Implant-Retained Partial Overdenture with Resilient Attachments

Digital wear analysis and retention of poly-ether-ether-ketone retentive inserts versus conventional nylon inserts in locator retained mandibular overdentures: in-vitro study

OBJECTIVE

this study aimed to digitally compare wear behavior and retention between PEEK and nylon retentive inserts used in locator-retained, mandibular implant overdentures when attachment design and size were standardized.

MATERIALS AND METHODS

A total of sixty-four inserts (32 PEEK and 32 nylon inserts); were picked-up in implant overdentures. Overdentures of both groups were submerged in artificial saliva and mounted to chewing simulator. After 480,000 chewing cycles (equivalent to 2 years of clinical use) all inserts were scanned by scanning electron microscope (SEM), then all acquired images were digitally analyzed by software to detect and compare quantitative and qualitative changes of inserts in both groups. On the other hand, retention of both groups was measured by universal testing machine and the collected data was statistically analyzed using one-way Analysis of Variance (ANOVA) test with significance level set at P ≤ 0.05.

RESULTS

PEEK inserts showed significantly higher mean retentive values compared to the nylon inserts in the control group. Also, PEEK retentive inserts exhibited statistically lower mean wear values than the control group P ≥ 0.000. Qualitative investigation revealed significant and more pronounced changes in the surface roughness of nylon inserts compared to PEEK ones.

CONCLUSIONS

Regarding retention, wear behavior and dimension stability, PEEK can be recommended as retentive insert material in cases of locator-retained mandibular implant overdentures.

CLINICAL RELEVANCE

PEEK inserts offer enhanced retention, reduced wear, and greater dimensional stability over two years time interval. Clinically, this reduces prosthodontic maintenance and adjustments, improving patient satisfaction and long-term prosthetic success.

Patient-reported outcome measures and clinical performance of implant-retained mandibular overdentures with stud and ball attachments: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Evidence regarding the retention system for a mandibular overdenture is important for treatment planning. However, the clinical performance of stud and ball attachments for mandibular overdenture retainers is unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to compare the clinical performance and self-reported patient outcomes of ball and stud attachments as mandibular overdenture retainers.

MATERIAL AND METHODS

Randomized (RCTs) and nonrandomized (N-RCTs) controlled clinical trials were selected based on the eligibility criteria. The risk of bias was assessed by using the Cochrane Collaboration Tools, and the certainty of the evidence (COE) by using the grades of recommendation, assessment, development, and evaluation (GRADE) workshop approach. Meta-analyses according to the follow-up period were performed for implant survival, prosthetic maintenance and complications, bleeding on probing (BoP), marginal bone loss (MBL), satisfaction, and oral health-related quality of life (OHRQoL).

RESULTS

Thirteen RCTs and 4 N-RCTs were included. Twelve studies presented a high risk of bias. The stud demonstrated a lower risk ratio (RR) (P<.001) for maintenance and complications concerning the need for matrix activation (RR 7.12 [2.65, 19.15]) (very low COE) and new overdentures (RR 2.47 [1.02, 5.96]) (moderate COE), ranging from 1 to 5 years of follow-up. Mean difference (MD) for MBL after 1 (MD 0.40 [0.28, 0.52]; P<.001) and 5 years (MD 0.18 [0.16, 0.20]; P<.001) was higher for ball attachments than that for stud (very low COE) attachments. Stud attachments also improved satisfaction (P<.001) when compared with ball attachments (very low COE). Implant survival rate (high COE), BoP (very low COE), and OHRQoL (low COE) were similar for the attachments.

CONCLUSIONS

Stud and ball attachments are clinically appropriate options as mandibular overdenture retainers and are capable of restoring OHRQoL. Nevertheless, the stud showed greater improvement in satisfaction and less prosthetic aftercare and MBL.

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.

Prosthetic complications with mandibular bar-retained implant overdentures having distal attachments and metal frameworks: A 2- to 12-year retrospective analysis

STATEMENT OF PROBLEM

Long-term reports on 2-implant-retained overdentures having metal frameworks and bars containing distal attachments are scarce.

PURPOSE

The purpose of this retrospective study was to evaluate prosthetic complications with 2-implant-retained mandibular overdentures with metal frameworks having either screw- or cement-retained cantilevered bars with distal attachments.

