Analysis of Strain Distribution in Common Clinical Designs of Posterior Implant-Supported Fixed Partial Restorations: Comparison between Six Configurations

The configuration of implant-supported prostheses is considered to influence the magnitude of stress concentrations, affecting their survival rate. The purpose of this study is to determine, through strain gauge measurements during load application, the dispersion and magnitude of strain concentrations in different implant-supported prosthesis designs. All designs matched those commonly used in posterior partially edentulous states. Three implants were inserted into an epoxy resin model (PLM-4B Vishay Measurements Group Inc., Raleigh, NC, USA), allowing for the delivery of three- and four-unit crowns in different cemented configurations. Loads were applied at vertical and oblique directions over the cast crowns in six different configurations representing various posterior partially edentulous restorations. The readings from the strain gauges adhered to the implant necks' presented data on implant strain. Prostheses including cantilevers showed the highest strain among the three-unit prostheses within the prosthetic complex, and three single units showed the least (8133 µs vs. 201 µs, respectively). Angulated load application also had a role in amplifying the strains recorded, resulting in total strains of between 3.5 and 20 times higher than during vertical loading in all configurations. It can be concluded that the configuration of implant-fixed partial prosthesis changes the loads engaging the restoration, the implant, and, probably, the supporting bone.

Simultaneous implant placement and restoration with guided bone regeneration in the mandibular anterior region

BACKGROUND

Restoring the mandibular anterior teeth by implants can be difficult due to potential complications arising from using prosthetic implant connections that are larger than the incisors at the cementoenamel junction level.

METHODS

This retrospective study is aimed at determining the survival and esthetic outcomes of anterior mandible implants immediately placed and restored in patients diagnosed with stages 3-4 periodontitis. The study included 75 implants that were inserted along with guided bone regeneration in 42 patients. Over a follow-up period of 3 to 8 years (mean of 6.95 ± 1.78 years), the study evaluated esthetic, marginal bone loss (MBL), and biological and prosthetic complications.

RESULTS

No failures were recorded during the follow-up period; after eight years, the survival rate was 100%. Patient's age and gender did not have a statistically significant impact on MBL, but smokers had a greater MBL than non-smokers at the 8-year (2.98 mm vs. 1.23 mm, respectively, p = 0.016) time-point. At 3 years, only 13.3% of the implants had mesial papillae, 36.0% had distal papillae, and 16.0% had the cervical metallic part of the abutment exposed. Peri-implantitis was diagnosed in 20.7% of the patients at the 8-year follow-up time.

CONCLUSIONS

Based on the limitations of this study, immediate placement and restoration of the mandibular incisors can be a feasible procedure, but only a few implants achieved the complete restoration of the papillae.

Risk factors contributing to early implant failure following sinus augmentation: A study of a challenging cohort

BACKGROUND

Sinus augmentation has become a more predictable and successful procedure as the knowledge of its indications and complications increased. However, knowledge of risk factors leading to early implant failure (EIF) among challenging systemic and local conditions is insufficient.

OBJECTIVES

The present study aims to assess risk factors for EIF following sinus augmentation in a challenging cohort.

METHODS

A retrospective cohort study conducted during a period of 8 years in a tertiary referral centre providing surgical and dental health care. Implant and patient variables including age, ASA (American Society of Anesthesiology) physical status classification, smoking, residual alveolar bone, type of anaesthesia and EIF were collected.

RESULTS

Cohort was comprised of 751 implants placed in 271 individuals. EIF rates at the implant and patient level were 6.3% and 12.5%, respectively. EIF was found to be higher among smokers (patient level: χ2 (1) = 8.74, p = .003), ASA 2 physical classification patients (patient level: χ2 (2) = 6.75, p = .03), sinuses augmented under general anaesthesia (patient level: χ2 (1)=8.97, p = .003), higher bone gain (implant level: W = 12 350, p = .004), lower residual alveolar bone height (implant level: W = 13 837, p = .001) and multiple implantations (patient level: W = 3016.5, p = 0.01). However, other variables such as age, gender, collagen membrane and implant's dimensions did not reach significance.

CONCLUSIONS

Within the limits of the study, we can conclude that smoking, ASA 2 physical status classification, general anaesthesia, low residual alveolar bone height and numerous implants are risk factors for EIF following sinus augmentation in challenging cohorts.

Referral Patterns of General Dental Practitioners for Implant Surgery Procedures

PURPOSE

The growing demand for implants has led to their implementation by general dental practitioners (GDPs) in clinical practice. The present study assessed referral patterns of GDPs for the surgical phase of implant dental treatment.

MATERIALS AND METHODS

One hundred fifty GDPs were asked to fill out a structured questionnaire containing their demographic data and answer six questions characterising their referral patterns for implant dentistry.

RESULTS

Forty-one (41%) percent performed the surgical phase, and 87% provided implant restoration. Gender was the only influencing factor for the surgical phase, as 51.4% of male GDPs and 6.5% of female GDPs performed implant surgery themselves. Experience and practice set-up did not influence the referring decision. Fifty-four percent of the practitioners referred 0 to 5 patients per month, and the chosen specialists were: 80% oral and maxillofacial surgeon, 11% periodontist, and 9% selected a specialist depending on the individual case. The major reasons influencing the referral pattern were the complexity of the surgical procedure, followed by systemic medical compromise of the patient.

CONCLUSIONS

Most implant surgeries in Israel are still performed by specialists.

