Direct Retainers Research Articles

Evaluation of Clinical Periodontal Parameters of Abutment Teeth Supporting Distal-Extension Base Removable Partial Dentures: A Cross-sectional Study.

To assess the clinical periodontal status of abutment teeth in regards of different design components of distal-extension removable partial dentures. Subjects (N=100) with acrylic or cobalt-chromium distal-extension removable partial dentures were enrolled and their periodontal parameters plaque and gingival indices [PI, GI], probing depths [PD], clinical attachment loss [CAL] and a mobility index [MI] evaluated. Denture base type, major connector, occlusal rests position, design of direct retainers, retention, stability and denture wearing habits were further evaluated. Acrylic RPDs were associated with higher mean±SE PI [1.70±0.74], GI [1.76±0.55], PD scores [2.47±1.02 mm] and CAL values [4.46±2.11 mm] compared to CO-CR RPDs [p⟨0.05]. For abutments, the PI [1.6±0.83], GI [1.72±0.57], PD [2.32±1.03] and CAL [4.26±2.08] were higher than their non-abutments counterparts [p⟨0.05]. CAL scores were found to be significantly higher for mandibular abutments compared to maxillary ones [P=0.002]. The highest PI [1.83±1.10] and GI [2.00±0.00] scores were associated with lingual bars and horse-shoe connectors, respectively. Full palatal coverage and lingual plates were associated with the highest PD [2.80±0.48] and CAL [4.70±0.37] scores. Acrylic RPDs, type of major connector, wrought wire clasps and distal occlusal rests may be considered as risk factors for periodontal disease progression in distal-extension removable partial denture wearers.

The impact of an additional implant under the saddle of removable partial dentures in Kennedy Class II edentulism on oral health-related quality of life and oral function: a case series report

BackgroundImplant-supported removable partial dentures (ISRPDs) provide effective prosthodontic treatment for partially edentulous patients. ISRPDs offer greater patient satisfaction and better oral function compared with removable partial dentures (RPDs) by enhancing denture stability and support. However, few clinical studies have focused on RPD design in patients with mandibular Kennedy Class II edentulism. The aim of this case reports was to investigate the oral function, oral health-related quality of life, and satisfaction of four patients with unilateral distal-extension mandibular RPDs with the same design which were replaced with ISRPDs. In addition, we investigated how each patient’s evaluation varied with the change from RPD to ISRPD.Case presentationFour patients had unilateral distal-extension mandibular edentulism and were missing the first and second molars and the first and second premolars. They received one implant (4.0 mm in diameter, 8.0 mm in length; IAT EXA PLUS Bone level; Nippon Piston Ring Co. Ltd, Saitama, Japan) at the position equivalent to the first molar in the edentulous residual ridge perpendicular to the occlusal plane. Implant position was determined by surgical guide plate. RPDs were fabricated after the residual mucosal membrane had healed. The basic design of the RPD was as follows: a cobalt–chromium alloy cast metal framework denture with a lingual bar as the major connector, a double Akers clasp on the molars and an auxiliary retainer on the premolar as indirect retainers, and a wrought wire clasp and a cast cingulum rest (combination clasp) as direct retainers. Masticatory performance, occlusal force, oral health-related quality of life, and satisfaction were estimated at baseline, and at time points after insertion of the RPD and after insertion of the adapted ISRPD. Each evaluation item showed a tendency for improvement on insertion of the new RPD. Masticatory performance and satisfaction tended to be better after insertion of the ISRPD than after insertion of the RPD.ConclusionOur findings suggest that ISRPDs provided better patient satisfaction and masticatory performance than RPDs in patients with mandibular Kennedy Class II edentulism.Trial registration UMIN Clinical Trials Registry and Japan Registry of Clinical Trials, UMIN000025283 and jRCTs012180003. Registered 19 February 2016 and 17 December 2018, https://www.umin.ac.jp/ and https://jrct.niph.go.jp/

