Immediate function dental implants inserted with less than 30N·cm of torque in full-arch maxillary rehabilitations using the All-on-4 concept: retrospective study

A retrospective study on patient satisfaction and Oral Health-Related Quality of Life with fixed 4- or 6-implant supported prostheses over 3-7 years

OBJECTIVES

To compare patients' satisfaction and oral health-related quality of life (OHRQoL) in edentulous patients treated by All-on-4 and All-on-6 implant-supported fixed prostheses rehabilitation over 3-7 years.

METHODS

All patients (n = 125) were divided into short-term (3-5 years, n = 71) and long-term (5-7 years, n = 54) follow-up groups. Patients' satisfaction was examined in a cross-sectional survey. OHRQoL and psychological impact were evaluated using the Oral Health Impact Profile (OHIP). Comparison of All-on-4 and All-on-6, including OHIP values, satisfaction scores, treatment duration and complications, were analyzed using the Chi-square test and the Mann-Whitney U test. Potential influence of patient-related factors on patient-reported outcome measures (PROMs) were analyzed via the Mann-Whitney U test, the Kruskal-Wallis test and multiple regression analyses. Power calculation was conducted in R Studio.

RESULTS

Both All-on-4 and All-on-6 follow-up groups showed high scores in total satisfaction and PROMs, including chewing comfort, aesthetics, cleanability, and stability, with no significant difference (p > 0.05). Meanwhile, no significant differences were observed in the OHIP scores between two groups in both follow-up durations (p > 0.05). However, in patients with 3-5 years follow-up, All-on-4 group had significantly lower phonetic satisfaction scores than All-on-6 group (p < 0.05). Additionally, during both follow-up periods, All-on-4 patients exhibited notably superior psychological effect in contrast to All-on-6 patients (p < 0.05).

CONCLUSIONS

Edentulous patients treated by four or six implant-supported fixed prostheses showed same high satisfaction in oral health-related quality of life in both 3-5 years and 5-7 years follow-ups.

Long-term survival and complications of Quad Zygoma Protocol with Anatomy-Guided Approach in severely atrophic maxilla: A retrospective follow-up analysis of up to 17 years

INTRODUCTION

The objective of the study was to provide long-term clinical outcomes and complications in the severely atrophic edentulous maxillae treated by means of the quad zygoma protocol (QZP) using the Anatomy-Guided Approach (AGA).

METHODS

This was a retrospective cohort study of all consecutive patients with severely atrophic edentulous maxilla and insufficient bone height and width in the anterior and posterior regions bilaterally, who underwent rehabilitation with the QZP between May 2006 and December 2021. All patients were followed for at least 1 year. All zygomatic implants (ZIs) were placed by the same surgeon. The primary endpoint of the study was the implant survival rate. Secondary endpoints were implant success rate, prosthesis success rate, complications, and Oral Health-Related Quality of Life using the OHIP-14 questionnaire.

RESULTS

A total of 56 patients (men 16, women 40) with 224 ZIs (Nobel Biocare, n = 204; Straumann, n = 16; Southern Implant, n = 4) placement were included with a mean follow-up period 8.8 ± 3.9 years (range, 1.2-17.0). The survival (success) rate was 97.7%. Five ZIs in four patients failed. The mean time between implant placement and failure was 8.6 years (range, 0.5-13.3). All patients received immediate loading with acrylic prosthesis. The successful rates for the definitive prosthesis were 98.2%. Forty-two patients received posterior cantilever for rehabilitation of fixed definitive prosthesis. Local orofacial inflammation (35.7%) and Sinusitis (12.5%) were the most common complications, occurring at a mean follow-up of 10.0 (range, 4.2-14.9) and 10.3 (range, 4.3-16.2) years, respectively. In 48 patients, the mean score of the OHIP-14 questionnaire was 1.7 ± 2.6 with the follow-up period of 9.0 ± 4.1 years.

CONCLUSIONS

The rehabilitation of severely atrophic edentulous maxilla using the QZP has shown a predictable and high survival rate in the long term. The implementation of an immediate loading protocol offers potential benefits in stabilizing ZIs with cross-arch stabilization. Moreover, the use of a posterior cantilever in reconstruction can effectively establish functional occlusion through well-distributed ZIs, eliminating the need for additional implant placement.

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.