Evaluation of Implant Surface Modification with Nanohydroxyapatite Associated with the Use of L-PRF: In Vivo Study in Rats

Leukocyte-platelet-rich fibrin (L-PRF) contains growth factors that stimulate bone regeneration. This study evaluated the bone repair in a tibia rat model around two implant surfaces in combination or not with L-PRF by assessing microtomographic and histomorphometric parameters. A total of 48 female rats were used in the study, in which 24 received implants with two types of surface treatments (dual acid etched-DAE or nanohydroxyapatite-nanoHA), and the other 24 received the same mini implants with L-PRF, which was collected by cardiac puncture, centrifugated, and inserted in the bone bed. The animals were euthanized 7 and 30 days after implant placement, and the retrieved samples were prepared for microtomographic and histomorphometric (bone-to-implant contact-BIC; and Bone Area Fraction Occupancy-BAFO) analyses. The adhesion of the nanoHA surface onto the implant surface was investigated by insertion and removal in simulated bone medium (Sawbones). The adhesion evaluation revealed that the loss of nanoHA after this procedure (as measured with SEM) from the implant surface was less than 1%. Overall, the nanoHA surface presented more bone in contact and in proximity to the implant, a higher bone surface/tissue volume fraction, a higher number of bone trabeculae, as well as trabecular separation relative to the DAE surface. Such results were more evident when the nanoHA surface was combined with L-PRF and after 30 days in vivo. The nanoHA surface presented higher BAFO when compared to DAE, with or without association with L-PRF. Therefore, implants with a nanoHA surface potentially benefit from the association to L-PRF.

Thermal Changes of One-Piece Versus Two-Piece Implants During Setting of an Autopolymerized Acrylic Resin

Purpose: To evaluate differences in the temperature rise at the cervical area of one-piece vs two-piece implants during the setting of relined provisional crowns. Materials and Methods: A K-type thermocouple was fixed to the coronal thread of 15 one-piece implants and 15 two-piece implants that were mounted on a plexiglass apparatus. Baseline temperature (Bl Temp) was recorded before starting the curing process. The maximum temperature (Max Temp) reached during the process in both implant groups was also recorded. Total heat flux (THF) was calculated as well as the thermal amplitude (Temp-Amp) at the implant surface. Finally, the differences between the implant types were compared using unpaired t test. Results: The increase in temperature from baseline was statistically significantly greater in the one-piece implants than in the two-piece implants (P < .01). Similarly, the THF and Temp-Amp were significantly greater in the one-piece implants compared to two-piece implants (P < .01). Conclusions: The polymerization of PMMA-based resin temporary crowns produces a significant temperature rise in both one-piece and two-piece implants. It is advisable to use two-piece implants to restore immediately loaded implants to reduce the risk to implant surroundings that may occur due to the temperature rise at the implant neck.

Evaluation of Two Configurations of Hydroxyapatite and Beta-Tricalcium Phosphate in Sinus Grafts with Simultaneous Implant Installation: An Experimental Study in Rabbits

BACKGROUND

This study aimed to evaluate peri-implant bone formation in rabbits after sinus grafting mediated by hydroxyapatite and beta-tricalcium phosphate (HA + β-TCP) in granule or paste configurations, concomitant with immediate implant installation.

MATERIAL & METHODS

Thirty-four rabbit maxillary sinuses were grafted with HA + β-TCP, half of which were applied in a granule and half in a paste composition. Implant placement was performed simultaneously. At 7 and 40 days postoperatively, the animals were euthanized, and samples were prepared for tomographic, microtomographic, histological, histometric (hematoxylin and eosin staining, HE), and immunohistochemical (labeling of transcription factor Runx-2 [RUNX2], vascular endothelial growth factor [VEGF], osteocalcin [OCN], and tartrate-resistant acid phosphatase [TRAP]) analysis. Implant removal torque was also measured.

RESULTS

On tomography, maintenance of sinus membrane integrity was observed in both the groups. Higher values of morphometric parameters evaluated by micro-CT were found in the "paste group" after seven days. At 40 days, there were no significant differences between the groups in most of the microtomographic parameters evaluated. In histological sections stained with HE, a higher percentage of newly formed bone was observed in the "granule group" after 40 days. Similar positive immunolabeling was observed for both RUNX2 and OCN in both the experimental groups. TRAP immunolabeling was similar in both groups as well. VEGF labeling increased in the "granule group", indicating a higher osteoconductive potential in this biomaterial. Similar removal torque values were observed in both groups. Thus, the two HA + β-TCP configurations showed similar healing patterns of simultaneously installed implants adjacent to sinus floor elevation. However, significantly higher bone values were observed for the "granule configuration".

CONCLUSIONS

The HA + β-TCP granules and paste presentations showed favorable long-term healing results, with bone formation in similar quantities and quality adjacent to the implants.

The Effect of Anticoagulants on Early Implant Failure: A Retrospective Cohort Study

Background: Anticoagulants (AC) are among the most often prescribed drugs in the world. Data regarding ACs’ effect on the osseointegration of dental implants is lacking. Purpose: The aim of the present retrospective cohort study was to evaluate the effect of anticoagulants (AC) on early implant failure (EIF). The null hypothesis was that the use of AC increases the incidence of EIF. Materials and Methods: The research included 687 patients who underwent 2971 dental implant placements in the department of oral and maxillofacial surgery in Rabin medical center, Beilinson hospital, by specialists in oral and maxillofacial surgery. The study group comprised 173 (25.2%) patients and 708 (23.8%) implants using AC. The rest of the cohort served as a control. A structured form was used to collect data at patient and implant level. EIF was defined as implant failure within a period of up to 12 months from loading. EIF was the primary outcome parameter. A logistic regression model was used to predict EIF. Results: Implants placed in individuals ≥ 80 (odds ratio (OR) = 0.34, p = 0.05), and ASA 2/3 vs. ASA 1 individuals (OR = 0.30, p = 0.02/OR = 0.33, p = 0.03, respectively) had decreased odds of EIF, and implants in those using anticoagulants (OR = 2.64, p = 0.01) had increased odds of EIF. At the patient level, the odds of EIF in ASA 3 (OR = 0.53, p = 0.02) and IHD (OR = 0.40, p = 0.02) individuals decreased. In AF/VF (OR = 2.95, p = 0.01) individuals, EIF odds increased. Conclusions: Within the limitations of the present study, the use of AC is significantly associated with an increased likelihood of EIF: the OR was 2.64. Future research is required to validate and examine the prospective impact of AC on the osseointegration phenomena.

