Mandibular Full-Arch Fixed Prostheses Supported on 4 Implants with Either Axial Or Tilted Distal Implants: A 3-Year Prospective Study

Prosthetic Rehabilitation of All-on-Six Implant-Supported Prosthesis: A Case Report

This clinical report explores the effectiveness of dental implants for rehabilitating fully edentulous arches, with a focus on the all-on-six treatment approach. Implant-supported fixed restorations, particularly using six implants, are presented as an expected and cost-effective solution for the rapid repair of the edentulous patient, avoiding the need for bone grafting. This report details the successful rehabilitation of a patient's completely edentulous arches using the all-on-six concept, highlighting the meticulous planning and execution involved. It concludes that precise diagnostic and implant planning, along with thorough attention to all the features, is crucial for successful implant-supported fixed prostheses, with the all-on-six concept offering improved clinical and radiological outcomes for atrophied maxillae.

Polyetheretherketone CAD-CAM framework for all-on-4 mandibular full arch prosthesis: Three years' retrospective study of periimplant soft tissue changes and ridge base relationship

PURPOSE

This study was conducted to evaluate the clinical peri-implant soft tissue changes during first year after occlusal loading and the ridge base relation after three years for mandibular CAD-CAM manufactured screw-retained implant-supported hybrid prosthesis of polyetheretherketone (PEEK) framework utilized with All-on-Four treatment concept.

MATERIAL AND METHODS

Sixteen completely edentulous patients were rehabilitated by 4 implants following the All-On-Four protocol. After 3 months, the definitive prosthesis was constructed to be a screw retained CAD-CAM milled framework from the modified PEEK (BioHPP), bonded to polymethylmethacrylate (PMMA) teeth and a pink shaded indirect light-polymerized nanofilled composite resin imitating the soft tissues. Peri-implant soft tissue changes regarding plaque, bleeding, gingival scores, and probing depth were evaluated at prosthesis insertion (T0), six months (T1) and 12 months (T2) after insertion. Also, monitoring of the ridge base relation was performed using cone beam computed tomography after one year (T0), two years (T1), and three years (T2) after mandibular fixed detachable All-on-Four framework insertion. Using Shapiro Wilk tests using SPSS^® software version 22 (SPSS Inc.), all clinical data were non- parametric while the ridge base relation data was parametric.

RESULTS

There were statistically significant differences regarding plaque, gingival, and bleeding scores for all implants with advancement of time. However, there was a statistically insignificant difference regarding probing depth in the posterior implants (p = .581). Regarding ridge base relation, there was a significant difference between observation times only in the anterior ridge area in between the two anterior implants (p = .011).

CONCLUSION

Within limitations of the study, the full arch PEEK framework of fixed-detachable, hybrid prosthesis used with All-on-Four concept for rehabilitation of mandibular edentulous arches is an acceptable treatment approach. Based on the stable ridge base relation posteriorly found in this study, less stress is distributed to the underlining bone due to the shock absorbing ability of PEEK. Special considerations for frequent soft tissue follow up and regular maintenance of oral hygiene measures are recommended. This article is protected by copyright. All rights reserved.

Peri-implant tissue health and patient satisfaction of vertical versus inclined posterior implants used to support overdentures with bar attachments. A one-year randomized trial

INTRODUCTION

This study aimed to evaluate peri-implant tissue health and patient satisfaction of vertical and inclined posterior implants for mandibular bar overdentures.

MATERIALS AND METHODS

Thirty edentulous participants received four implants in the interforaminal area of the mandible. The patients were randomly assigned into two equal groups; (1) vertical group (control): all implants were inserted vertically parallel to each other. Inclined group (study): the anterior implants were placed vertically, and the posterior implants were tilted 30° distally. Hader bar attachment with two 7 mm-distal cantilevers (vertical group) and without cantilevers (inclined group) was used to connect the implants to mandibular overdentures. Peri-implant tissue health (Plaque [PL] and gingival [GI] indices, pocket depth [PD], and crestal bone loss [CBL]) were evaluated after denture insertion (T0), 6 (T6), and 12 (T12) months after insertion. Patient satisfaction was evaluated using a visual analog scale after 12 months.

