Mandibular implant-supported removable partial denture with distal extension: a systematic review

Implant-assisted removable partial dentures: Part I. a scoping review of clinical applications

PURPOSE

This scoping review aimed to systematically map research regarding implant-assisted removable partial dentures (IARPDs), and identify existing gaps in knowledge.

STUDY SELECTION

Two reviewers independently conducted a search of the MEDLINE-PubMed and Scopus databases according to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) extension for Scoping Review and included articles published in English up to August 31, 2022, including human studies, reviews, and in vitro studies. Expert opinions, animal studies, and clinical studies involving complete overdentures were excluded, and ten aspects for establishing the treatment strategy for IARPDs were examined.

RESULTS

One hundred and twelve articles were chosen. There were two treatment modalities: IARPDs retained by implant- and tooth-supported surveyed single crowns (SCs) or fixed partial dentures (FPDs). In IARPDs retained by tooth-supported surveyed SCs or FPDs, the survival rate of dental implants for IARPDs was relatively higher with a wide range of marginal bone loss and many complications, but with improved functional performance, oral health-related quality of life, and patient satisfaction. There were limited data on survival or success rates and designs of IARPDs, attachment selections, length and diameter, inclination, placement sites, and loading protocols of implants, regardless of prosthetic types. There was limited information on maxillary IARPDs except for survival rates of implants.

CONCLUSIONS

Although IARPDs could become a useful treatment strategy, there is limited scientific consensus with gaps in knowledge about their use. Additional well-designed clinical and in vitro studies are necessary to scientifically establish IARPDs as definitive prostheses in implant dentistry.

Impact of implant location on load distribution of implant-assisted removable partial dentures: a review of in vitro model and finite-element analysis studies

BACKGROUND

Appropriate load distribution among the supporting elements is essential for the long-term success of implant-assisted removable partial dentures; however, there is little information available on load distribution.

PURPOSE

This study aimed to evaluate the effect of implant location on load distribution in implant-assisted removable partial dentures by reviewing in vitro models and finite-element analysis studies.

MATERIALS AND METHODS

English-language studies which examined the load distribution of implant-assisted removable partial dentures and were published between January 2001 and October 2022 were extracted from PubMed, ScienceDirect, and Scopus online databases, and manual searching. Two reviewers selected the articles based on the predetermined inclusion and exclusion criteria, followed by data extraction and analysis.

RESULTS

Forty-seven studies were selected after evaluating the titles and abstracts of 264 articles; two were identified manually. After screening the text, 12 studies were included: six in vitro model experiments and six finite-element analysis studies. All included studies used a mandibular free-end missing model (Kennedy Class I or II). The influence of implant location on load distribution to the abutment tooth, implant, and mucosa under the denture base was summarized in three cases: implant at the premolar, first molar, and second molar region. Due to differences in the measurement method of load distribution and loading condition to the denture, the results differed among the studies.

CONCLUSIONS

The implant location in implant-assisted removable partial dentures can affect load distribution to the supporting elements, such as the abutment tooth, implant, and mucosa under the denture base.

Survival and stability of strategic mini-implants with immediate or delayed loading under removable partial dentures: a 3-year randomized controlled clinical trial

Objectives

Stability values of mini-implants (MIs) are ambiguous. Survival data for MIs as supplementary abutments in reduced dentitions are not available. The aim of this explorative research was to estimate the 3-year stability and survival of strategic MIs after immediate and delayed loading by existing removable partial dentures (RPDs).

Material and methods

In a university and three dental practices, patients with unfavorable tooth distributions received supplementary MIs with diameters of 1.8, 2.1, and 2.4 mm. The participants were randomly allocated to group A (if the insertion torque ≥ 35 Ncm: immediate loading by housings; otherwise, immediate loading by RPD soft relining was performed) or delayed loading group B. Periotest values (PTVs) and resonance frequency analysis (RFA) values were longitudinally compared using mixed models.

Results

A total of 112 maxillary and 120 mandibular MIs were placed under 79 RPDs (31 maxillae). The 1st and 3rd quartile of the PTVs ranged between 1.7 and 7.8, and the RFA values ranged between 30 and 46 with nonrelevant group differences. The 3-year survival rates were 92% in group A versus 95% in group B and 99% in the mandible (one failure) versus 87% in the maxilla (eleven failures among four participants).

Conclusions

Within the limitations of explorative analyses, there were no relevant differences between immediate and delayed loading regarding survival or stability of strategic MIs.

Clinical relevance

The stability values for MIs are lower than for conventional implants. The MI failure rate in the maxilla is higher than in the mandible with cluster failure participants.

Clinical trial registration

German Clinical Trials Register (Deutsches Register Klinischer Studien, DRKS-ID: DRKS00007589, www.germanctr.de), January 15, 2015.