Designing Cast Partial Dentures in Relation to Partial Edentulism

Objective: To determine the pattern of partial edentulism and the cast removable dental prosthesis design in relation to the Classes recorded.
 Study Design: Cross-sectional study.
 Place and Duration of Study: Department of Prosthodontics, Armed Forces Institute of Dentistry (AFID), Rawalpindi Pakistan, from Apr to Sep 2021.
 Methodology: A total of 67 partially dentate male and female patients presenting to the Prosthodontics Department requiring partial cast dentures were included in the study. Visual inspection of the master casts and partial denture frameworks was carried out in the laboratory. Kennedy's Classification, modification areas, type of major connector, direct retainer, rest and use of indirect retention were recorded.
 Results: The most prevalent Class of partially dentate arch was Kennedy Class-II in maxilla 10 (45.5%) and Class-I and III in mandible 15 (33.3%) each. Major connectors most frequently encountered were anteroposterior palatal strap (59.1%) and lingual bar (57.8%). Circumferential clasp (35.8%) was the most used retainer type in Classes II and III, whereas RPI was mostly found in Classes I and II (32.1%). Occlusal rests were most commonly used (72.4%). Indirect retention was mostly used in Class-I and II denture frameworks (95.9%).
 Conclusion: The most commonly encountered partial edentulism pattern was Kennedy's Class I and II. Following basic principles of RPD design can help elevate the standards of removable denture treatment.

Comparative biomechanical analyses for kennedy’s class-I cast partial denture using acrylic denture base with Co-Cr I bar and nylon denture base with nylon retentive clasp-A 3D finite element study

Introduction: The goal of present PRPD is to optimize esthetics with denture design that ensures minimal invasion to the remaining oral tissues, since the function of an PRPD is affected by physical properties of direct retainers. A comparative 3-D Finite Element (FE) stress analysis for mandibular Kennedy’s class-I situation using two different denture base and direct retainer material on distal abutment was done Method: FE models were developed, with simulated alveolar bone, mucosa, abutments, periodontal ligaments, framework and artificial teeth in the models. The 2 FE models, Model A having PMMA denture base and Co-Cr gingival approaching clasp and Model B having nylon denture base and retentive clasp made up of nylon only were developed. Structural analysis for two designs was carried out using ANSYS FEA software. Results: During analysis static distributed load of 150N over artificial teeth vertically and 45ᵒ diagonally was applied. The stresses and deformation produced in assembly were evaluated Structural analysis results were analyzed for various supporting structures. The two designs showed considerable differences in stresses and displacement developed in supporting structures. Cast partial denture with nylon direct retainer and denture base showed greater stresses and displacement than acrylic denture base and Co-Cr clasp on diagonal loading whereas on vertical loading it showed almost similar displacement but slightly greater stresses. Conclusion: The results of this study suggest the use of nylon as denture base and direct retainer in esthetic region for class I situation as it generate favorable biomechanical stress, being all values are under the physiologic limit.

Perio-Prosthodontics Considerations in Removable Partial Denture: The Role of the Prosthodontist

OBJECTIVE: To review the periodontal considerations associated with removable partial denture therapy. METHODOLOGY: Using a MEDLINE search, for "removable partial dentures periodontal", a total of 712 papers from peer-reviewed journals came in results. The MEDLINE search was made more specific by applying filters to the key phrase with other key words such as "periodontal evaluation"(140), "direct retainers"(77), "non-surgical periodontal"(8), "surgical periodontal"(180), "plaque"(249), "periodontal indices"(112), "tooth mobility,"(180) "periodontal maintenance,"(60) "splinting,"(198) and "split major connector"(2). Both in vivo and in vitro studies on the Perio-prosthodontic aspects of RPD treatment were included in the study pool whereas case Series and case reports were excluded. RESULT: A total of 1206 studies were collected from the search engine. After applying the exclusion criteria and filtering the duplicates a total of 95 studies were included for the narrative review. CONCLUSIONS: Out of all the factors, recall and oral and denture hygiene have the utmost importance. KEYWORDS: Perio-prosthodontics, removable partial denture, periodontal indices.