RESULTS

At T12, the vertical group showed significantly higher PL, PD, and CBL than the inclined group for anterior (p < 0.037) and posterior (p < 0.017) implants. The vertical group showed significantly higher GI than the inclined group for anterior implants (p = 0.003), and the inclined group showed significantly higher GI than the vertical group for posterior implants (p = 0.016). The inclined group showed significantly higher scores for general satisfaction (p = 0.049), prosthesis as a part of you (p = 0.013), appearance (p < 0.001), stability (p = 0.002), ease of cleaning (p < 0.001), and comfort (p = 0.001) than the vertical group.

CONCLUSION

Inclined posterior implants used to support mandibular bar overdentures are recommended than vertical implants, as it was associated with improved patient satisfaction and peri-implant tissue health.

Biomechanical variables affect peri-implant bone loss in implant-supported fixed complete dentures: a methodological and prospective study

PURPOSE

Implant-supported fixed complete dentures (IFCD) experience failures and complications related to biological and technical risk factors. This study investigated the effect of biomechanical variables of IFCD on 1-year peri-implant bone loss at the buccal, palatal/lingual, mesial, and distal implant sides. A new method was used to measure the geometric biomechanical variables of IFCD using cone beam computed tomography (CBCT).

METHODS

The study sample consisted of 246 external hexagon implants supporting 48 hybrid IFCD in 44 patients. CBCT images obtained immediately (T0) and 1 year (T1) after prosthesis installation were used to measure the support polygon area, clinical crown/implant (C/I) ratio (vertical lever), anteroposterior power and resistance arms, anterior and posterior cantilevers (horizontal levers), and peri-implant bone remodeling (T1-T0). Data were analyzed using multilevel multivariable models.

RESULTS

The average total bone loss in the mandible and maxilla were 0.88 mm, with a loss of 0.62 mm in the mandible and 1.08 mm in the maxilla. The C/I ratio had a significant effect on bone loss on the mesial, distal, and palatal/lingual sides (P <.05). The anterior cantilever had a protective effect on the lingual side of the anterior implant. No effect on bone loss was found for the support polygon area, posterior cantilever, resistance arm, or power arm (P >.05).

CONCLUSIONS

The results suggest that the C/I ratio and anterior cantilever in IFCD affect peri-implant bone loss according to the implant side and position in the arch.

Decompression technique - A modified approach for lateral alveolar ridge augmentation: A case report

A particular technique can increase the mucosal and peri-implant bone thickness, prevent compression around implant neck, and obtain proper space for the following prosthetic treatment with an adequate emergence profile.

Crestal bone stability after flapless placement of sloped implants with immediate temporization in edentulous mandible. A prospective comparative clinical trial

Objectives

The purpose of this study was to evaluate crestal bone stability around sloped implants using the flapless procedure and compare it with conventional implants placed axially.

Materials and methods

A total of 40 bone‐level implants with platform switching were used for this study for 10 patients (4 males and 6 females) in edentulous mandible. Twenty mesial conventional implants were placed in upright position and 20 distal 30° sloped implants tilted 30°. Bone loss was estimated using radiographic imaging after a 6‐ and a 12‐month follow‐up period. Comparison of the bone loss in the distal and mesial region at both implantation angles were conducted to understand the nature and progression of crestal bone loss.

Results

Crestal bone loss around the sloped implants was 0.29 mm (SD = 0.292) on average, while around conventional implants it was 0.22 mm (SD = 0.202) after one‐year follow‐up. However, there was no significant difference in the average of crestal bone loss between two trial groups after 6 months (p < 0.243) and one‐year (p < 0.614) follow‐up. The results indicated a 100% implant survival rate after one‐year follow‐up. Additionally, three fixed prostheses needed realignment after fracturing during the follow‐up time.

Conclusion

Considering the limitations of this study, it can be presumed that sloped and conventional implants with platform switching and conical connection have the same potential for minimal crestal bone loss.

Comparison of Four Implant-Supported Fixed Rehabilitation Options of the Edentulous Mandible: A 3D Finite Element Analysis

Aim:

This study aims to compare four implant-supported rehabilitation concepts of an edentulous mandible and determines the most biomechanically advantageous technique.

Materials and Methods:

Five models with four implants in different configurations were formed: four axial interforaminal implants, All-on-4 concept (two anterior axial and two posterior distally tilted implants), All-on-4v4 concept (four distally tilted interforaminal implants), All-on-4W (two anterior mesially tilted and two posterior distally tilted implants), and two axial interforaminal implants and two posterior extra-short implants. Straumann bone-level (4.1 × 12 mm) and tissue-level (4.1 × 4 mm) extra-short implants were used for this study. Spherical loadings from canine and molar regions were applied to evaluate tension, compression, and von Mises stresses by implementing 3D finite element analysis.

