Longevity of dental implants in type IV bone: a systematic review

Impact of Osteoporosis on Autogenous Bone Graft Resorption

BACKGROUND

Osteoporosis is a common disorder that is characterized by decreased bone density and increased bone resorption. This bone resorption may affect the grafted bone during the maxillofacial reconstruction.

PURPOSE

This study aimed to measure the association between osteoporosis and resorption of anterior iliac crest bone grafts used to reconstruct the atrophic anterior maxillae.

STUDY DESIGN, SETTING, SAMPLE

This prospective cohort study included female patients requiring bone augmentation of the anterior maxilla. Patients with a ridge width of <4 mm and ridge height of >7 mm were enrolled in the study. Exclusion criteria were chronic use of corticosteroids or intravenous bisphosphonates, history of maxillofacial radiation therapy, current smoking, and underlying conditions contributing to bone metabolism (eg, hyperparathyroidism, chronic renal failure, and hypophosphatemia).

PREDICTOR/EXPOSURE/INDEPENDENT VARIABLE

Osteoporosis status was a predictor variable. Patients were allocated to the osteoporosis or control group based on T-scores obtained by dual-energy x-ray absorptiometry. Mean T-scores ≤ -2.5 were assigned to the osteoporosis group.

MAIN OUTCOME VARIABLE(S)

The outcome variable was graft resorption, defined as the difference in ridge width between measurements made immediately (T1) and 6 months postoperatively (T2) using cone-beam computed tomography.

COVARIATES

Patient age, preoperative (T0) bone width, and the amount of bone augmentation, defined as the differences in ridge width between measurements made preoperatively (T0) and immediately after grafting (T1), were covariates of this study.

ANALYSES

Descriptive, analytic, and general linear models were computed. Statistical significance was set a P < .05.

RESULTS

Thirty-two patients were included in the study (15 in the osteoporosis group and 17 in the control group). The amount of graft resorption at 6 months after grafting was 2.57 ± 0.59 mm in the osteoporosis group and 0.97 ± 0.59 mm in the control group (P < .001). A significant correlation was found between the mean T-score and graft resorption 6 months after grafting (P < .001).

CONCLUSION AND RELEVANCE

A significant correlation was observed between osteoporosis and graft resorption in the anterior maxilla after 6 months.

Radiographic graft changes following maxillary sinus floor augmentation with autogenous bone compared with composite grafts: a one-year single-blind randomized controlled trial

This study evaluated radiographic graft changes following maxillary sinus floor augmentation with (A) autogenous bone, (B) 1:1 autogenous bone and deproteinized porcine bone mineral, or (C) 1:1 autogenous bone and biphasic bone graft material. Sixty patients were randomly allocated to groups A, B, and C (20 in each). CBCT scans were obtained at enrolment, after surgery (T1), after prosthetic rehabilitation (T2), and 1 year after implant loading (T3). Significant decreases in graft volume (3D) and graft height (2D) from T1 to T3 were observed in all groups (P < 0.05). However, at T2 and T3, graft volume was significantly higher in group B than in groups A and C (P < 0.05), and graft height was significantly higher in group B than in group A (P < 0.05). Bone density increased significantly from T1 to T2 in all groups (P < 0.001). However, bone density was significantly higher in group B than in groups A and C, at T2 and T3 (P < 0.05). No significant correlation between graft volume or height and implant protrusion length or residual bone height was found. In conclusion, 1:1 autogenous bone and porcine bone resulted in significantly higher graft volume, height, and bone density when compared with autogenous bone or a 1:1 ratio of autogenous bone and biphasic bone. However the higher graft volume, height, and bone density did not appear to lead to improved outcomes at 1 year of functional loading when compared to the other groups.

Multi-objective optimization of custom implant abutment design for enhanced bone remodeling in single-crown implants using 3D finite element analysis

The optimal configuration of a customized implant abutment is crucial for bone remodeling and is influenced by various design parameters. This study introduces an optimization process for designing two-piece zirconia dental implant abutments. The aim is to enhance bone remodeling, increase bone density in the peri-implant region, and reduce the risk of late implant failure. A 12-month bone remodeling algorithm subroutine in finite element analysis to optimize three parameters: implant placement depth, abutment taper degree, and gingival height of the titanium base abutment. The response surface analysis shows that implant placement depth and gingival height significantly impact bone density and uniformity. The taper degree has a smaller effect on bone remodeling. The optimization identified optimal values of 1.5 mm for depth, 35° for taper, and 0.5 mm for gingival height. The optimum model significantly increased cortical bone density from 1.2 to 1.937 g/cm3 in 2 months, while the original model reached 1.91 g/cm3 in 11 months. The standard deviation of density showed more uniform bone apposition, with the optimum model showing values 2 to 6 times lower than the original over 12 months. The cancellous bone showed a similar trend. In conclusion, the depth and taper have a significant effect on bone remodeling. This optimized model significantly improves bone density uniformity.

Dental implant considerations in patients with systemic diseases: An updated comprehensive review

BACKGROUND

Various medical conditions and the drugs used to treat them have been shown to impede or complicate dental implant surgery. It is crucial to carefully monitor the medical status and potential post-operative complications of patients with systemic diseases, particularly elderly patients, to minimize the risk of health complications that may arise.

AIM

The purpose of this study was to review the existing evidence on the viability of dental implants in patients with systemic diseases and to provide practical recommendations to achieve the best possible results in the corresponding patient population.

METHODS

The information for our study was compiled using data from PubMed, Scopus, Web of Science and Google Scholar databases and searched separately for each systemic disease included in our work until October 2023. An additional manual search was also performed to increase the search sensitivity. Only English-language publications were included and assessed according to titles, abstracts and full texts.

RESULTS

In total, 6784 studies were found. After checking for duplicates and full-text availability, screening for the inclusion criteria and manually searching reference lists, 570 articles remained to be considered in this study.

CONCLUSION

In treating patients with systemic conditions, the cost-benefit analysis should consider the patient's quality of life and expected lifespan. The success of dental implants depends heavily on ensuring appropriate maintenance therapy, ideal oral hygiene standards, no smoking and avoiding other risk factors. Indications and contraindications for dental implants in cases of systemic diseases are yet to be more understood; broader and hardcore research needs to be done for a guideline foundation.

A study on the morphology of iliac crest based on the objectives of jaw bone defect reconstruction

OBJECTIVES

to understand the morphological characteristics of iliac crest and provide advice and assistance for jaw bone reconstruction with iliac bone flap by evaluating the thickness and curvature of iliac crest.

MATERIALS AND METHODS

100 patients who had taken Spiral CT of the Abdominal region before surgeries between 2020 and 2022 were included in this study. 3D reconstruction images of the iliac bones were created. 5 vertical planes perpendicular to the iliac crest were made every 2 cm along the centerline of the iliac crest (VP2 ~ VP10). On these vertical planes, 4 perpendicular lines were made every 1 cm along the long axis of the iliac crest (D1 ~ D4). The thicknesses at these sites, horizontal angle (HA) of iliac crest and the distance between inflection point and the central point of anterior superior iliac spine (DIA) were measured.

RESULTS

The thickness of iliac bone decreased significantly from D1 ~ D4 on VP6 ~ VP10 and from VP2 ~ VP10 on D3 and D4 level (P<0.05). HA of iliac crests was 149.13 ± 6.92°, and DIA was 7.36 ± 1.01 cm. Iliac bone thickness, HA and DIA had very weak or weak correlation with patient's age, height and weight.

CONCLUSIONS

The average thicknesses of iliac crest were decreased approximately from front to back, from top to bottom. The thickness and curvature of the iliac crest were difficult to predict by age, height and weight.

CLINICAL RELEVANCE

Virtual surgical planning is recommended before jaw bone reconstruction surgery with iliac bone flap, and iliac crest process towards alveolar process might be a better choice.

Clinical achievements of implantology in the pterygoid region: A systematic review and meta-analysis of the literature

The purpose of the study is to evaluate the survival rate of pterygoid implants compared to implants placed in different maxilla area and to settle as an alternative solution for the rehabilitation of the posterior maxilla atrophy. Studies that were included for this systematic review were selected using different database of references: PubMed Medline, Lilacs and Cochrane Library. Other journal platforms were also used for the research. Five articles met the strict inclusion/exclusion criteria of the 180 articles founded. This systematic review was registered on Prospero (CRD42023409706) and followed PRISMA statement. A total of 768 implants placed presented 97.43 % with a peak of 100 % of survival rate. Follow-up period varies from a minimum of 1 year to a maximum of six years. Pterygoid implants could be a valid alternative in patients presenting a posterior maxilla atrophy, but results should be interpreted cautiously due to the difficulty of the surgical technique. Further studies in the future should be taken in consideration to confirm the success rate of pterygoid implants since there is only one prospective RCT, potentially incorporating modern technologies such as guided surgery or navigated surgery could be a solution for the success of pterygoid implants, minimizing the risk and less dependent on the operator.