Designing metal framework partial denture

The number of partiallyedentulous adults is increasing, and many patients will require replacement of missing teeth. Although current treatment options also include fixed partial dentures and implants, removable partial dentures (RPDs) can have advant-ages and are widely used in clinical practice. However, a significant need exists to advance materials and fabrication technologies because of the unwanted health consequences associated with current RPDs. The RPDs consists of many components, such as major and minor connector, direct and indirect retainer, also rests. The variety of anatomic considerations related to oral con-ditions may affect selection of these components. The objective of this review is to discuss data related to RPDs design and factors affecting its selection. It was concluded that prosthodontists need to fully understand the basic of RPDs design princi-ples and should be familiar with those structures.

Influence of rigidity of retainers on dynamic behavior of implant-supported removable partial dentures

BackgroundImplant-supported removable partial dentures (ISRPDs) are an effective treatment for partially edentulous patients. ISRPDs improve patients’ satisfaction and oral function to a greater extent than RPDs by improving denture stability and enhancing support. However, the effect of a type of direct retainer on displacement of the abutment teeth and dentures in ISRPDs remains unclear. Therefore, we made a resin mandibular model of unilateral mandibular distal-extension partial edentulism for mechanical simulation and compared the dynamic behavior of the abutment teeth and the denture base among different tooth-borne retainers with various rigidities for RPDs and ISRPDs.MethodsA resin mandibular model for mechanical simulation that had unilateral mandibular distal-extension edentulism and was missing the first molar, second molar, first premolar, and second premolar, and a denture fabricated from the patient’s computed tomography images were used. Three types of direct retainers with different connecting rigidities were evaluated. The vertical displacement of the denture base and buccal and lingual sides and the mesial displacement of the abutment teeth were measured.ResultsRegardless of the rigidity of the direct retainers and loading positions, the displacement of the denture bases in the ISRPDs was significantly smaller than that in the RPDs (P < 0.001). There was no significant difference in vertical displacement of the denture bases among direct retainers with various connecting rigidities in the ISRPDs. Conversely, horizontal displacement of the abutment teeth in both the RPDs and ISRPDs tended to be larger with the cone crown telescope, which has high rigidity, than with the cast cingulum rest and wire clasp, which have much lower rigidities.ConclusionOur results suggested that cast cingulum rest and wire clasps as direct retainers are appropriate ISRPDs to minimize denture movement and suppress displacement of the remaining teeth in patients with unilateral mandibular distal-extension partial edentulism.

Quality of communicating design features for cobalt chromium removable partial dentures in Riyadh, Saudi Arabia

This survey aimed to investigate quality of communicating design features for the construction of cobalt chromium removable partial dentures (RPDs) among dentists in Riyadh, Saudi Arabia. A survey of nine commercial dental laboratories located in Riyadh was carried out. In each visit, master casts for cobalt chromium RPDs and dentists' prescriptions were examined. A quality score for the provided instructions was developed and ranged from 0 to 4. A zero score means that no instructions were sent from the dentist for the design of the RPD. A score of 4 means that instructions were provided for the design of four main elements of the RPD, i.e., shape of major connector, type of direct retainers, position of direct retainers, position of dental rests. 162 dentists' prescriptions for RPDs and related casts were assessed. The majority of RPD cases were designed by the dental technician alone (64.2%). Shape of the major connector was the most frequent element in dentists' prescriptions (35.8%). The mean quality score of dentists' instructions was 0.96 (sd=1.54). 18% of the provided instructions achieved quality score equal to 4. Prescriptions for Kennedy Class III cases achieved significantly higher mean quality score compared to Kennedy Class II cases (p<0.05). 16.7% of the evaluated casts had clearly defined rest seat preparation. The results of this survey indicate inadequate quality of communicating the design features of cobalt chromium RPDs among practicing dentists in Riyadh, Saudi Arabia. The reliance on the dental technician to design the cast RPDs seems to be high.