Immediate Restoration of an Endosseous Implant

As the field of implant dentistry continues to evolve, new techniques and technologies arise that can provide great benefits to the partial or completely edentulous patient. The purpose of this article is to review the history, definition, and rationale of immediate loading of dental implants with the goal of providing evidence-based recommendations for implementation into clinical practice. Relevant literature is summarized and includes discussion regarding prerequisites for immediate loading/restoration of an endosseous implant. Surgical techniques and methodologies to prevent implant failure in immediate-load cases are discussed as well. The greatest success has been demonstrated with 4 or more mandibular implants. Although there is support in the literature demonstrating successful outcomes in immediate functional loading of single implants, the opinion of the author is to opt for a nonfunctional load that does not have any occlusal contacts when considering immediate loading of a single dental implant.

Evaluation of two treatment concepts of four implants supporting fixed prosthesis in an atrophic maxilla: finite element analysis

BACKGROUND

Currently, oblique placement of long implants or the use of short implants to circumvent the maxillary sinus area and provide support for fixed prostheses are viable alternatives. The purpose of this study was to compare these two treatment concepts and ascertain which one exhibits superior biomechanical characteristics.

METHODS

Two different treatment concept models were constructed. The first one, LT4I, consisting of two mesial vertical implants positioned in lateral incisor regions and two distal tilted implants (45°) situated in second premolar regions of the maxilla. The second model, VS4I, includes two mesial vertical implants in lateral incisor regions and two vertically positioned short implants in second premolar regions. Numerical simulations were conducted under three loading types: firstly, oblique forces upon the molars; secondly, vertical forces upon the molars; thirdly, oblique forces upon the incisors. The maximum principal stress (σmax) and minimum principal stress (σmin) of the bone, as well as von Mises stress of the implants, were calcuated.

RESULTS

Under oblique loading on the molar, higher stress values in the bone were observed in LT4I group. Under vertical loading on molar, higher stress values in the bone were also observed in LT4I group. Furthermore, little difference was found between the two groups under oblique loading on the incisor.

CONCLUSION

Both treatment concepts can be applicable for edentulous individuals with moderate atrophic maxilla. Compared to tilted implants, short implants can transmit less occlusal force to the supporting tissues.

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.

The All-on-four concept for fixed full-arch rehabilitation of the edentulous maxilla and mandible: a longitudinal study in Japanese patients with 3-17-year follow-up and analysis of risk factors for survival rate

PURPOSE

Implant-supported immediately loaded fixed full-arch rehabilitation via All-on-four treatment yields good long-term results for both the maxilla and the mandible. However, the risk factors affecting long-term implant survival are unknown, and the long-term prognosis of All-on-four concept procedures in Japanese individuals has not been elucidated. We aimed to determine the cumulative implant survival rate after 3-17-year follow-up and identify the associated risk factors.

METHODS

We analysed 561 cases (307 maxillae, 254 mandibles) with 2364 implants (1324 maxillae, 1040 mandibles) that received All-on-four treatment. We investigated the cumulative implant- and patient-level survival rates and various risk factors for implant failure. Statistical analysis was performed using the log-rank test for differences in Kaplan-Meier curves, univariate analysis using the Chi-square test, and multivariate analysis for risk factors affecting the survival rate.

RESULTS

The cumulative survival rate was 94.4% by patient level and 97.4% by implant level for the maxilla, and 96.7% by patient level and 98.9% by implant for the mandible, with up to 17 years of follow-up. The maxillary survival rate at the implant level was significantly lower (p < 0.05). Furthermore, the maxillary survival rate within 24 months was significantly lower at the implant level (p < 0.01). Multivariate analysis revealed that the maxilla was the most significant risk factor (p < 0.01).

CONCLUSIONS

All-on-four treatment yielded high long-term survival rates in Japanese patients. However, the maxilla showed a significantly lower cumulative survival rate than the mandible, while early failure was significantly higher. Furthermore, the maxilla was a significant risk factor influencing the survival rate.

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.