Do antihypertensive medications have an effect on dental implants? A systematic review

PURPOSE

The purpose of this systematic review was to compare the clinical outcomes of dental implants in users of antihypertensive medication with those of nonusers.

METHODS

This systematic review followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and was registered in the International Prospective Register of Systematic Reviews under the number CRD42022319336. The electronic databases Medline (PubMed) and Central Cochrane were searched for relevant scientific literature published in English through May 2022. The focused question was, "Do patients taking antihypertensive medications have a similar impact on the clinical outcome and survival of dental implants compared with nonusers?".

RESULTS

A total of 49 articles were found, of which 3 articles were finally selected for a qualitative synthesis. The three studies included 959 patients. In all three studies, the commonly used medication was renin-angiotensin system (RAS) inhibitors. Two studies mentioned implant survival rate, which was 99.4% in antihypertensive medication users and 96.1% in the nonusers. One study found a higher implant stability quotient (ISQ) in patients taking antihypertensive medication (75.7 ± 5.9) compared with patients not taking antihypertensive medication (73.7 ± 8.1).

CONCLUSIONS

The limited available evidence showed that patient taking antihypertensive medications had comparable success rate and implant stability to patients not taking medications. The studies included patients taking different antihypertensive medications, so a drug-specific conclusion regarding the clinical outcome of dental implants is not possible. Further studies are needed, including patients taking certain antihypertensive medications, to determine their effects on dental implants.

Addition of recombinant human bone morphogenic protein-2 to the graft materials improves the clinical outcomes of implants placed in grafted maxillary sinus

Background/purpose

The long-term outcomes of implants placed in grafted sinuses using recombinant human bone morphogenetic protein-2 (rhBMP-2) are unclear. This study aimed to compare 3- and 5-year implant survival rates and marginal bone loss (MBL) during functional loading.

Materials and methods

In this retrospective study, we analyzed 63 implants inserted after maxillary sinus floor augmentation (MSFA) in 45 patients between January 2016 and April 2019. The outcome variables were: 1) 3- and 5-year cumulative survival rates of the implants and 2) MBL after functional loading. Other assessed variables included patient demographic information, preoperative residual bone height (RBH), surgical site, implant length and diameter, graft material, healing period before loading, prosthetic type, and opposing dentition.

Results

The cumulative 3- and 5-year survival rates of the implants were 100% in the rhBMP-2 group and 95.5% and 86.4% in the non-rhBMP-2 group, respectively. The average 3- and 5-year MBL were 1.14 ± 0.67 mm, 1.30 ± 0.74 mm in the rhBMP-2 group and 1.68 ± 0.90 mm, 2.27 ± 1.29 mm in the non-rhBMP-2 group, respectively. Significant differences were observed between 3 and 5 years between the two groups.

Conclusion

Addition of the rhBMP-2 to the graft materials positively affects implant placement in the grafted maxillary sinus in terms of implant survival and MBL when preoperative RBH is unfavorable.

Do dental implants installed in different types of bone (I, II, III, IV) have different success rates? A systematic review and meta-analysis

Purpose

The objective of this systematic review and meta-analysis was to evaluate the survival rate of implants installed in bone type IV (Lekholm and Zarb, 1995) compared to that of implants installed in bone types I, II, and III.

Material and methods

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA) and was registered in the PROSPERO International Database of Systematic Reviews (CRD42021229775). The PubMed/MEDLINE, Scopus, and Cochrane databases were searched through July 2021. The PICO question was: "Dental implants installed in type IV bone have a lower success rate when compared to implants installed in type I bone, II and III?". The established inclusion criteria were: 1) controlled and randomized clinical trials (RCT), 2) prospective and retrospective studies with at least 10 participants with dental implants, and 3) patients with dental implants installed in bone tissue types I, II, III, and IV (Lekholm and Zarb, 1985). The minimum followup duration was 1 year.

Results

After searching the identified databases, 117 articles were selected for full reading and 68 were excluded. Thus, 49 studies were included for qualitative and quantitative analyses. The total number of participants included was 12,056, with a mean age of 41.56 years and 29,905 implants installed. Bone types I, II, and III exhibit a lower implant failure rate when compared to bone type IV.

Conclusion

Dental implants installed in bone types I, II, and III showed significantly higher survival rates than those installed in type IV. The bone type I success rate was not significantly different than that of type II; however, the success rate of bone type I and II was higher than that of type III.

Bacterial Flora in Screw-Fixed Superstructures with Different Sealing Materials: A Comparative Clinical Trial

A screw-fixed superstructure is predominantly selected for implant prostheses because of the concern regarding developing peri-implantitis, although its infection route remains unclear. Focusing on microleakage from access holes, the present study clinically investigated the bacterial flora in access holes with different sealing materials. We examined 38 sites in 19 patients with two adjacent screw-fixed superstructures. Composite resin was used in the control group, and zinc-containing glass ionomer cement was used in the test group. Bacteria were collected from the access holes 28 days after superstructure placement and were subjected to DNA hybridization analysis. The same patient comparisons of the bacterial counts showed a significant decrease in 14 bacterial species for the red, yellow, and purple complexes in the test group (p < 0.05). In addition, the same patient comparisons of the bacterial ratios showed a significant decrease in six bacterial species for the orange, green, yellow, and purple complexes in the test group (p < 0.05). Furthermore, the same patient comparisons of the implant positivity rates showed a significant decrease in the six bacterial species for the orange, yellow, and purple complexes in the test group. The results of this study indicate that zinc-containing glass ionomer cement is effective as a sealing material for access holes.

Emerging factors affecting peri-implant bone metabolism

Implant dentistry has evolved to the point that standard implant osseointegration is predictable. This is attributed in part to the advancements in material sciences that have led toward improvements in implant surface technology and characteristics. Nonetheless, there remain several cases where implant therapy fails (specifically at early time points), most commonly attributed to factors affecting bone metabolism. Among these patients, smokers are known to have impaired bone metabolism and thus be subject to higher risks of early implant failure and/or late complications related to the stability of the peri-implant bone and mucosal tissues. Notably, however, emerging data have unveiled other critical factors affecting osseointegration, namely, those related to the metabolism of bone tissues. The aim of this review is to shed light on the effects of implant-related factors, like implant surface or titanium particle release; surgical-related factors, like osseodensification or implanted biomaterials; various drugs, like selective serotonin reuptake inhibitors, proton pump inhibitors, anti-hypertensives, nonsteroidal anti-inflammatory medication, and statins, and host-related factors, like smoking, diet, and metabolic syndrome on bone metabolism, and aseptic peri-implant bone loss. Despite the infectious nature of peri-implant biological complications, these factors must be surveyed for the effective prevention and management of peri-implantitis.

A naïve comparison to assess the success of ultra-short implants

Introduction

Conventional implants are associated with ridge augmentation/sinus lift procedures in vertically insufficient ridges, which increase morbidity and healing time. Short implants provided some hope in this context. The present study considered the use of ultra-short implants in vertically insufficient posterior mandibular ridges and evaluated their success. Hence, study was done to evaluate the success of ultra-short implants in partially edentulous posterior mandible clinically and radiographically.

Materials and Methods

The study is a "Naïve direct comparison" of ultra-short implants to conventional implants for assessing their success in vertically insufficient posterior mandibular ridges. A total of 10 ultra-short implants were placed in a partially edentulous posterior mandibular ridge with at least 8-mm horizontal (at crest) and vertical dimensions. A delayed loading was done at three-month follow-up. Data acquisition was done at baseline (immediately after loading), 6-, 9-, 12-month intervals. Parameters assessed were marginal bone loss (MBL), probing pocket depth reduction (PPDR), modified plaque index (mPI), modified gingival index (mGI).

Results

All the placed 10 implants survived, and no failure was observed. "Independent sample t-test" and "paired sample t-test" was done for intergroup and intragroup analysis, respectively. Intergroup comparison between the ultra-short and conventional implants presented a statistically insignificant difference between all the parameters at all the follow-up visits (baseline, 6-, 9-, 12 months).

Conclusions

Within the limitations, it was thus concluded that ultra-short implants may be considered as a viable treatment option for vertically insufficient mandibular ridge. Further, long-term randomized controlled trials are required to establish the evidence.

Fracture Resistance of a Two-Piece Zirconia Implant System after Artificial Loading and/or Hydrothermal Aging-An In Vitro Investigation

The purpose of the present study was to assess the fracture resistance of a two-piece alumina-toughened zirconia implant system with a carbon-reinforced PEEK abutment screw.

METHODS

Thirty-two implants with screw-retained zirconia abutments were divided into four groups of eight samples each. Group 0 (control group) was neither loaded nor aged in a chewing simulator; group H was hydrothermally aged; group L was loaded with 98 N; and group HL was subjected to both hydrothermal aging and loading in a chewing simulator. One sample of each group was evaluated for t-m phase transformation, and the others were loaded until fracture. A one-way ANOVA was applied to evaluate differences between the groups.

