Dentistry Commons^™

Bond Strength Of Reline Materials To 3d-Printed Provisional Crown Resins, Jorge Palavicini, Sherrod L. Quin, Wael Zakkour, Karim Zakkour, Safa Manafi Varkiani, Xiaoming Xu, Nathaniel C. Lawson, Amir Hossein Nejat

School of Dentistry Faculty Publications

(1) Purpose: The aim of the present study was to compare the bond strength between two 3D-printed resins designed for long-term provisional crowns and three different reline materials. (2) Materials and Methods: Rectangular specimens were prepared from two 3D-printed resins (Envision Tech and NextDent C&B) and a conventional self-cure PMMA. Transparent tubes filled with three different reline materials including composite resin, Bis-acryl, and PMMA were bonded to the 3D-printed specimens (n = 11 per group, total of 6 study groups). Tubes filled with PMMA were bonded to the prepared PMMA specimens which served as the control group (n = 11, …

Impacts Of A Duf2207 Family Protein On Streptococcus Mutans Stress Tolerance Responses And Biofilm Formation, Xiaochang Huang, Camile G. Laird, Paul P. Riley, Zezhang Tom Wen

School of Dentistry Faculty Publications

Locus SMU.243 in Streptococcus mutans was annotated as a member of the DUF2207 family proteins highly conserved in all bacteria but with unknown function. To investigate its role in S. mutans physiology, a SMU.243-deficient mutant was constructed using allelic exchange mutagenesis, and the impacts of SMU.243 deletion on bacterial growth, stress tolerance response, and biofilm formation were analyzed. Compared to the wild-type UA159, S. mutans lacking SMU.243 displayed a reduced growth rate and a reduced overnight culture density (p < 0.01) when grown at low pH and in the presence of methyl viologen. Relative to the parent strain, the deficient mutant also had a reduced survival rate following incubation in a buffer of pH 2.8 (p < 0.01) and in a buffer containing hydrogen peroxide at 58 mM after 60 min (p < 0.001) and had a reduced capacity in biofilm formation especially in the presence of sucrose (p < 0.01). To study any ensuing functional/phenotypical links between SMU.243 and uppP, which is located immediately downstream of SMU.243 and encodes an undecaprenyl pyrophosphate phosphatase involved in recycling of carrier lipid undecaprenyl phosphate, a uppP deficient mutant was generated using allelic exchange mutagenesis. Unlike the SMU.243 mutant, deletion of uppP affected cell envelope biogenesis and caused major increases in susceptibility to bacitracin. In addition, two variant morphological mutants, one forming rough colonies and the other forming mucoid, smooth colonies, also emerged following the deletion of uppP. The results suggest that the SMU.243-encoded protein of the DUF2207 family in S. mutans plays an important role in stress tolerance response and biofilm formation, but unlike the downstream uppP, does not seem to be involved in cell envelope biogenesis, although the exact roles in S. mutans’ physiology awaits further investigation.

Current Oral Hygiene And Recreational Behavioral Trends In Hiv Disease, Donald E. Mercante, Emily Guarisco, Elizabeth A. Lilly, Arni Rao, Kelly Treas, Clifford J. Beall, Zach Thompson, Ann L. Griffen, Eugene J. Leys, Jose A. Vazquez, Michael E. Hagensee, Paul L. Fidel

School of Dentistry Faculty Publications

Objective: HIV disease is evolving with more HIV+ persons experiencing a high quality of life with well-controlled viremia. We recently enrolled a large cohort of HIV+ and clinically relevant HIV− persons for oral microbiome analyses that included a questionnaire related to oral hygiene and recreational behaviors. Here, the questionnaire responses were analyzed for behavioral trends within the cohort, together with trends over time by comparison to a previous geographically centered HIV+ cohort. Methods: Data were collected by questionnaire at baseline visits as cross-sectional assessments. Multivariable analyses were conducted for associations of HIV status as well as age, race, and sex, …

Defining Success In Healthcare Education: Us Dental Student And Faculty Perspectives., David Alexandre Cruz Walma, Mathieu Alexander Cruz Walma, Shirin Khoynezhad, Sang E. Park, Carly Timmons Mckenzie, Et Al

