Immediate loading short implants inserted on low bone quantity for the rehabilitation of the edentulous maxilla using an All-on-4 design

Five years of radiographic evaluation for the peri-implant bone changes of all-on-four implant prostheses constructed from different framework materials using different digital construction techniques

BACKGROUND

There is insufficient evidence recommending a framework material and a CAD/CAM manufacturing technique for mandibular implant-supported prostheses. The study objective was to evaluate the clinical application of different materials and construction techniques used for mandibular All-on-4 prosthesis on circumferential peri-implant bony changes after 5 years.

METHODS

Thirty-six male patients with all-on-4 mandibular implant-supported prostheses were recalled and divided into three groups. Group PK (patients with frameworks milled from PEEK blocks), Group PSM (patients with frameworks milled from soft metal blocks), and Group SLM (patients with frameworks constructed with additive manufacturing; selective laser melting). The circumferential bone level on all implant faces was assessed with a CBCT. Two-way repeated measures ANOVA was used to compare vertical bone loss (VBL) and horizontal bone loss (HBL) between different groups, implant positions, and observation times followed by Tukey's multiple comparisons.

RESULTS

For all observation times, there was a significant difference in VBL between groups for both anterior and posterior implants (P < .001). For anterior implants, group PSM showed the lowest VBL while group PK showed the highest for anterior and posterior implants. For all groups, HBL significantly increased after 5 years for both anterior and posterior implants (P < .001). For anterior implants, group PSM showed the highest HBL. For posterior implants, group PK and SLM showed the highest.

CONCLUSION

Within the study's limitations, mandibular implant-supported fixed frameworks fabricated with either milling from PEEK or soft metal blocks, or additive manufacturing (laser melting technology) exhibited significant vertical and horizontal bone height changes after 5 years.

CLINICAL TRIAL REGISTRY NUMBER

(NCT06071689) (11/10/2023).

What Is the Survival Rate of Implants Loaded Immediately with a Branemark Protocol Prosthesis? A Review

The aim of this review was to determine the survival rate of implants loaded immediately with a Branemark protocol prosthesis. An electronic search was performed in the PubMed/MEDLINE database from 2006 to February 2024, using a combination of Medical Subject Headings descriptors: "completely edentulous" and "immediate loading." Human clinical articles in English that evaluated the survival rate of implants loaded immediately with a Branemark protocol prosthesis after placement in the bone were included. A total of 546 articles were identified, of which 15 were included in this study. The 15 articles included in the literature showed a high implant survival rate (more than 93%) after immediate loading.

Survival Rates of Short Dental Implants (≤6 mm) Used as an Alternative to Longer (>6 mm) Implants for the Rehabilitation of Posterior Partial Edentulism: A Systematic Review of RCTs

Short dental implants have been proposed as an alternative treatment option to bone regeneration procedures for the rehabilitation of resorbed alveolar ridges. The aim of this paper was to systematically review randomized controlled trials (RCTs) comparing short implants (≤6 mm) and longer implants (>6 mm) in atrophic alveolar ridges in terms of implant survival rates, peri-implant marginal bone loss (MBL), prevalence of peri-implantitis and technical complications. A thorough electronic search was performed until September 2023. RCTs with follow-up of at least 1-year post-loading comparing short implants with rough surfaces to longer implants in the posterior jaws of systemically and periodontally healthy, partially edentulous adults were considered. Studies with incomplete information on the number of patients, follow-up or definition of "short implants" were excluded. The revised Cochrane risk-of-bias tool for randomized trials was used for Risk of bias assessment. Fixed-effects meta-analysis of the selected studies was applied to compare the outcome variables. Random-effect meta-analysis was performed, on the basis of within-study comparisons. In total, 16 articles were selected for meta-analysis and incorporated 408 short implants and 475 longer implants inserted in 317 and 388 patients, respectively. The survival rates of longer implants in pristine or augmented bone were significantly increased compared to short implants (95%CI: 2-5%, p < 0.001). Standard-length implants displayed increased, although non-statistically significant MBL (95%CI: -0.17-0.04, p > 0.05), and prevalence of peri-implantitis (95%CI: 0-5%, p > 0.05). No statistically significant differences were observed between short and long implants in terms of technical complications (implant-level 95%CI: -4-6%, p > 0.05). Short implants represent a promising alternative treatment option for the rehabilitation of posterior jaws to avoid additional bone augmentation procedures. Nonetheless, they should be selected cautiously due to a potentially limited survival rate compared to longer implants. A major limitation of this study is the variability in the included studies regarding sample size, patient profile, type of bone, loading protocol, definition of peri-implantitis, among others. This study received no external funding. The study protocol was registered in PROSPERO (CRD42023485514).