The Effect of Proton Pump Inhibitors on Early Implant Failure A Retrospective Cohort Study

Background and Objectives: Maintenance of a firm and long-term stable osseointegration is the primary goal of implant dentistry. Time is used to define implant failure characteristics. Early implant failure (EIF) occurs up to one year after loading. Recent studies indicated an association between proton pump inhibitors (PPI) therapy and failure of osseointegration. The present study assessed whether the use of PPIs is a risk factor to EIF. Materials and methods: A retrospective cohort study including 687 patients and 2971 dental implants. The study group (PPIs users) comprised 17.3% (119) individuals and 18.7% (555) implants. The remaining cohort (82.7% (568) individuals and 81.3% (2416) implants) served as control. The information was taken from the patients' files. The following information was collected: age, gender, physical status, systemic diseases, HbA1C values before and after implant-supported prosthesis delivery in cases of diabetes mellitus, smoking, implant location, number of implants per individual, bone augmentation, implant brand, length and width, and EIF. EIF was defined as implant removal within a period of up to 12 months from loading. Results: EIF in PPIs vs. non-PPIs users was 19.3% vs. 14.3% (p = 0.16) at patient level and 5.4% vs. 3.5% at implant level (p = 0.03). Univariate analysis yielded factors significantly associated with PPIs use, including older age, physical status of the American Society of Anesthesiology (ASA) 3, hypertension, hyperlipidemia, diabetes mellitus, osteoporosis, cardiovascular accident (CVA), location (anterior mandible), shorter and narrower implants, and higher number of implants per individual. Multivariate analysis yielded statistically significant OR of 1.91; p = 0.01 for EIF following PPIs use and 2.3; p < 0.001 for location in anterior mandible. Conclusions: Patients and their healthcare providers are advised to carefully consider the potential risks of taking PPIs prior to dental implant surgery. Further research is needed to confirm these risks and elucidate systemic and local factors that may be involved in such outcomes.

The Use of Cancellous Block Allografts for Reconstruction and Following Implant Failure Associated with Severe Bone Loss: A Prospective Survival and Histomorphometric Study

A failed implant site is prone to reduced alveolar bone volume, both horizontally and vertically. The present study assessed the outcome of using cancellous bone block allografts for ridge reconstruction following the removal of failed implants associated with severe bone loss. Individuals presenting with failed implants and massive bone loss were included. Cancellous bone block allografts were used for reconstruction of the atrophic alveolar ridge. Radiographic evaluation at 6 months postgrafting revealed favorable bone healing, allowing implant placement. Bone biopsy samples were taken during implant placement. Twenty-four blocks and 58 implants were placed in 16 patients. Over a mean follow-up time of 40 ± 15 months, the mean bone gain was 5 ± 0.5 mm horizontally and 7 ± 0.5 mm vertically. Block and implant survival rates were 96% (1 block failed) and 95% (3 implants failed), respectively. Histomorphometrically, the mean percentage of newly formed bone was 40%, with 20% residual cancellous block allograft and 40% marrow and connective tissue. Cancellous bone block allograft is a viable treatment alternative for reconstructing the alveolar ridge to achieve a successful second reimplantation, even in the presence of initial severe bone loss.

Screw-Type Collar vs. Non-Screw-Type Collar Implants—Comparison of Initial Stability, Soft Tissue Adaptation, and Early Marginal Bone Loss—A Preclinical Study in the Dog

Simple Summary

Implant neck characteristics may affect initial implant stability, soft tissue healing, and early marginal bone loss (EMBL) at second-stage surgery. Screw-type rough-surface collar implants had statistically significant poorer soft tissue healing and increased marginal bone loss compared to non-screw type implants at the time of 2nd-stage surgery. The significance of the novel implant design results in preventing EMBL awaits further research.

Abstract

Background: Implant neck characteristics may affect initial implant stability, soft tissue healing, and early marginal bone loss (EMBL) at second-stage surgery. The null hypothesis was that, following two-stage implant insertion, rough surface, non-screw-type collar implants will present lower EMBL at 2nd-stage surgery than rough-surface, screw-type collar implants. Methods: The study comprised seven male beagle dogs (mean weight 10.57 ± 2.8 kg; range 9–17 kg). A novel implant design was developed, composed of 2 parts: an apical part resembling a regular threaded implant, and a coronal non-screw-type collar, 4.2 mm long, served as the study group, whereas standard threaded implants served as control. Twenty-eight implants were placed: two on each side of the mandible. All implants were sand-blasted/acid-etched and of similar dimensions. Each dog received four implants. To assess location (anterior vs. posterior) impact on the outcomes, implants were placed as follows: group I—posterior mandible right—non-screw-type collar implants; group II—anterior mandible right—similar non-screw-type collar implants. To assess the collar-design effect on the outcomes, implants were placed as follows—Group III—anterior mandible left—control group, screw-type collar implants; Group IV—study group, posterior mandible left—non-screw-type collar implants. The following parameters were measured and recorded: insertion torque, soft tissue healing, early implant failure, and EMBL at 2nd-stage surgery. Results: No statistically significant differences were noted between groups I and II regarding all outcome parameters. At the same time, although insertion torque (55 N/cm) and early implant failure (0) were similar between groups III and IV, group III presented significantly poorer soft tissue healing (1.43 vs. 0.14) and increased marginal bone loss (0.86 vs. 0 mm). Conclusions: When a two-stage implant protocol was used, rough-surface non-screw-type collar implants led to superior outcomes at 2nd-stage surgery. Implant location did not affect the results. The significance of this result in preventing EMBL awaits further research.

Immediate versus Delayed Attachment Incorporation Impact on Prosthetic Aftercare among Mandibular Implant-Supported Overdenture Wearers

Background: Substantial effort is dedicated to finding the most favorable parameters that will ensure low aftercare demands among edentulous patients wearing mandibular implant supported overdentures (MISODs). The purpose of this retrospective cohort study was to compare prosthetic aftercare between MISOD patients with a simultaneous (group A) vs. a three-week settling in period (group B) prior to attachment incorporation. Methods: Forty-five patients enrolled in this study. Two implants per patient were placed using a two-stage implant insertion protocol. Second-stage surgery was performed after three months. All patients received ball attachments using the direct (chairside) incorporation method. Twenty-two patients received their dentures with simultaneous attachment activation and the rest—twenty-three patients—after a three-week settling in period. Patients’ files were scanned for aftercare visits. Outcome parameters included sore spot relief, attachment incorporation, and denture repair. Additionally, gingival index measurements were compared. Confounding factors included age, gender, and implant dimensions. Results: The mean follow-up for the entire cohort was 84 ± 21 months, and the range 39–120 months. The mean number of visits for group A vs. B respectively: pressure sores relieve (3.63 ± 0.84 vs. 3.71 ± 0.61, p = 0.581), liner exchange due to loss of retention (2.09 ± 1.03 vs. 2.31 ± 1.04 p = 0.487), and gingival index (1.3 ± 0.3 vs. 1.03 ± 0.2, p = 0.653) exhibited no statistically significant differences between the tested groups. No statistically significant differences between the groups were also noted for the denture repair aftercare treatments (p = 0.318) and the independent variables including age, gender, and implant length. Conclusions: Prosthetic aftercare in MISOD wearers is similar whether a simultaneous or a three-week settling in period for attachment incorporation is applied.