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

BACKGROUND

Implant-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 PRESENTATION

Four 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.

CONCLUSION

Our 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/.

In vitro study of the effect of implant position and attachment type on stress distribution of implant-assisted removable partial dentures

Background/purpose

Implant assisted removable partial dentures (IARPDs) improved biomechanical behavior of removable partial dentures (RPDs), but information of the effect of attachment type and implant position is limited. This study aimed to investigate the effect of implant position and attachment type on the stress distribution of IARPDs.

Material and methods

Four implants, 10 mm in length and 4.1 mm in diameter, were bilaterally placed close to first premolar and second molar regions of a mandibular Kennedy class I model having artificial dentition from canine to canine, vertical to the occlusal plane. Five IARPDs were fabricated to accommodate locator and magnetic attachments. Strain gauges were placed on the model surface to measure the strain around implants during loading. Unilateral vertical loading was applied to the right first molar area with magnitude of 120 N and crosshead speed of 10 mm/min. Measurements were recorded under following conditions: premolar IARPDs with locator or magnetic attachments, molar IARPDs with locator or magnetic attachments. Two-way multiple analysis of variance was performed to compare the maximum principal strain (MPS) around the implants with a significance level of 0.05.

Results

Implant position had significant effect on the MPS of IARPD on loading and nonloading sides while attachment type only significant on nonloading side. Molar implants showed larger MPS than premolar implants with both locator and magnetic attachments during unilateral loading.

Conclusion

The stress distribution of the IARPD is significantly affected by implant position wherein anteriorly placed implants exhibit lower MPS than relatively posteriorly placed implants.

Effect of Number and Location on Stress Distribution of Mini Dental Implant-Assisted Mandibular Kennedy Class I Removable Partial Denture: Three-Dimensional Finite Element Analysis

Purpose. To investigate effects of number and location on patterns of von Mises stress distribution and volume average stress on abutment tooth, edentulous ridge, mini dental implant, and surrounding bone of mini dental implant-assisted mandibular Kennedy class I removable partial denture. Materials and Methods. Eight three-dimensional finite element models of mandibular Kennedy class I with different numbers and locations of mini dental implants were constructed. Mini dental implants were generated in the area of second premolar, first molar, and second molar, respectively. A static load of 400 N was applied on all models. The von Mises stress and volumetric average stress were calculated by three-dimensional finite element analysis. Result. The minimum volumetric average stress of abutment tooth was found in the model, where there was one mini dental implant at the second molar position and 2 mini dental implants at first molar and second molar positions. The model with three mini dental implants had reduced volumetric average stress of abutment tooth, which was not different from the model with two mini dental implants. However, the minimum volumetric average stress of mini dental implant and surrounding bone were found when three mini dental implants were applied, followed by two and one mini dental implants, respectively. Conclusion. Placing at least one mini dental implant at a second molar position can help reduce stress transferred to the abutment tooth. Stresses around each implant and surrounding bone reduced with increased numbers of mini dental implants.

Stress Distribution Pattern in Mini Dental Implant-Assisted RPD with Different Clasp Designs: 3D Finite Element Analysis

Introduction

The removable partial denture (RPD) components, especially the retentive arm, play a major role in the loading characteristic on supporting structures.

Objective

To evaluate and compare the effect of different clasp designs on the stress distribution pattern, maximum von Mises stress, and average hydrostatic pressure on abutment teeth, as well as edentulous ridges, mini dental implants (MDIs), and peri-implant bone between the conventional removable partial denture (CRPD) and mini dental implant-assisted distal extension removable partial denture (IARPD) using a three-dimensional finite element analysis (3D FEA).

Materials and Methods

3D FEA models of mandibular arches, with and without bilateral MDI at the second molar areas, and Kennedy class I RPD frameworks, with RPA, RPI, Akers, and no clasp component, were generated. A total of 200 N vertical load was bilaterally applied on both sides of distal extension areas, and the stress was analyzed by 3D FEA.

Results

The stress concentration of IARPD with RPI clasp design was located more lingually on abutment teeth, MDI, and peri-implant bone, while the other designs were observed distally on the supporting structures. The maximum von Mises stress on the abutment root surface was decreased when the RPDs were assisted with MDIs. The CRPD and IARPD with the Akers clasp design showed the highest von Mises stress followed by the designs with RPA and RPI clasp, respectively. The average hydrostatic pressure in each group was in approximation.

Conclusion

The placement of MDIs on distal extension ridges helps to reduce the stress concentration on denture supporting structures. The maximum von Mises stress is affected by the different designs of clasp components. The CRPD and the IARPD with RPI clasp provide the least stress on supporting structures.

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

OBJECTIVES

The purpose of this systematic review and meta-analysis was to compare implant-supported removable partial dentures (ISRPDs) with distal extension removable partial dentures (DERPDs) in terms of patient-reported outcome measures (PROMs: patients' quality of life and satisfaction) and to determine mechanical and biological complications associated with ISRPDs.