Biomechanical behavior of implant retained prostheses in the posterior maxilla using different materials: a finite element study

BACKGROUND

The aim of this study is to evaluate the biomechanical behavior of the mesial and distal off-axial extensions of implant-retained prostheses in the posterior maxilla with different prosthetic materials using finite element analysis (FEA).

METHODS

Three dimensional (3D) finite element models with three implant configurations and prosthetic designs (fixed-fixed, mesial cantilever, and distal cantilever) were designed and modelled depending upon cone beam computed tomography (CBCT) images of an intact maxilla of an anonymous patient. Implant prostheses with two materials; Monolithic zirconia (Zr) and polyetherketoneketone (PEKK) were also modeled .The 3D modeling software Mimics Innovation Suite (Mimics 14.0 / 3-matic 7.01; Materialise, Leuven, Belgium) was used. All the models were imported into the FE package Marc/Mentat (ver. 2015; MSC Software, Los Angeles, Calif). Then, individual models were subjected to separate axial loads of 300 N. Von mises stress values were computed for the prostheses, implants, and bone under axial loading.

RESULTS

The highest von Mises stresses in implant (111.6 MPa) and bone (100.0 MPa) were recorded in distal cantilever model with PEKK material, while the lowest values in implant (48.9 MPa) and bone (19.6 MPa) were displayed in fixed fixed model with zirconia material. The distal cantilever model with zirconia material yielded the most elevated levels of von Mises stresses within the prosthesis (105 MPa), while the least stresses in prosthesis (35.4 MPa) were recorded in fixed fixed models with PEKK material.

CONCLUSIONS

In the light of this study, the combination of fixed fixed implant prosthesis without cantilever using a rigid zirconia material exhibits better biomechanical behavior and stress distribution around bone and implants. As a prosthetic material, low elastic modulus PEKK transmitted more stress to implants and surrounding bone especially with distal cantilever.

Outcomes that may affect implant and prosthesis survival and complications in maxillary fixed prosthesis supported by four or six implants: A systematic review and meta-analysis

Objective

To investigate whether the clinical and radiographical outcomes are affected when four or six implants support the maxillary fixed complete denture (FCD).

Materials and methods

This study was registered on PROSPERO (CRD42021226432) and followed the PRISMA guidelines. The focused PICO question was, "For an edentulous maxillary patient rehabilitated with an implant-supported fixed prosthesis, do the clinical and radiographical outcomes differ when four or six implants support the prosthesis ". A thorough search of the relevant studies was designed and performed electronically. The survival rate of implant and prosthesis, marginal bone loss, and complications (mechanical and biological) were the primary outcomes, whereas implant distribution and using the surgical guide, follow-up, and framework material were evaluated as secondary outcomes.

Results

Out of 1099 articles initially retrieved, 53 clearly stated the outcomes of interest and were included in this study. There were no significant differences in implant and prosthesis survival, technical/mechanical complications, and biological complications between the 4-implant group (4-IG) and the 6-implant group (6-IG). However, marginal bone loss (MBL) was significantly higher in the 4-IG (p < 0.01). The surgical guide and follow-up period did not significantly affect implant/prosthesis survival. Additionally, using the CAD/CAM milled framework and anteroposterior implant distribution were associated with significantly higher implant survival in the 6-IG (p < 0.01).

Conclusion

The findings of this study indicated that having a greater number of implants, as seen in the 6-implant group, can lead to a decrease in technical and biological complications and reduce marginal bone loss. It is worth noting that factors such as using CAD/CAM frameworks and the anteroposterior distribution of implants were recognized as important in improving implant survival rates when more implants are present.

Implant-Retained Prosthetic Rehabilitation of a Patient with Severe Oral Lichen Sclerosus

Background

Lichen sclerosus is a rare condition that occurs in the genital area or on the extraoral skin but can also manifest orally (oral lichen sclerosus (OLS)). The condition is associated with atrophy, scarring, and functional limitations of the tissues. In the present case, an extremely pronounced variant is described, and the oral rehabilitation of the patient is presented. Case Report. The edentulous patient showed a progressive course with severely restricted mouth opening and persistent pain. Conventional dental treatment was therefore impossible. To address this issue, two implants were placed in each jaw at the position of the lateral incisors. After osseointegration and exposure of the implants, provisional bridges made of polymethyl-methacrylate were fitted to test the new jaw relation. After a successful provisional phase, an FDP in the sense of an extreme short dental arch (ESDA) has been inserted.