On the Association between Implant-Supported Prosthesis and Glycemic Control (HbA1c Values)

Background: Dietary habits, food intake and oral health are important factors for general health. The aim of these present study was to assess the association between implant-supported fixed oral rehabilitation and glycemia, by monitoring HbA1c values before and after implant-supported prostheses (ISP) delivery to diabetic individuals. Methods: Retrospective, cohort study based on dental records. All treatments were performed by experienced oral and maxillofacial surgeons and experienced prosthodontists. Inclusion criteria: ISP delivery, diagnosis of diabetes in the medical files, consecutive individuals. Variables included—primary outcome—differences (delta) in HbA1c values prior to implant placement and one year after ISP delivery, early implant failure (EIF). Confounding factors included age, gender, physical status, smoking, implant jaw location, implant length, implant width, total implant count per individual. Results: Statistically significant (p < 0.01) decrease in HbA1c from 7.10 ± 1.09% to 6.66 ± 1.02% following ISP delivery was recorded. The mean HbA1c delta was 0.44 ± 0.73%, where 39.0% of the patients had a significant improvement (delta decrease > 0.5%). Univariate and multivariate model using logistic regression at individual level showed that initial high HbA1c levels was the only factor positively predicting improvement (OR = 1.96, CI [1.22, 3.14], p < 0.01). Univariate model at implant level demonstrated that implants placed in the anterior maxilla also contributed to significant improvement in HbA1c values. Multivariate analysis at implant level was similar to individual level. Number of missing teeth did not affect the results significantly. Conclusion: ISP delivery to partially or completely edentulous diabetic individuals may improve HbA1c balance. The mechanism awaits future elucidation.

Minimizing MRONJ after Tooth Extraction in Cancer Patients Receiving Bone-Modifying Agents

Background: Medication-related osteonecrosis of the jaws (MRONJ) is a mucosal lesion of the maxillofacial region with necrotic bone exposure. MRONJ is believed to be multifactorial. Tooth extraction is debatably a risk factor for MRONJ. The targets of the present study were to examine MRONJ occurrence in patients using bone modifying agents (BMAs) for oncology indications and undergoing a dental extraction, and to assess whether suspected predisposing factors can predict MRONJ. Materials and Methods: This retrospective, cohort study included all patients fitting the inclusion criteria and a large tertiary medical center. Data were obtained from the hospital’s medical records using a structured questionnaire. Results: We performed 103 extractions on 93 patients. Local inflammation/infection of the extraction site was most associated with a complication (p = 0.001) OR = 13.46, 95% CI = (1.71, 105.41), OR = 13.5. When the indication for extraction was periodontal disease, vertical root fracture, or periapical pathosis, the odds of developing MRONJ were 4.29 times higher than for all other indications (p = 0.1), OR = 4.29, 95% CI = (1.16, 15.85). A significant association was found between the time of onset of BMA treatment and time of extraction and the development of MRONJ, OR = 3.34, 95% CI = (1.01, 10.18). Other variables did not correlate with the development of MRONJ. Conclusion: Local inflammation/infection and onset of BMA treatment prior to extraction yield a 10.23 times higher chance of developing MRONJ following tooth extraction. Future protocols should use this information to minimize MRONJ incidence.

The Use of Bone Block Allografts for Vertical Augmentation of the Extremely Atrophic Mandible

PURPOSE

Treatment alternatives based on implant-supported prostheses (ISPs) may be almost impossible in cases with extremely atrophic mandibles. Vertical bone augmentation is then the only possibility to achieve an ISP.

MATERIALS AND METHODS

The consequences of vertical augmentation in extremely atrophic mandibles (≤ 10-mm bone height) of edentulous patients using allogeneic block grafts via a submental approach were assessed. The recorded parameters were sex, age, physical status, hospitalization duration, postoperative complications, implant characteristics (length, diameter), early and late implant failure (yes/no; primary outcome variable). Bone height was measured at three points using the pre-grafting and pre-implant placement CBCT imaging. The difference between the measurements was defined as bone gain (primary outcome variable).

RESULTS

Sixteen patients (2 men, 14 women) were included. The preoperative bone height ranged from 4 to 10 mm. A mean of 5.3 ± 1 months was allowed for graft consolidation. The average bone height gain was 11.2 ± 3.1 mm. Two to six dental implants were placed in the grafted bone. Early implant failure occurred in 4 out of 73 (5.5%). Follow-up ranged from 12 to 92 (mean: 48 ± 30) months. All patients were followed for more than a year, and two additional late implant failures were recorded, rendering a 92% cumulative survival rate.

CONCLUSION

Bone grafting using allogeneic bone blocks via a submental approach seems to be a promising solution for reconstruction of the extremely atrophic mandible.

Esthetic Assessment Succeeding Anterior Atrophic Maxilla Augmentation with Cancellous Bone-Block Allograft and Late Restoration Loading

Background: Various conditions may lead to bony deficiency in the anterior maxilla. The present study evaluated esthetic (PES—pink esthetic score and WES—white esthetic score) results after augmentation of the anterior atrophic maxilla using cancellous bone-block allograft followed by implant placement and late (conventional) loading. Methods: Cohort study that included 33 patients with missing teeth in the upper anterior region characterized by extensive bone loss. Allogeneic cancellous bone-blocks were used for augmentation. Six months later, a dental implant was inserted. After a waiting time of an additional six-months, implant exposure and reconstruction were performed. The mean follow-up period was 62.93 ± 17.37 months (range 19–82 months). Results: The mean value of PES/WES was 17.8 ± 2.78. All patients had a PES/WES value above 12 (threshold value defined as clinically acceptable esthetics). The mean value of PES was 9.0 ± 1.79 and the mean value of WES was 8.8 ±1.84. Conclusions: Bone augmentation of the anterior atrophic maxilla using cancellous block-allograft and late loading supports achievement of a predictable esthetic result with long-term stability of soft and hard tissues around implant-supported reconstructions.