Quality of models supplied to dental laboratories for the fabrication of partial removable denture framework

ABSTRACT Objective The aim of this study was to evaluate the models and plannings of metallic framework of removable partial prosthesis sent to dental laboratories in the city of Recife. Methods: The physical and technical conditions of plaster models were sent by the dentists to 4 dental laboratories. All models were examined, photographed and recorded on a form according to the research objective. Results: A total number of 235 models sent by dental surgeons were used to prepare the metallic structure, in which none of the models presented surveying nor the path of insertion. Out of the 235 models, 41 (17.44%) presented serious failures, such as positive and negative bubbles, broken dental elements, direct retainers and damaged edentulous areas. With respect to the planning, only 22 (9.35%) models were presented with the metallic framework planning, but in an unsatisfactory way. Regarding mouth preparation, no model presented a guide plane, and only 6.8% of models had rests seats, but incorrectly prepared. Conclusion: The models evaluated presented poor quality, lack of planning and no mouth preparation. This shows the need for dental surgeons to be aware of the appropriate prosthesis models and plannings in order to ensure a satisfactory and long-term rehabilitation of the patient, as well as preserving the remaining mouth structures.

Mechanical behavior of implant assisted removable partial denture for Kennedy class II.

This study evaluated the mechanical response of a removable partial denture (RPD) in Kennedy Class II according to being associated or not with implants. Four RPDs were manufactured for a Kennedy Class II: CRPD - Conventional RPD, RPD+1M, RPD+2M and RPD+12M, respectively, signifying implant assisted RPDs with the implant installed in the first molar, second molar, and in the first and second molars. The finite element method was used to determine the most damaged support tooth under compressive load (300N, 10s) and strain gauge analysis was used to evaluate the microstrain. All groups were submitted to a retentive force analysis (0.5 mm/mm, 100kgf). Microstrain and retentive force data were submitted to One-way ANOVA and the Tukey test, all with α=5%. High microstrain was observed in the second premolar adjacent to the edentulous space under compression load (p< 0.01). RPD+12M presented lower microstrain, however being similar to RPD+2M. RPD+1M presented a higher mean value of retentive force, but similar to RPD+12M. FEM showed RPD assisted by implants concentrates less stress in the periodontal ligament. The association of two implants was sufficient to decrease the stress generated in the implants. The most stressed region for the o-ring abutment was the threads, and the group with two implants showed the lowest stress concentration. In cases of Kennedy Class II, the association of RPD with implants in the molar region is a favorable option for patient rehabilitation, reducing the movement of the direct retainer adjacent to the edentulous space, increasing the removal force and decreasing the stress magnitude in the periodontal ligament. Key words:Removable partial denture, Finite element analysis, Prosthetic dentistry, Implant-assisted RPD, Distal extension RPD considerations.

Mechanical behavior of implant assisted removable partial denture for Kennedy class II

BackgroundThis study evaluated the mechanical response of a removable partial denture (RPD) in Kennedy Class II according to being associated or not with implants. Material and MethodsFour RPDs were manufactured for a Kennedy Class II: CRPD - Conventional RPD, RPD+1M, RPD+2M and RPD+12M, respectively, signifying implant assisted RPDs with the implant installed in the first molar, second molar, and in the first and second molars. The finite element method was used to determine the most damaged support tooth under compressive load (300N, 10s) and strain gauge analysis was used to evaluate the microstrain. All groups were submitted to a retentive force analysis (0.5 mm/mm, 100kgf). Microstrain and retentive force data were submitted to One-way ANOVA and the Tukey test, all with α=5%. ResultsHigh microstrain was observed in the second premolar adjacent to the edentulous space under compression load (p< 0.01). RPD+12M presented lower microstrain, however being similar to RPD+2M. RPD+1M presented a higher mean value of retentive force, but similar to RPD+12M. FEM showed RPD assisted by implants concentrates less stress in the periodontal ligament. The association of two implants was sufficient to decrease the stress generated in the implants. The most stressed region for the o-ring abutment was the threads, and the group with two implants showed the lowest stress concentration. ConclusionsIn cases of Kennedy Class II, the association of RPD with implants in the molar region is a favorable option for patient rehabilitation, reducing the movement of the direct retainer adjacent to the edentulous space, increasing the removal force and decreasing the stress magnitude in the periodontal ligament. Key words:Removable partial denture, Finite element analysis, Prosthetic dentistry, Implant-assisted RPD, Distal extension RPD considerations.