RESULTS

No implant fracture occurred during the artificial chewing simulation. Furthermore, there were no statistically significant differences (p > 0.05) between the groups in terms of fracture resistance (group 0: 783 ± 43 N; group H: 742 ± 43 N; group L: 757 ± 86 N; group HL: 740 ± 43 N) and bending moment (group 0: 433 ± 26 Ncm; group H: 413 ± 23 Ncm; group L: 422 ± 49 Ncm; group HL: 408 ± 27 Ncm).

CONCLUSIONS

Within the limitations of the present investigation, it can be concluded that artificial loading and hydrothermal aging do not reduce the fracture resistance of the investigated implant system.

Biomaterials and Clinical Application of Dental Implants in Relation to Bone Density-A Narrative Review

Titanium has been the material of choice for dental implant fixtures due to its exceptional qualities, such as its excellent balance of rigidity and stiffness. Since zirconia is a soft-tissue-friendly material and caters to esthetic demands, it is an alternative to titanium for use in implants. Nevertheless, bone density plays a vital role in determining the material and design of implants. Compromised bone density leads to both early and late implant failures due to a lack of implant stability. Therefore, this narrative review aims to investigate the influence of implant material/design and surgical technique on bone density from both biomechanical and biological standpoints. Relevant articles were included for analysis. Dental implant materials can be fabricated from titanium, zirconia, and PEEK. In terms of mechanical and biological aspects, titanium is still the gold standard for dental implant materials. Additionally, the macro- and microgeometry of dental implants play a role in determining and planning the appropriate treatment because it can enhance the mechanical stress transmitted to the bone tissue. Under low-density conditions, a conical titanium implant design, longer length, large diameter, reverse buttress with self-tapping, small thread pitch, and deep thread depth are recommended. Implant material, implant design, surgical techniques, and bone density are pivotal factors affecting the success rates of dental implant placement in low-density bone. Further study is required to find the optimal implant material for a clinical setting's bone state.

Biomechanical effects of different materials for an occlusal device on implant-supported rehabilitation in a tooth clenching situation. A 3D finite element analysis

PURPOSE

The purpose of this 3D finite element analysis was to evaluate the biomechanical effects of different materials used to fabricate occlusal devices to achieve stress distribution in simulated abutment screws, dental implants, and peri-implant bone tissue in individuals who clench their teeth.

MATERIALS AND METHODS

Eight 3D models simulated a posterior maxillary bone block with three external hexagon implants (Ø4.0 × 7.0 mm) supporting a 3-unit screw-retained metal-ceramic prosthesis with different crown connection (splinting), and the use of an occlusal device (OD). The OD was modeled to be 2-mm thick. ANSYS 19.2 software was used to generate the finite-element models in the pre-and post-processing phases. Simulated abutment screws and dental implants were evaluated by von Mises stress maps, and simulated bone was evaluated by maximum principal stress and microstrain maps by using a finite element software program.

RESULTS

The highest stress values in the dental implants and screws were observed in single crowns without OD (M1). Furthermore, the highest stress values and bone tissue strain were found in single crowns without OD (M1). The simulated material for the OD did not cause many discrepancies in terms of the stress magnitude in the simulated dental implant and abutment screw for both single and splinted crowns; however, more rigid materials exhibited lower stress values.

CONCLUSION

The use of OD was effective in reducing stress in the simulated implants and abutment screws and stress and strain in the simulated bone tissue. The material used to simulate the OD influenced the biomechanical behavior of implant-supported fixed prostheses, whereas splints with rigid materials such as PEEK and PMMA exhibited better biomechanical behavior.

Pterygoid and tuberosity implants in the atrophic posterior maxilla: A retrospective cohort study

STATEMENT OF PROBLEM

Rehabilitation of the partially or completely edentulous posterior maxilla using dental implants is a clinical challenge because of the presence of the maxillary sinus, as well as the low quality and quantity of bone in that region. In addition to bone augmentation procedures, posterior maxillary rehabilitation using implants includes their anchoring in bones such as the zygoma, pterygoid, and maxillary tuberosity, as well as in short implants. However, the performance of pterygoid and tuberosity implants in the atrophic posterior maxilla is unclear.

PURPOSE

The purpose of this retrospective cohort study was to evaluate the survival of tuberosity and pterygoid implants in patients with posterior maxillary atrophy.

MATERIAL AND METHODS

A nonprobability convenient sample of patients who had received fixed prostheses on implants placed in the maxillary tuberosity or pterygoid regions was analyzed retrospectively. Demographic variables included sex (male, female) and age. Implant-related variables included surface characteristics, site of placement, implant design, length, diameter, and anteroposterior insertion angle. Prosthetic-related variables included the type of reconstruction for rehabilitation and loading protocols. Implant survival, complications, crestal bone loss, and follow-up intervals were also documented. Collected data were analyzed at both patient and implant levels. The demographics and implant characteristics of patients receiving pterygoid or tuberosity implants were analyzed with a statistical software program (α=.05). Survival analysis was estimated by using the nonparametric Kaplan-Meier curve.

RESULTS

A total of 119 patients had 183 pterygoid or tuberosity implants inserted. Most implants in the pterygoid region (71.5%) were Ø4.1 mm (87.4%) and 15 mm in length (60.1%). The most common prostheses were complete maxillary reconstructions (49.2%) with late loading (74.3%). The average implant anteroposterior insertion angle was 60.8 degrees. The cumulative survival rate was 97.3% (n=178) during the mean follow-up period of 57 months (range 1 to 168 months). Among all implants placed, 2.7% failed (n=5) within 2 months of their placement. The statistically significant differences noted between tuberosity and pterygoid implants were related to design, surface characteristics, and loading. The average crestal bone loss was 1.5 mm.

CONCLUSIONS

The survival of the implants placed in the maxillary tuberosity and pterygoid regions was high in patients with posterior maxillary atrophy.

Changes in Peri-implant Marginal Bone Level by Jaw Location: A Systematic Review and Meta-Analysis of 4970 Implants

The purpose of this study was to evaluate the current evidence on marginal bone-level changes (ΔMBL) around internal connection implants with fixed prostheses by jaw location over time. An electronic literature search for ΔMBL (change in marginal bone level) was conducted in 6 databases. The data from the included manuscripts were categorized by jaw sextant of the implants and duration of follow-up (<2 years, 2-5 years, and >5 years). Meta-analyses were performed on groups with at least 5 studies. A total of 1270 records were screened. Full-text review of 413 papers resulted in a total of 46 studies (representing 2259 patients with 4970 implants) included for quantitative synthesis and analysis. The ΔMBL was summarized at 2 time intervals with the following results: <2 years (anterior maxilla = 0.393 mm [95% confidence interval {CI}, 0.172, 0.613], posterior maxilla = 0.468 mm [95% CI, 0.288, 0.648], and posterior mandible 0.559 mm [95% CI, 0.397, 0.72]), 2 to 5 years (anterior maxilla = 0.683 mm [95% CI, 0.224, 1.142], posterior maxilla = 0.645 mm [95% CI, 0.42, 0.87], and posterior mandible 0.563 mm [95% CI, 0.278, 0.849]). There were insufficient studies in the anterior mandible and with follow-up data over 5 years for quantitative synthesis. Within the limitations of this study, location within the maxillary and mandibular jaws does not seem to influence ΔMBL around internal connection bone level implants with fixed restorations. Although there may be a tendency for greater initial remodeling in the posterior mandible followed by long-term stability, additional studies are needed to evaluate this further.

The Potential Value of Probiotics after Dental Implant Placement

Dental implantation is currently the optimal solution for tooth loss. However, the health and stability of dental implants have emerged as global public health concerns. Dental implant placement, healing of the surgical site, osseointegration, stability of bone tissues, and prevention of peri-implant diseases are challenges faced in achieving the long-term health and stability of implants. These have been ongoing concerns in the field of oral implantation. Probiotics, as beneficial microorganisms, play a significant role in the body by inhibiting pathogens, promoting bone tissue homeostasis, and facilitating tissue regeneration, modulating immune-inflammatory levels. This review explores the potential of probiotics in addressing post-implantation challenges. We summarize the existing research regarding the importance of probiotics in managing dental implant health and advocate for further research into their potential applications.

Effect of bone density on the survival of 407 sandblasted and acid-etched dental implants: A retrospective multicenter study

Background

This study evaluated the success and survival rate of sandblasted and acid-etched dental implants according to the patient's bone quality.

Methods

A multicenter retrospective study was conducted in five clinical centers between 2016 and March 2019. A total of 407 implants (KONTACTTM S, Biotech Dental, France) placed in 229 patients (61.5±12.9 years old) were included. Bone quality, classified as types D1 to D4 (Misch classification), maximal insertion torque, and bone loss were measured. The implant survival rate was evaluated after one year for the overall cohort and for each bone quality. The overall survival rate after four years was also estimated with a Kaplan-Meier analysis.