Results:

Among the alternative concepts, the classic All-on-4 and the All-on-4v4 techniques were the most successful treatment option in biomechanical terms. On the other hand, the use of extra-short implants in the posterior region was found to be the last method of choice. This was because of the high stresses on bones in most conditions, even though it balances the forces from the molar region on the implants.

Conclusion:

The results of the present study indicate that the classic All-on-4 and the All-on-4v4 techniques were the most successful treatment options in biomechanical terms for the rehabilitation of an edentulous mandible with four implant-supported fixed full-arch prostheses.

Does the natural maxillary dentition influence the survival rate of mandibular metal-resin implant-supported fixed complete dentures? A systematic review and meta-analysis

STATEMENT OF PROBLEM

Consensus is lacking regarding the influence of the maxillary dentition on the survival rate of a mandibular metal-resin implant-supported fixed complete denture (MRISFCD) with distal cantilevers.

PURPOSE

The purpose of this systematic review was to identify whether an opposing natural dentition influences the survival rate of mandibular MRISFCDs.

MATERIAL AND METHODS

A literature search was performed up to February 2018 from MEDLINE/PubMed, Scopus, Web of Science, Cochrane Library, BBO/LILACS databases and also in the non-peer-reviewed literature through Open Grey. Clinical studies regarding natural (ND), removable prostheses (RP), and complete fixed maxillary implant dentitions (ID) with at least a year of follow-up were included. The quality of the included studies was analyzed, and the risk of bias was reported. A meta-analysis comparing the survival rate of ND with RP and ND with ID was performed with a confidence interval (CI) of 95%, and heterogeneity was tested by an I² index. Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach was used to determine the certainty of the evidence.

RESULTS

From a total of 112 ND, 69 ID, and 204 RP in the maxillary dentition, the overall prevalence of failures was 5.4% (6/112; 95% CI [2.3 to 10.76]) for ND, 13.99% (20/69; 95% CI [0.77 to 39.41]) for ID, and 4.9% (10/204; 95% CI [0.69 to 12.18]) for RP. No statistical differences were detected in the success rates between ND and RP (risk difference = 0.00 [-0.06, 0.06]; P=.93; I²=27%) or between ND and ID (risk difference=0.00 [-0.06, 0.07]; P=.97; I²=0%), both with moderate evidence.

CONCLUSION

With a moderate certainty of evidence, it is suggested that natural maxillary dentitions do not affect the survival rate of mandibular MRISFCDs differently from other prosthetic designs.

Treatment of Resorbed Mandibles with Titanium Plate and Immediate Implant-Supported Prosthesis - Case Series

Severely resorbed mandibles with only cortical bone remaining can fracture during or after implant placement. This case series presents a technique to reduce the risk or the consequences of mandibular fracture. Seven patients with only cortical mandibular bone remaining were treated with the fixation of a titanium plate in the frontal surface previously to implant placement, during the same surgical procedure. Immediate complete-arch implant supported prosthesis were installed. Patient's systemic and local conditions that could influence implant survival were registered previously to surgery and during the follow up period. Biological and biomechanical complications were recorded. The condition of peri-implant tissues was evaluated. The follow-ups ranged from 12 to 84 months. Twenty-nine implants were placed and no implant failure or other biological complication was observed. The peri-implant tissue evaluation demonstrated most implants was surrounded by keratinized tissue (89.5%). No marginal recession (implant platform cervical to gingival margin) was observed. Probing depth was normal, ranging from 0 to 3 mm. Low scores of plaque index or bleeding on probing were recorded. Biomechanical complications evolved loosening of 4 prosthetic screws and 1 fractured. The use of a titanium plate for the fixation of severely resorbed mandibles with only cortical bone remaining was a safe treatment procedure, avoiding biological and major biomechanical complications in the treatment with immediate complete-arch implant-supported prosthesis.

Are There Alternatives to Invasive Site Development for Dental Implants? Part II

Despite improvements in bone preservation following tooth extraction, edentulous sites are often deficient in bone volume for conventional dental implant therapy. Missing bone volume is often recaptured by surgery and grafting. This article discusses noninvasive alternatives to bone grafting. Part I of this topic discussed the use of short and narrow diameter implants. Part II discusses three additional alternatives: the use of tilted implants, the use of four or fewer tilted and axially-loaded implants to support a full-arch fixed-dental-prosthesis (FAFDP), and the use of zygomatic implants to restore the severely-atrophic edentulous maxillae lacking adequate bone for conventional treatment.