Influence of Implant Macro-Design, -Length, and -Diameter on Primary Implant Stability Depending on Different Bone Qualities Using Standard Drilling Protocols-An In Vitro Analysis

(1) Background: Primary implant stability is vital for successful implant therapy. This study explores the influence of implant shape, length, and diameter on primary stability in different bone qualities. (2) Methods: Three implant systems (two parallel-walled and one tapered) with various lengths and diameters were inserted into polyurethane foam blocks of different densities (35, 25, 15, and 10 PCF) using standard drilling protocols. Primary stability was assessed through insertion torque (IT) and resonance frequency analysis (RFA). Optimal ranges were defined for IT (25 to 50 Ncm) and RFA (ISQ 60 to 80). A comparison of implant groups was conducted to determine adherence to the optimal ranges. (3) Results: Implant macro-design, -length, and -diameter and bone block density significantly influenced IT and RFA. Optimal IT was observed in 8/40 and 9/40 groups for the parallel-walled implants, while the tapered implant achieved optimal IT in 13/40 groups (within a 25-50 Ncm range). Implant diameter strongly impacted primary stability, with sufficient stability achieved in only one-third of cases despite the tapered implant's superiority. (4) Conclusions: The findings highlight the need to adapt the drilling protocol based on diverse bone qualities in clinical practice. Further investigations should explore the impact of these adapted protocols on implant outcomes.

Clinical effects of conventional and underprepared drilling preparation of the implant site based on bone density: A systematic review and meta-regression

PURPOSE

There is no clinical consensus to determine the right balance between underpreparation and marginal bone level changes. The purpose of this systematic review and meta-regression was to investigate the influence of the type of drilling preparation of the implant site in relation to the bone mineral density on the clinical success, expressed in terms of the MBL and implant failure rate.

STUDY SELECTION

A thorough search was performed using the digital databases MEDLINE PubMed, EMBASE, and Cochrane Central Register of Controlled Trials by entering research lines or various combinations of free words. The main keywords used were "dental implants", "bone density", and "torque".

RESULTS

The mean bone resorption in the conventional preparation group was -0.43 (± 0.28) mm, whereas it was -0.80 (± 0.37) mm in the underprepared group. For the D1/D2/D3 bone group, the slope was significantly different from zero and linearity; the D4 bone group slope was not significantly different from zero and was almost parallel, although it was significantly different from linearity. The box and whiskers plot shows that the MBL in underprepared sites tended to be significantly higher with a higher variation than that in conventionally prepared sites.

CONCLUSIONS

Within its limits, our meta-regression analysis showed that MBL is influenced by the type of drilling preparation and bone mineral density. In particular, a lower MBL was observed in the D1 bone with conventional preparation than with underpreparation. Moreover, a greater implant-to-osteotomy site mismatch was positively associated with greater MBLs in the bone densities of D1/D2/D3.

Fabrication of immediately loaded implant-retained maxillary overdenture with flapless surgery using a CAD/CAM surgical guide: A technical report

This report describes a digital workflow and two-year follow-up of an immediately loaded implant-retained overdenture using flapless surgery and a computer-aided design/computer-aided manufacturing (CAD/CAM) surgical guide. A prosthetically-driven approach, utilising a three-dimensional (3D) planning software and a CAD/CAM surgical guide, was used to place four implants in the edentulous maxillary arch of a 59-year-old male patient. All four implants were inserted through the surgical guide without raising soft tissue flaps. After placement, the patient was delivered an immediately loaded maxillary overdenture. Surgical implant placement was well tolerated by the patient, who reported no discomfort. Following a four-month period, a new implant-retained maxillary overdenture reinforced by a metal framework was fabricated and delivered to the patient. There were no adverse issues noted with neither the implants nor the maxillary overdenture during the two-year follow up period. The technique using the workflow described in this report may be a predictable and affordable alternative in the restoration of edentulous arches as compared to full-arch fixed restorations.

[Application evaluation of prefabricated rigid connecting bar in implants immediate impression preparation of edentulous jaw]

OBJECTIVE

To compare the operation complexity and accuracy of traditional splint impression technique and impression technique with prefabricated rigid connecting bar system for full-arch implants-supported fixed protheses in vitro.

METHODS

Standard mandibular edentulous model with six implant analogs was prepared. The implants were placed at the bone level and multiunit abutments screwed into the implants. Two impression techniques were performed: the traditional splint impression technique was used in the control group, and the rigid connecting bar system was used in the test group. In the control group, impression copings were screwed into the multiunit abutments and connected with autopolymerizing acrylic resin. Open tray impression was fabricated with custom tray and polyether. In the test group, cylinders were screwed into the multiunit abutments. Prefabricated rigid bars with suitable length were selected and connected to the cylinders with small amount of autopolymerizing acrylic resin, and open tray impression was obtained. Impression procedures were repeated 6 times in each group. The working time of the two impression methods were recorded and compared. Analogs were screws into the impressions and gypsum casts were poured. The gypsum casts and the standard model were transferred to stereolithography (STL) files with model scanner. Comparative analysis of the STL files of the gypsum casts and the standard model was carried out and the root mean square (RMS) error value of the gypsum casts of the control and test groups compared with the standard model was recorded. The trueness of the two impression techniques was compared.