Assessment of Undercuts Relative to Abutment Teeth and Edentulous Area: A Retrospective Cross-sectional Study

Undercuts on abutment teeth (AT) should be identified and quantified to establish the exact location of the active tip of the retentive arm of the direct retainer. The aim of this study was to locate and evaluate tissue and tooth undercut areas in various Kennedy's classes and to assess the correlation, if any, between Kennedy's classes and the location and depth of undercuts. One hundred and seven patients' casts, with designated AT and edentulous areas (EAs), were surveyed. The undercuts on AT and EAs were measured using undercut gauges. Statistical analysis was performed. The median depth of the undercut was maximum on distal the surface of mandibular AT in a Kennedy's class III edentulous situation. No significant difference was found between the amount of tissue undercuts measured on the EA in each of the Kennedy's classes in the maxillary and mandibular arches. No significant difference was found between the amounts of undercut measured on AT and the EA in each of the Kennedy's classes in the maxillary and mandibular arches. No correlation was found between Kennedy's classes and the location and depth of undercuts. The results of our study reinforce that the diagnosis and selection of ideal abutments should be stressed while planning for a removable dental prosthesis (RDP). In the majority of the cases, the anticipated design of the direct retainer can be applied, though one cannot overlook the need for proper diagnosis and survey.

Effect of Direct Retainer Types for a Dento-maxillary Prosthesis on Abutment Teeth of Maxillectomy Patients: In Vitro Study

Effect of Direct Retainer Types for a Dento-maxillary Prosthesis on Abutment Teeth of Maxillectomy Patients: In Vitro Study

Effect of different materials and undercut on the removal force and stress distribution in circumferential clasps during direct retainer action in removable partial dentures

ObjectivesThis study aimed to evaluate the effect of different materials and undercut on the removal force and stress distribution in the supporting tooth and in the circumferential clasp used in removable partial prosthesis. MethodsUpper molars prepared for Akers circumferential clasp with retention and opposing arm were modeled, scanned, elaborated with CAD software and the geometries imported in FEA and analyzed. Six different materials were selected for the clasp (Polyamide, Polyoxymethylene, Polyetheretherketone - PEEK, Gold alloy, Titanium and CoCr) and 3 different undercuts (0.25, 0.50 and 0.75mm), totaling 18 groups. ResultsThe clasps presented greater stress in their structure and potentially greater damage to the dental enamel when made with rigid materials and with more undercut; however, they presented greater ability to remain in position. SignificancePolyamide with a higher undercut is an esthetic alternative to rigid metallic clasps. It showed promising behavior because it strongly reduces the damage to the enamel, and even with an undercut of 0.75, the retention is lower than for CoCr with a 0.25 undercut, and this retention might still be sufficient. Polyoxymethylene and Polyetheretherketone (PEEK) are not suitable materials for the clasps, because the maximum stress occurring during removal with higher undercuts is higher than the material strength.

Different Materials Used as Denture Retainers and Their Colour Stability.