MATERIAL AND METHODS

Seventy-three edentulous study participants who had been treated with mandibular overdentures with 2 implants were included. The parameters assessed were acrylic resin fractures (base fracture, fracture at midline), debonding of teeth, opposing prosthesis fracture, need for relining or rebasing, abutment and bar screw loosening and fracture, ball or bar attachment or clip wear, fracture or detachment, bar fracture, and implant loss. Statistical analysis was performed by using the Mann-Whitney U test as the data were not normally distributed. The categorical variables between the groups were analyzed by using the Fisher exact test (α=.05).

RESULTS

Twenty-seven prostheses had a cement-retained bar, and 46 bars were screw-retained. Of 73 overdentures, 68 were metal-reinforced. The mean observation time was 5.9 years with a range between 2 and 12 years. The most common complication was wear of the Rhein 83 polymer attachment followed by bar screw loosening. The cumulative survival rate for overdentures was 91.9% at 6.8 years. The service life of cement-retained prostheses was significantly longer (P<.05). Bar, resin base, and mid-line fractures were only seen with cement-retained prostheses. The number of times an attachment change was required did not differ between cement- and screw-retained bars. Of 191 implants, 3 were lost, and the cumulative survival rate was 93.5% at 7.5 years. No significant difference was found between retention types in terms of implant loss (P>.05).

CONCLUSIONS

Based on the participant population observed, the survival rates of 2-implant-retained mandibular overdentures and their implants in the medium term were high. Wear of the polymer attachment was commonly seen. Overdentures with cement-retained bars had bar or acrylic resin fractures. Mandibular 2-implant-retained overdentures with a screw-retained bar containing bilateral distal attachments had fewer prosthetic complications and high implant survival in the medium term.

Influence of Denture Cleansers on the Retention Loss of Attachment Systems Retained Implant Overdenture

Background

This study aimed to evaluate the effects of different denture cleansing solutions (DCSs) on the retention of Locator and Locator R-Tx attachment systems of implant retained overdentures (IRO).

Methods

Two part acrylic resin blocks were fabricated, upper part contained metal housing and plastic inserts and lower part contained implant analogs and abutments. Eighty pink plastic inserts (40/attachment, 10/solution) were immersed in Corega, Fittydent, sodium hypochlorite, and water for a time simulating upto 1-year of clinical usage. Acrylic blocks were held on a universal testing machine for a pull-out test to record the dislodgement force. Measurements were conducted after 6 months (T1) and 12 months (T2). One-way ANOVA followed by Tukey's HSD test was used to analyze the results (α = 0.05).

Results

For both attachments, retention significantly decreased after immersion in different solutions at T2 (P < 0.001). Locator R-Tx attachment in NaOCl showed a significant decrease in retention compared with other solutions at T1. At T2, there was a significant decrease in retention for all DCS compared with water (P < 0.001). Locator R-TX showed higher retention values per solution compared to Locator attachment (P < 0.001). In terms of retention loss %, NaOCl recorded the highest (61.87%) loss, followed by Corega (55.54%) and Fittydent (43.13%), whereas water demonstrated the best retention (16.13%) in both groups.

Conclusion

Locator R-TX has better retention with different DCS immersion. The loss of retention varied with different types of DCS and NaOCl recorded the highest retention loss. Therefore, denture cleanser selection must be guided by the type of IRO attachment.

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.

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.

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.

Survival rate and clinical evaluation of the implants in implant assisted removable partial dentures: surveyed crown and overdenture

PURPOSE

The purpose of this study was to investigate survival rates of the implants used in implant assisted removable partial dentures (IARPDs).

MATERIALS AND METHODS

The study was conducted on 21 patients who were treated with IARPDs. The mean follow-up period for IARPD patients ranged from 12 to 185 months (mean 47.9 months). A total of 58 implants were used for IARPDs in two different modalities: 41 for surveyed crowns and 17 for overdentures. The survival of implants was determined by clinical and radiographic evaluations considering relevant factors: location, RPD classification, opposing dentition, splinting, and implant diameter.

RESULTS

The survival rate of total 58 implants was 93.1%: 95.1% for implants supporting surveyed crowns and 88.2% for implants used in overdentures. Considering only the implants supporting surveyed crown, regular diameter implants showed a higher survival rate than narrow or wide diameter implants.