Results

After one year (12.8±9.6 months), eight implants were lost out of 407, representing an overall survival rate of 98%. It ranged from 100% for D1 to 89.7% for D4 (n=39), with significantly higher survival rates for D2 (n=93) and D3 (n=165) (98.9% and 98.2%, respectively) compared to D4. According to the Kaplan-Meier analysis, an overall survival rate of 96.5% was estimated after four years. An average maximal insertion torque of 45±12.6 N.cm and bone loss of 0.2±1.2 mm were measured.

Conclusion

The high overall survival rate (98%), the average maximal insertion torque (45 N.cm), and the low marginal bone loss indicated good clinical results with acid-etched implants. Despite the relatively high survival rate for each bone quality, the significantly lower results in the D4 group highlight the expected benefits of bone quality-based implants and surgical protocols.

Short implants compared to regular dental implants after bone augmentation in the atrophic posterior mandible: umbrella review and meta-analysis of success outcomes

PURPOSE

To assess the body of evidence of short versus regular implants after bone augmentation (BA) in the atrophic posterior mandible in the context of implant treatment success outcomes.

METHODS

Seven databases, two registries, and reference lists were searched for systematic reviews and meta-analysis (SR/MA), randomized controlled trials (RCTs) and longitudinal studies published in English, Spanish or German since 2012. Confidence in the SR/MA methodology was evaluated using AMSTAR-2 and the risk of bias of primary studies using Cochrane's RoB 2.0 and ROBINS-I. A random-effects meta-analysis and a meta-regression were performed for continuous and dichotomous outcomes. GRADE approach was used to assess the certainty of the evidence.

RESULTS

Eighteen SRs/MAs, most of them "critically low" and "low" confidence with substantial overlap, included 14 relevant RCTs with a high risk of bias. A cohort study with moderate risk of bias was added. Quantitative synthesis of 595 implants and 281 hemiarches/patients indicates that the use of short implants (< 10 mm) compared to regular implants and BA may reduce implant failure at 1-year follow-up, and marginal bone loss (MBL) at 3-, 5-, and 8-year follow-up; is likely to reduce the risk of biological complications at 1-, 3-, 5-, and 8-year follow-up; and may be the patient's preferred alternative. There is a correlation between bone height, MBL and biological complications.

CONCLUSIONS

The available evidence partially suggests that the use of short implants could decrease implant failure, MBL, and biological complications, and increase patient satisfaction. However, given the need for further RCTs and real-world evidence to fully evaluate short- and long-term outcomes, it would be prudent for clinicians to carefully consider the individual needs and circumstances of the patients before deciding whether to use short implants. Trial registration PROSPERO CRD42022333526.

Can radiomic features extracted from intra-oral radiographs predict physiological bone remodelling around dental implants? A hypothesis-generating study

AIM

The rate of physiological bone remodelling (PBR) occurring after implant placement has been associated with the later onset of progressive bone loss and peri-implantitis, leading to medium- and long-term implant therapy failure. It is still questionable, however, whether PBR is associated with specific bone characteristics. The aim of this study was to assess whether radiomic analysis could reveal not readily appreciable bone features useful for the prediction of PBR.

MATERIALS AND METHODS

Radiomic features were extracted from the radiographs taken at implant placement (T0) using LifeX software. Because of the multi-centre design of the source study, ComBat harmonization was applied to the cohort. Different machine-learning models were trained on selected radiomic features to develop and internally validate algorithms capable of predicting high PBR. In addition, results of the algorithm were included in a multivariate analysis with other clinical variables (tissue thickness and depth of implant position) to test their independent correlation with PBR.

RESULTS

Specific radiomic features extracted at T0 are associated with higher PBR around tissue-level implants after 3 months of unsubmerged healing (T1). In addition, taking advantage of machine-learning methods, a naive Bayes model was trained using radiomic features selected by fast correlation-based filter (FCBF), which showed the best performance in the prediction of PBR (AUC = 0.751, sensitivity = 66.0%, specificity = 68.4%, positive predictive value = 73.3%, negative predictive value = 60.5%). In addition, results of the whole model were included in a multivariate analysis with tissue thickness and depth of implant position, which were still found to be independently associated with PBR (p-value < .01).

CONCLUSION

The combination of radiomics and machine-learning methods seems to be a promising approach for the early prediction of PBR. Such an innovative approach could be also used for the study of not readily disclosed bone characteristics, thus helping to explain not fully understood clinical phenomena. Although promising, the performance of the radiomic model should be improved in terms of specificity and sensitivity by further studies in this field.

Avoiding implant-related complications in medically compromised patients with or without unhealthy lifestyle/Elevated oxidative stress

Increased human life expectancy broadens the alternatives for missing teeth and played a role in the widespread use of dental implants and related augmentation procedures for the aging population. Though, many of these patients may have one or more diseases. These systemic conditions may directly lead to surgical complications, compromise implant/bone healing, or influence long-term peri-implant health and its response to biologic nuisances. Offering patients credible expectations regarding intra- and postoperative complications and therapeutic prognosis is an ethical and legal obligation. Clear identification of potential types of adverse effects, complications, or errors is important for decision-making processes as they may be related to different local, systemic, and technical aspects. Therefore, the present review structures the underlying biological mechanisms, clinical evidence, and clinical recommendations for the most common systemic risk factors for implant-related complications.

Employing Indirect Adenosine 2A Receptors (A2AR) to Enhance Osseointegration of Titanium Devices: A Pre-Clinical Study

The present study aimed to evaluate the effect of dipyridamole, an indirect adenosine 2A receptors (A_2AR), on the osseointegration of titanium implants in a large, translational pre-clinical model. Sixty tapered, acid-etched titanium implants, treated with four different coatings ((i) Type I Bovine Collagen (control), (ii) 10 μM dipyridamole (DIPY), (iii) 100 μM DIPY, and (iv) 1000 μM DIPY), were inserted in the vertebral bodies of 15 female sheep (weight ~65 kg). Qualitative and quantitative analysis were performed after 3, 6, and 12 weeks in vivo to assess histological features, and percentages of bone-to-implant contact (%BIC) and bone area fraction occupancy (%BAFO). Data was analyzed using a general linear mixed model analysis with time in vivo and coating as fixed factors. Histomorphometric analysis after 3 weeks in vivo revealed higher BIC for DIPY coated implant groups (10 μM (30.42% ± 10.62), 100 μM (36.41% ± 10.62), and 1000 μM (32.46% ± 10.62)) in comparison to the control group (17.99% ± 5.82). Further, significantly higher BAFO was observed for implants augmented with 1000 μM of DIPY (43.84% ± 9.97) compared to the control group (31.89% ± 5.46). At 6 and 12 weeks, no significant differences were observed among groups. Histological analysis evidenced similar osseointegration features and an intramembranous-type healing pattern for all groups. Qualitative observation corroborated the increased presence of woven bone formation in intimate contact with the surface of the implant and within the threads at 3 weeks with increased concentrations of DIPY. Coating the implant surface with dipyridamole yielded a favorable effect with regard to BIC and BAFO at 3 weeks in vivo. These findings suggest a positive effect of DIPY on the early stages of osseointegration.

Do dental implants placed in patients with osteoporosis have higher risks of failure and marginal bone loss compared to those in healthy patients? A systematic review with meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to compare the dental implant survival rate and marginal bone loss between patients with and without osteoporosis.

MATERIALS AND METHODS

This systematic review was registered in PROSPERO (CRD42022356377). A systematic search was performed using five databases: MEDLINE/PubMed, Web of Science, Scopus, Embase, and ProQuest for articles published up to July 2022. Additional searches in ClinicalTrials.gov and the reference lists of included studies were performed. The eligibility criteria comprised observational studies with a direct comparison between patients with and without osteoporosis, with a minimum follow-up of 1 year and 10 implants placed in each group, which consider data analysis based on implant level, without restrictions on period or language of publication. The meta-analysis was performed using RevMan 5.4 program. Risk of bias analysis of the included studies was performed using the Newcastle-Ottawa scale (NOS).

RESULTS

Twelve studies met the eligibility criteria, totaling 1132 patients with a mean age range from 54 to 76.6 years. Most of the included patients were women (73.6%). A total of 3505 implants were evaluated-983 in patients with osteoporosis and 2522 in patients without osteoporosis. The meta-analysis indicated no difference in implant survival rates between patients with and without osteoporosis (OR, 1.78; 95% confidence interval [CI], 0.86-3.70; P = 0.12). However, significant bone loss was observed around dental implants placed in patients with osteoporosis (SMD, 0.71 mm; 95% CI, 0.06-0.87 mm). The NOS indicated a low risk of bias in the studies included. However, the certainty of the evidence was classified as very low and low for implant survival rates and bone loss, respectively.