School of Dentistry Faculty Publications

Purpose/objectives Academic metrics and clinical performance are necessary but alone insufficient in describing success in dental education. This paper identifies themes critical for dental student success as commonly cited by both dental students and faculty. Methods Dental faculty interviews and pre-doctoral D2/D3/D4 student focus groups at two dental institutions generated data for thematic analysis. Themes were individually identified then merged, compared, and contrasted to establish a definitive list of key themes reflected in student and faculty comments. Results Twenty-five pre-doctoral students participated in one of four focus groups (two focus groups at each dental institution). Thirteen dental education faculty across …

Acceptability Of Fully Guided Virtual Implant Planning Software Among Dental Undergraduate Students, Shishir Ram Shetty, Colin Murray, Sausan Al Kawas, Sara Jaser, Wael Talaat, Medhini Madi, Vinayak Kamath, Nisha Manila, Raghavendra Shetty, Vidya Ajila

School of Dentistry Faculty Publications

Background: Fully guided implant surgery as a technique is gaining popularity. It has been observed that use of surgical guides improves precision and predictability for dental implant placement. However, like any other newer technology, the acceptance of fully guided dental implant technology among users is based upon its perceived usability. This study aimed at evaluating the perception about using Virtual Implant Planning Software (VIPS) among undergraduate dental students at the university of Sharjah. Methods: Ninety-Six dental surgery students from the University of Sharjah were included in the study. One week after the Virtual Implant Planning Software (Planmeca Romexis version 6.2 …

Independent Effects Of Hiv And Antiretroviral Therapy On The Oral Microbiome Identified By Multivariate Analyses, Clifford J. Beall, Elizabeth A. Lilly, Carolina Granada, Kelly Treas, Kenneth R. Dubois, Shahr B. Hashmi, Jose A. Vazquez, Michael E. Hagensee, Ann L. Griffen, Eugene J. Leys, Paul L. Fidel

School of Dentistry Faculty Publications

The oral microbiome is an important predictor of health and disease. We recently reported significant yet modest effects of HIV under highly active antiretroviral therapy (ART) on the oral microbiome (bacterial and fungal) in a large cohort of HIV-positive (HIV+) and matched HIV-negative (HIV-) individuals. As it was unclear whether ART added to or masked further effects of HIV on the oral microbiome, the present study aimed to analyze the effects of HIV and ART independently, which also included HIV- subjects on preexposure prophylaxis (PrEP) therapy. Cross-sectional analyses of the effect of HIV devoid of ART (HIV+ ART- versus matched …

Enhanced Human Periodontal Ligament Stem Cell Viability And Osteogenic Differentiation On Two Implant Materials: An Experimental In Vitro Study, Engy Adel Ahmed Farag, Sara Fikry Dr, Shereen N. Raafat

Dentistry

Background: Surface roughness of dental implants impacts the survival of adult periodontal stem cells and rate of differentiation. This research was conducted to test how human periodontal ligament stem cells behaved on yttria stabilized tetragonal zirconia polycrystals and polyetheretherketone (PEEK) discs with different surface topographies.

Methods: Discs roughening was prepared by sandblasting. Stem cells were cultivated on zirconia discs with a polished surface, polyetheretherketone (PEEK) discs with a polished surface, sandblasted zirconia discs and sandblasted polyetheretherketone (PEEK) discs. Cells viability was assessed after 24, 48, 72 hours. Scanning electron microscopy was used to examine the adherence and attachment of cells. …

Effect Of Different Polishing Systems On Surface Roughness And Color Stability Of Lithium Disilicate Ceramics, Mahmoud Al Ankily, Fatma Makkeyah

Dentistry

Objective: This study aimed to investigate the effect of two polishing systems on the surface roughness and color stability of lithium disilicate ceramic. Materials and Methods: Forty disc-shaped lithium disilicate samples were constructed and cemented into a cavity prepared onto the labial surface of freshly extracted bovine teeth; The samples were divided into four groups (10 samples per group); C: Control, SS: Scaling only, SE: Scaling followed by polishing using Eve Diapro lithium disilicate polishers, SD: Scaling followed by polishing using Diatech ShapeGuard ceramic polishing plus kit. The surface roughness was measured before scaling, after scaling and finally after the …