CONCLUSION

The survival rate of the implants used in IARPDs was 93.1% (surveyed crown: 95.1%, overdenture: 88.2%).

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.

Rehabilitation with Fixed Prosthodontics Associated with Removable Partial Prosthesis: A 5-Year Follow-Up Clinical Evaluation

Dental implants are a common and successful option for the rehabilitation of edentulous areas. However, there are some limitations to their use. The present clinical report describes a 5-year follow-up of maxillary rehabilitation using an attachment-retained removable partial denture (RPD) associated with fixed partial denture (FPD) units as an alternative to orthodontic treatment associated with orthognathic surgery and dental implant placement. Rehabilitation with fixed prosthodontics associated with a removable partial prosthesis was proposed. For greater precision and stability, a gold attachment was prepared. The patient was very satisfied with the rehabilitation and has been clinically followed for 5 years. In cases where the use of dental implants and/or conventional FPDs is limited or not indicate the association between an FPD and an RPD by means of attachments remains an important alternative to conventional clasp-retained RPDs.

Effect of LOCATOR attachments with different retentive forces on the stability of 2-implant-retained mandibular overdenture

STATEMENT OF PROBLEM

The LOCATOR system has been widely used for 2-implant-retained mandibular overdentures (2-MOs), but the influence of different LOCATOR attachments on the stability of 2-MOs has not been assessed.

PURPOSE

The purpose of this in vitro study was to investigate the stability of 2-MOs anchored by LOCATOR attachments with different retentive forces.

MATERIAL AND METHODS

An edentulous mandibular test cast with 2 bone-level implants inserted in the left and right mandibular canine regions was used. Twelve overdentures were then fabricated and anchored on the cast, following the instructions of the LOCATOR system. By replacing inserts of the 12 overdentures, the stability of 3 groups of LOCATOR inserts with different retentive forces was evaluated: blue group, pink group, and transparent group. With artificial saliva used on the cast and overdentures, vertical forces of 40 N, 55 N, and 100 N were loaded on the occlusal surface of the left incisor, left canine, and left molar, respectively. Under each loading condition, the vertical displacements at the loading point and the vertical and horizontal displacements of overdentures at the right distal edge were measured at the same time. One-way ANOVA and the post hoc Tukey honestly significant difference (HSD) test were used to compare the stability of 2-MOs with different LOCATOR attachments (α=.05 for all tests).

RESULTS

When a force of 40 N was applied to the incisor, the largest vertical movement of the incisor loading point appeared in the blue group (P<.05), and the displacements of the pink group showed significant difference from those of the transparent group (P>.05). When 55 N was loaded on the canine, the blue group showed the largest vertical displacements of both the loading point and the right distal edge of the overdentures (P<.05). No significant difference was found in the vertical displacements between the pink group and the transparent group (P>.05). When a force of 100 N was loaded on the molar point, the transparent group indicated a smaller movement in the vertical direction at the edge of the overdentures than the blue group (P<.05) or the pink group (P<.05).

CONCLUSIONS

LOCATOR attachments with different retentive forces had a significant effect on the denture stability of 2-MOs. Compared with the blue inserts, the pink and transparent inserts can offer greater stability for 2-MOs and could therefore be suggested for clinical situations.

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.

A Clinical Retrospective Study of Distal Extension Removable Partial Denture with Implant Surveyed Bridge or Stud Type Attachment

This study was performed to make comparative analysis of the clinical findings between the two different types of the implant-assisted removable partial dentures: removable partial dentures using implant surveyed bridge as an abutment (ISBRPD) and overdenture type of removable partial denture using implant attachment (IARPD). Implant cumulative survival rate, marginal bone resorption, probing depth, peri-implant inflammation, bleeding, plaque, calculus, and complications were evaluated on 24 patients who were treated with implants in conjunction with removable partial denture and have used them for at least 1 year (ISCRPD: n = 12; IARPD: n = 12). There was no failed implant and all implants were functioning without clinical mobility. Marginal bone loss of ISCRPD (1.44 ± 0.57 mm) was significantly lower than that of IARPD (p < 0.05). There was no significant difference in probing depth, peri-implant inflammation, bleeding, and plaque between the two groups (p > 0.05), while the calculus was significantly more observed in ISCRPD group than in IARPD group (p < 0.05). The retention loss of IARPD was the most common complication. Within the limits of the present study, it was found that well-planned ISBRPD was clinically appropriate. Longitudinal and systematic clinical studies are necessary to confirm these results.

