Expansion of Mandibular Knife-Edge Ridge and Simultaneous Implant Placement to Retain Overdentures: One-Year Clinical and Radiographic Results of a Prospective Study

Marginal bone loss and soft tissue health around two-implant mandibular overdenture retained with milled versus selective laser melted cobalt chromium bar: a randomized clinical trial

BACKGROUND

To assess marginal bone loss and soft tissue health around two-implant mandibular overdenture retained with milled versus selective laser-melted cobalt chromium (Co-Cr) bars.

METHOD

This research was set to be a parallel, triple-blinded, randomised controlled trial. Twenty completely edentulous patients received new conventional complete dentures according to conventional techniques. Two implants were placed at mandibular canine areas bilaterally, and patients were randomly allocated into two equal groups: the milled Co-Cr bar group and the selective laser melted (SLM) Co-Cr bar group. Marginal bone loss (MBL), modified plaque index (mPI), modified gingival index (mGI), and probing depth (PD) were evaluated at 0-month (baseline), 6-month, and 12-month follow-up visits. Repeated measures ANOVA test and Bonferroni's post-hoc test were used for parametric data as PD, while for non-parametric data as MBL, mGI, and mPI, Mann-Whitney U test and Friedman's test were used. A P-value ≤ 0.05 was set as the statistical level of significance. The study protocol was approved by the Faculty Research Ethics Committee at Minia University (636 4/10/2022). Registration for the clinical trial was made retrospectively on clinicaltrials.gov with ID NCT06401200 at 04/30/2024.

RESULTS

The follow-up period (one year) was completed without a dropout. Regarding MBL, no statistically significant difference was found between the two groups throughout the study. However, the milled group showed significantly increased MBL from 0- to 6-month follow up period. In both groups, mPI increased significantly from 0- to 6-months post-loading. On the other hand, no statistically significant difference between the two groups was found regarding mPI and mGI throughout the study follow-up periods. The PD was significantly lower in the milled compared to the SLM group at the 6- and 12-month follow up period.

CONCLUSION

Two-implant mandibular overdenture retained with milled or SLM Co-Cr bar can provide an acceptable treatment option for completely edentulous patients regarding marginal bone loss and soft tissue outcomes.

Efficacy of laser biostimulation for mandibular narrow ridges treated with one-stage ridge splitting and two-implant overdentures: A one-year preliminary study

STATEMENT OF PROBLEM

The management of patients with narrow-mandibular ridges who seek prosthetic rehabilitation is challenging.

PURPOSE

The purpose of this one-year preliminary clinical study was to compare the effects of laser biostimulation and a placebo on peri-implant tissues for a 2-implant-retained mandibular polyetheretherketone (PEEK) overdenture on expanded narrow mandibular ridges.

MATERIAL AND METHODS

Eighteen completely edentulous participants were enrolled for mandibular ridge splitting in the canine regions, followed by expansion, the placement of implants, and the application of a bone graft. In the test group, laser therapy was applied labially and lingually at the surgical sites, while a placebo laser was used in the control group. PEEK overdentures retained by LOCATOR attachments were provided after 6 months. Clinical evaluations were performed using probing depth, plaque, bleeding, and gingival indices at insertion and 3, 6, and 12 months after insertion. Vertical bone loss (VBL) was evaluated with periapical radiograph at insertion and 6 and 12 months later. The Mann-Whitney test was used to test the difference between the 2 different groups at each evaluation time (α=.05). The Friedman-test was used, followed by Wilcoxon signed rank test, to test the change over time in the same group, and the Bonferroni adjusted significance level was used for multiple comparisons.

RESULTS

Some clinical and radiographic parameters significantly increased with time in both groups (P<.001). Significant differences between the 2 groups were revealed in bleeding scores at 3 months (P=.006) and 6 months (P=.018). Also, significant differences between the 2 groups were observed in gingival scores at 3 months (P=.002), 6 months (P=.015), and 12 months (P=.019) after overdenture insertion in favor of the laser group. Peri-implant VBL was significantly higher in the non-laser group at 6 months (P=.015), and 12 months (P=.001).