A Small Molecule Produced By Lactobacillus Species Blocks Candida Albicans Filamentation By Inhibiting A Dyrk1-Family Kinase, Jessie Macalpine, Martin Daniel-Ivad, Zhongle Liu, Junko Yano, Nicole M. Revie, Robert T. Todd, Peter J. Stogios, Hiram Sanchez, Teresa R. O’Meara, Thomas A. Tompkins, Alexei Savchenko, Anna Selmecki, Amanda O. Veri, David R. Andes, Paul L. Fidel, Nicole Robbins, Justin Nodwell, Luke Whitesell, Leah E. Cowen

School of Dentistry Faculty Publications

The fungus Candida albicans is an opportunistic pathogen that can exploit imbalances in microbiome composition to invade its human host, causing pathologies ranging from vaginal candidiasis to fungal sepsis. Bacteria of the genus Lactobacillus are colonizers of human mucosa and can produce compounds with bioactivity against C. albicans. Here, we show that some Lactobacillus species produce a small molecule under laboratory conditions that blocks the C. albicans yeast-to-filament transition, an important virulence trait. It remains unexplored whether the compound is produced in the context of the human host. Bioassay-guided fractionation of Lactobacillus-conditioned medium linked this activity to 1-acetyl-β-carboline (1-ABC). We …

Leukotrienes Are Dispensable For Vaginal Neutrophil Recruitment As Part Of The Immunopathological Response During Experimental Vulvovaginal Candidiasis, Junko Yano, David J. White, Anthony P. Sampson, Floyd L. Wormley, Paul L. Fidel

School of Dentistry Faculty Publications

Recruitment of polymorphonuclear neutrophils (PMNs) into the vaginal lumen is the hallmark of an acute immunopathologic inflammatory response during vulvovaginal candidiasis (VVC) caused by Candida albicans. Recurrent VVC (RVVC) remains a chronic health burden in affected women worldwide despite the use of antifungal therapy. Based on the role leukotrienes (LTs) play in promoting inflammation, leukotriene receptor antagonists (LTRAs) targeted for LTB4 (etalocib) or LTC4, LTD4, and LTE4 (zafirlukast or montelukast) have been shown to reduce inflammation of epithelial tissues. An open-label pilot study using long-term regimens of zafirlukast in women with RVVC indicated the potential for some relief from recurrent …

Streptococcus Mutans Lacking Sufcdsub Is Viable, But Displays Major Defects In Growth, Stress Tolerance Responses And Biofilm Formation, Kassapa Ellepola, Xiaochang Huang, Ryan P. Riley, Jacob P. Bitoun, Zezhang Tom Wen

School of Dentistry Faculty Publications

Streptococcus mutans appears to possess a sole iron-sulfur (Fe-S) cluster biosynthesis system encoded by the sufCDSUB cluster. This study was designed to examine the role of sufCDSUB in S. mutans physiology. Allelic exchange mutants deficient of the whole sufCDSUB cluster and in individual genes were constructed. Compared to the wild-type, UA159, the sufCDSUB-deficient mutant, Δsuf::kanr, had a significantly reduced growth rate, especially in medium with the absence of isoleucine, leucine or glutamate/glutamine, amino acids that require Fe-S clusters for biosynthesis and when grown with medium adjusted to pH 6.0 and under oxidative and nitrosative stress conditions. Relative to UA159, Δsuf::kanr …

An In Vitro Evaluation Of Surface Roughness, Color Stability And Bacterial Accumulation Of Lithium Disilicate Ceramic After Prophylactic Periodontal Treatment, Fatma Makkeyah, Tarek Salah Morsi, Marwa Mohamed Wahsh, Amr Saleh El-Etreby

Dentistry

Objective: To evaluate the effect of scaling procedures using different ultrasonic tips on the surface roughness, color stability and bacterial accumulation of lithium disilicate ceramic. Material and Methods: Scaling procedure was carried out using ultrasonic scaler (Satalec, Acteon, North America) with stainless-steel tip (US), titanium tip (UT) and plastic tip (UP), on disc shaped lithium disilicate samples cemented into a cavity prepared onto the labial surface of freshly extracted bovine teeth (10 samples per group). The samples were stored in coffee solution in an incubator at 37°C for 12 days, which is equivalent to 1 year of coffee consumption. The …

The Effect Of Different Drilling Protocols On Bone Healing Around Dental Implants., Sara Fikry, Amr Amin Ghanim, Hisham El Sheikh, Omar El Sergany