Locator Versus Bar Attachment Effect on the Retention and Stability of Implant-Retained Maxillary Overdenture: An In Vitro Study

PURPOSE

To compare retention and stability of Locator and bar attachments for implant-retained maxillary overdentures.

MATERIALS AND METHODS

Four implants were inserted into a maxillary acrylic resin model in canines and second premolar areas. Experimental overdentures were connected to the implants with bar (group I) or Locator (group II) attachments. Locators were divided into 3 subgroups according the degree of retention of the patrix nylon insert: Locator blue (group IIa), Locator pink (group IIb), and Locator transparent (group IIc). Retention (vertical dislodging) and stability (lateral, anterior, posterior dislodging) forces (N) were measured at the start of the experiment (initial retention) and after 540 cycles of denture insertion and removal (final retention).

RESULTS

The highest initial and final stability was recorded with group IIc, followed by group IIb and group IIa, and the lowest retention and stability was noted with group I. For all groups, the highest final retention and stability forces were noted with vertical dislodging, followed by posterior dislodging, anterior dislodging, and lateral dislodging. The highest loss of retention and stability was recorded with group I, followed by group IIc, group IIb, and group IIa.

CONCLUSION

Locator attachments are recommended to retain maxillary overdentures over Dolder bar attachments, as Locator attachments were associated with high retention and stability after wear simulation with minimal retention loss.

Retentive Properties of O-Ring and Locator Attachments for Implant-Retained Maxillary Overdentures: An In Vitro Study

PURPOSE

To evaluate and compare retentive properties of O-ring and Locator attachments for implant-retained maxillary overdentures.

MATERIALS AND METHODS

Four implant analogs were inserted in canine and second premolar areas of an acrylic edentulous maxillary model. A metal-reinforced experimental acrylic overdenture was constructed and connected to the analogs using either O-ring (group I) or Locator (group II) attachments. Locators were divided into 3 subgroups according the degree of retention of the patrix nylon insert: Locator extra-light retention (group IIa), Locator light retention (group IIb), and Locator medium retention (group IIc). Vertical and oblique (lateral, anterior, and posterior) dislodging forces were measured at the beginning of the study (initial retention) and after 540 cycles of denture insertion and removal (final retention).

RESULTS

For vertical, lateral, and anterior dislodging, group IIc recorded the highest initial and final retention, and group I recorded the lowest retention. For posterior dislodging, group I recorded the highest retention, and group IIa recorded the lowest retention. For group II, vertical dislodging recorded the highest initial and final retention, and lateral dislodging recorded the lowest retention. For group I, posterior dislodging recorded the highest initial and final retention, and lateral dislodging recorded the lowest retention. For all dislodging forces (except posterior dislodging), the highest retention loss was recorded in group I, and the lowest retention loss was recorded in group IIa.

CONCLUSION

Locator medium attachment was associated with favorable retention during axial (vertical) and nonaxial (anterior and lateral) dislodging compared to other types of Locator inserts and O-ring attachments after a simulated 6-month period of overdenture use.

Strains around distally inclined implants retaining mandibular overdentures with Locator attachments: an in vitro study

PURPOSE

The aim of the present study was to evaluate, by means of strain gauge analysis, the effect of different implant angulations on strains around two implants retaining mandibular overdenture with Locator attachments.

MATERIALS AND METHODS

Four duplicate mandibular acrylic models were constructed. Two implants were inserted in the canine regions using the following degrees of distal inclinations: group I (control); 0°, group II; 10°, group III; 20°, and group IV; 30°. Locator pink attachments were used to connect the overdenture to the implants and Locator red (designed for severely angled implants) was used for group IV (group IV_red). For each group, two linear strain gauges were attached at the mesial and distal surfaces of the acrylic resin around each implant. Peri-implant strain was measured on loading and non-loading sides during bilateral and unilateral loading.