CONCLUSIONS

Within the limitations of this clinical study, respecting the small sample size and the short follow-up period, laser bio-stimulation after 1-stage ridge splitting in narrow mandibular ridges enhanced the soft and hard peri implant tissues when used with LOCATOR attachments and PEEK overdentures.

Effect of Ridge Splitting of Mandibular Knife Edge Ridges with Two-implant Retained Overdenture with Locator Attachments on Peri-implant Bone Level and Posterior Ridge Resorption: A One-year Preliminary Study

AIM

This study was conducted to evaluate peri-implant bone height changes and posterior ridge resorption by using two-implant retained polyetheretherketone (PEEK) overdentures with locator attachments following expansion of mandibular knife edge ridges by ridge splitting.

MATERIALS AND METHODS

Eighteen patients were selected for ridge splitting followed by expansion, implant placement, and bone graft application. Six months later, the fabrication of PEEK overdentures retained by locator attachments was accomplished. Friedman test, Wilcoxon signed-rank test, and Spearman correlation were used to evaluate the changes over time.

RESULTS

Peri-implant bone height loss increased significantly with the advance of time between 6 and 12 months following denture insertion. Posterior area index changes were significant over time when measured at the time of denture insertion and twelve months following denture insertion.

CONCLUSION

The effect of using PEEK as overdenture base material retained with two locator attachments allowed sharing the load between the peri-implant bone anteriorly and residual ridge posteriorly in cases with ridge splitting technique.

CLINICAL SIGNIFICANCE

Using PEEK as an overdenture base material is a successful means of bone preservation. How to cite this article: Helmy MA, El-Shaheed NH, El Waseef FA, et al. Effect of Ridge Splitting of Mandibular Knife Edge Ridges with Two-implant Retained Overdenture with Locator Attachments on Peri-implant Bone Level and Posterior Ridge Resorption: A One-year Preliminary Study. J Contemp Dent Pract 2023;24(11):834-839.

Evaluation of immediately loaded mandibular four vertical versus tilted posterior implants supporting fixed detachable restorations without versus with posterior cantilevers

BACKGROUND

Distally inclining posterior implants may be technically challenging in certain situations. The presence of a posterior cantilever can also exert unfavorable forces on supporting implants. The aim of the present study was to evaluate and compare peri-implant soft and hard tissues around 4 mandibular interforaminal implants having tilted posterior implants with posterior cantilevers, versus vertical implants, 2 in the interforaminal region and 2 in the first molar regions, without posterior cantilevers. All implants supported full-arch fixed detachable restorations opposing complete dentures.

MATERIAL AND METHODS

A total of 80 implants were placed flapless in the mandibles of 20 edentulous participants. Four implants were placed for every participant, who were randomly assigned into 2 equal groups. Axial group implants were vertically aligned, with 2 implants in the interforaminal area and 2 in the molar area. Tilted group implants have 2 anterior axial and 2 posterior distally inclined implants. Interim screw-retained prostheses converted from pre-existing dentures were immediately fabricated and loaded on the same day of surgery. After awaiting period of 3 months, all participants received fixed detachable metal acrylic resin definitive restorations. A follow-up protocol of 3, 6, and 12 months was scheduled to assess the modified gingival index, modified plaque index, peri-implant probing depth, implant stability, and marginal bone level and bone density changes.

RESULTS

No statistically significant differences (P > .05) were found in the modified gingival index, modified plaque index, peri-implant probing depth, implant stability, bone density, and marginal bone level between the axial and tilted implant groups after the 1-year follow-up period.

CONCLUSION

Placing 4 flapless immediately loaded implants in mandibular edentulous patients that supported full-arch fixed restorations provided high implant and prosthodontic success rates whether posterior implants were tilted with posterior cantilevers or vertically aligned without posterior cantilevers.

TRIAL REGISTRATION

Pan African Clinical Trial Registry database, PACTR201907776166846. Registered 3 July 2019, www.pactr.org .