BACKGROUND:Retainers are of great importance for the longevity of the prosthetic removable partial denture during various functions especially the esthetic one. The key of successful clasp selection is to select a direct retainer that will control tipping and torquing forces on the abutment teeth, provide retention against reasonable dislodging forces and are compatible with both tooth and tissue contour together with the aesthetic desire of the patient.AIM:This study aims to compare different clasp material to enhance the choice of the clasp based on the aesthetic point of view.METHODS:The colour evaluation of the tested materials had been evaluated by computer aided technique with digital camera with 3 Mega Pixels of resolution.RESULTS:In the current research, the technique of colour evaluation was carried out to compare different clasp materials to enhance the choice of the clasp based on the aesthetic point of view. Most commonly, Removable Partial Denture (RPD) retainers are fabricated identically from the metal framework’s alloy as Cobalt Chromium (CoCr) alloy although it is unaesthetic. This esthetic problem has been overcome by other methods and by utilising different materials, these included covering the retainers with tooth-coloured acrylic resin, as well as the introduction of esthetic materials as; Thermoplastic Acetal, Versacryl, and Thermopress.CONCLUSION:It has been concluded that the non-metallic Acetal resin clasp shows superior physical properties regarding colour stability.

Comparative Study Clarifying the Most Suitable Material to Be Used as Partial Denture Clasps.

BACKGROUND:Removable partial denture’s clasp is of particular importance as it affects the denture longevity during the function. The key of successful clasp selection is to select a direct retainer that will control tipping and torquing forces on the abutment teeth, provide retention against reasonable dislodging forces and are compatible with both tooth and tissue contour and the aesthetic desire of the patient. In this consideration, different materials employed for the clasp construction were compared mechanically.AIM:This study aims to compare the most usable esthetic clasps mechanically to clarify the most suitable material to be used as partial denture clasps.METHODS:Evaluation of surface roughness, retention and deformation has been investigated utilising different in-vitro methods. All these techniques provide valuable information regarding the mechanical properties of the materials tested. However, none of the in-vitro techniques can expose the tested materials to conditions similar to that of the oral environment (in-vivo) such as pH value and temperature variations.RESULTS:Most commonly, RPD clasps are fabricated from the same alloy of the metal framework, as cobalt-chromium (CoCr) alloy although it is unaesthetic. Other methods consumed to avoid such esthetic mystery have included coating retainers with tooth-coloured resin or introduction of esthetic materials as Thermoplastic Acetal, Versacryl, and Thermopress.CONCLUSION:It has been concluded that the non-metal Acetal resin retainer reveals superior mechanical properties.

Comparison Between Two Treatment Protocols For Completely Edentulous Maxilla Opposing Mandibular Kennedy Class I

Objectives: This research was carried out to determine whether mandibular implant supported overdenture or maxillary implant supported overdenture is more effective in prevention of combination syndrome.Materials and Methods: Totally, fourteen patients with completely edentulous upper arch and mandibular bilateral distal extensions (Kennedy class I) with the canines or first premolar as the last standing tooth were selected to participate in this study. Inclusion criteria: Patients had well-formed residual ridge covered with dense fibrous connective tissue, Angle class I ridge relationship, and adequate inter arch space. Patients with systemic diseases that might affect the oral tissues or bone, neuromuscular disorders, temporomandibular joint disorders and smokers were excluded. Patients were randomly divided into two equal groups, Group I: patients were rehabilitated with mucosa supported maxillary complete denture and lower tooth-implant partial denture retained by two osseointegrated implants on each side of the lower arch in the first molar area and RPI direct retainer. Group II: patients were rehabilitated with implant retained and supported maxillary complete overdenture by four osseointegrated implants in the anterior maxillary area and tooth-tissue supported partial denture retained by RPI direct retainer. In this study, marginal bone height changes in the premaxillary region and mucosal thickness at the crest of maxillary ridge were evaluated at the time of prostheses insertion, six, twelve and eighteen months. Results: In this study, an insignificant difference was detected between the two groups at the different follow-up intervals, regarding marginal bone loss and mucosal thickness. After 18 months follow up, bone loss & mucosal thickness were 0.5±0.2, 0.6±0.3 mm for group I and 0.5±0.2, 0.3±0.2 mm for group II respectively. Although group II showed decrease in marginal bone loss and decrease in mucosal thickness compared to group I however difference between groups were statistically insignificant.Conclusion: Within the limitations of the number of studied patients and follow up period of this study it could be concluded that, preventing the degenerative oral changes that occurs when complete maxillary dentures opposes the Kennedy class I partial dentures may be possible through accurate treatment planning and, the development of stable posterior occlusion that controls of occlusal pressures on the anterior maxilla. Also, maxillary implant retained overdentures should be considered preferable treatment option, whenever the available bone quantity and quality permits.