RESULTS

For all groups, the mesial surfaces of the implants at loading and non-loading sides experienced compressive (negative) strains, while the distal implant surfaces showed tensile (positive) strains. Group IV showed the highest strain, followed by group III, group II. Both group I and group IV_red showed the lowest strain. The strain gauges at the mesial surface of the loading side recorded the highest strain, and the distal surface at non-loading side showed the lowest strain. Unilateral loading recorded significantly higher strain than bilateral loading.

CONCLUSION

Peri-implant strains around two implants used to retain mandibular overdentures with Locator attachments increase as distal implant inclination increases, except when red nylon inserts were used.

Locators versus magnetic attachment effect on peri-implant tissue health of immediate loaded two implants retaining a mandibular overdenture: a 1-year randomised trial

This study aimed to evaluate peri-implant tissue health of immediate loaded two implants retaining a mandibular overdenture with either magnetic or locator attachment. Thirty two completely edentulous patients (20 males/12 females) were randomly assigned into two groups. Each patient received two implants in the canine area of the mandible using flapless surgical technique. Mandibular overdentures were immediately connected to the implants with either magnetic (group I, GI) or locator (group II, GII) attachments. Peri-implant tissue health was evaluated clinically in terms of plaque scores (PI), bleeding scores (BI), probing depth (PD), implant stability (ISQ) and interleukin-1-β (IL-1b) concentrations in peri-implant sulcular fluid. PI, BI and PD were measured at mesial, distal, buccal and lingual surfaces of each implant. Radiographic evaluation was performed in terms of vertical (VBL) and horizontal (HBLO) alveolar bone loss. Evaluations were performed 2 weeks (T0), 6 months (T1) and 12 months (T2) after overdenture insertion. Plague scores, PD, IL-1b, VBL and HBLO increased significantly with time. ISQ decreased significantly with time. BI showed no significant differences between observation times. GI recorded significant higher PI, ISQ and IL-1b at T2 compared to GII. GII recorded significant higher VBL than GI at T2 only. For HBLO, no significant differences between groups were noted. VBL and HBLO showed a significant positive correlation with PD. Locator attachments for immediate loaded implants retaining mandibular overdentures are associated with decreased plaque accumulation, decreased implant stability, decreased interleukin-1β concentration in peri-implant crevicular fluid and increased per-implant vertical bone loss compared to magnetic attachments after 1 year.

A finite element study on stress distribution of two different attachment designs under implant supported overdenture

OBJECTIVE

This study aimed to evaluate stress patterns generated within implant-supported mandibular overdentures retained by two different attachment types: ball and socket and locator attachments.

MATERIALS AND METHODS

Commercial CAD/CAM and finite element analysis software packages were utilized to construct two 3D finite element models for the two attachment types. Unilateral masticatory compressive loads of 50, 100, and 150 N were applied vertically to the overdentures, parallel to the longitudinal axes of the implants. Loads were directed toward the central fossa in the molar region of each overdenture, that linear static analysis was carried out to find the generated stresses and deformation on each part of the studied model.

RESULTS

According to FEA results the ball attachment neck is highly stressed in comparison to the locator one. On the other hand mucosa and cortical bone received less stresses under ball and socket attachment.

CONCLUSIONS

Locator and ball and socket attachments induce equivalent stresses on bone surrounding implants. Locator attachment performance was superior to that of the ball and socket attachment in the implants, nylon caps, and overdenture. Locator attachments are highly recommended and can increase the interval between successive maintenance sessions.

A Technique to Evaluate the Space for Retentive Components under a Removable Prosthesis

Space analysis for retentive components is a critical part of a treatment plan for an implant-retained prosthesis. This article describes a technique to evaluate the retentive component space between the mucosa and intaglio surface of a removable prosthesis. This technique uses a silicone mold to represent the relieved space. Two silicone matrices are fabricated over the silicone space replica as a reference for selecting or fabricating retentive components for the implant-retained removable prosthesis.

The influence of saliva pH value on the retention and durability of bar-clip attachments

PURPOSE

The aim of this study was to compare the durability and retention of 4 types of attachments placed over computer aided design/computer aided manufacturing (CAD/CAM) titanium bars when subjected to different pH conditions.

MATERIALS AND METHODS

Four commercially available attachments were investigated: Hader Yellow, Hader Red, Ackerman Gold and Ackerman Stainless Steel. These attachments and Ackerman CAD/CAM titanium bars were placed in 2 vessels containing different artificial saliva solutions (pH 7/pH 4) at 37℃ for one month to simulate corrosion conditions, and they were then subjected to mechanical testing (5400 cycles of insertion and removal).