Factors affecting the decision to rehabilitate the posterior maxilla following surgical closure of oroantral communications/fistulae - A cohort study

BACKGROUND

Search of the English literature yielded no studies assessing the chosen dental treatment following surgical closure of oroantral communication/oroantral fistula (OAC/OAF). The purpose of the present study was to assess factors affecting the decision to rehabilitate the posterior maxilla following surgical closure of OAC/OAF.

METHODS

Consecutive patients at a single center. A structured form served to collect the data. The differences between groups (cases with versus cases without restoration) were assessed statistically.

RESULTS

A total of 58/121 responding individuals (62.1% men). Average age 51.57 years. Average waiting time prior to restoration 10.34 months. Most (51.7%) healthy. Most had a dental etiology (60.3%). Thirty-nine (67.2%) patients had a restoration of the posterior maxilla. Most of the patients responded that the reason not to do any restoration is the fear of failure (65.5%). Most of the patients completed the restoration procedure in a private clinic (87.2%). Only one patient (2.6%) reported a complication. Approximately half of the patients had implant supported prosthesis (ISP) following sinus augmentation (48.3%) with delayed implant placement. Most of the patients responded that the reason not to have ISP was the fear of failure (72.7%), and the rest responded because of financial issues (27.3%). For tooth supported restoration, most of the patients responded removable (90.9%).

CONCLUSIONS

Surgeons generally wait 6-12 months following surgical treatment of OAC/OAF prior to reconstruction with ISP. The chance for complications is low. Healthy women after dental induced OAC/OAF have the highest chances to seek for ISP in such circumstances.

Micro-CT Analysis of Microgap at a Novel Two-Piece Dental Implant Comprising a Replaceable Sleeve In Vitro

PURPOSE

Microcomputed tomography (micro-CT) is a relatively new modality to investigate mechanical deformations. The purpose of this study was to assess the microgap at the implant-sleeve connection of a new two-piece dental implant with a replaceable sleeve.

MATERIALS AND METHODS

Implants were assembled with 25-degree angulated abutments. Micro-CT was used to assess implant-sleeve connection gaps under the following mechanical conditions: (1) unloading; (2) compressive 10,000 cyclic loading with 400 N; (3) static compressive load of 200 N or 400 N for 24 hours.

RESULTS

The mean gap in the unloaded sample was 2.9 ± 0.9 μm. The mean gap difference after cyclic compressive load was 0.3 ± 0.15 μm, demonstrating a negligible effect for the cyclic loading. Under static compressive load, there was no increase in microgap size at 200 N. At 400 N, a significant (P < .05) increase was noted. While the mean values increased by 1.9 μm, the most pronounced significant increase in mean microgap was noted in the direction of force application (5.1 ± 2.14 μm), while a significant decrease in mean microgap (1.2 ± 1.47 μm) was noted on the opposite side.

CONCLUSION

The mechanical behavior of the implant-sleeve connection under static and dynamic loads was found to be within the previously reported range of implant dentistry.

Age-Related Palatal Wound Healing: An Experimental In Vivo Study

We assessed age-related excisional palatal mucoperiosteal wound closure in rats. A 4.2 mm diameter punch was used to create a secondary healing defect in the palate of Wistar rats. Study group-21, 18-month-old vs. control 21, 2-month-old males. The 2-dimensional area, maximum length and width of the soft tissue defect served as clinical outcome parameters. The dynamics of the initial three healing weeks were assessed. Semi-quantitative histomorphometric analysis of inflammation and myofibroblasts served for the evaluation of the inflammatory and proliferative wound healing phases. Complete wound closure was faster in the old rats. A dimensional related wound closure was observed in the young rats versus a symmetrical wound closure in the old rats. Inflammatory response was significantly delayed and of lower intensity in the old rats. Myofibroblastic response, representing the proliferative stage, was delayed and of lower intensity in the old rats, albeit not statistically significant. Reduced initial tissue damage due to decreased and delayed inflammatory response in the old rats ultimately led to faster clinical wound healing compared to the young rats, despite a statistically non-significant lower proliferative response in the old rats.

Fatigue Evaluation of a New Two-Piece Dental Implant, Having a Replaceable Titanium Sleeve

A new two-piece dental implant, having a replaceable thin titanium sleeve in its 5 mm crestal part was designed. The use of a sleeve of near 0.2 mm thickness reduces implant diameter by 0.4 mm. Narrower diameter implants may increase the likelihood of component fracture in dental implant systems. 14 two-piece dental implants, with 25 deg abutment angle were subjected to a dynamic fatigue test according to DIN EN ISO 14801. The highest load at which a runout (nonfailure) occurred at 5 × 106 cycles, amounted to 575 N. This load level was confirmed with n = 3 samples. The Wöhler curve was determined. Accordingly, the runout at 106 cycles can be anticipated as 625 N. The new two-piece Implant B™ design using a 0.2 mm sleeve is compatible with the DIN EN ISO 14801 standards for dimensions of 4.2 mm diameter and 13 mm length. It withstands dynamic fatigue test at least as good as any other standard endosseous implant.

Clinical and radiological characteristics of oro-antral communications/fistulae due to implant dentistry procedures: A cross-sectional retrospective study

OBJECTIVES

Assess the unique clinical and radiological sequelae following oro-antral communications/fistulae (OAC/OAF) due to implant dentistry vs other etiologies.

MATERIALS AND METHODS

A structured form served to collect data from medical records. All consecutive patients who underwent surgical closure of OACs/OAFs between 2003 and 2020, at a single center were included. Demographic, radiological, clinical, operative and postoperative characteristics were collected. The differences between groups (cases with implant dentistry etiology [IDE] vs cases with other etiologies) were assessed statistically.