CONCLUSION

According to the limitations of the present review, the data suggest that dental implants are a viable treatment option for the rehabilitation of patients with osteoporosis. However, clinical care by professionals is necessary to ensure the maintenance of peri-implant bone stability, as these patients may be susceptible to increased bone loss.

Bone resorption after maxillary reconstruction with the vascularized free iliac flap

The aim of this study was to evaluate the resorption of the iliac bone after maxillary reconstruction with a vascularized free iliac flap. Twenty-seven patients with maxillary defects who underwent maxillary reconstruction with the vascularized free iliac flap between January 2017 and January 2021 were included. Computed tomography (CT) images taken at 1 week, approximately 6 months, and 1 year after the surgery were used for evaluation. The total iliac bone thickness and height, cortical bone thickness, and cancellous bone density were measured in the CT images. Compared with 1 week after the surgery, the total thickness and height of the iliac bone were reduced significantly 1 year after the surgery, and the cortical bone thickness and cancellous bone density were reduced significantly at 6 months and 1 year after the surgery. Compared with 6 months after the surgery, cancellous bone density was reduced significantly 1 year after the surgery. In conclusion, during the first year after maxillary reconstruction with a vascularized free iliac flap, there was significant resorption of iliac bone, including the total iliac bone thickness and height, the cortical bone thickness, and the cancellous bone density.

Randomized clinical study of injectable dextrin-based hydrogel as a carrier of a synthetic bone substitute

OBJECTIVES

This study aimed to improve the performance and mode of administration of a glass-reinforced hydroxyapatite synthetic bone substitute, Bonelike by Biosckin® (BL®), by association with a dextrin-based hydrogel, DEXGEL, to achieve an injectable and moldable device named DEXGEL Bone.

METHODS

Twelve participants requiring pre-molar tooth extraction and implant placement were enrolled in this study. BL® granules (250-500 µm) were administered to 6 randomized participants whereas the other 6 received DEXGEL Bone. After 6 months, a bone biopsy of the grafted area was collected for histological and histomorphometric evaluation, prior to implant placement. The performance of DEXGEL Bone and BL® treatments on alveolar preservation were further analyzed by computed tomography and Hounsfield density analysis. Primary implant stability was analyzed by implant stability coefficient technique.

RESULTS

The healing of defects was free of any local or systemic complications. Both treatments showed good osseointegration with no signs of adverse reaction. DEXGEL Bone exhibited increased granule resorption (p = 0.029) accompanied by a tendency for more new bone ingrowth (although not statistically significant) compared to the BL® group. The addition of DEXGEL to BL® granules did not compromise bone volume or density, being even beneficial for implant primary stability (p = 0.017).

CONCLUSIONS

The hydrogel-reinforced biomaterial exhibited an easier handling, a better defect filling, and benefits in implant stability.

CLINICAL RELEVANCE

This study validates DEXGEL Bone safety and performance as an injectable carrier of granular bone substitutes for alveolar ridge preservation.

TRIAL REGISTRATION

European Databank on Medical Devices (EUDAMED) No. CIV-PT-18-01-02,705; Registo Nacional de Estudos Clínicos, RNEC, No. 30122.

Do antihypertensive medications effect the mandibular cortical bone thickness? A study using cone beam computed tomography images

OBJECTIVE

The aim of this study was to measure the association between antihypertensive medication use and mandibular cortical thickness.

STUDY DESIGN

This retrospective cross-sectional study was comprised of a study sample of 169 patients aged 40 to 69. Cone beam computed tomography scans were examined. The buccal cortical thickness of the mandibular ramus was measured. Participants were separated into the control or study group based on use of antihypertensive medications. The predictor variable was the use of antihypertensive medications. The primary outcome variable was cortical thickness of the mandible. Age was identified as a covariate affecting the outcome variable. The data was analyzed with a one-way analysis of covariance (ANCOVA) to remove the effect of age on the outcome variable. The groups were subdivided based on the sex of the patient.

RESULTS

The study sample was composed of 169 patients with a mean age of 52.1, and 54% were female. There were 67 patients in the antihypertensive group (39.6%). A mean difference of 0.21 mm was found (P = .0010, 95% CI 0.09, 0.34 mm). The difference persisted after adjusting for age with one-way ANCOVA testing (P < .001).

CONCLUSIONS

This study suggests that there may be an association between antihypertensive use and mandibular cortical thickness. Age may be an effect modifier with the effect increasing in older patients.

Bone-Regenerative Ability of Platelet-Rich Plasma Following Sinus Augmentation with Anorganic Bovine Bone: A Systematic Review with Meta-Analysis

BACKGROUND

The objective of this systematic review is to assess the effect of the adjuvant use of platelet-rich plasma (PRP) and its type on new bone formation by anorganic bovine bone during maxillary sinus floor augmentation procedure.

METHODS

PubMed, Cochrane Central Register of Controlled Trials, and Ovid databases were searched for relevant studies published up to 16 September 2021. Randomized clinical trials (RCTs) and non-randomized controlled clinical trials (CCTs) that reported data on the new bone formation (measured by histomorphometric analysis) were considered. Risk of bias and quality assessment of included studies were evaluated following the Cochrane Handbook for Systematic Reviews of Interventions and the Risk Of Bias In Non-randomised Studies of Interventions (ROBINS-I) tool. Strength of evidence was assessed following the approach of the Agency for Healthcare Research and Quality (AHRQ) through its evidence-based practice center (AHRQ EPC). The meta-analysis was based on the primary outcome of newly formed bone, for which the standard mean difference was calculated.

RESULTS

After the application of eligibility criteria, six clinical trials (three RCTs and three CCTs) covering 85 maxillary sinus floor elevation procedures were included. The pooled new bone formation value for PRP was 1.67 (95% CI: -0.15 to 3.49; I2: 86%), indicating the absence of significant effect. Plasma rich in growth factors (PRGF) was the pure PRP tested in five of the included studies. When sub-group (type of PRP) meta-analysis was performed, significantly higher new bone formation was observed in the PRGF group [2.85 (95% CI: 0.07 to 5.64; I2: 88%)] in comparison to the control group.

CONCLUSIONS

A beneficial effect on new bone formation after maxillary sinus floor elevation can be obtained when anorganic bovine bone is mixed with PRGF.

Clinical Evaluation of Short Tuberosity Implants among Type 2 Diabetic and Non-Diabetic Patients: A 5 Year Follow-Up

Aim: To assess clinical and radiographic parameters including bleeding on probing (BoP); probing depth (PD), plaque index (PI) and crestal bone loss (CBL) around short tuberosity implants (STI) supporting fixed partial dentures in patients with Type 2 diabetes mellitus (T2DM) and non-diabetics. Material and Methods: Participants with T2DM and without T2DM with at least one STI (6 mm) posteriorly restored with a fixed partial denture splinting premolar implant were included. A questionnaire collected demographic details including gender, age, duration of diabetes, habits of brushing, the total number of dental implants and location, implant loading after placement, restoration type, and family history of DM. Clinical and radiographic assessment of peri-implant parameters, i.e., bleeding on probing (BoP), probing depth (PD), plaque index (PI), and crestal bone loss (CBL) was performed. The restorative success of STI was determined by no sensation of the foreign body, lack of pain and dysesthesia, lack of infection, no radiolucency around the implant, and no mobility. The Kruskal-Wallis test was used for statistical analysis. A p-value of less than 0.05 was considered statistically significant. Results: Twenty-five T2DM (19 males and 6 females) and 25 non-diabetic (18 males and 7 females) participants were included. The number of STIs in T2DM was 41, whereas in non-diabetic it was 38. At 1 year follow-up, mean PI% in T2DM participants was 18.9% (19.2-21.4%) and in non-diabetics it was 17.6% (16.3-18.5%). The mean PD was recorded in diabetics (1.3 ± 5.0 mm) and non-diabetics (1.1 ± 3.2 mm). The BoP value in diabetics was 44.9% (39.8-46.4%) and 28.2% in non-diabetics (17.2-24.6%). At 5 years of follow-up, the mean PI% range in T2DM participants was 26.18% (25.4-29.1%) and 24.42% in non-diabetic (20.1-25.5%). The mean PD in millimeters around STI in T2DM was observed to be 2.3 ± 4.8 mm and 1.4 ± 3.4 mm in non-diabetics. In addition, BoP in diabetic participants was 39.54% (27.7-42.1%) and 24.42% in non-diabetics (20.1-25.5%). A total of six STIs failed, i.e., two in the non-diabetic and four in the T2DM group. Conclusions: Patients with T2DM have poor periodontal (BoP, PD, CBL) and restorative peri-implant parameters around STIs when compared to healthy (non-diabetic) participants at five years of follow-up. For long-term stability, glycemic control is pivotal along with following good plaque control.