Conclusion

The experimental treatment of the patient with only a total of four implants and the ESDA concept represented a satisfactory therapy for the patient. The patient regained her chewing ability, which significantly increased her oral health-related quality of life (OHRQoL). Still, it should be noted that this is a high-risk and experimental prosthetic treatment.

Implant survival rate and marginal bone loss with the all-on-4 immediate-loading strategy: A clinical retrospective study with 1 to 4 years of follow-up

STATEMENT OF PROBLEM

Assessing peri-implant marginal bone loss (MBL) and its risk factors with cone beam computed tomography (CBCT) may clarify the risk factors for the all-on-4 (5 or 6) strategy and further improve its survival rate.

PURPOSE

The purpose of this retrospective clinical study was to evaluate the implant survival rate, MBL, and associated risk factors of all-on-4 (5 or 6) prostheses after 1 to 4 years of follow-up with CBCT.

MATERIAL AND METHODS

A total of 56 participants rehabilitated with 325 implants by using the all-on-4 (5 or 6) concept between October 2015 and December 2019 were included. Outcome measures were cumulative implant survival (life-table analysis) and MBL. Four CBCT scans, a scan immediately after surgery (T0), a scan 1 year after surgery (T1), a scan 2 years after surgery (T2), and a scan 3 to 4 years after treatment (T3), were obtained to evaluate the MBL. The Pearson correlation coefficient analysis and linear mixed models were performed to assess the potential risk factors for MBL (α=.05).

RESULTS

The implant survival rate was 99.38%, and the prosthesis survival rate was 100%. The reductions in the vertical buccal bone height (△VBBH) were 0.74 ±0.10 mm (T0-T1), 0.37 ±0.12 mm (T1-T2), and 0.15 ±0.14 mm (T2-T3). Except for T2-T3, the △VBBH showed a significant difference at T0-T1 and T1-T2 (P≤.05). The alterations in vertical mesial bone height (VMBH), vertical distal bone height (VDBH), and vertical lingual bone height (VLBH) were similar to the trend observed in VBBH. The △VBBH (T0-T3) was negatively correlated with the horizontal buccal bone thickness (HBBT) (T0) (r=-.394, P<.001). Linear mixed models revealed that factors such as smoking (P=.001), mandible implant site (P<.001), immediate implant (P=.026), tilted implant (P<.001), female sex (P=.003), systemic disease (P=.025), and bruxism (P=.022) negatively affected MBL. The cantilever length (CL) also had a negative effect on MBL around the implants at the distal extension (P<.001).

CONCLUSIONS

The high implant and prosthesis survival rates and low MBL confirmed the predictability of the all-on-4 (5 or 6) concept. Smoking, mandible implant site, systemic disease, bruxism, female sex, immediate implant, tilted implant, and CL were identified as potential risk factors for MBL.

Clinical outcomes of implant-supported prosthetic rehabilitation of severely atrophic maxilla: A systematic review

Aim

The purpose of this systematic review is to evaluate the clinical outcomes for the various methods of rehabilitation of a severely atrophic maxilla with the help of implant-supported fixed prosthesis.

Materials and Methods

The relevant publications published between 2013 and 2022 and written only in English were identified using an electronic search. The primary research question for this study was developed based on the PICO framework, which stands for population, intervention, control, and outcomes which was "What are the clinical outcomes of implant-supported prosthetic rehabilitation in patients with severely atrophic maxilla?" The relevancy of the articles was confirmed by examining their titles, abstracts, and complete texts to determine whether they satisfied the requirements for inclusion. Utilizing specialized study design-related bias assessment forms, the risk of bias was evaluated.

Results

The database search resulted in 1568 results; however, 1529 of them were eliminated because of insufficient, duplicate, or missing data. Additionally, manual searching yielded 11 articles. After 50 full-text papers were assessed for eligibility, 17 articles were eliminated. Thus, 33 studies in total are included in the current systematic review. Risk of bias analysis and GRADE evidence analysis were performed. Data were found to be heterogeneous and thus meta-analysis could not be done and narrative synthesis is presented.