RESULTS

The work time in the test group was significantly lower than that in the control group and the difference was statistically significant [(984.5±63.3) s vs. (1 478.3±156.2) s, P < 0.05]. Compared with the standard model, the RMS error value of the implant abutments in the test group was (16.9±5.5) μm. The RMS value in the control group was (20.2±8.0) μm. The difference between the two groups was not significant (P>0.05).

CONCLUSION

The prefabricated rigid connecting bar can save the chair-side work time in implants immediate loading of edentulous jaw and simplify the impression process. The impression accuracy is not significantly different from the traditional impression technology. The impression technique with prefabricated rigid connecting bar system is worthy of clinical application.

Extra-long transnasal implants as alternative for Quad Zygoma: Case report

Introduction and importance

The aim of this case report is to present a technical report for rehabilitation of patients with atrophic maxilla with the use of extra-long transnasal implants associated with unilateral zygomatic implants.

Case presentation

The indications, contraindications, planning and surgical procedure are described in order to give surgeons confidence in the management of this surgical approach to how to increase the range of rehabilitative options available to surgeons and patients.

Clinical discussion

Maxillary bone atrophy is a challenge demanding a high degree of experience of dental surgeons who trains themselves to rehabilitate these patients, whose treatment options range from bone grafts through to zygomatic implants. Extensive regions of atrophy require the use of 4 zygomatic implants which, in spite of offering predictability of the treatment, increase the surgical risk, require zygomatic bone with volume for anchoring 2 zygomatic implants. Generally, this bone density is reduced in elderly patients, making apical anchorage of the implants unfeasible.

Conclusion

The case report presented is a feasible alternative for replacing the placement of a second zygomatic implant, thereby diminishing the surgical risk, and making it possible for the technique to be more extensively used and performed by a larger number of surgeons.

•

Present a case report with the use of extra-long transnasal implants.

•

Alternative for substituting the insertion of a second zygomatic implant.

•

Decrease the surgical risk.

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.

The influence of insertion torque values on the failure and complication rates of dental implants: A systematic review and meta-analysis

BACKGROUND

The influence of using different insertion torque values on clinical and radiographic outcomes of implant therapy is unclear in the current literature. The aim of this systematic review and meta-analysis was to evaluate the implant outcomes and complications rates using high insertion torque values compared with those using regular insertion torque value levels.

METHODS

Randomized controlled trials (RCTs), nonrandomized controlled clinical trials (NRCCTs), prospective and retrospective cohorts were searched for in electronic databases and complemented by hand searching relevant dental journals. The risk of bias was assessed using the Cochrane Collaboration's Risk of Bias tool for randomized and nonrandomized studies. Data were analyzed using a statistical software.

RESULTS

A total of 718 studies were identified, of which, nine studies were included with 1229 dental implants in 684 participants. The meta-analysis of RCTs showed that the overall implant failure rate was not notably in favor of any insertion torque value and the difference between the two groups was not statistically significant (risk ratio 0.85; 95% confidence interval 0.07-10.52; P = 0.90). None of the RCTs was registered. The secondary analyses of non-RCTs did not either show any statistically significant difference. Overall meta-analysis did not show any significant differences in peri-implant marginal bone loss or biological/technical complications between high (≥50 Ncm) and regular insertion torque (<50 Ncm).

CONCLUSIONS

There is insufficient evidence to support the use of high or regular insertion torque even with immediate implant restoration/loading. The short-term implant failure rates, changes in marginal bone level and complication rates were comparable when high or regular insertion torques were used for implant placement. The wide confidence interval indicated that results cannot be interpreted with clinically meaningful benefit for using either high or regular insertion torque.

Internal oblique line implants in severe mandibular atrophies

Background

Maxillary atrophy may be related to mechanical, inflammatory or systemic factors, being a consequence of a reduction in the amount and quality of available bone. Several surgical techniques have been developed for the restoration of bone volume needed for placing dental implants; guided bone regeneration or three-dimensional reconstructions with autologous bone, inter alia, are techniques described in the literature which demonstrate this, all of which preceded by a proper prosthetic surgical assessment. Even when the majority of authors recommend the use of these techniques prior to placing implants, it has been shown that implants with a smaller diameter and length may be placed in severely atrophied jaws without the need for performing any surgery, offering excellent results.