MATERIAL AND METHODS

An electronic search was performed on four databases to identify studies treating Kennedy class I or II edentulous patients and which compared ISRPDs with DERPDs in terms of PROMS and studies, which evaluated mechanical and biological complications associated ISRPDs. Two authors independently extracted data on quality of life, patient satisfaction, and biomechanical complications from these studies. The risk of bias was assessed for each study, and for PROMs, the authors performed a meta-analysis by using a random-effects model.

RESULTS

Thirteen articles were included based on the selection criteria. The difference in mean scores for quality of life (30.5 ± 1.8; 95% confidence interval [CI], 24.9-36.1) and patient satisfaction (-20.8 ± 0.2; 95% CI, -23.7 to -17.8) between treatments with conventional and implant-supported removable dentures was statistically significant (p < .05). Implant-supported removable dentures improved patients' overall quality of life and satisfaction. Some mechanical and biological complications, such as clasp adjustment, abutment or implant loosening, marginal bone resorption, and peri-implant mucositis, were noted in ISRPDs during patient follow-up. Studies assessing PROMs were very heterogeneous (I2  = 65%, p = .85; I2  = 75%, p = .88).

CONCLUSIONS

ISRPDs significantly improved quality of life and patient satisfaction. Some mechanical and biological complications have been associated with ISRPDs treatment, requiring regular monitoring of patients to avoid the occurrence of these complications.

Clinical performance of tooth implant-supported removable partial dentures: a systematic review and meta-analysis

OBJECTIVE

To assess the clinical performance of tooth implant-supported removable partial dentures in terms of abutment survival in relation to the attachment system used.

METHODS

An electronic search in MEDLINE/PubMed Web of Science and Cochrane Central Register of Controlled Trials databases was performed. The methodological quality of the studies was assessed using the Newcastle-Ottawa Scale. Survival rates after 3 years and 5 years, loss, and complication rates per 100 years were estimated by Poisson regression.

RESULTS

A total of twelve studies were included; eleven studies were used for the meta-analysis. Survival analysis for mixed attachments showed an estimated survival rate of 100% after 3 years and 5 years. For uniform attachments, the estimated survival rate was 99.3% after 3 years and 98.8% after 5 years. Tooth abutment survival analysis for mixed attachments estimated a survival rate of 95% after 3 years and 91.7% after 5 years: Uniform attachments reached a survival rate of 97.2% after 3 years and 95.4% after 5 years. The prosthetic survival rate was 100% for mixed and uniform abutments after 3 years and 5 years of function.

CONCLUSIONS

Tooth implant-supported removable partial dentures can be considered as a reliable option with excellent prosthetic and implant survival rates and favorable rates for the abutments after 3-year and 5-year follow-ups. Complications may be reduced when 5 or more abutments are used.

CLINICAL RELEVANCE

Tooth implant-supported removable partial dentures are a favorable and potential alternative to restore a partially edentulous arch by optimizing the number and distribution of abutments.

Clinical and radiographic evaluations of implants as surveyed crowns for Class I removable partial dentures: A retrospective study

PURPOSE

The purpose of this study was to evaluate survival rates and marginal bone loss (MBL) of implants in IC-RPDs.

MATERIALS AND METHODS

Seventy implants were placed and used as surveyed crowns in 30 RPDs. The survival rates and MBL around implants based on multiple variables, e.g., position, sex, age, opposing dentitions, splinting, type of used retainer, and first year bone loss, were analyzed. Patient reported outcome measures (PROMs) regarding functional/esthetic improvement after IC-RPD treatment, and complications were also inspected.

RESULTS

The 100% implant survival rates were observed, and 60 of those implants showed MBL levels less than 1.5 mm. No significant differences in MBL of implants were observed between implant positions (maxilla vs. mandible; P = .341) and type of used retainers (P = .630). The implant MBL of greater than 0.5 mm at 1 year showed significantly higher MBL after that (P < .001). Splinted implant surveyed crowns showed lower MBL in the maxilla (splinted vs. non-splinted; P = .037). There were significant esthetic/functional improvements observed after treatment, but there were no significant differences in esthetic results based on implant position (maxilla vs. mandible). Implants in mandible showed significantly greater improvement in function than implants in the maxilla (P = .002). Prosthetic complication of IC-RPD was not observed frequently. However, 2 abutment teeth among 60 were failed. The bone loss of abutment teeth was lower than MBL of implants in IC-RPDs (P = .001).

CONCLUSION

Class I RPD connected to residual teeth and strategically positioned implants as surveyed crowns can be a viable treatment modality.