Longitudinal Improvement in Periodontal Parameters between RPD Abutment Teeth with Direct and Indirect Retainers, after Periodontal Therapy.

To evaluate the effect of basic periodontal treatment on clinical periodontal parameters associated with abutment teeth of patients with mandibular Kennedy class I removable partial dentures (RPD) 18 months after treatment. Thirty patients with periodontal disease were treated and evaluated according to the following periodontal parameters: visible plaque index (VPI), bleeding on probing (BOP), probing depth (PD), gingival recession (GR), clinical attachment loss (CAL), and keratinized mucosa (KM). These parameters were compared between abutment teeth with direct and indirect retainers at baseline, and after 6 and 18 months. Data were analyzed by Friedman Test and Wilcoxon Test for all variables. Most patients (n=26; 86.7%) included in the study were female and had a mean age of 61 years (±7.54). Results showed that VPI and BOP decreased over time, and that VPI values were higher in abutment teeth with direct retainers (p=0.001). There was a reduction in PD after 6 months, which was maintained up to 18 months. In general, abutment teeth with direct retainers had significantly higher values for PD, GR, and CAL (p=0.029). Data also indicated that the parameters for VPI, BOP, and PD improved; however, abutment teeth with direct retainers presented smaller improvements, compared with abutment teeth with indirect retainers, which presented significant improvements for almost all variables. Periodontal treatment and oral hygiene care of patients were adequate for maintenance of adequate periodontal conditions, regardless of the use of prostheses.

OSNC1: Effect of Direct Retainer Types of Dent-Maxillary Prosthesis in Maxillectomy Patients: An In Vitro Study.

OSNC1: Effect of Direct Retainer Types of Dent-Maxillary Prosthesis in Maxillectomy Patients: An In Vitro Study.

THE EFFECT OF TWO MANDIBULAR CLASS I REMOVABLE PARTIAL DENTURE DESIGNS ON THE PERIODONTAL HEALTH OF THE ABUTMENT TEETH: A RANDOMIZED SPLIT-MOUTH CLINICAL TRIAL

The aim of this study was to assess the effect of RPI direct retainer designs in mandibular Kennedy’s class I removable partial denture cases, on the periodontal conditions of their abutment teeth.Materials and methods: A total of 10 systemically healthy Patients were selected with mandibular Kennedy class I with symmetrical healthy periodontium at first premolar abutments split mouth mandibular class I removable partial denture designs RPI, I-bar (Rest, proximal plate and I bar) in one side (side A) and a modified RPI clasp assembly (Rest, proximal plate connected by lingual bracing arm to the rest and I Bar) in other side (side B) were constructed. Clinical evaluation(gingival index, pocket depth and clinical attachment loss) and recording of GCF levels of Interlukin1s IL1 –β using ELISA were carried out for all patients at base line (time of denture insertion), 3 months and 6 months after denture insertion at mandibular free end saddle abutments.Results: A statistically significant increase in the mean IL-1s levels after 3 months with further significant increase after 6 months was recorded in both sides (P ≤ 0.05) further, side B showed a statistically increased IL-β levels compared to side A. Regarding clinical parameters, side B showed a statistical significant increase at 6 months compared to side A regarding PD with no significant difference between the 2 sides at 3 months ,as for CAL and GI, although side B showed an increased readings in 6 months and 3 months compared to side A, a non significant difference was recorded between the 2 sides, as well, a non significant change in GI and CAL was recorded in both sides over the study period .Conclusion: within the limitation of our study, the modified RPI clasp induced increasing of proinflammatory cytokines IL- 1s levels in GCF compared conventional RPI clasp assembly. Both Clasp designs have an effect on periodontal health of free end saddle’s partial denture abutments.