Material and Methods

Twenty-four (24) implants were placed in six patients with severe mandibular atrophy. The implants were placed in the anterior sector and on an internal oblique line. Patients were rehabilitated with a total implant-supported prosthesis, with monitoring over a 10-year period.

Results

After a 12-month monitoring period, all the patients presented successful rehabilitation. Marginal bone loss in general (n=24 implants) was +0.11 mm ± 0.53. In the implants in zones 1 and 4 (posterior) it was +0.06 mm ± 0.48 and in implants in zones 2 and 3 (anterior), +0.14 mm ± 0.57.

Conclusions

Implants can be placed in the anterior zone and on an internal oblique line in patients with severe mandibular atrophy, using a diameter and length adapted to bone availability, for later prosthetic rehabilitation, offering satisfactory results since phonetic and masticatory function can be restored, as well as facial and buccal aesthetics, in a single surgical operation, with minimum morbidity. Key words:Severe atrophy, implants, bone grafts, ridge atrophy, internal oblique line.

Clinical effect of the high insertion torque on dental implants: A systematic review and meta-analysis

STATEMENT OF PROBLEM

A consensus on the clinical performance in dental implants placed with different insertion torques is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate the effect of high insertion torque compared with regular or low torques during dental implant placement in terms of implant survival rate and marginal bone loss.

MATERIAL AND METHODS

Two independent reviewers searched electronic databases for studies published until April 2019. The population, intervention, comparison, outcome (PICO) question was "Do patients who receive implants with a high torque (equal or higher than 50 Ncm) show similar implant survival rates and marginal bone loss as compared with those who receive implants with a regular or low torque (less than 50 Ncm)?". The meta-analysis was based on the Mantel-Haenszel (MH) and the inverse variance (IV) methods (α=.05).

RESULTS

The search yielded 6 articles, which included 389 patients (mean age: 55.28 years) who had received 651 dental implants (437 with high torque and 214 with low or regular torque). Most studies evaluated delayed loading, except 1 study that evaluated immediate implant loading (n=50 for each group). Low or regular insertion torque had a high failure rate (4.2%) compared with high insertion torque (1.1%), chiefly because of immediate loading. However, the meta-analysis indicated no significant difference between high- and regular- or low-torque implant placement in implant survival rate (P=.52, risk ratio [RR]: 0.51, 95% confidence interval [CI]: 0.06-4.06) and marginal bone loss (P=.30, mean difference [MD]: 0.15, 95% CI: -0.14 to 0.44).

CONCLUSIONS

A high insertion torque during implant placement does not affect implant survival rate or marginal bone loss. However, further research is recommended to reassess this clinical performance.

Is there any predictive bone parameter for implant stability in 2-dimensional and 3-dimensional radiologic images?

OBJECTIVES

This ex vivo study aimed to compare radiomorphometric parameters between 2-dimensional (2-D) and 3-dimensional (3-D) radiographs and evaluate the influence of preoperative radiologic bone parameters on the clinical outcomes of implant stability.

STUDY DESIGN

Implant recipient sites in fresh bovine blocks were evaluated on panoramic radiographs for gray value (GV), fractal dimension (FD), number of connected trabeculae (Co), and density of connected trabeculae (CoD). Cone beam computed tomography (CBCT) scans were evaluated for trabecular thickness (TbTh), cortical thickness (CTh), degree of anisotropy (DA), FD, and Co. Insertion torque (IT) and implant stability quotient (ISQ) were measured.

RESULTS

GV was significantly correlated with all parameters in 2-D and 3-D images except FD in 2-D and Co in 3-D, and with all surgical parameters (P ≤ .029). Co and CoD values on panoramic radiographs had significant correlation with TbTh, CTh, and DA values on CBCT images (P < .001). All 2-D parameters and TbTh and CTh in the CBCT data were significantly correlated with IT only (P ≤ .047). Only GV was correlated with ISQ measurements (P ≤ .029).

CONCLUSIONS

GV, Co, and CoD values on panoramic radiographs reflect the architecture of trabecular bone and the thickness of cortical bone, and might help predict implant stability in clinical situations.