Effect of mandibular residual ridge regularization on peri-implant wound healing when narrow diameter implants are used as overdenture retainers

STATEMENT OF PROBLEM

Alveolar ridge regularization involves the smoothing and minimal reduction of rough alveolar bone ridge to achieve adequate bone thickness around the implant. The effect of this procedure on peri-implant health is unclear.

PURPOSE

The purpose of this clinical study was to evaluate whether bone regularization affects the clinical and biological parameters of peri-implant health when narrow diameter implants are placed as mandibular implant overdenture retainers during initial healing and after occlusal loading.

MATERIAL AND METHODS

The need for mandibular ridge regularization in the anterior mandibular region was analyzed before the placement of 2 implants (2.9×10 mm, Facility; Neodent) in 21 participants provided with mandibular overdentures. Primary stability was measured by the insertion torque and implant stability quotient (ISQ). Clinical and biological evaluations measuring the plaque index, presence of calculus, probing depth, bleeding on probing index, gingival index, secondary stability (ISQ), and interleukine-1β (IL-1β) and tumor necrosis factor-α (TNF-α) concentrations in peri-implant crevicular fluid were measured during osseointegration on days 7, 15, 30, 60, and 90 and after loading on day 180 after implant placement. Multilevel mixed-effects linear regression analysis and the Kaplan-Meier test were used to analyze the data (α=.05).

RESULTS

The ISQ values showed significant differences on days 7 (P<.001) and 15 (P=.002) with higher values and on day 180 (P=.008) with a lower value compared with the baseline value in the ridge regularization group. Additionally, a significant decrease in probing depth was observed on days 60 (P=.008) and 180 (P=.027) compared with that on day 15 after implant placement. In the nonridge regularization group, significant decreases in probing depth were observed on days 30 and 180. Moreover, TNF-α levels in this group were significantly lower on days 30 (P=.001), 60, 90, and 180 (P<.001) when compared with the value on day 7 (P<.001). The ridge regularization group presented with significant differences in TNF-α and IL-1β levels on days 60 (P=.004) and 30 (P=.007), respectively, when compared with the values on day 7. The ISQ and probing depth in the ridge regularization group were associated with changes in TNF-α and IL-1β levels; furthermore, bone type, duration of edentulism, and mandibular bone atrophy were correlated with the clinical outcomes and TNF-α release. The implant survival rate was 67% in the nonridge regularization group and 100% in the ridge regularization group.

CONCLUSIONS

Mandibular ridge regularization appeared to be beneficial for peri-implant healing during the early stages and after 3 months of occlusal loading in patients with an atrophic ridge, prolonged time since edentulism, and poor bone quality.

Effect of Low-Level Laser Irradiation on Stability and Marginal Bone of Narrow Implants Retaining Overdentures in Moderately Controlled Diabetic Patients

The researchers investigated the influence of low-level laser irradiation (LLLI) on implant stability and marginal bone of small-diameter implants retaining mandibular overdentures in patients with moderately controlled diabetes. Twenty patients (mean age = 59.32 ± 4.1 years) with moderately controlled diabetes mellitus (glycated hemoglobin A1c [HbA1c] = 8.1%-10.0 %) were rehabilitated by maxillary and mandibular conventional dentures. Two small-diameter implants (3 × 12 mm) were inserted in the canine areas of the mandible and immediately loaded by mandibular dentures. In a split-mouth design, LLLI was applied to 1 of the 2 implants in a random order (study group [SG]); the other implant was left as a control (control group [CG]). For each patient, gallium aluminum-arsenide diode low-level laser (940-nm wavelength, 0.50 ± 2 mW output power, 0.004 cm² spot size; Epic, Biolase, Inc, San Clemente, Calif) was applied around each implant with total delivered energy of 90 J (equally divided by 6 irradiation points) in 3 sessions. The application was done immediately after implant insertion, 3 days and 1 week after surgery. Implant stability (measured by Periotest) and marginal bone loss (MBL; measured by cone beam computerized tomography) were evaluated at implant loading (T1), 6 months (T6), and 12 months (T12). One implant failed in the CG and no failures occurred in the SG, resulting in 95% and 100% survival rates, respectively. The SG recorded higher Periotest values than the CG at all observation times. However, the difference was significant (P = .039) at T6 only. The SG recorded lower MBL values than the CG. No difference in MBL was detected between groups or peri-implant sites (mesial, distal, buccal, and lingual) at T6 and T12. Within the limits of this study, LLLI had no effect on marginal bone around immediately loaded small-diameter implants retaining overdentures in patients with moderately controlled diabetes. However, it was beneficial in improving implant stability 6 months after overdenture insertion.