Understanding the Stress Distribution on Anatomic Customized Root-Analog Dental Implant at Bone-Implant Interface for Different Bone Densities

The aim of this study is to assess the stress distribution on the bone tissue and bone-implant interface of a customized anatomic root-analog dental implant (RAI) by means of finite element analysis (FEA) for different types of bone density. A mandibular right second premolar was selected from the CBCT database. A DICOM file was converted to an STL file to create a CAD model in FEA software. The bone boundary model was created, while bone density types I-IV were determined. Von Mises stress was measured at bone tissues and bone-implant interfaces. To validate the models, the RAI was 3D printed through a laser powder-bed fusion (L-PBF) approach. The results revealed that all RAI designs could not cause plastic deformation or fracture resulting in lower stress than the ultimate tensile stress of natural bone and implant. Compared to a conventional screw-type implant, RAIs possess a more favorable stress distribution pattern around the bone tissue and the bone-implant interface. The presence of a porous structure was found to reduce the stress at cancellous bone in type IV bone density.

Short Implants versus Longer Implants with Sinus Floor Elevation: A Systemic Review and Meta-Analysis of Randomized Controlled Trials with a Post-Loading Follow-Up Duration of 5 Years

This study compared the outcome of fixed prostheses supported by short implants (<8 mm) and longer implants (≥8 mm) with an elevated sinus floor after 5 years of follow-up. The literature searches were performed electronically and manually in PubMed, EMBASE, and Web of Science databases to identify relevant articles published from 1 January 2013 to 31 January 2020. We selected eligible studies using inclusion criteria and assessed their quality. From 1688 identified studies, five randomized controlled trials were included. Between the short implant group and the control group, the implant failure-related pooled risk ratio (RR) was 3.64 (p = 0.07). The RR for technical complications was 2.61 (p = 0.0002), favoring longer implants. Marginal peri-implant bone loss after 1 and 5 years of function showed statistically significant less bone loss at short implants (1 year: mean difference = 0.21 mm; p < 0.00001; 5 years: mean difference = 0.26 mm; p = 0.02). The implant failure and the biological failure of both groups were similar after 5 years of follow-up. Short implants could be an alternative to long implants with an elevated sinus floor for atrophic maxillae in aging populations. Studies with larger trials and longer periods of follow-up (10 years) remain essential.

Effects of assessing the bone remodeling process in biomechanical finite element stability evaluations of dental implants

BACKGROUND AND OBJECTIVE

While an accurate assessment of the biomechanical stability of implants is essential in dental prosthesis planning and associated treatment assurance, the bone remodeling process is often ignored in biomechanical studies using finite element (FE) analysis. In this study, we aimed to analyze the significance of assessing the bone remodeling process in FE analysis for evaluating the biomechanical stability of dental implants. We compared the FE results considering the bone remodeling process with FE results simulated using commonly used conditions, with no considerations of the bone remodeling process.

METHODS

The mathematical model proposed by Komarova et al. was used to calculate cell population dynamics and changes in bone density at a discrete site. The model was implemented in the FE software ABAQUS, using the UMAT subroutine. Three-dimensional FE models were constructed for two types of bone (III and IV) and three values of implant diameter (4.0, 4.5, and 5.0 mm). An average biting force of 50 N in the vertical direction was applied during the bone remodeling process for 150 days. Afterwards, the maximum biting force of 200 N in the 30° oblique direction was applied to evaluate the stability of the implant systems.

RESULTS

To understand the impact of bone remodeling on the resultant mechanical responses, we focused on peri-implant cancellous bone based on two parameters: apparent density change and microstrain distribution. The bone density decreased by an average of 5.3 % after implantation, and it was the lowest on the 6^th day. The average density increases of the peri-implant cancellous bone were 264.4 kgm³ (bone type III) and 220.0 kgm³ (bone type IV) over 150 days. For the bone stability analysis, the maximum principal strain in the peri-implant bone was used to evaluate the bone stability. If the bone remodeling process is ignored, then the bone volume within the fatigue failure range of the microstrain differs significantly from that if the bone remodeling process is considered, i.e., 60 % higher for bone type III and 33.4 % lower for bone type IV than when the bone remodeling process is considered.

CONCLUSIONS

The FE result without considering the bone remodeling process could be considered a conservative criterion for bone type III. However, in bone type IV, the FE result without considering the bone remodeling process tends to underestimate the risks. The bone remodeling process is more affected by the initial bone quality than the implant diameter.

Effects of Magnetic Stimulation on Dental Implant Osseointegration: A Scoping Review

This PRISMA-ScR driven scoping review aims to evaluate the influence of magnetic field stimulation on dental implant osseointegration. Seven databases were screened adopting ad-hoc strings. All clinical and preclinical studies analyzing the effects of magnetic fields on dental implant osseointegration were included. From 3124 initial items, on the basis of the eligibility criteria, 33 articles, regarding both Pulsed ElectroMagnetic Fields (PEMF) and Static magnetic Fields from permanent Magnets (SFM) were finally included and critically analyzed. In vitro studies showed a positive effect of PEMF, but contrasting effects of SFM on bone cell proliferation, whereas cell adhesion and osteogenic differentiation were induced by both types of stimulation. In vivo studies showed an increased bone-to-implant contact rate in different animal models and clinical studies revealed positive effects on implant stability, under magnetic stimulation. In conclusion, although positive effects of magnetic exposure on osteogenesis activity and osseointegration emerged, this scoping review highlighted the need for further preclinical and clinical studies. More standardized designs, accurate choice of stimulation parameters, adequate methods of evaluation of the outcomes, greater sample size and longer follow-ups are needed to clearly assess the effect of magnetic fields on dental implant osseointegration.

Bone quality effect on short implants in the edentulous mandible: a finite element study

Introduction

The aim of this study was to verify whether the use of short implants could optimize stress distribution of bone surrounding implants in atrophic mandibles with different bone qualities.

Methods

A three-dimensional model of the atrophic mandible with three levels of bone quality was made using computer software. Short implants (6 mm) and standard implants (10 mm) were used in four designs: Design 1 "All-On four", Design 2 "All-On-four" with two short implants, Design 3 four vertical implants with two short implants, and Design 4 six short implants. The distal short implants were placed at the first molar position. All twelve models were imported into finite element analysis software, and 110 N oblique force was loaded on the left second premolar. Maximum principal stress values of peri-implant bone and the volumes of bone with over 3000 microstrians (overload)were analyzed.

Result

Stress values and volumes of overload bone increased in all four groups with the decline of bone quality. The highest stress values were found in the cortical bone surrounding the Design 1 inclined implant in two lower bone quality mandibles, and the lowest in Design 3. However, Design 1 had less overload bone tissue than all three designs with short implants.

Conclusion

Short implants placed posteriorly helped decrease stress values in peri-implant bone, while bone surrounding short implants had a high resorption risk in low bone quality mandible.

Association between Interleukin-1 Polymorphisms and Susceptibility to Dental Peri-Implant Disease: A Meta-Analysis

Background and objective: Interleukins (ILs), as important biochemical mediators, control the host response to inflammation and are associated with bone resorption. In the present meta-analysis, we investigated the association between IL−1 polymorphisms and susceptibility to dental peri-implant disease (PID). Materials and methods: We searched Web of Science, Cochrane Library, Scopus, and PubMed/Medline databases for studies published until 9 September2021, without any restrictions. We calculated the crude OR and 95% confidence intervals (CI) to estimate the associations between IL−1 polymorphisms and PID risk in the five genetic models. We further performed the subgroup analysis, sensitivity analysis, meta-regression, trial sequential analysis, and calculated the publication bias. Results: Out of 212 retrieved records, sixteen articles were used in the meta-analysis. There was no association between IL−1A (–889), IL−1B (−511), IL−1B (+3953), and IL−1RN (VNTR) polymorphisms and the risk of dental PIDs, but there was an increased risk of IL−1B (+3954) in the patients with PIDs. In addition, an association of the composite genotype of IL−1A (−889)/IL−1B (+3953) was observed with the risk of PIDs, but not for the composite genotype of IL−1A (−889)/IL−1B (+3954). The publication year, the ethnicity, sample size, and the outcome were significantly influenced pooled estimates of some genetic models. Trial sequential analysis showed the lack of sufficient sample sizes in the studies. Conclusions: Among IL−1 polymorphisms evaluated in the meta-analysis, the composite genotype of IL−1A (−889)/IL−1B (+3953) and IL−1B (+3954) were the only polymorphisms associated with the risk of PID. The T allele and CT genotype of IL−1B (+3954) polymorphism were also associated with an elevated risk of PID.

Effect of Splinting of Tilted External Hexagon Implants on 3-Unit Implant-Supported Prostheses in the Posterior Maxilla: A 3D Finite Element Analysis

PURPOSE

To assess the effects of tilted external hexagon implants and splinted restorations in terms of stress distribution on the bone tissue, implants, and prosthetic screws, using three-dimensional finite element analysis.