RESULTS

Data were gathered from 121 cases. The findings show that IDE cases were more likely to be of older age (OR = 1.07, CI [1.02, 1.13] P = .02); to have a foreign body in the maxillary sinus (OR = 21.04, CI [4.34, 114.92] P < .01); to have fluid passage (OR = 11.40, CI [1.87, 118.73] P = .02) and purulent discharge through the fistula (OR = 3.52, CI [0.86, 16.34] P = .09).

CONCLUSIONS

Clinical and radiological sequelae due to OACs/OAFs secondary to implant dentistry procedures are more severe compared to other etiologies. The suggested pathogenesis is foreign body reaction. Early and accurate diagnosis of the foreign body location, followed by its early removal is recommended.

Influence of Vinyl Polysiloxane Impression Techniques on Marginal Fit of Metal Frameworks for Fixed Partial Dentures

Impression technique is one of the factors affecting restoration fit accuracy, which is a major aspect influencing its survival. The purpose of this study is to compare, in vivo, the effect of two commonly used Vinyl Polysiloxane (VPS) impression techniques on the metal framework fitting of fixed partial dentures. Ninety-two consecutive patients, diagnosed as partially edentulous, treated by fixed partial denture restorations, participated in the study. Group 1-impressions (n = 44) were subjected to the 1-step technique, while group 2 impressions (n = 48) were subjected the 2-step technique. Three accuracy assessment common methods: probe, tactile sense and radiographic test, were used to validate the clinical fit of the metal framework. Misfit was defined as even one test failure. Twenty-one (22.8%) out of 92 metal frameworks exhibited metal frameworks misfit, whereas the other 71 (77.2%) were found to be accurate. Group 1 presented significantly (p = 0.04) more metal frameworks misfit, 14/44 (31.8%) vs. 7/48 (14.6%). Restoration location (maxilla vs. mandible) had no statistically significant impact on the results (p = 0.461). The use of the VPS putty/wash 2-step impression technique is recommended to improve the clinical fit of fixed partial denture restorations.

Sinus augmentation - autograft vs. fresh frozen allograft: Bone density dynamics and implant stability

OBJECTIVES

Compare bone density changes and initial implant stability following sinus augmentation with autogenous bone (AB) vs. fresh frozen bone (FFB).

MATERIALS AND METHODS

Randomized, prospective, split mouth study. Sinus augmentation executed using either AB or FFB. Dental implants were inserted after 6 months of healing. Implant dimensions and insertion torques were recorded. Prostheses were delivered 6 months thereafter. All patients had computerized tomography (CT) scans 1 week (T1) and 6 months (T2) after initial bone grafting. Third CT (T3) was taken 12 months after prosthesis delivery. Data from CT scans was used to analyze bone density at each period.

RESULTS

A total of 15 patients (8 males, 7 females) following bilateral sinus augmentation procedures, were included. Mean age was 54 ± 5 years (range 48-60 years). All patients had 3 CT examinations. The initial augmented AB density was higher than the initial FFB density. Nevertheless, density differences between the two groups were not statistically significant at any time frame. At T2 density of both grafts showed a statistically significant increase. A significant increase from T2 to T3 was noted only for the FFB group. Implant insertion torque was significantly higher in the FFB group. Insertion torque ≥32 N/cm was achieved in significantly more patients in the FFB group.

CONCLUSION

The use of FFB for sinus augmentation is a reliable option of graft material. The newly formed bone quality performance, evaluated by CBCT density, is as good as AB, allowing predictable initial implant stability and osseointegration. Unnecessary morbidity associated with AB harvesting is thus avoided.

Effects of peri-implant infection on serum biochemical analysis

BACKGROUND

Peri-implant disease (PID) has not been directly linked to pathological organ changes. The present study assessed the dynamics of serum biochemical parameters in a model of experimental peri-implantitis in dogs, followed by open flap debridement.

METHODS

Seven male beagle dogs comprised the study group. Procedures were performed as follows-extractions of two premolars and one molar on each mandibular quadrant (Day 0); bone healing time (week14); placement of four rough-surface endoosseous implants, two on each mandibular side; implant uncovering (week 28); induction of experimental peri-implantitis by the use of three ligatures (weeks 31, 34, 37) followed by open flap debridement (week 42). Serum biochemical analysis following each procedure was compared to baseline. Biochemical parameters were assigned into four subsets of variables-inflammation, renal function, liver function, and blood glucose. Wilcoxon paired tests were conducted in order to identify statistically significant differences between baseline data and values obtained after each procedure RESULTS: Following experimental peri-implantitis, the dynamics of renal parameters and blood glucose were minimal whereas statistically significant (P < 0.05) increases were noted for inflammatory (total protein and albumin concentrations) and hepatic (ALT, AST) parameters. A statistically significant (P < 0.05) decrease was only noted for total bilirubin. After open flap debridement, inflammatory (total protein and albumin concentrations) and hepatic (AST) parameters returned to baseline.

CONCLUSIONS

Within their limits, the present results indicate that: (a) PID affects inflammatory and hepatic serum biochemical parameters, and (b) following open flap debridement most of the values returned to baseline.

Curcumin Promotes Primary Oral Wound Healing in a Rat Model

Curcumin is known as an anti-tumor, anti-aging, and wound healing promoter. The aim this study was to examine the effect of 2% curcumin paste application on primary wound healing in a palatal rat model. A mid-crestal incision was initiated on the maxillary alveolar ridge. A full thickness flap was raised on either side of the incision and was then repositioned and sutured. Experimental groups consisted of 2% curcumin (Cur), orabase (O), cut only (C), and intact control-no incision, no paste (N). Curcumin 2% and orabase were applied postoperatively every 12 h for 3 consecutive days. Rats were equally killed after 1 and 2 weeks. Histological data included-epithelial gap, inflammatory infiltrate, myofibroblasts, epithelial and connective tissue stem cell-related markers. Data were collected at two time points-1 and 2 weeks. There was no residual epithelial gap 1 week from incision in the Cur and O group vs. residual gap in the C group (P = .031). Curcumin 2% was associated with upregulated expression of epithelial-related markers (P < .05) although not statistically significant compared with orabase alone. Upregulation of connective tissue-related markers (P < .05) was unique to curcumin 2%. Curcumin promotes epithelial gap closure in a primary wound healing model in rats, possibly through upregulation of connective tissue stem cells leading to further epithelial differentiation and proliferation. Tel-Aviv University Animal Care Committee (approval Number: 01-16-031).