Dentistry

Materials and Methods: 20 patients with kennedy class III modification 1 edentulous areas were recruited for this study and divided into two groups; Control group received implants with conventional osteotomy preparation following standard drilling protocol (speed= 1200 rpm) with torque of 30N and sufficient saline irrigation, while Study group received implants with osteotomy preparation following a low speed drilling protocol (speed < 200 rpm) without irrigation and a torque of 50 N. Cone Beam CT was used to evaluate bone height and density around the implants at 3, 6 and 12 months after insertion. Implant primary stability was evaluated using Ostell by Resonance Frequency Analysis. Results The results showed no significant difference between bone height changes and densities in the control and study groups. Implants primary stability also showed no significant difference in ISQ values between both groups. Conclusion Biologic drilling is a promising implant drilling protocol with a potential to insert implants showing successful osseointegration and acceptable bone changes.

Care And Maintenance Of Dental Restorations, Ibeth Erazo

Publications and Research

Contributing to the longevity of the restoration by minimizing the effects of surface corrosion, maintaining the esthetic appearance and the smooth surface characterization, and contributing to gingival health by lessening the potential for plaque retention are the principal reasons for taking care of dental restorations. However, during oral hygiene routine procedures and prevention treatments, these desired effects are not always achieved. In many cases, the restorative materials are not identified in a patient’s record leading to damage during oral hygiene performance by dental professionals. Therefore, it is important to be able to recognize the different restorative materials and employ the …

Cad/Cam Milling Versus Rapid Prototyping Surgical Guide Techniques In Dental Implant Placement, Fardos N. Rizk Prof., Marwa Sabet Prof., Hebatallah Mohammed, Adham Elghamry

Dentistry

No abstract provided.

Efficacy Of Stem Cell Allograft In Maxillary Sinus Bone Regeneration: A Randomized Controlled Clinical And Blinded Histomorphometric Study, Josh Whitt, Mohanad Al-Sabbagh, Dolph R. Dawson Iii, Ehab Shehata, Moly Housley-Smith, Alejandro G. Villasante Tezanos, Ahmad Kutkut

Oral Health Practice Faculty Publications

Purpose: This study aimed to evaluate the quality and quantity of newly generated bone in the maxillary sinus grafted with stem cell-based allograft material.

Methods: This study was a single site, prospective, blinded, randomized, and controlled clinical trial. Eleven subjects with 18 edentulous posterior maxillary sites requiring sinus augmentation for delayed implant placement using a lateral window approach were enrolled. At the time of sinus augmentation, test sinus was grafted with stem cell-based allograft (Osteocel Plus; NuVasive Therapeutics), while the control sinus was grafted with conventional cortico-cancellous allograft (alloOss; ACE Surgical). Cone beam computer tomography (CBCT) scan was taken before …

Replacing A Single Tooth: Single Implant Vs. Three Unit Bridge, Ibeth Erazo, Aneeza Hussain

Publications and Research

There are more than two options for restoring a single tooth but our research includes a three-unit bridge and a single-tooth implant as the main options. In this paper, we discuss the advantages and disadvantages of these methods and the factors that must be considered when choosing between them for the replacement of a single tooth. Although in some cases a three-unit bridge is the most appropriate choice, implants have the advantage of allowing preservation of the integrity of sound teeth adjacent to the edentulous area. Many factors must be considered when choosing between a three-unit bridge and an implant …

Current Status Of Magnetic Resonance On Saliva For Oral And Dental Health Early Diagnosis, Anastasia Katsavochristou, Dimitrios Koumoulis

Oral Health Practice Faculty Publications

Magnetic resonance spectroscopy of biomolecules has recently gained attention for clinical diagnosis. Its combination with saliva collection and analysis can promote early disease detection and monitoring, by identifying biomarkers of specific underlying pathology or disease as detected in saliva. With this novel, non-invasive technique, certain salivary biomarkers have been linked to dental and periodontal tissues pathology, as well as to specific head and neck cancer malignancies. At present, diagnostic biomarkers are still in need for further identification (e.g., diagnosis and monitoring of Sjögren’s syndrome), and nuclear magnetic resonance spectroscopy has been found to be a promising technique to compliment the …

Radiographic Bone Changes Surrounding Implants Of Different Attachment Systems., Sara Fikry El Shafei Dr, Fardos N Rizk Prof

