [CFU] values were evaluated using a microprocessor colony counter. The statistical analysis was performed. The intragroup comparison showed a statistically significant difference between all groups except the compression moulded samples inoculated with Streptococcus mutans. The intergroup comparison revealed no statistically significant differences between the compared groups. The reduction in CFU values is evident in the effective anti-microbial activity of Sapindus mukorossi. A concentration of 25% Sapindus mukorossi solution showed the greatest efficiency. The maximum anti-microbial activity was observed against Candida albicans in a 25% concentration of Sapindus mukorossi. Among all, injection moulded samples showed better results.

Deformation and retentive forces variations of the additively manufactured cobalt-chromium and titanium alloys dental clasps.

This in vitro study aimed to evaluate the additive manufacturing (AM) of cobalt chromium Co-Cr and titanium Ti alloy clasps for clinical use. After scanning the Ni-Cr die of the first molar, Akers' clasps were designed using computer-aided design/ computer-aided manufacturing (CAD/CAM). The clasps were manufactured from Co-Cr-W dental alloy and Ti-6Al-4V alloy powder using AM machines. Then, they were divided into two groups. The initial retentive force of the clasps was measured using a universal testing machine. Cyclic loading of the clasps was carried out by a specially designed insertion-removal testing apparatus in wet condition up to 5000 cycles. Retentive force was measured at 1000, 2000, 3000, 4000, and 5000 cycles. Moreover, the intaglio surface of each clasp was scanned using the scanner; and superimposition between the pre- and post-cycling clasp files was performed to evaluate deformation after cyclic loading. The fitting surfaces of retentive clasp tips were examined with a scanning electron microscope (SEM). Finally, it has been found that the initial retentive force for the Co-Cr group was 10.81 ± 0.37 N, and for the Ti group was 5.41 ± 0.18 N. Additionally, during the testing periods, both Co-Cr and Ti clasps continued to lose retentive force within the cycles of placement and removal. This effect was more prominent in the Co-Cr than in the Ti clasps. The distances between pre- and post-cycling in the retentive arm were -0.290 ± 0.11 mm and -0.004 ± 0.01 mm in Co-Cr and Ti alloys, respectively, and in the reciprocal arm were -0.072 ± 0.04 mm and -0.032 ± 0.04 mm in Co-Cr and Ti alloys, respectively. The retentive force required to remove the Ti clasps was found to be significantly lower than those required to dislodge the Co-Cr clasps. Co-Cr and Ti clasps lost significant amounts of retentive force from the initial use to the 3.5-year periods of simulated clinical use.

Influence of different palatal morphologies on the accuracy of intraoral scanning of the edentulous maxilla: A three-dimensional analysis.

PURPOSE: This study investigated the influence of different palatal morphologies on the accuracy of intraoral scanning (TRIOS 4) of edentulous maxillae. METHODS: Six typodonts were fabricated for different palatal morphologies with flat (F), medium (M), and deep (D) palates, with palatal wrinkles (W), or smooth palates (S), resulting in six groups: WF, WM, WD and SF, SM, SD. Ten scans were performed for each group; standard tessellation language files obtained were imported into a software to measure trueness and precision in micrometer. Trueness was calculated as the mean of the standard deviation values obtained by superimposing each scan onto the reference scan. Precision was achieved by overlapping each scan with that with the best trueness in the group. Descriptive and post-hoc analyses were conducted. RESULTS: The mean values for trueness were as follows: WM=48.7±4.7, WD=161.7±18.4, WF=85.9±16, SM=48.1±2.4, SD=349.9±8.8, and SF=349.1±25.5. The precision values were as follows: WM=46.7±7.3, WD=46.9±9, WF=48.9±6.7, SM=46±2.7, SD=105.9±17.4, SF=72.6±10.8. Significant differences were observed for trueness between SM and SD (P < 0.001), SM and SF (P < 0.001), and WF and SF (P = 0.003); whereas for precision, significant differences were reported between WD and SD (P = 0.015). Regarding trueness and precision, no difference was found between WM and SM (P = 1.0). CONCLUSIONS: Medium palatal depth showed the best accuracy. The mean accuracy values were within the clinical acceptability thresholds for all palatal morphologies. The presence of rugae improved the precision of deeper palates and the trueness of flat palates. No differences were observed in the medium palates with or without rugae.