RESULTS

The results revealed that there were significant differences in the average values of insertion/removal force due to the pH (F (1, 24)=9.207, P<.05) and the type of attachment (F (3, 24)=11.742, P<.05).

CONCLUSION

More acidic pH values were found to have a negative influence on the retention capacity of the attachments.

A unique method of retention for gum stripper- a case report

Successful restoration of partially edentulous situations, especially kennedy's class-I, II &IV requires lot of contemporary and conventional treatment approaches. Semi precision attachments play a major role in retention of clinically challenging partially edentulous situation. Attachment retained partial dentures can be one of the successful treatment option in prosthdontics. This article presents a unique technique of retaining gum stripper using semi precision attachments.

Clinical and radiographic evaluation of narrow-diameter titanium-zirconium implants in unilateral atrophic mandibular distal extensions: a 1-year pilot study

BACKGROUND

The use of endosseous dental implants has led to more sophisticated fxed options when considering treatment of patients with distal extensions. The use of narrow-diameter implants may reduce the necessity for bone augmentation. The mechanical strength of titanium is limited, so titanium alloys with greater tensile and fatigue strength may be preferable.

PURPOSE

The purpose of this study was to evaluate clinically and radiographically the performance of narrow-diameter bone level implants made from titanium-zirconium alloy (TiZr, Roxolid(TM)) in restoring unilateral atrophic mandibular distal extensions with fxed dental prostheses.

MATERIALS AND METHODS

Twenty partially edentulous patients with unilateral atrophic mandibular distal extensions received two 3.3 mm diameter bone level TiZr implants (Straumann AG, Basel, Switzerland). The two implants were restored with 3-units ceramo-metal fxed partial dentures. Standardized clinical and radiographic parameters (survival rate, probing pocket depth and marginal bone loss) were evaluated at the time of the completion of the prosthetic treatment (baseline) and after 3, 6 and 12 months of functional loading. Prosthetic complications were also assessed.

RESULTS

The survival rate for narrow-diameter bone level TiZr implants was 100% after 1 year of functional loading. There were no statistically significant differences between the values of probing pocket depth over the follow-up period. All implants showed less than 1 mm of marginal bone loss at the end of the follow-up period.

CONCLUSION

Within the limitations of this 1-year pilot study, the use of narrow-diameter bone level TiZr implants appears to be predictable in restoring the unilateral atrophic mandibular distal extensions. This type of implants meets established success and survival criteria after 1 year.

Influence of matrix attachment installation load on movement and resultant forces in implant overdentures

PURPOSE

This in vitro study investigated the effect of attachment installation conditions on the load transfer and denture movements of implant overdentures, and aims to clarify the differences among the three types of attachments, namely ball, Locator, and magnet attachments.

MATERIALS AND METHODS

Three types of attachments, namely ball, Locator, and magnetic attachments were used. An acrylic resin mandibular edentulous model with two implants placed in the bilateral canine regions and removable overdenture were prepared. The two implants and bilateral molar ridges were connected to three-axis load-cell transducers, and a universal testing machine was used to apply a 50 N vertical force to each site of the occlusal table in the first molar region. The denture movement was measured using a G(2) motion sensor. Three installation conditions, namely, the application of 0, 50, and 100 N loads were used to install each attachment on the denture base. The load transfer and denture movement were then evaluated.

RESULTS

The resultant force decreased with increasing installation load for all attachments. In particular, the resultant force on implants on the loading side of the Locator attachment significantly decreased when the installation load was increased from 0 to 50 N, and that for magnetic attachment significantly decreased when the installation load was increased from 50 to 100 N. For the residual ridges on the loading side, the direction of the forces for all attachments changed to downward with increasing installation load. Furthermore, the yaw Euler angle increased with increasing installation load for the magnetic attachment.

CONCLUSIONS

Subject to the limitations of this study, the use of any installation load greater than 0 N is recommended for the installation of ball and Locator attachments on a denture base. Regarding magnetic attachments, our results also recommend installation on a denture base using any installation load greater than 0 N, and suggest that the resultant force acting on the implant can be decreased by increasing the installation load; however, a large installation load of 100 N should be avoided when installing the attachment on the denture base to avoid increasing the denture movement.