Dentistry

This study was conducted to compare the effect of GPS attachment, OT Equator attachment and Ball and Socket attachment on crestal bone around implants in implant retained mandibular overdenture cases. Materials and Methods: Following two stage surgical protocol eighteen completely edentulous patients received two implants placed bilaterally in the canine region (36 implants) to retain mandibular overdentures. Inclusion Criteria: Patients were all healthy men, non-smokers, Following Misch rules of bone classification patients with bone density ranging from 850-1250 HU (D2) and bone height and width more than 10 mm and 5 mm respectively. Four months following the surgery patients were …

Comparative Study Of Two Fifferent Telescopic Crown Materials Retaining Lower Partial Overdenture, Fardos N. Rizk Prof., Ayman Hany Amin Dr., Gehan Fikry Prof., Amr Ismail Dr.

Dentistry

Background and Objective: This study was conducted to measure the difference between Chrome Cobalt telescopic crowns and Poly ether ether ketone (PEEK) telescopic crowns retaining implant retained partial overdenture.

Materials and Methods: This is a comparitive study that included fourteen lower kennedy class I partially edendulous patients. All patients received posterior implant in the second molar area in each side. The patients were divided into 2 groups, the first group received chrome cobalt telescopic crown and the second group received poly ether ketone telescopic crowns over the implants. Partial overdenture was constructed for all the patients in the two groups. …

Part I: Comparative Analysis Between Natural And Ceramic Teeth, Aneeza Hussain, Ibeth Erazo

Publications and Research

Ceramics play a fundamental role in Dentistry and are used widely, due to their ability to mimic the optical characteristics of enamel and dentine, as well as for their biocompatibility and strength. Initially, dental ceramics were materials that formed part of systems, designed with the purpose of producing dental prosthetics that in turn were used to replace missing or damaged dental structures. However, due to the increased demand for esthetics, its development has gone beyond in such a way that it has led to the development of all ceramic restorations. So that, in the last few decades, there have been …

Pink Tooth Of Mummery In The Maxillary Left Canine After Fixed Partial Denture (Fpd) Preparation, Eger V. Korolevsky, Takashi Komabayashi, Denise Foran

Dental Medicine Faculty Publications

Pink tooth of Mummery is typically found after trauma. However, this case report describes an unusual occurrence of pink tooth in a 67-year-old Caucasian male after fixed partial denture (FPD) tooth preparation. Pink tooth in this case may be due to one or more factors: tooth reduction and heat generation during tooth preparation; heat generation during polymerization of provisional material; and hyperocclusion of a provisional FPD. This case highlights the importance of choosing the appropriate materials and techniques to avoid pulpal complications after dental prosthesis work.

Part I: Complete Dentures And Diabetes Correlation, Ibeth Erazo

Publications and Research

Diabetes is one of the most frequent pathologies that dentists encounter, due to its high prevalence worldwide. The aim of this study is to present the correlation between diabetes and complete denture wearers, intending to emphasize the importance of proper control and denture adaptation to oral environment for this type of patient. Within the sphere of the dental office, one of the main complications to consider in this type of patient is periodontal disease, which is their most frequent complication. Other important oral manifestations considered in the research are fungal infections, xerostomia, and burning mouth syndrome. It is common for …

Implant Impression Accuracy Of Parallel And Non-Parallel Implants: A Comparative In-Vitro Analysis Of Open And Closed Tray Techniques, Motaz S. Osman, Hassan M. Ziada, Neamat H. Abubakr, Ahmed M. Suliman

Dental Medicine Faculty Publications

Background The outcome of the evaluation of impression techniques accuracy may improve the selection criteria for an ideal technique. The aim was to evaluate the accuracy of the open and closed tray techniques for implant impressions, in a partially edentulous maxilla, replaced with a three-unit fixed partial denture, as well as to assess the effect of implants parallelism on accuracy. Material and methods This is an experimental in vitro study to evaluate impressions accuracy of a simulated area restored with an implant retained FPD, using the open and closed tray implant impression techniques. The effect of implant position angulation, parallelism, …

The Effect Of Framework Material On Partial Overdenture Supporting Structure, Sara Fikry El Shafei