The influence of prosthetic material on implant and prosthetic survival of implant-supported fixed complete dentures: a systematic review and meta-analysis

PURPOSE

Evaluating the impact of the prosthetic material on implant- and prosthetic survival of implant-supported fixed complete dentures.

STUDY SELECTION

Electronic and hand searches were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) to identify clinical studies including at least 10 patients restored with implant-supported dentures. The primary outcome was to evaluate the implant survival rate according to the applied restorative materials. The prosthetic survival rate was evaluated as secondary outcomes.

RESULTS

Forty-one of 2254 studies were finally selected. A statistically significant difference (p = 0.0337) was found between implant survival rates in the main restorative groups (metal-ceramic:97%(95%CI [0.96;0.98]), all-ceramic:99%(95%CI [0.98;1.00]), metal-resin:97%(95%CI [0.96;0.98])). Prosthetic survival rates were: (metal-ceramic:95%(95%CI [0.89;0.97]), all-ceramic:97%(95%CI [0.92;0.99]), metal-resin:97%(95%CI [0.95;0.98]), with no statistically significant difference (p = 0.3796) between the groups. Chipping incidence rates were as follows: metal-ceramic:8%(95%CI[0.03;0.20]), all-ceramic:15%(95%CI [0.06;0.32]), and metal-resin:22%(95%CI [0.13;0.33]). Five types of exact restorative materials were identified (porcelain-fused-to-non-precious alloy, porcelain-fused-to-zirconia, precious-metal-acrylic-resin, non-precious-metal-acrylic resin, and PMMA). Again, implant survival rates were statistically significantly influenced by the applied restorative materials (p = 0.0126), whereas, no significant differences were reported regarding prosthetic survival rate.

CONCLUSIONS

Prosthetic material selection seems to have no clinically relevant influence on implant- and prosthetic survival rate in implant-supported fixed complete dentures. Due to the high chipping rate, quantifying prosthetic survival alone does not seem to be a reliable tool for evaluating the outcome of the restorations and providing recommendations. These results, along with the obvious lack of evidence, suggest that clinicians must exercise caution whenever porcelain-fused-to-zirconia or metal-resin restorations are considered.

Clinical performance of intentionally tilted implants versus axially positioned implants: A systematic review

OBJECTIVES

The aim of this review was to determine the clinical performance of dental implants that are intentionally tilted when compared with implants that are placed following the long axis of the residual alveolar ridge.

MATERIALS AND METHODS

A systematic review of the scientific literature using a predefined research question (PICO) and search strategy was undertaken. This search included five electronic databases. Two independent reviewers examined electronic databases and performed a manual review following search strategy to accomplish the item generation and reduction. Included articles were evaluated to determine the level of evidence. Data were extracted only from level I and level II studies, based on the Oxford Centre for Evidence-based Medicine-Levels of Evidence (March 2009). If included studies were homogeneous in nature, data were to be accumulated. However, if included studies were heterogeneous in nature, only descriptive data would be reviewed and analyzed.

RESULTS

A total of 811 articles were identified through the PICO question and search strategy. Detailed review of the abstracts and articles resulted in further item reduction, and 46 articles were included for full-text review. A total of 42 articles were then selected for inclusion in the systematic review. The identified articles included two level I and 20 level II studies. In addition, 15 level IV, one gray literature, and four previous systematic reviews with meta-analyses were also used in the study. The extracted data from the included studies demonstrated heterogeneity that prevented quantitative assessment, and only one level II study directly compared tilted and axially placed implants. Assessment of the descriptive data demonstrated no differences in implant survival, marginal bone loss, prosthesis survival, or patient-reported outcome measures (PROMs) whether implants are placed axially or with intentional inclination of the coronal aspect of the implant toward the distal aspect of edentulous jaws.

CONCLUSIONS

Based upon the systematic review of the literature, an analysis of the descriptive data suggested no differences in clinical performance between implants that are placed in an axial position relative to the residual alveolar ridge when compared with implants that are intentionally tilted toward the distal aspect of edentulous jaws.