Hybrid Polyetheretherketone (PEEK)-Acrylic Resin Prostheses and the All-on-4 Concept: A Full-Arch Implant-Supported Fixed Solution with 3 Years of Follow-Up

Background: The aim of this three-year prospective study was to examine the outcome of a solution for full-arch rehabilitation through a fixed implant-supported hybrid prosthesis (polyetheretherketone (PEEK)-acrylic resin) used in conjunction with the All-on-4 concept. Methods: Thirty-seven patients (29 females, 8 males), with an age range of 38 to 78 years (average: 59.8 years) were rehabilitated with 49 full-arch implant-supported prostheses (12 maxillary rehabilitations, 13 mandibular rehabilitations and 12 bimaxillary rehabilitations). The primary outcome measure was prosthetic survival. Secondary outcome measures were marginal bone loss, plaque and bleeding scores, veneer adhesion issues, biological complications, mechanical complications, and the patients’ subjective evaluation. Results: There were two patients (maxillary rehabilitations) lost to follow-up, while one patient withdrew (maxillary rehabilitation). One patient with bimaxillary rehabilitation fractured the mandibular PEEK framework, rendering a 98% prosthetic survival rate. Implant survival was 100%. Average (standard deviation) marginal bone loss at 3-years was 0.40 mm (0.73 mm). Veneer adhesion was the only technical complication (n = 8 patients), resolved for all patients. Nine patients (n = 11 prostheses) experienced mechanical complications (all resolved): fracture of acrylic resin crowns (n = 3 patients), prosthetic and abutment screw loosening (n = 4 patients and 3 patients, respectively), abutment wearing (n = 1 patient). One patient experienced a biological complication (peri-implant pathology), resolved through non-surgical therapy. A 90% satisfaction rate was registered for the patients’ subjective evaluation. Conclusions: Based on the results, the three-year outcome suggests the proposed rehabilitation solution as a legitimate treatment option, providing a potential shock-absorbing alternative that could benefit the implant biological outcome.

Influence of Bone Quality, Drilling Protocol, Implant Diameter/Length on Primary Stability: An In Vitro Comparative Study on Insertion Torque and Resonance Frequency Analysis

The aim of this study was to evaluate the influence of bone quality, drilling technique, implant diameter, and implant length on insertion torque (IT) and resonance frequency analysis (RFA) of a prototype-tapered implant with knife-edge threads. The investigators hypothesized that IT would be affected by variations in bone quality and drilling protocol, whereas RFA would be less influenced by such variables. The investigators implemented an in vitro experiment in which a prototype implant was inserted with different testing conditions into rigid polyurethane foam blocks. The independent variables were: bone quality, drilling protocol, implant diameter, and implant length. Group A implants were inserted with a conventional drilling protocol, whereas Group B implants were inserted with an undersized drilling protocol. Values of IT and RFA were measured at implant installation. IT and RFA values were significantly correlated (Pearson correlation coefficient: 0.54). A multivariable analysis showed a strong model. Higher IT values were associated with drilling protocol B vs A (mean difference: 71.7 Ncm), implant length (3.6 Ncm increase per mm in length), and substrate density (0.199 Ncm increase per mg/cm3 in density). Higher RFA values were associated with drilling protocol B vs A (mean difference: 3.9), implant length (1.0 increase per mm in length), and substrate density (0.032 increase per mg/cm3 in density). Implant diameter was not associated with RFA or IT. Within the limitations of an in vitro study, the results of this study suggest that the studied implant can achieve good level of primary stability in terms of IT and RFA. A strong correlation was found between values of IT and RFA. Both parameters are influenced by the drilling protocol, implant length, and substrate density. Further studies are required to investigate the clinical response in primary stability and marginal bone response.

Le Fort I Distraction Osteogenesis of Edentulous Maxillae Combined with Simultaneous Sinus Floor Grafting to Obtain Orthoalveolar Form for Emergence Profile Dental Implant Restorations: Report of Three Patient Treatments Followed for 12 Years

Three edentulous maxillary patients were treated with 9- to 15-mm advances of the maxilla by Le Fort I distraction osteogenesis combined with simultaneous sinus floor autograft placement. The patients were subsequently treated with 8 implants placed in the molar, bicuspid, and canine regions for complete arch ceramo-metal fixed restorations. Anterior emergence profile esthetics was obtained in 2 patients who had high smile lines. Following final restoration, no maxillary relapse was evident, and no implants were lost. Implant bone levels were stable, although 2 implants had 3 mm of bone loss over the 12-year follow-up period.