Conclusion

The patient's condition and the clinician's expertise play a role in taking the decision on choice of technique for the fixed implant-supported rehabilitation of the severely atrophic maxilla. A high success and survival rate is produced by the majority of fixed implant-assisted prostheses despite the biologic and prosthetic problems. A single approach cannot be recommended as the gold standard. The choice is dependent on the patient's biological factors as well as the clinician's expertise. The included studies were assessed using GRADE criteria. The quality of evidence is low-medium. Therefore, to better comprehend the clinical effectiveness of the treatment alternatives, more well-designed randomized controlled trials with longer follow-up period are required.

Evaluation of a platform-switched Morse taper connection for all-on-four or six treatment in edentulous or terminal dentition treatment: A retrospective study with 1-8 years of follow-up

BACKGROUND

The survival rate, marginal bone loss and soft tissue health of the Ankylos implants and the balanced base abutments in all-on-four or six implant restoration of edentulous or terminal dentition patients has not been reported in the clinical research.

PURPOSE

This retrospective study aimed to evaluate the Ankylos implants and the balanced base abutments in all-on-four or six implant restoration of edentulous or terminal dentition patients after 1-8 years of follow-up.

MATERIALS AND METHODS

A retrospective study was conducted based on the medical records of 33 patients who received all-on-four or six treatments from April 2014 to May 2020. Four radiographic examinations [immediate postoperative (T0), definitive restorations (T1), 1-3 years after prosthetic restorations (T2), and more than 3 years after prosthetic restorations (T3)] were obtained to evaluate vertical bone height (VBH). We also calculated the survival rate and examined the condition of soft tissue with this implant system in edentulous or terminal dentition patients. Three-level linear model analyses were used to explore potential risk factors for VBH changes on the mesial and distal sides. The generalized linear model was used to analyze the influencing factors of BOP and plaque.

RESULTS

A total of 218 implants were included in this study. The cumulative survival rate of the implants was 97.25% before the definitive prosthesis, 96.33% within 3 years of follow-up and 95.32% after more than 3 years of follow-up. The mean ± standard deviation (SD) bone losses of the VBH were 0.27 ± 0.05 mm (T1-T3) on the mesial side and 0.49 ± 0.06 mm (T1-T3) on the distal side. During 1-8 years of follow-up, the height and angle of the abutment (p < 0.001), the mandible implant site (p < 0.001), the length of the implant (p = 0.014 < 0.05) and age (p = 0.029 < 0.05) showed statistically significant effects on vertical mesial bone height (VMBH) and vertical distal bone height (VDBH). The risk of BOP among participants who brushed three times a day was lower than those who brushed less than three times. The plaque risk of short abutment height was higher than the long abutment.

CONCLUSION

The current study showed that the Ankylos implants with the balanced base abutments in all-on-four or six implants treatment is a viable and predictable option with a high survival rate and low marginal bone loss in edentulous or terminal dentition patients. VBH around the implants was strongly associated with the mandible implant site, abutment height and angle, the length of the implant and age. Moreover, teeth-brushing times and abutment height significantly affect soft tissue health.

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.

Failure Risk of Short Dental Implants Under Immediate Loading: A Meta-Analysis

PURPOSE

Currently, there is no clear clinical evidence that short implants are suitable for immediate loading. Therefore, this meta-analysis aims to evaluate whether immediate loading increases the failure risk of short dental implants.

MATERIALS AND METHODS

This meta-analysis was registered at PROSPERO (CRD 42020195890). PubMed, Embase, and Cochrane Library databases were searched to collect all clinical studies comparing the failure rates of short dental implants (<10 mm) and standard implants (≥10 mm) under the condition of immediate loading and studies comparing the failure rates of short dental implants under immediate loading versus early or delayed loading. All of the clinical studies with available relevant data were eligible for inclusion. The Cochrane Risk of Bias tool was adopted to evaluate the risk of bias for the randomized controlled trial (RCT), while Newcastle-Ottawa Quality Assessment Scale (NOS) was used for the observational studies (OS). The OR value of each included study and its 95% CI were pooled to estimate the failure risk of short dental implants under immediate loading. The heterogeneity among studies was evaluated through Cochran's Q test and I² .

RESULTS

Seventeen studies, 5 RCTs and 12 OS studies, with a total of 2461 dental implants were analyzed. Four of the RCT studies were of low risk of bias and one was of unclear risk, while all of the OS studies were of moderate or high quality. Compared with standard implants, short implants did not have an increased failure risk under immediate loading (OR: 1.38, 95% CI: 0.67-2.84, p = 0.997, fixed model). In addition, the OR value of implant failure for short implants under immediate loading compared to that for short implants under early or delayed loading was 1.22 (95% CI: 0.33-4.55, p = 0.104, random model), which was also not significantly different.