Treatment outcomes of implant-assisted removable partial denture with distal extension based on the Kennedy classification and attachment type: a systematic review

BACKGROUND

Implant-assisted removable partial dentures (IARPDs) have recently become popular, but little information is available on the treatment outcomes based on the Kennedy classification and attachment types.

OBJECTIVE

The objective of this review was to evaluate the treatment outcomes of IARPD delivered for distal extension edentulous areas based on the differences in the Kennedy classification and attachment type.

MATERIALS AND METHODS

English-language clinical studies on IARPD published between January 1980 and February 2020 were collected from MEDLINE (via PubMed), the Cochrane Library (via the Cochrane Central Register of Controlled Trials), Scopus online database, and manual searching. Two reviewers selected the articles based on pre-determined inclusion and exclusion criteria, followed by data extraction and analysis.

RESULTS

Eighty-one studies were selected after evaluating the titles and abstracts of 2410 papers. Nineteen studies were finally included after the perusal of the full text. Fourteen studies focused on Class I, 4 studies investigated both Class I and II, and only 1 study was conducted on Kennedy's class II. Eight types of attachments were reported. The ball attachment was the most frequently used attachment, which was employed in 8 of the included studies. The implant survival rate ranged from 91 to 100%. The reported marginal bone loss ranged from 0.3 mm to 2.30 mm. The patient satisfaction was higher with IARPD than with conventional RPDs or that before treatment. The results of prosthetic complications were heterogeneous and inconclusive.

CONCLUSION

IARPD exhibited favorable clinical outcomes when used as a replacement for distal extension edentulous areas. The comparison between the clinical outcomes of Kennedy's class I and II was inconclusive owing to the lack of studies focusing on Kennedy Class II alone. The stud attachment was the most commonly used type in IARPDs. Overall, the different attachment systems did not influence the implant survival rate and patient satisfaction. Further high-quality studies are needed to investigate the attachment systems used in IARPD.

Short strategic implants for mandibular removable partial dentures: One-year results from a pilot randomized crossover abutment type study

Objectives

The present pilot study analyzed two abutment types (a retentive ball and a non‐retentive dome) in implant‐assisted removable partial dentures (IARPDs) on 6 mm short implants with respect to clinical, radiological, and patient‐reported outcomes (PROs), during the first year.

Materials and Methods

Two implants were placed bilaterally in mandibular molar sites, converting existing free‐end removable partial dentures (RPDs) to IARPDs. Twelve subjects were randomized to initially receive either the dome (Group A, n = 6) or the ball abutment (Group B, n = 6). After eight weeks, the abutments were exchanged. After another 8 weeks, the participants were given the choice of one of the abutments. Mean values and standard deviations (SD) were calculated, and random‐effect linear regression analyses were applied to analyze marginal bone level alterations and PROs (α < .05).

Results

Twelve participants were included in the study; however, one dropout occurred. Patient ratings increased significantly in both study groups. The majority of the participants (82%) ultimately chose the ball abutment. The implant survival rate was 100%, and the success rate was 90.9% twelve months after implant placement (mean peri‐implant bone‐loss: −1.2; SD: 0.6 mm) without a statistically significant difference between the study groups, in terms of clinical‐ and radiological outcomes.

Conclusion

Placing 6 mm short implants at mandibular molar sites of RPD wearers seems to be a viable treatment option, based on this investigation with a short‐term follow‐up. Although only minor differences between the two abutments were observed, patients seem to prefer the ball over the dome abutment.

Are implant-supported removable partial dentures a suitable treatment for partially edentulous patients? A systematic review and meta-analysis

STATEMENT OF PROBLEM

A consensus on the clinical performance of implant-supported removable partial dentures (ISRPDs) is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate the clinical performance of ISRPDs in terms of the implant survival rates, marginal bone loss, and patient-reported outcome measures (PROMs).

MATERIAL AND METHODS

Four electronic databases (MEDLINE/PubMed, EMBASE, Web of Science, and Cochrane Library) were independently searched by 2 reviewers for articles published up to December 2020. A single-arm meta-analysis was performed to evaluate the implant survival rates and marginal bone loss by using the R program. The Cochrane collaboration tool was used to evaluate the risk of bias of randomized controlled trials (RCTs), and the Newcastle-Ottawa scale for non-RCT studies.

RESULTS

Sixteen studies were included, with a total of 334 participants and a mean age of 58 years. The participants received a total of 581 dental implants, 475 conventional and 106 mini-implants. All included studies reported implant survival rate above 90% (range: 92% to 100%). Meta-analysis indicated a high proportion of implant survival rates of 3% (95% confidence interval [CI]: 2% to 5%) and a low mean raw score of marginal bone loss 0.98 mm (CI: 0.61 to 1.36 mm). Compared with conventional RPDs, improved patient quality of life and satisfaction were reported by studies that evaluated ISRPDs. RCT studies exhibited a low risk of bias for most domains, while most non-RCT studies were classified as good quality.