MATERIALS AND METHODS

Six models were used to simulate a posterior maxilla bone block (type IV) from the first premolar to the first molar. Each model included three 4.1-mm-diameter external hexagon implants with varying inclinations (0°, 17°, and 30°) and crown designs (splinted and nonsplinted restorations). The forces applied were as follows: 400 N axially (50 N for each slope of the cusp) and 200 N obliquely (45° only on the buccal slope of the cusp). Stress distribution on the implants and prosthetic screw was evaluated using Von Mises stress, while the maximum principal stress was used to evaluate the stress distribution in the bone tissue.

RESULTS

The oblique load increased the stress on all the structures in all the models. Increased inclination of the implants resulted in higher stress concentration in the bone tissue, implants, and prosthetic screws. However, splinted restorations contributed to reduction of the stress for the oblique loading, mainly in the bone tissue and prosthetic screw of the first molar, as the stress was shared between the first and second premolar restorations.

CONCLUSIONS

Tilted implants increased proportionally the stress on bone tissue and prosthetic screws of models. Additionally, splinting restorations reduced the stress concentration area in the simulated bone tissue, implants, and prosthetic screws in the first molar, as the stress was shared with the adjacent implants.

What is the influence of implant surface characteristics and/or implant material on the incidence and progression of peri-implantitis? A systematic literature review

OBJECTIVES

To answer the focused question, 'In animals or patients with dental implants, does implant surface characteristics and/or implant material have an effect on incidence and progression of peri-implantitis?'

MATERIAL AND METHODS

Pre-clinical in vivo experiments on experimental peri-implantitis and clinical trials with any aim and design, and ≥5 years follow-up, where the effect of ≥2 different type of implant material and/or surface characteristics on peri-implantitis incidence or severity, and/or progression, implant survival or losses due to peri-implantitis, and/or marginal bone levels/loss was assessed.

RESULTS

Meta-analyses based on data of pre-clinical experiments, using the ligature induced peri-implantitis model in the dog, indicated that after the spontaneous progression phase implants with a modified surface showed significantly greater radiographic bone loss (effect size 0.44 mm; 95%CI 0.10-0.79; p = .012; 8 publications) and area of infiltrated connective tissue (effect size 0.75 mm² ; 95%CI 0.15-1.34; p = .014; 5 publications) compared to non-modified surfaces. However, in 9 out of the 18 included experiments, reported in 25 publications, no significant differences were shown among the different implant surface types assessed. Clinical and/or radiographic data from 7605 patients with 26,188 implants, reported in 31 publications (20 RCTs, 3 CTs, 4 prospective cohort, and 4 retrospective studies; 12 with follow-up ≥10 years), overall did not show significant differences in the incidence of peri-implantitis, when this was reported or could be inferred, among the various implant surfaces. In general, high survival rates (90-100%) up to 30 years and no clinically relevant differences in marginal bone loss/levels, merely compatible with crestal remodelling, were presented for the various implant types.

CONCLUSION

Pre-clinical in vivo experiments indicate that surface characteristics of modified implants may have a significant negative impact on peri-implantitis progression, while clinical studies do not support the notion that there is a difference in peri-implantitis incidence among the various types of implant surfaces. No assumptions can be made regarding the possible impact of implant material on incidence and/or peri-implantitis progression due to limited information.

Osseodensification enables bone healing chambers with improved low-density bone site primary stability: an in vivo study

Primary implant stability is a prerequisite for successful implant osseointegration. The osseodensification technique (OD) is a non-subtractive drilling technique that preserves the bone tissue, increases osteotomy wall density, and improves the primary stability. This study aimed to investigate the hypothesis that OD, through a wider osteotomy, produces healing chambers (HCs) at the implant-bone interface without impacting low-density bone primary stability. Twenty implants (3.5 × 10 mm) with a nanohydroxyapatite (nHA) surface were inserted in the ilium of ten sheep. Implant beds were prepared as follows: (i) 2.7-mm-wide using subtractive conventional drilling (SCD) technique (n = 10); (ii) 3.8-mm-wide using an OD bur system (n = 10). The sheep were randomized to two groups, with samples collected at either 14-(n = 5) or 28-days (n = 5) post-surgery and processed for histological and histomorphometric evaluation of bone-implant contact (BIC) and bone area fraction occupancy (BAFO). No significant group differences were found with respect to final insertion torque and implant stability quotient (p > 0.050). BIC values were higher for SCD after 14 and 28 days (p < 0.050); however, BAFO values were similar (p > 0.050). It was possible to conclude that the OD technique allowed a wider implant bed preparation without prejudice on primary stability and bone remodeling.

Clinical, radiographic and restorative parameters for short tuberosity implants placed in smokers: a retrospective study with 5 year follow-up

This study aimed to estimate and compare the clinical, radiographic, and restorative parameters around short tuberosity implants (STIs) placed in cigarette smokers (CS) and never smokers (NS). In this 60-month follow-up retrospective study, a total of 50 (37 males + 13 females) individuals who had received 82 dental implants were included. These participants were categorized into two groups as follows: (i) Group-1: 25 self-reported systemically healthy CS with 43 STIs; and (ii) Group-2: 25 self-reported systemically healthy NS with 39 STIs. In both groups, peri-implant plaque index (PI), probing depth (PD), bleeding on probing (BOP), and crestal bone loss (CBL) and restorative parameters were measured at 12 and 60 months of follow-up. Group comparisons were performed utilizing the Kruskal-Wallis test. The significance level was set at p < 0.05. In CS and NS, the mean age of participants was 58.5 and 60.7 years, respectively. No statistically significant differences were observed in the overall mean levels of PD and CBL around STIs among CS and NS. However, a statistically significant increase was observed in the mean scores of BOP and PI around STIs in the NS and CS at 12 and 60 months follow-up, respectively. In both groups, the loosening of the implant was the most frequently encountered type of STI failure. The outcomes of the present study suggest that STIs placed in maxillary tuberosity can show reliable clinical, radiographic, and restorative stability among cigarettes smokers and non-smokers. However, the role of smoking status and oral hygiene cannot be disregarded in this scenario.

Quantitative assessment of the jawbone quality classification: A meta-analysis study

AIM

Bone quality is evaluated using bone density for qualitative classification, a characteristic that may be delicate to evaluate. Contemporary implantology that relies on modern measurement techniques, needs a more quantitative estimate of the bone quality.

MATERIALS AND METHODS

PubMed and EMBASE databases were searched with no time restriction. Clinical and radiographic studies reporting on alveolar ridge dimensions and its parameters in different areas of the dentate and edentulous jaws were included. A meta-analysis was performed using random effect models to report a combined mean for alveolar ridge and its parameters. Meta regression statistical tests were performed in order to identify differences in those outcome parameters.

RESULTS

30 studies were included. The majority of the selected studies (total of 27) used live human subjects and CBCT to analyze alveolar ridge dimensions and its parameters. Using the combined mean obtained from the meta-analysis, a typical portrait of the alveolar ridge was constructed, and a geometrically based quantitative bone classification proposed. The quantitative classification was found to match the existing qualitative classification.

CONCLUSION

A geometry-based analysis was constructed that yields valuable insights on the bone type based on its components and on the dynamics of the dentate / edentulous states.

Biomechanical effect of an occlusal device for patients with an implant-supported fixed dental prosthesis under parafunctional loading: A 3D finite element analysis

STATEMENT OF PROBLEM

Whether providing an occlusal device for a patient with bruxism and an implant-supported fixed dental prosthesis leads to improved biomechanics is unclear.

PURPOSE

The purpose of this 3D finite element analysis (FEA) study was to evaluate the biomechanical behavior of 3-unit implant-supported prostheses under parafunctional forces with and without an occlusal device.

MATERIALS AND METHODS

Eight 3D models consisting of a posterior (type IV) maxillary bone block with 3 external hexagon implants (Ø4.0×7.0 mm) and 3-unit implant-supported prostheses with different crown connections (splinted or unsplinted) and an occlusal device under functional and parafunctional loading were simulated. The abutment screws were evaluated by von Mises stress maps, and the bone tissue by maximum principal stress and microstrain maps by using a finite element software program.

RESULTS

An occlusal device improved the biomechanical behavior of the prostheses by reducing stress in the abutment screws and stress and strain in the bone tissue. However, the use of an occlusal device was not sufficiently effective to negate the biomechanical benefit of splinting.

CONCLUSIONS

The use of splinted crowns in the posterior maxillary region with an occlusal device was the most effective method of reducing stress in the abutment screws and stress and strain in the bone tissue when parafunction was modeled.

Porous Bone Increases the Risk of Posterior Mandibular Implant Failure

PURPOSE

Our recent study indicated that patients with osteoporosis had an increased risk for early and late implant failure perhaps due to a large cancellous space. Therefore, the purpose of the article is to explore the relationship between the amount of cancellous space in an implant site and implant failure.