CONCLUSIONS

There is not enough evidence to show that short dental implants under immediate loading may have higher implant failure risk compared to standard implants under immediate loading and short implants under early or delayed loading. Therefore, an immediate loading protocol may not increase the failure risk of short dental implants.

Biomechanical Behavior of All-on-4 and M-4 Configurations in an Atrophic Maxilla: A 3D Finite Element Method

BACKGROUND In edentulous patients, the concept of 4 implants with early loading has been widely used in clinical settings. In the case of bone atrophy in the anterior maxilla, using short implants or an angulated implant may be a good choice for treatment. The occlusal scheme remains a key aspect of All-on-4. The aim of this study was to use the 3-dimensional (3D) finite element method (FEM) to evaluate how different All-on-4 designs for canine-guided and group function occlusion affected the distribution of stress in the atrophic premaxilla. MATERIAL AND METHODS A 3D edentulous maxilla model was created and in 3D FEM, 3 different configurations - M4, All-on-4, and short implant - were modeled by changing the anterior implants and using 2 different occlusal schemes. For each model, the occlusal load was applied to simulate lateral movements. For cortical bone, the maximum and minimum principal stress values were generated, and for ductile materials, von Mises stress values were obtained. RESULTS No significant differences were detected among the models; generally, however, the highest stress values were observed in the M-4 model and the models with short implants. Slightly higher stress values were observed in the group function occlusion group than in the canine-guided occlusion group. CONCLUSIONS To promote better primary stabilization, M-4 or short implant configurations with canine-guided occlusion appear to be preferable for patients who have severe atrophy in the anterior maxilla.

Stress Distribution on the Prosthetic Screws in the All-on-4 Concept: A Three-Dimensional Finite Element Analysis

The all-on-4 concept, which is used to rehabilitate edentulous patients, can present with mechanical complications such as screw loosening and fracture. The purpose of this study was to evaluate the stress patterns induced in the prosthetic screws by the different prosthetic screw and abutment designs in the all-on-4 concept using finite element analysis. Von Mises stress values on 6 groups of each screw type, including short and narrow screw, short abutment; short and wide screw, short abutment; long and wide screw, short abutment; short and narrow screw, long abutment; short and wide screw, long abutment; and long and wide screw, long abutment, were compared under a cantilever loading of 200 N that was applied on the farther posterior to the position of the connection between the distal implant and the metal framework. Posterior prosthetic screws showed higher stress values than anterior prosthetic screws. The stress values in posterior prosthetic screws decreased as the length and diameter increased. In conclusion, the long and wide screw design offers advantages in stress distribution when compared with the short and narrow design.

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

Edentulous sites are often characterized by inadequate bone volume for dental implant therapy. Bone augmentation procedures for site development involve longer healing period and are often invasive, costly, and associated with postoperative morbidity. This article discusses alternatives to invasive bone grafting procedures that are often used to develop implant sites. Owing to the broad nature of this topic, it is presented in two articles. In part I, the use of short and narrow-diameter implants are discussed. Part II reviews the use of tilted as well as fewer implants to support a prosthesis.

Management of Edentulous Patients

Edentulism, defined as the complete loss of all dentition, is a worldwide phenomenon. Edentulism occurs because of biologic disease processes, such as dental caries, periodontal diseases, trauma, and oral cancer. Edentulism is accompanied by several comorbidities that can significantly influence an individual. Although the rate of edentulism is declining, the number of edentulous patients continues to rise because of the increase in population. The management of edentulous patient has been addressed since the early days of dentistry. This article describes complete dentures and their maintenance, and advanced technology in complete dentures, and in implant-retained and implant-supported prosthesis.

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.

Minimally Invasive Approach Based on Pterygoid and Short Implants for Rehabilitation of an Extremely Atrophic Maxilla: Case Report

INTRODUCTION

Extremely atrophic maxillae can be considered the most important indication for three-dimensional maxillary reconstruction. Different bone-augmentation techniques have been suggested to accomplish this. This article illustrates a minimally invasive approach to rehabilitation of the extremely atrophic maxilla.

MATERIAL AND METHODS

A 63-year-old male patient was referred for restoration of his totally edentulous maxilla with a fixed full-arch implant-prosthetic rehabilitation. Four short implants in the premaxillary region and 2 longer implants in the pterygomaxillary regions were inserted with piezoelectric implant site preparation.

DISCUSSION

At the 1-year follow-up appointment, no clinical or radiographic changes in the soft-tissue contours or crestal bone levels were observed.