Biological and technical complications of tilted implants in comparison with straight implants supporting fixed dental prostheses. A systematic review and meta-analysis

OBJECTIVES

To evaluate the implant failure, marginal bone loss (MBL), and other biological or technical complications of restorations supported by tilted and straight implants after at least 3 years in function.

METHODS

Electronic and manual searches were performed in MEDLINE, Embase, Web of Science, and OpenGrey to identify clinical studies published up to December 2017. After duplicate study selection and data extraction, the risk of bias was assessed with the ROBINS-I tool. Random-effects meta-analyses of relative risks (RRs) or mean differences (MD) and their 95% confidence intervals (CIs) were performed, followed by subgroup/sensitivity analyses and application of the GRADE approach.

RESULTS

A total of 17 nonrandomized studies (eight prospective/nine retrospective) were included. The number of implants of the overall systematic review was 7,568 implants placed in 1,849 patients supporting either full-arch or partial implant prostheses. No difference in the failure of tilted and straight implants was seen (eight studies; 4,436 implants; RR = 0.95; 95% CI = 0.70 to 1.28; p = 0.74), with the quality of evidence being very low due to bias and imprecision. Likewise, no difference in MBL was seen between tilted and straight implants (16 studies; 5,293 implants; MD = 0.03 mm; 95% CI = -0.03 to 0.10 mm; p = 0.32), with the quality of evidence being very low due to bias and inconsistency. Contradictory results regarding implant survival were found from prospective and retrospective studies, which could indicate bias from the latter.

CONCLUSIONS

Within the limitations of the present systematic review, no effect of implant inclination on implant survival or peri-implant bone loss was found.

Peri-Implant Behavior of Sloped Shoulder Dental Implants Used for All-On-Four Protocols: An Histomorphometric Analysis in Dogs

The aim of this study was to evaluate the soft tissue thickness and marginal bone loss around dental implants with sloped micro-threaded shoulder (30° angle) in comparing with conventional design, inserted 30° degrees angulated in post extraction sockets and immediate loaded with temporary prosthesis simulating the all-on-four protocol. Materials and Methods: Six fox hound dogs received forty-eight post extraction dental implants with the different diameter and length (Medentika, Germany), but with different neck configurations. Two group of implants were inserted 1mm subcrestal [corrected]. Control group has a micro-threaded neck and the Test group has a sloped microthreaded neck. Immediate loading was applied using a constructed metallic structure. After three months, soft and hard tissue levels were assessed by histomorphometric analysis. Results: The mean soft tissue thickness (STT) was 2.5 ± 0.2 mm for the Control group and 3.3 ± 0.3 mm for Test group (p = 0.036), meanwhile the mean marginal bone loss (MBL) was 1.53 ± 0.34 mm for Control group and, 1.62 ± 0.22 mm for Test group (p > 0.05). Conclusions: Within the limitations of this experimental model in dogs, the findings showed that dental implants with microthreaded and microthreaded sloped necks installed in immediate post extraction sites with immediate load, presented a comparable perimplant tissue behavior.

The all-on-four treatment concept: Systematic review

Objectives

To systematically review the literature on the “all-on-four” treatment concept regarding its indications, surgical procedures, prosthetic protocols and technical and biological complications after at least three years in function.

Study Design

The three major electronic databases were screened: MEDLINE (via PubMed), EMBASE, and the Cochrane Library of the Cochrane Collaboration (CENTRAL). In addition, electronic screening was made of the ‘grey literature’ using the System for Information on Grey Literature in Europe - Open Grey, covering the period from January 2005 up to and including April 2016.

Results

A total of 728 articles were obtained from the initial screening process. Of these articles, 24 fulfilled the inclusion criteria. Methodological quality assessment showed sample size calculation to be reported by only one study, and follow-up did not include a large number of participants - a fact that may introduce bias and lead to misleading interpretations of the study results.

Conclusions

The all-on-four treatment concept offers a predictable way to treat the atrophic jaw in patients that do not prefer regenerative procedures, which increase morbidity and the treatment fees. The results obtained indicate a survival rate for more than 24 months of 99.8%. However, current evidence is limited due the scarcity of information referred to methodological quality, a lack of adequate follow-up, and sample attrition. Biological complications (e.g., peri-implantitis) are reported in few patients after a mean follow-up of two years. Adequate definition of the success / survival criteria is thus necessary, due the high prevalence of peri-implant diseases.

Key words:All-on-four, all-on-4, tilted implants, dental prostheses, immediate loading.