PATIENTS AND METHODS

The authors conducted a retrospective cohort study on patients who received dental implants in the posterior mandible at the senior author's practice from January 1, 2008 to October 1, 2019. The primary outcome variable was time to implant failure. The primary predictor variable was the amount of cancellous bone between the buccal and lingual cortices (cancellous space). Other study variables included demographic variables, medical history variables, and implant site measurements. Statistical analysis was performed using descriptive statistics, chi-squared tests, single variable and multiple Cox proportional hazard analyses.

RESULTS

The study cohort (n = 220) was composed of 62.3% women and the average age was 58.2 years. The median follow-up time was 3.5 years (range: 1-12). Five-year survival rates for patients with a cancellous space of <4 mm was 100%, with a cancellous space of 4-6 mm was 95.3%, with a cancellous space of 6-8 mm was 88.2%, and with a cancellous space of >8 mm was 64.1%. In the final multivariate Cox proportional hazard model adjusting for age, gender, smoking status, site and buccal cortex width, cancellous space remained significantly associated with time to implant failure (aHR 1.7 per millimeter change [1.4 - 2.2], P < .0001).

CONCLUSIONS

The width of the cancellous space and subsequent gap between implant and cortical bone should be considered when placing implants into the mandibular molar sites. When the patient presents for an implant in the mandibular molar region, if the cancellous space is large, the patient should be informed of the risk.

How Do Parameters of Implant Primary Stability Correspond with CT-Evaluated Bone Quality in the Posterior Maxilla? A Correlation Analysis

The aim of the present study was to evaluate correlations between bone density and implant primary stability, considering various determinants such as age, gender, and geometry of implants (design, diameter). Bone density of edentulous posterior maxillae was assessed by computed tomography (CT)-derived Hounsfield units, and implant primary stability values were measured with insertion torque and resonance frequency analysis (RFA). A total of 60 implants in 30 partially edentulous patients were evaluated in the posterior maxilla with two different types of dental implants. The bone density evaluated by CT-derived Hounsfield units showed a significant correlation with primary stability parameters. The bone quality was more influenced by gender rather than age, and the type of implant was insignificant when determining primary stability. Such results imply that primary stability parameters can be used for objective assessment of bone quality, allowing surgical modifications especially in sites suspected of poor bone quality.

Clinical comparison between crestal and subcrestal dental implants: A systematic review and meta-analysis

STATEMENT OF PROBLEM

How the performance of dental implants is related to their occlusogingival placement, crestal or subcrestal, is unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate marginal bone loss, implant survival rate, and peri-implant soft tissue parameters between implants placed at the crestal and subcrestal bone level.

MATERIAL AND METHODS

Two independent reviewers searched the PubMed/MEDLINE, Embase, and Cochrane Library databases for randomized clinical trials published up to September 2020. The meta-analysis was based on the Mantel-Haenszel and the inverse variance methods (α=.05).

RESULTS

The search identified 928 references, and 10 studies met the eligibility criteria. A total of 393 participants received 709 implants, 351 at crestal bone levels and 358 at subcrestal bone levels. Meta-analysis indicated that crestal bone level implants showed similar marginal bone loss to that seen with subcrestal bone level implants (mm) (P=.79), independent of the subcrestal level (P=.05) and healing protocol (P=.24). The bone level implant placement did not affect the implant survival rate (P=.76), keratinized tissue (mm) (P=.91), probing depth (mm) (P=.70), or plaque index (%) (P=.92).

CONCLUSIONS

The evidence suggests that both approaches of implant placement are clinically acceptable in terms of peri-implant tissue parameters and implant-supported restoration survival.

Influence of Implant Dimensions in the Resorbed and Bone Augmented Mandible: A Finite Element Study

Aims:

The scope of this study was to analyze the influence of clinically feasible implant diameter and length on the stress transmitted to the peri-implant bone in the case of a resorbed and bone augmented mandible through finite element analysis.

Settings and Design:

The study was carried out in silico.

Subjects and Methods:

Resorbed and bone-augmented 3D models were derived from in vivo cone-beam computed tomography scans of the same patient. Corresponding implant systems were modeled with the diameter ranging from 3.3 to 6 mm and length ranging from 5 to 13 mm, and masticatory loads were applied on the abutment surface.

Statistical Analysis Used:

None.

Results:

In the bone augmented ridge, maximum stress values in the peri-implant region drastically decreased only when using implants of a diameter of 5 mm and 6 mm. Implants up to 4 mm in diameter led to comparable stress values with the ones obtained in the resorbed ridge, when using the larger implants. The increase of length reduced stress in the resorbed mandible, whereas in the bone augmented model, it led to small variations only in implants up to 4 mm in diameter.

Conclusions:

It was concluded that bone augmentation provides the optimal framework for clinicians to use larger implants, which, in turn, reduces stress in the peri-implant region. Diameter and length play an equally important role in decreasing stress. Implant dimensions should be carefully considered with ridge geometry.

Immediate Implants

Immediate implants have become a popular option for replacing teeth. This article describes the surgical and restorative considerations involved in the planning and placement of an immediate implant. Immediate implants require appropriate hard and soft tissue assessment. Virtual planning can help assist in planning of immediate implants. Radiographic and computed tomographic guidance can help in establishing the relationship between the planned implant to the hard tissue and anatomic structures. This article discusses a technique in fabrication of the immediate provisional and final restoration.

Porous Tantalum VS. Titanium Implants: Enhanced Mineralized Matrix Formation after Stem Cells Proliferation and Differentiation

Titanium dental implants are used routinely, with surgical procedure, to replace missing teeth. Even though they lead to satisfactory results, novel developments with implant materials can still improve implant treatment outcomes. The aim of this study was to investigate the efficiency of porous tantalum (Ta) dental implants for osseointegration, in comparison to classical titanium (Ti). Mesenchymal stem cells from the dental pulp (DPSC) were incubated on Ta, smooth titanium (STi), and rough titanium (RTi) to assess their adhesion, proliferation, osteodifferentiation, and mineralized matrix production. Cell proliferation was measured at 4 h, 24 h, 48 h with MTT test. Early osteogenic differentiation was followed after 4, 8, 12 days by alkaline phosphatase (ALP) quantification. Cells organization and matrix microstructure were studied with scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Collagen production and matrix mineralization were evaluated by immunostaining and histological staining. MTT test showed significantly higher proliferation of DPSC on Ta at 24 h and 48 h. However, APL quantification after 8 and 12 days was significantly lower for Ta, revealing a delayed differentiation, where cells were proliferating the more. After 3 weeks, collagen immunostaining showed an efficient production of collagen on all samples. However, Red Alizarin staining clearly revealed a higher calcification on Ta. The overall results tend to demonstrate that DPSC differentiation is delayed on Ta surface, due to a longer proliferation period until cells cover the 3D porous Ta structure. However, after 3 weeks, a more abundant mineralized matrix is produced on and inside Ta implants. Cell populations on porous Ta proliferate greater and faster, leading to the production of more calcium phosphate deposits than cells on roughened and smooth titanium surfaces, revealing a potential enhanced capacity for osseointegration.

Effect of bone quality and bone loss level around internal and external connection implants: A finite element analysis study

STATEMENT OF PROBLEM

A consensus regarding the biomechanical effects of vertical bone loss in normal and osteoporotic bone tissue according to different implant-abutment interfaces is lacking.

PURPOSE

The purpose of this finite element analysis study was to evaluate the effect of vertical bone loss (without bone loss; with 1.5-mm bone loss; with 3-mm bone loss; and with 4.5-mm bone loss) in normal and osteoporotic bone that received a Ø4×10-mm implant with different implant-abutment connections (external connection [external hexagon] and internal connection [Morse taper]) by using 3D finite element analysis.

MATERIAL AND METHODS

Sixteen 3D models were simulated. Axial and oblique forces of 200 N and 100 N, respectively, were applied on the occlusal surfaces of the prostheses. Maximum principal stress and microstrain were determined from the bone tissue of each model. von Mises stress analysis was used to evaluate the stress distribution in implants and prosthetic components (fixation screws, abutment, and crown).

RESULTS

The results showed higher stress concentrations in models with bone loss as increased vertical bone loss contributed to higher stress and microstrain in the bone tissue, regardless of the quality of bone and implant-abutment connection. Osteoporotic bone contributed to increase in microstrain in the trabecular bone. The internal connection showed lower stress than the external connection implants only in models without marginal bone loss. Furthermore, higher stress concentrations were observed in the implants and fixation screws in models with increased bone loss and external connection implants, mainly under oblique loading. Osteoporotic bone did not affect stress distribution in the implants and prosthetic components.

CONCLUSIONS

Progressive bone loss contributed to higher stress in the bone tissue, implants, and prosthetic components. The osteoporotic bone affects only the microstrain in the trabecular bone, but not the stress in the implants and prosthetic components. The internal connection implants showed lower stress in the cortical bone only in models without bone loss, while external connection implants exhibited higher stress in the implants and screws under oblique loading.