CONCLUSIONS

ISRPDs exhibited high implant survival rates and acceptable bone loss with improvement in the quality of life and satisfaction of patients when compared with conventional RPDs. Therefore, they can be considered suitable for the rehabilitation of partially edentulous patients.

Effect of the attachments on clinical outcomes of mandibular distal extension implant-supported removable partial dentures: A systematic review

STATEMENT OF PROBLEM

Healing abutments and attachments have been used for implant-supported removable partial dentures (ISRPDs). However, the effects of these abutments and attachments on the clinical outcomes of the implants and prostheses are elusive because of the lack of standardized research protocols.

PURPOSE

The purpose of this systematic review was to determine the clinical outcomes of mandibular distal extension ISRPDs with healing abutments and attachments by analyzing qualified studies.

MATERIAL AND METHODS

An electronic and manual literature search was conducted on PubMed, Web of Science, Scopus, Embase, and Cochrane Library databases including articles published in English from 1980 to 2020. Publications of clinical outcome studies on the mandibular distal extension ISRPDs with healing abutments or attachments were screened by inclusion and exclusion criteria. Clinical outcomes of removable partial dentures (RPDs) and ISRPDs with different types of abutments or attachments were compared by using patient-reported outcome measures, implant survival rate, masticatory performance, and implant- or prosthesis-related complications. Study designs and clinical outcome data were extracted and analyzed. The evidence of the selected studies and degree of recommendation were made according to the Oxford Centre for Evidence-based Medicine, and the risk of bias of the studies was assessed based on Newcastle-Ottawa criteria.

RESULTS

Of 541 articles initially identified after removing duplicate records, 11 articles were selected by applying the inclusion and exclusion criteria, by inter-viewer agreement, and by hand searching. Nine prospective cohort studies, 1 retrospective cohort study, and 1 randomized controlled trial were included with evidence levels assessed at 1b, 2b, and 2c. The risk of bias varied from 5 to 8 out of 9. Patient overall satisfaction, oral health-related quality of life (OHRQoL) scores, and masticatory ability were significantly improved for ISRPDs with either healing abutments, ball, or LOCATOR attachments when compared with RPDs. The implant survival rate varied from 92% to 97% at 2 to 10 years for ball attachment and was 100% at 1 year for LOCATOR attachment-supported ISRPDs. Marginal bone loss (MBL) varied from 0 to 1 mm in all studies, although LOCATOR attachments had significantly less MBL compared with ball attachments. The maximal pocket depth and bleeding on probing index around implants at 1 year were 1.7 to 1.8 mm and 0.1 to 0.3. Loose healing caps were the main mechanical complication of implants. There were more prosthetic complications in ISRPDs with ball attachments than RPDs at 10-year follow-up, including gold matrix loosening, loss of retention, and denture base fractures. No direct comparisons were made of patient-reported outcomes or prosthetic complications between ball and LOCATOR attachment-supported ISRPDs.

CONCLUSIONS

Healing abutments and attachments (ball or LOCATOR) improved patient-reported outcomes and the masticatory function of mandibular distal extension ISRPDs. However, insufficient evidence was found to determine the relative effectiveness of different attachment systems on the clinical outcomes of mandibular distal extension ISRPDs. Abutment loosening was the most frequent mechanical complication for healing abutments. More prosthetic complications were associated with ball attachment-supported ISRPDs than RPDs. The major weaknesses of this systematic review were the relatively moderate level of evidence and the publication language, since implant attachments are used in many non-English speaking countries.

Patient-reported outcomes of implant-assisted removable partial dentures with magnetic attachments using short implants: A prospective study

PURPOSE

Implant-assisted removable partial dentures (IARPDs) with short implants improve the oral functions of removable partial dentures (RPDs). This study aimed to compare the patient-reported outcomes of RPDs and IARPDs with short implants retained by magnetic attachments.

METHODS

We recruited 30 participants with mandibular Kennedy Class I or II and distal extension defects of three or more teeth. RPDs, IARPDs with a healing cap, and IARPDs with a magnetic attachment were evaluated across stages using patient-reported outcomes. All participants completed questionnaires (oral health-related quality of life [OHRQoL], patient general satisfaction, and patient's denture assessment [PDA]) at each stage. The OHRQoL was evaluated using the Oral Health Impact Profile-J 54 (OHIP-J 54) score. The general patient satisfaction was evaluated using a 100 mm visual analog scale. The Wilcoxon signed-rank test and Bonferroni correction were used to evaluate differences between the groups (α=0.05).

RESULTS

The OHRQoL of IARPDs was significantly higher than that of RPDs. IARPDs with a magnetic attachment had significantly better patient general satisfaction and PDA than IARPDs with a healing cap.