Dentistry

Purpose: In this study the effect of two partial denture framework materials on the bone tissues surrounding a the implants, in an implant retained partial overdenture is compared. Materials and Mehods: 12 partially edentulous patients with mandibular kennedy class I configuration were selected for this study. They were divided into two groups; Group 1 received a mandibular implant retained partial overdentures with a framework made of cobalt chromium. Group 2 received implant retained partial overdentures with a framework made of acetal resin. The results were evaluated using cone beam ct. Results: The results showed that bone changes produced in metallic …

Deviation Between Planned And Actual Implant Positions Inserted Using Mucosa-Supported Stereolithographic Surgical Guide In Edentulous Mandible And Maxilla, Fardos N. Rizk, Marwa Sabet Prof., Omar Yehia

Dentistry

Purpose: estimate the deviation between the planned and the actual implant inserted using a mucosa-supported stereolithographic surgical guide in different edentulous arches and determine the effect of the arch (mandible or maxilla) on accuracy. Materials and Methods: 16 implants were placed in completely edentulous arches and divided into two groups. Group (A): Eight implants were placed in four patients in the mandible using completely limiting mucosa-supported stereolithographic (SLA) surgical guide during implant insertion. Two implants were placed in each patient intraforamina. Group (B): Eight implants were placed in Two patients in the maxilla using completely limiting mucosa-supported stereolithographic (SLA) surgical …

Osseointegrated Implants Versus Zirconium Mucosal Inserts In Complete Denture Patients, Sara Fikry El Shafei Dr, Fardos N Rizk

Dentistry

Purpose: To evaluate the effect of osseointegrated implants versus mucosal inserts used for retention of complete dentures. Materials and Methods: Twelve completely edentulous patients were selected for this study and divided into two groups of six. Group I received implant retained maxillary overdentures, while group II received maxillary overdentures retained by muchor zirconium mucosal inserts. Bone changes in both groups were evaluated using cone beam ct at insertion and after six and twelve months. Results: The results showed that the bone changes produced in mucosal overdenture wearers were greater than those produced in implant overdenture wearers. Conclusion: Zirconium mucosal inserts …

Design Of Parallel Robot For Dental Articulation And Its Optimization, Abulimiti Delimulati

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

A dental articulator is a mechanical device used to simulate the relative position and motion between the upper and lower jaw when constructing and testing dental prostheses. Typically, it can be adjusted to approximate patient-specific jaw kinematics in order to analogue the static relationship and specific motions of a patient’s mandible to maxilla. However, the use of dental articulators is essentially a trial-and-error method in order to fine-tune fit and function of a dental prosthesis. Some of the most advanced current dental articulators can reproduce the position and the motion passively; furthermore, dentists need special training for measuring patients’ maxillofacial …

Short Length Versus Conventional Implants In Rehabilitation Of Completely Edentulous Mandible, Fardos N. Rizk, Engy Tallat, Mahmoud Elhomossany, Ahmed Lasheen Dr., Hebatalla Mahmoud

Dentistry

Various bone augmentation strategies have been proposed to overcome the anatomic and physiologic limitations of implant placement in patients with atrophic edentulous ridges. The use of short implants may provide an alternative treatment to avoid complications associated with alveolar bone augmentation. However, the clinical effectiveness of short implants versus long implants was not thoroughly investigated. Marginal bone height changes around short and conventional implants were evaluated in this study Methods: Fourteen completely edentulous male patients were selected and divided into two equal groups. Group (I) Patients received conventional complete maxillary dentures opposed by mandibular overdentures supported and retained by two …

Effect Of One Piece Versus Two Piece Mini Implants On Bone Height Of Implant Retained Mandibular Overdenture, Fardos N. Rizk, Jehan Fikry Prof., Amr Badr, Ahmed Damarisy Dr.

Dentistry

Introduction: Severely atrophied mandibles are a common problem within elderly completely edentulous patients. Given their small diameters, long height and self-tapping characteristics, miniimplant retained over-dentures are a valuable treatment option in such patients. Mini-implants are usually once-piece implants, however recently two-piece mini-implants were introduced with aim of addressing the angulation problems. The success of the latter has not been thoroughly studied. Crestal bone height measurements are normally used to evaluate implant success. Therefore this study was conducted to evaluate the effect of one piece versus two piece ERA mini implants on crestal bone height of implant retained mandibular over-denture. Materials …