CONCLUSION

This surgical approach, based on the combination of short implants in the premaxillary regions and pterygoid implants in the pterygomaxillary regions, represents a way to shorten treatment timing, minimize the risk of surgical complications, and reduce patient discomfort and costs.

The Influence of the Crown-Implant Ratio on the Crestal Bone Level and Implant Secondary Stability: 36-Month Clinical Study

Introduction

When the era of dental implantology began, the pioneers defined some gold standards used in dental prosthetics treatment for implant-supported restorations. Referring to traditional prosthetics, it was taken for granted that the length of an implant placed in the alveolar bone (the equivalent of the root) should exceed the length of the superstructure.

Aim of the Study

The aim of the study was to determine whether implant length and the crown-to-implant (C/I) ratio influence implant stability and the loss of the surrounding marginal bone and whether short implants can be used instead of sinus augmentation procedures.

Material and Methods

The patients participating in the study (n = 30) had one single tooth implant, a short (OsseoSpeed™ L6 Ø4 mm, Implants) or a regular implant (OsseoSpeed L11 and L13 Ø4 mm, DENTSPLY Implants), placed in the maxilla. The evaluation was based on clinical and radiological examination. The crown-to-implant ratio was determined by dividing the length of the crown together with the abutment by the length of the implant placed crestally. Mean crown-to-implant ratios were calculated separately for each group and its correlation with the MBL (marginal bone loss) and stability was assessed. The authors compared the correlation between the C/I ratio values, MBL, and secondary implant stability.

Results

Positive results in terms of primary and secondary stability were achieved with both (short and conventional) implants. The MBL was low for short and conventional implants being 0.34 ± 0.24 mm and 0.22 ± 0.46 mm, respectively. No significant correlation was found between the C/I ratio and secondary stability as well as the C/I ratio and the marginal bone loss.

Conclusions

Short implants can be successfully used to support single crowns. The study has revealed no significant differences in the clinical performance of prosthetic restorations supported by short implants. Clinical trial registration number is NCT03471000.

Fiber-Reinforced Resin Fixed Prostheses on 4 Short Implants in Severely Atrophic Maxillas: 1-Year Results of a Prospective Cohort Study

PURPOSE

The aim of this study was to report on 1-year outcomes of fixed full-arch fiber-reinforced resin bridges on short implants in atrophic maxillary jaws.

MATERIALS AND METHODS

A prospective cohort study was designed and patients with severely atrophic maxillas, corresponding to Cawood and Howell Classes V and VI, were included. Mesial and distal peri-implant bone levels were assessed on panoramic radiographs that were taken at the time of implant insertion (baseline) and during follow-up visits.

RESULTS

Eighteen patients with 72 implants inserted in atrophic maxillary jaws were included in this study. All patients had a follow-up visit 1 year after loading. The cumulative 1-year patient-based implant survival rate was 88.8%, and the cumulative 1-year implant-based survival rate was 97.2%. The marginal bone level (MBL) was -0.5 ± 0.5 mm at the time of loading (n = 72) and -0.8 ± 0.6 mm (n = 72) after 1 year. The MBL depended substantially on the depth at the time of insertion. No prosthetic failure, such as chipping or fracture, occurred within the first year of loading.

CONCLUSION

Prosthetic rehabilitation of atrophic maxillas with prostheses supported by 4 4.0- × 5.0-mm or 3.0- × 8.0-mm implants seems to be a viable and cost-effective treatment option in the short-term.

Immediate Loading of Short Implants in Posterior Maxillae: Case Series

BACKGROUND

There is an increasing number of scientific evidence supporting the clinical use of short dental implants. However, few studies have evaluated the long-term outcomes of immediate loading protocols in short implants. This study aims to evaluate immediate loading of short dental implants in the posterior regions of the maxillae.

MATERIALS AND METHODS

Patients having short implants in maxillae posterior areas inserted before December, 2010 and immediately loaded were selected. The following data were gathered regarding patients' age and gender, implant dimensions, anatomical location, and prosthodontic treatment. The outcome variables were peri-implant bone remodeling and the survival rates of the short implants and the prosthesis.

RESULTS

A 10 short implants were placed in 8 patients. The mean follow-up time was 4.6 ± 1.21 years after loading and 1 implant failed. One prosthetic complication occurred. No prostheses failed resulting in a survival rate of 100%.

CONCLUSIONS

The immediate loading of short implants in maxillae posterior areas could save time, cost and could be regarded as a successful treatment.

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.