Removable partial denture supported by implants with prefabricated telescopic abutments - a case report

Implants have been designed to rehabilitate edentulous patients with fixed prosthesis or implant supported overdentures. Implant-supported single crowns and fixed partial dentures have become successful treatment alternatives to removable and fixed partial dentures. However, it is common to have clinical situations which make it impossible to use conventional as well as implant supported fixed partial dentures. The implant supported removable partial dentures can be a treatment modality that offers the multitude of benefits of implant-based therapy-biologic, biomechanical, social, and psychological to such patients. The aim of this article is to present a case report describing the fabrication and advantages of removable partial denture supported by teeth and implants for a patient with long edentulous span. The patient was satisfied with his dentures in terms of function and aesthetics. Regular follow-up visits over a period of three years revealed that the periodontal condition of remaining natural dentition and peri-implant conditions were stable. There was no evidence of excessive residual ridge resorption or mobility of the teeth, nor were any visible changes in the bone levels of the natural teeth or implants noted on radiographs.

Marginal bone resorption around immediate and delayed loaded implants supporting a locator-retained mandibular overdenture. A 1-year randomised controlled trial

The aim of this 1-year study was to evaluate and compare crestal bone loss and clinical outcomes of immediate and delayed loaded implants supporting mandibular overdentures with Locator attachments. In a randomised controlled clinical trial, 36 completely edentulous patients (mean age 59.6 years) who desired to improve the stability of their mandibular dentures were randomly assigned into two groups. Each patient received two implants in the canine area of the mandible after a minimal flap reflection. Implants were loaded by mandibular overdentures either 3 months (delayed loading group, G1) or the same day (immediate loading group, G2) after implant placement. Locator attachments were used to retain all overdentures to the implants. Peri-implant vertical (VBL) and horizontal (HBLO) bone losses and clinical parameters [plaque scores (PI), gingival scores (GI), probing depths (PD) and implant stability (ISQ)] were assessed at time of overdenture insertion (T0), 6 months (T6) and 12 months (T12) after overdenture insertion. After 12 months of overdenture insertion, two implants (5.5%) failed in G2. Vertical bone loss was significantly higher in G2 compared with G1, while HBLO demonstrated insignificant differences between groups. All clinical parameters (PI, GI, PD and ISQ) did not differ significantly between groups. Vertical bone loss was significantly correlated with PD and HBLO. Immediately loaded two implants supporting a Locator-retained mandibular overdenture are associated with more vertical bone resorption when compared to delayed loaded implants after 1 year. Clinical outcomes do not differ significantly between loading protocols.

Precision attachments for aesthetics and function: a case report

Successful restoration of the dentition requires plenty of contemporary and conventional treatment techniques and planning and attachment retained partial dentures are one such kind of treatment modality in prosthodontics. Limited space for extracoronal attachments is a serious gap in the design and the fabrication of a precision attachment Removable Partial Denture (RPD). A custom semi-precision attachment with a partial denture offers strength and improved aesthetics in cases with minimal space. This article presents a method of fabrication of semi-precision attachment to eliminate metal display and enhance aestheticity.

Removable dental prosthesis splint. An occlusal device for nocturnal bruxing partial denture users

Nocturnal bruxing is a parafunctional activity of the masticatory system that may create problems for removable dental prosthesis (RDP) users. Such problems may include root fractures, increased mobility of abutment teeth, excessive wear of resin denture teeth, minor connector bending, or denture base cracking. This clinical report presents an occlusal device fabricated for an RDP patient. The device used existing ERA attachments for added retention designed with the intended purpose of protecting the definitive fixed and RDP from damage due to nocturnal bruxing activity and providing for even distribution of parafunctional forces.

Maxillary rehabilitation using fixed and removable partial dentures with attachments: a clinical report

Despite requiring dental crown preparation and possible root canal treatment, besides the difficulty of clinical and laboratory repairs, and financial burden, the association between fixed (FPD) and removable partial dentures (RPD) by means of attachments is an important alternative for oral rehabilitation, particularly when the use of dental implants and FPDs is limited or not indicated. Among the advantages of attachment-retained RPDs are the improvements in esthetics and biomechanics, as well as correction of the buccal arrangement of anterior teeth in Kennedy Class III partially edentulous arches. This article describes the treatment sequence and technique for the use of attachments in therapy combining FPD/RPD.