CONCLUSIONS

The OHRQoL, patient general satisfaction, and PDA were improved by IARPD with a short implant using a magnetic attachment.

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

Background

Implant-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.

Methods

A 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.

Results

Regardless 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.

Conclusion

Our 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.

Retrospective clinical evaluation of implant-assisted removable partial dentures combined with implant surveyed prostheses

STATEMENT OF PROBLEM

Implant-assisted removable partial dentures (IARPDs) have been proposed as a treatment option for partially edentulous patients. However, evidence regarding the outcome of implant-assisted removable partial dentures with implant surveyed prostheses is limited.

PURPOSE

The purpose of this retrospective clinical study was to evaluate the clinical status and complications of IARPDs combined with implant surveyed prostheses in terms of clinical tissue condition, marginal bone resorption, and prosthetic complications.

MATERIAL AND METHODS

Patients treated with IARPDs combined with implant surveyed prostheses who had worn an IARPD for at least 12 months were included. Twenty-four participants (25 prostheses, 12 maxillary, and 13 mandibular) were evaluated, with 80 implants used as abutments for IARPDs. The average follow-up period was 27.6 months, and the maximum follow-up was 78 months. Implant cumulative survival rate, marginal bone resorption, probing depth, peri-implant inflammation, bleeding, plaque, calculus, and complications were evaluated.

RESULTS

No implant failure occurred, and all implants functioned without clinical mobility. Mean marginal bone resorption of implants at 1 year after loading was 0.77 ±0.63 mm, and mean probing depth was 3.4 ±0.1 mm. No patient developed peri-implantitis, and no implant failed. Two clasp fractures, 1 rest fracture, 1 decementation, and 1 fracture of porcelain on an implant surveyed prosthesis were detected at 12 months after loading.

CONCLUSIONS

Well-planned IARPDs using implant surveyed prostheses were clinically successful. Longitudinal and systematic clinical studies are necessary to confirm these results.

Immediate versus delayed loading of strategic mini-implants under existing removable partial dentures: patient satisfaction in a multi-center randomized clinical trial

OBJECTIVE

The purpose of this study was to evaluate and compare the effects of the immediate and delayed loading of strategic mini-implants (MIs) on the satisfaction of patients with removable partial dentures (RPDs).

MATERIALS AND METHODS

In this multi-center randomized clinical trial, strategic MIs were inserted under 79 RPDs in 76 participants. Two questionnaires, one for the upper jaw and one for the lower jaw, were given before surgical intervention and 2 weeks, 4 months, 4.5 months, 1 year, 2 years, and 3 years after implant insertion. To estimate the loading effect (immediate vs. delayed) in terms of the odds ratio, an ordinal logistic regression model was used. The Wilcoxon matched-pairs signed-rank test, which was corrected for clusters in the patient population, was used to evaluate changes in patient satisfaction.

RESULTS

After 4 months, a statistically significant difference in favor of the immediate loading group was recognized in terms of the overall satisfaction score. The patient satisfaction scores recorded after 4.5 months and 1, 2, and 3 years showed substantial improvements compared with the scores recorded before implant insertion in both groups. At the item level, substantial improvements were noted in the following domains: general satisfaction, RPD retention, stability, support, eating, speaking, and aesthetics.

CONCLUSIONS

Strategic MIs improved the satisfaction of patients with RPDs during the medium-term follow-up period. An earlier improvement in the satisfaction of patients with RPDs was seen after immediate loading of the MIs as compared with delayed loading.

CLINICAL RELEVANCE

Inserting MIs under existing RPDs can improve patients' satisfaction with their RPDs in several domains.

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

Background

This 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 Methods

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%.

Results

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.

Conclusions

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.

Distal extension mandibular removable partial denture with implant support

This case report describes the fabrication of a distal extension removable partial denture (RPD) of a 65-year-old man with implant support. Loss of fibroelasticity of the peripheral tissues and reduced mandibular vestibular sulcular depth due to a previous surgical resection and radiotherapy at the right side were the main clinical factors that created difficulty for denture retention and stability. The fabrication of a mandibular RPD supported by anterior teeth and two bilaterally placed implants in the molar area to convert from Kennedy Class 1 design to Kennedy Class 3 implant-bounded RPD is reported. Retention and stability of the denture were improved with implant support on the distal extension site of the RPD. The common clinical problems about distally extended RPDs are lack of retention and stability due to the movement around the rotational axis. Dental implant placement to the distal edentulous site minimizes the potential dislodgement of the RPD is popular. Implant-supported RPD can be suggested as an advantageous and cost-effective treatment option for the partially edentulous patients.