Sclerotherapy of Vascular Malformations in the Oral Cavity-Minimizing Postoperative Morbidity

Vascular malformations (VMs) are a wide vascular or lymphatic group of lesions common on the head and neck. The objective of this study was to assess the efficacy and morbidity of sclerotherapy for the treatment of VMs in the oral and perioral area. Special attention was given to factors that may contribute to minimizing postoperative morbidity. Data from 25 patients (32 lesions) with oral VMs submitted to sclerotherapy with monoethanolamine oleate (EAO) were included. A structured form was used to collect data. An arbitrary score was determined to evaluate postoperative morbidity. Each of the following signs or symptoms received one point: pain, swelling, hematoma, ulceration, erythema, transient numbness, and transient itching. Pain and swelling were further divided into mild to moderate (1 point) and severe (2 points). Theoretically, the score was in the range of 0–9. Calculated scores ranged 0–4. The patients were further divided into two groups with scores of 0–1 denoting minimal morbidity (MIN) and 2–4 denoting significant morbidity (SIG). The number of lesions in each morbidity-score group were comparable (MIN 17and SIG 15). There were no statistically significant differences between the groups regarding age, number of applications, or average injection volume per mm lesion. Statistically significant differences were noted regarding gender (p = 0.05), lesion diameter (p = 0.030), total volume of first (p = 0.007) and second application (p = 0.05), and total injected volume (p = 0.03). Factors contributing to the risk for significant morbidity included being male, lesion diameter > 5 mm, volume > 0.3 mL per application, and total injected volume > 0.3 mL. A waiting time of 12 weeks prior to additional EAO application was required in 12 out of 29 lesions for clinical observation of complete regression. It was concluded that sclerotherapy with EAO as monotherapy is easy to apply, safe, and effective within a small number of sessions. Application of <0.3 mL EAO per session, and a waiting time of 12 weeks prior to the second application, would significantly minimize morbidity.

Peri-implant disease affects systemic complete blood count values-an experimental in vivo study

OBJECTIVES

To assess complete blood count (CBC) dynamics following ligature removal and open flap debridement in experimental peri-implantitis in dogs.

MATERIALS AND METHODS

Seven male beagle dogs were included in the study. Four rough-surface implants were placed pair-wise in both sides of the mandible 14 weeks after tooth extraction. Second stage surgery was performed after 14 weeks. Experimental peri-implantitis was initiated 3 weeks later by ligature placement around the healing caps thus facilitating plaque accumulation and inducing inflammation and destruction of peri-implant tissues. Ligature removal and open flap debridement were performed 11 weeks later. The CBC values were compared with baseline after each procedure. Wilcoxon paired tests were conducted in order to identify statistically significant differences between baseline data and values obtained after each procedure.

RESULTS

Following experimental peri-implantitis, statistically significant (p < 0.05) increases were noted for white blood cells-WBC (9.62 ± 4.34 vs. 6.48 ± 1.34 cells per microliter of blood × 1000), hemoglobin-Hb (15.25 ± 0.94 vs. 13.52 ± 1.46, grams per deciliter), red blood cells-RBC (7.26 ± 0.79 vs. 5.9 ± 0.61 cells per microliter of blood × 1000), mean corpuscular hemoglobin-MCH (23.64 ± 0.96 vs. 23.16 ± 0.83 picograms/cell), platelets-PLT (349.86 ± 51.05 vs. 277.57 ± 66 cells per microliter of blood × 1000), and mean corpuscular hemoglobin concentration-MCHC (35.83 ± 0.27 vs. 31.04 ± 0.48 grams per deciliter). A statistically significant (p < 0.05) decrease in values was noted only for after ligature removal and open flap debridement. Mean corpuscular volume-MCV values were significantly lower (65.99 ± 2.31 vs. 74.65 ± 2.85 femtoliter) following 1^st ligature. Values returned to baseline after open flap debridement.

CONCLUSIONS

Within its limits, the present data suggest that experimentally induced peri-implantitis affects CBC values. Following surgical treatment, CBC values returned to normal. Clinical relevance This is the first study suggesting possible relationships between peri-implantitis and CBC values. Future studies, confirming such correlation, may provide an insight into the importance of peri-implant maintenance and treatment to minimize supporting tissues disease and reduce systemic effects.

The dynamics of closure following excisional mid-palatal mucoperiosteal wound in a rat model

OBJECTIVES

The aim of the present study was to assess macroscopically the time-related dimensional pattern of excisional palatal mucoperiosteal wound closure in rats, concomitantly with microscopic analysis of the density of inflammatory infiltrate and myofibroblasts.

MATERIALS AND METHODS

Excisional palatal wounds, 4.2 mm in diameter, were made in twenty-one 2-month-old male Wistar rats. The total area and anteroposterior/laterolateral dimensions of the wounds were measured macroscopically at 1, 2, and 3 weeks post-operatively. In addition, histomorphometry was used for assessment of the intensity of inflammation and density of myofibroblasts in the wound area.

RESULTS

A significant decrease was found in the total area and anteroposterior but not the laterolateral dimension of the wounds during the 2nd week. These changes were less prominent in the 3rd week. Three weeks post-operatively, the density of inflammatory infiltrate remained high in the central part of the wound concomitant with a significant increase in the number of myofibroblasts.

CONCLUSIONS

We concluded that the second week was the most significant in wound closure, with wound contraction first occurring in an anteroposterior plane followed by the laterolateral plane. The increased inflammatory reaction and changes in the density of myofibroblasts may explain the macroscopic decrease in wound dimensions in a time-related manner.

CLINICAL RELEVANCE

These findings emphasize the importance of the amount of soft tissue left at surgery, and suggest that the most appropriate time for the use of healing promoters would be the second post-operative week.