Two versus three narrow-diameter implants with locator attachments supporting mandibular overdentures: a two-year prospective study

Purpose. To compare treatment outcome (survival rate, condition of hard and soft peri-implant tissues) and prosthodontic maintenance requirements of two versus three narrow-diameter bone level implants with Locator attachments supporting mandibular overdentures. Materials and Methods. Twenty completely edentulous patients with atrophic mandibles were treated. Ten patients (Group A) were treated with overdentures supported by two narrow (3.3-mm diameter) implants (Straumann AG, Basel, Switzerland) and ten patients (Group B) were treated with overdentures supported by three narrow implants. Locator (Zest Anchors, USA) attachments were used for prosthetic anchorage. Standardized clinical and radiographic parameters (survival rate, plaque index, calculus index, gingival index, bleeding index, probing depth and marginal bone loss) were evaluated at the time of the completion of the prosthetic treatment (baseline) and after 6, 12 and 24 months of functional loading. Prosthodontic maintenance requirements were also scored. Results. Only one implant was lost (Group B) during the healing period. There were no significant differences with regards to any of the studied clinical and radiographic parameters between the two groups (P > 0.05). Few prosthetic complications were recorded. Conclusions. No need to insert more than two narrow-diameter bone level implants with Locator attachments in cases of atrophic mandible to support an overdenture, however, long-term prospective studies are required to support this notion.

Effects of rigid and nonrigid extracoronal attachments on supporting tissues in extension base partial removable dental prostheses: a nonlinear finite element study

STATEMENT OF PROBLEM

Resilient (nonrigid) and non-resilient (rigid) attachments are used in extension base partial removable dental prostheses for retention. However, the biomechanical effects of these 2 types of retainers on the terminal abutment and supporting tissues, which may influence clinical treatment planning, have not been compared.

PURPOSE

The purpose of this study was to compare the mechanical effects of 2 types of extracoronal attachments (rigid and nonrigid) in distal extension removable partial prostheses on the alveolar ridge and abutment tooth periodontal ligament.

MATERIAL AND METHODS

A finite element model of a human left mandible edentulous arch distal to the second premolar was fabricated. The second premolar was the terminal abutment for an attachment-retained denture. Two types of attachments (rigid and nonrigid) were modeled in the study. For the nonrigid attachment, there was movement between the patrix and matrix component of the attachment, but there was no movement between the 2 component parts for the rigid attachment. Six levels of loading (100, 150, 200, 250, 300, and 350 N) were applied from 3 directions (axial, buccolingual, and mesiodistal) on the central fossa of the first and second molars. Denture motion and stress distributions of denture supporting tissues were observed. Maximum equivalent stress values (SEQV) were recorded for 6 regions (cervical bone, cervical and apical periodontal ligaments, mesial and distal ridges, and mucosa). The data were divided into 2 groups according to the attachment type. Paired t tests were used to compare the values of the 2 groups. Factorial ANOVA was used to test the difference between the loading directions (α=.05). Multiple linear regression was used to analyze the interactions among the factors of region, direction, and level (α=.05).

RESULTS

Stress distributions in the rigid and nonrigid attachment models were similar but the magnitudes were different. For all 3 loading directions, significantly different stresses in the alveolar ridge and periodontal tissue of the terminal abutment were found between the rigid and nonrigid groups (P<.05). There were significant differences among the 3 loading directions (P<.05). In the nonrigid group, the stress ratio of the mesial to the distal area was higher than that of the rigid group from axial and mesiodistal loading (P<.05). Linear interactions were found between the direction and level and region and level combinations (P<.05). Movement between the patrix and matrix components increased as loading increased. The most obvious movement of attachment occurred when loading was in the buccolingual direction.

CONCLUSIONS

Stress on the terminal abutment can be reduced by the use of an extracoronal resilient attachment that allocates more loads onto the distal edentulous ridge. The level of loading influenced the extent of reduction. A resilient attachment with a universal hinge had the most movement when loading was in the buccolingual direction. Interactions were found between direction and level, as well as region and level combinations (P<.05).