Implant overdentures retained by self-aligning stud-type attachments: A clinical report

The functionality of a new overdenture attachment (LOCATOR R-Tx) was described for different clinical situations: a conventional mandibular implant overdenture (IOD) retained by 2 implants, a straightforward chairside maintenance procedure for replacing a worn LOCATOR (Legacy) attachment with the new LOCATOR R-Tx, and a complex clinical situation with nonideal implant positions with compromised parallelism. The LOCATOR R-Tx is an advance on the existing LOCATOR Legacy attachment and has an improved abutment head design with a more durable surface coating to prevent attachment wear and thereby reduce frequency of maintenance.

Revisiting the Removable Partial Denture

The partial edentulous population is increasing because of an increasing aging population, increased life expectancy, and individuals retaining more teeth at an older age. Therefore, the need for fixed and removable partial denture (RPD) therapy will remain high and will continue into the future. RPDs provide minimally invasive, cost-effective, timely care, and are preferred to fixed dental prostheses using teeth or implant therapy in many clinical scenarios. This article discusses RPD classification systems to review basic concepts and special framework design considerations, and explores advancements in the field such as implant-assisted RPD, CAD/CAM RPD, and new polymer framework materials.

A Novel Extended Range Attachment System to Retain Implant Overdentures: A Clinical Report

Various attachment systems have been used to facilitate the retention, stability, and support of overdentures. The low profile design, pivoting technology, and durability of the Locator attachment made it one of the commonly used tissue-supported implant-retained overdentures. It has been successfully used to retain overdentures as well as partial dentures. This article describes the uses of the new Locator R-Tx abutment and illustrates both the direct and indirect techniques used to process the denture attachment housing into the prosthesis to retain overdentures and partial dentures.

Evidence-based dentistry for planning restorative treatments: barriers and potential solutions

INTRODUCTION

Evidence-based dentistry (EBD) can help provide the best treatment option for every patient, however, its implementation in restorative dentistry is very limited.

OBJECTIVE

This study aimed at assessing the barriers preventing the implementation of EBD among dental undergraduate and graduate students in Montreal, and explore possible solutions to overcome these barriers.

MATERIALS AND METHODS

A cross-sectional survey was conducted by means of a paper format self-administrated questionnaire distributed among dental students. The survey assessed the barriers and potential solutions for implementation of an evidence-based practice.

RESULTS

Sixty-one students completed the questionnaire. Forty-one percent of respondents found evidence-based literature to be the most reliable source of information for restorative treatment planning, however, only 16% used it. They considered that finding reliable information was difficult and they sometimes encountered conflicting information when consulting different sources. Dental students had positive attitudes towards the need for better access to evidence-based literature to assist learning and decision making in restorative treatment planning and to improve treatment outcomes. Even for dentists trained in EBD, online searching takes too much time, and even though it can provide information of better quality than personal intuition, it might not be enough to identify the best available evidence.

CONCLUSIONS

Even though dental students are aware of the importance of EBD in restorative dentistry they rarely apply the concept, mainly due to time constraints. For this reason, implementation of EBD would probably require faster access to evidence-based knowledge.

Mandibular implant-retained overdenture relining procedure with an attachment system: A step-by-step demonstration of the technique

BACKGROUND AND OVERVIEW

Because of continuous alveolar bone resorption, implant-retained overdentures need to be relined. The purpose of this study was to describe a method for relining an implant-retained overdenture.

CASE DESCRIPTION

The authors present a step-by-step technique. A 65-year-old patient sought care for trauma and pain in the oral mucosa underneath his mandibular implant-retained overdenture. The overdenture had been fabricated 4 years previously. In addition, the patient mentioned the denture's lack of stability during function. On the basis of the patient's dental history, and clinical and radiographic examination results, the authors found alveolar bone resorption.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

In this case report, the authors describe the technique, analyze the procedure of implant-retained overdenture relining with a Locator attachment system (Locator abutment, H3, SP MB SZL03 for internal hex implants; MIS Seven), and describe how to restore the contact of the denture base with the denture-bearing tissues. The goal of this technique for the general dentist is to eliminate patients' tissue trauma and pain and increase the stability and support of the prosthesis.

Finite element analysis of implant-assisted removable partial dentures: Framework design considerations

STATEMENT OF PROBLEM

Connecting an acrylic resin base to both a metal framework and a rigidly fixed implant may affect the rotational displacement of the prosthesis during loading.

PURPOSE

The purpose of this finite element analysis study was to analyze the effect of connecting a denture base metal framework to an implant with the aim of decreasing the rotational movement of an implant-assisted removable partial denture.

MATERIAL AND METHODS

A mesial occlusal rest direct retainer and a distal occlusal rest direct retainer were modeled and adapted to incorporate a modified denture base metal framework in the connection area for each model. The stress and deformation patterns of the prosthesis structure were determined using finite element analysis and compared for both situations.