One-year clinical outcomes of locking taper Equator attachments retaining mandibular overdentures to narrow diameter implants

BACKGROUND

Narrow diameter implants (NDI) are recommended to retain mandibular overdentures (MOs) in cases of limited bone thickness. It is necessary to evaluate the clinical behavior of NDI as MO retainers connected to a new screwless locking taper abutments, their predictability and maintenance problems.

OBJECTIVES

To evaluate the peri-implant tissue behavior around NDI and the performance of locking taper stud abutments as MO retainers.

METHODOLOGY

Thirty patients (average age of 67.5 years) received 2 NDI implants (2.9 × 10 mm) loaded after 12 weeks using Equator stud attachments. The plaque index (PI), calculus index (CI), gingival index (GI), probing depth (PD), bleeding on probing (BOP), and implant stability quotient (ISQ) were monitored during osseointegration at 0, 4, 8, and 12 weeks and postloading at 24, 48, and 60 weeks. The marginal bone level (MBL) and bone level changes (BLC) were determined at baseline and 60 weeks.

RESULTS

The cumulative success rate was 83.3%. The PI oscillated in the first 24 weeks and decreased from 48 weeks onward, while the CI score showed significantly higher values at week 8 (22%). The GI also peaked at week 8 (18.6%) and decreased from week 12 onward. The PD decreased gradually over time, but no significant differences were found between weeks 8 and 12. The ISQ decreased significantly between 0 and 12 weeks. After MO loading, the ISQ values increased linearly and significantly between 12 and 24, 24 and 48, and 48 and 60 weeks and reached values similar to the primary stability after 60 weeks [56.1(42.0-65.3)]. No significant MBL was observed at 60 weeks, with an average BLC of -0.06 ± 0.64 mm.

CONCLUSION

NDI connected to locking taper Equator attachments showed a stable clinical behavior as an MO retainer for edentulous patients with clinical mandibular atrophy.

Effect of implant- and occlusal load location on stress distribution in Locator attachments of mandibular overdenture. A finite element study

PURPOSE

The aim of this study is to evaluate and compare the stress distribution in Locator attachments in mandibular two-implant overdentures according to implant locations and different loading conditions.

MATERIALS AND METHODS

Four three-dimensional finite element models were created, simulating two osseointegrated implants in the mandible to support two Locator attachments and an overdenture. The models simulated an overdenture with implants located in the position of the level of lateral incisors, canines, second premolars, and crossed implant. A 150 N vertical unilateral and bilateral load was applied at different locations and 40 N was also applied when combined with anterior load at the midline. Data for von Mises stresses in the abutment (matrix) of the attachment and the plastic insert (patrix) of the attachment were produced numerically, color-coded, and compared between the models for attachments and loading conditions.

RESULTS

Regardless of the load, the greatest stress values were recorded in the overdenture attachments with implants at lateral incisor locations. In all models and load conditions, the attachment abutment (matrix) withstood a much greater stress than the insert plastic (patrix). Regardless of the model, when a unilateral load was applied, the load side Locator attachments recorded a much higher stress compared to the contralateral side. However, with load bilateral posterior alone or combined at midline load, the stress distribution was more symmetrical. The stress is distributed primarily in the occlusal and lateral surface of the insert plastic patrix and threadless area of the abutment (matrix).

CONCLUSION

The overdenture model with lateral incisor level implants is the worst design in terms of biomechanical environment for the attachment components. The bilateral load in general favors a more uniform stress distribution in both attachments compared to a much greater stress registered with unilateral load in the load side attachments. Regardless of the implant positions and the occlusal load application site, the stress transferred to the insert plastic is much lower than that registered in the abutment.