RESULTS

A maximum von Mises stress of 923 MPa was observed on the metal framework of the prosthesis with a mesial occlusal rest, and the maximum value was 1478 MPa for the distal occlusal rest. A maximum von Mises stress of 17 MPa occurred on the acrylic resin denture base for the mesial occlusal rest, and a maximum von Mises stress of 29 MPa occurred for the distal occlusal rest.

CONCLUSIONS

The distal occlusal rest direct retainer is stiffer than the mesial design and undergoes approximately 66% less deformation. The modified denture base framework with an I-bar and distal occlusal rest design provides more effective support to the acrylic resin structure.

Immediate versus delayed loading of strategic mini dental implants for the stabilization of partial removable dental prostheses: a patient cluster randomized, parallel-group 3-year trial

Background

Acceptable short-term survival rates (>90 %) of mini-implants (diameter < 3.0 mm) are only documented for mandibular overdentures. Sound data for mini-implants as strategic abutments for a better retention of partial removable dental prosthesis (PRDP) are not available.

Methods/design

The purpose of this study is to test the hypothesis that immediately loaded mini-implants show more bone loss and less success than strategic mini-implants with delayed loading. In this four-center (one university hospital, three dental practices in Germany), parallel-group, controlled clinical trial, which is cluster randomized on patient level, a total of 80 partially edentulous patients with unfavourable number and distribution of remaining abutment teeth in at least one jaw will receive supplementary min-implants to stabilize their PRDP. The mini-implant are either immediately loaded after implant placement (test group) or delayed after four months (control group). Follow-up of the patients will be performed for 36 months. The primary outcome is the radiographic bone level changes at implants. The secondary outcome is the implant success as a composite variable. Tertiary outcomes include clinical, subjective (quality of life, satisfaction, chewing ability) and dental or technical complications.

Discussion

Strategic implants under an existing PRDP are only documented for standard-diameter implants. Mini-implants could be a minimal invasive and low cost solution for this treatment modality.

Trial registration

The trial is registered at Deutsches Register Klinischer Studien (German register of clinical trials) under DRKS-ID: DRKS00007589 (www.germanctr.de) on January 13^th, 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s12903-016-0259-z) contains supplementary material, which is available to authorized users.

Implant-Supported Removable Partial Denture Improves the Quality of Life of Patients with Extreme Tooth Loss

Abstract: This study aimed to evaluate oral health-related quality of life (OHRQoL) in partially dentate subjects, presenting extreme tooth loss in posterior region with missing post-canines, comparing the use of conventional removable partial dentures (RPDs) and implant-supported RPDs. OHRQoL was measured using the Brazilian version of the Oral Health Impact Profile. Twelve subjects presenting maxillary total and mandibular Kennedy Class I edentulism (mean age 62.6±7.8 years) first received complete maxillary dentures and conventional mandibular free-end RPDs. After two months, the subjects had their OHRQoL assessed. Osseointegrated implants were inserted bilaterally in the mandibular first molar regions, and after four months ball abutments were placed to support the free-end RPD. Two months later, the patients had their OHRQoL reassessed. Wilcoxon signed-rank test was used to evaluate differences in OHRQoL (α=0.05). Results showed improvement in all OHIP-49 domains (p<0.05) after associating implants to the RPD. The mandibular implant-supported free-end RPD significantly improved OHRQoL.

Complications associated with implant-retained removable prostheses

Implant-supported removable prostheses improve patients' satisfaction with treatment and quality of life. Improvements in the implant's surface and in attachment elements have made this treatment method very successful. However, some biological and mechanical complications remain. Mechanical complications associated with implant-supported overdentures and implant-supported removable partial dentures are loss of retention of attachment systems, the need to replace retention elements and to reline or repair the resin portion of the denture, and implant fracture. Despite their success, implant-supported removable prostheses require periodic maintenance.

Mastication improvement after partial implant-supported prosthesis use

Partially edentulous patients may be rehabilitated by the placement of removable dental prostheses, implant-supported removable dental prostheses, or partial implant fixed dental prostheses. However, it is unclear the impact of each prosthesis type over the masticatory aspects, which represents the objective of this paired clinical trial. Twelve patients sequentially received and used each of these 3 prosthesis types for 2 months, after which maximum bite force was assessed by a strain sensor and food comminution index was determined with the sieving method. Masseter and temporal muscle thicknesses during rest and maximal clenching were also evaluated by ultrasonography. Each maxillary arch received a new complete denture that was used throughout the study. Data were analyzed by analysis of variance for repeated measures, followed by the Tukey test (p < .05). Maximum bite force and food comminution index increased (p < .0001) after implant-supported dental prosthesis and implant fixed dental prosthesis use, with the higher improvement found after the latter's use. Regardless of implant-retained prosthesis type, masseter muscle thickness during maximal clenching also increased (p < .05) after implant insertion. Partial implant-supported prostheses significantly improved masseter muscle thickness and mastication, and the magnitude of this effect was related to prosthesis type.