Sinus Augmentation with Simultaneous, Non-Submerged, Implant Placement Using a Minimally Invasive Hydraulic Technique

Background and objectives: To evaluate whether sinus augmentation, using a minimally invasive implant device, via a non-submerged surgical approach, might negatively influence the outcome. Materials and Methods: A retrospective cohort study was conducted by evaluating patients’ files, classifying them into two groups. Fifty patients (22 men 28 women) were included in the study, 25 in each group. The use of an implant device based on residual alveolar ridge height for sinus augmentation, radiographic evaluation, insertion torque, membrane perforation, post-operative healing, and a minimum of 12 months follow-up were evaluated. Results: The mean residual alveolar ridge height was 5.4 mm for the non-submerged group and 4.2 mm for the submerged group. There were no intraoperative or postoperative complications (including membrane perforations). The mean insertion torque was 45 N/cm for the study group and 20 N/cm for the control group. Complete soft tissue healing was observed within three weeks. Mean bone gain height was 8 mm for the study and 9.3 mm for the control group. All implants osseointegrated after 6–9 months of healing time. Mean follow-up was 17.5 months, range 12–36 months. Marginal bone loss at last follow-up was not statistically significantly different: 1 mm in the non-submerged vs. 1.2 mm in the submerged group. Conclusions: Submerged and non-submerged healing following maxillary sinus augmentation was comparable provided residual alveolar ridge height >5 mm and insertion torque >25 N/cm.

Allograft and Collagen Membrane Augmentation Procedures Preserve the Bone Level around Implants after Immediate Placement and Restoration

Background: Immediate implant placement and restoration (IPR), is a reliable treatment modality. Purpose: This historical prospective study evaluated the medium-term outcomes of hard tissue after IPR in the anterior maxilla with simultaneous hard tissue augmentation. Methods: Seventy-three patients treated with single-implant IPR in the anterior maxilla were followed for 1-8 years. Treatment involved, atraumatic extraction, immediate implant placement and abutment adaptation, followed by simultaneous augmentation with mineralized freeze-dried bone allograft (FDBA) particles to fill the gaps and restore the ridge. The surgical site was stabilized with a resorbable collagen membrane, followed by the connection of an acrylic provisional restoration. Results: All implants osseointegrated during the follow-up period (mean, 34 ± 22 months). Radiographic evaluation of the distance between the implant shoulder (IS) and crestal bone level (CBL) was of 0.86 ± 0.86 mm and 0.8 ± 0.84 mm mesially and distally, respectively. Splitting the results into up to 3 years and 3-8 years of follow-up data, the corresponding values were 0.90 ± 0.83 and 0.68 ± 0.88 for the mesial aspect and 0.99 ± 0.87and 0.74 ± 0.83 for the distal aspect, respectively. Mean peri-implant probing depth was 3.63 mm (SD ± 1.06) and 16 implants (22%) presented at least one bleeding pocket of ≥5 mm (peri implant mucositis). Conclusions: The immediate replacement of a single maxillary tooth by implants combined with guided bone regeneration is a predictable treatment modality with favorable peri-implant bony response.

Bone-implant-contact and new bone formation around implants placed in FDB blocks compared to placement at the adjunction of particulate FDB

BACKGROUND

The efficacy of human freeze-dried bone (h-FDB) as particulate vs block forms as a proper onlay augmented bone graft material to accommodate implants is undetermined.

PURPOSE

To evaluate osseointegration and new bone formation at implants placed in FDB blocks (BL group) and those at the adjunction of particulate FDB (PR group).

MATERIALS AND METHODS

Twelve pairs of h-FDB blocks were stabilized bilaterally to the calvaria of 12 rabbits. Twenty-four SLA implants were placed at the remodeled grafted blocks, 4 months later. A circumferential gap was created around one implant in each pair and packed with particulate h-FDB. Section biopsies were obtained at 2-month post implant placement (6 months post-block grafting). Bone-to-implant contact (BIC) and bone-area fraction (BAF) were histomorphometrically calculated.

RESULTS

The mean BIC was 34.4% and 33.5% for the BL and PR groups, respectively. The mean BAF was 23.9% and 26.4% for the corresponding groups, respectively. Osseointegration and newly formed bone were evident mostly between the threaded portions of the implants in proximity to the host rabbit calvaria compared to its cervical neck.

CONCLUSION

The particulate and the cancellous block h-FDB forms yielded similar BIC and BAF outcome. Full revascularization/revitalization is questioned.

Anterior atrophic mandible restoration using cancellous bone block allograft

BACKGROUND

Bone block grafting may be required to restore the alveolar process prior to implant placement in Kennedy Class IV partial edentulism of the anterior mandible.

PURPOSE

Evaluate the application of allograft cancellous bone blocks for the augmentation of the anterior atrophic mandible.

MATERIALS AND METHODS

Fourteen consecutive patients underwent augmentation with cancellous bone block allografts in the anterior mandible. A bony deficiency of at least 3 mm horizontally and up to 3 mm vertically according to computerized tomography para-axial reconstruction served as inclusion criteria. Following 6 months, 26 implants were placed and a cylindrical sample core was collected. All specimens were prepared for histological and histomorphometrical examination. The rehabilitation scheme was two dental implants, placed in the lateral incisor area, supporting a 4-unit implant-supported prosthesis.

RESULTS

Twenty-four blocks were placed in 14 patients. Mean follow-up was 26 ± 17 months. Mean bone gain was 5 ± 0.5 mm horizontally, and 2 ± 0.5 mm vertically. Twenty-six implants were used. Marginal bone loss at last follow up did not extend beyond the first thread. Block and implant survival rates were 91.6% and 100%, respectively. All patients but one received a fixed implant-supported prosthesis. Histomorphometrically, the mean fraction of the newly formed bone was 42%, that of the residual cancellous block-allograft 17%, and of the marrow and connective tissue 41%.

CONCLUSIONS

The potential of cancellous bone block allografts for reconstruction of Kennedy Class IV partial edentulism in the anterior mandible seems promising but still has to be evaluated scientifically in long-term observations.

The Feasibility of Flapless Approach to Sinus Augmentation Using an Implant Device Designed According to Residual Alveolar Ridge Height

Hydraulic sinus lift and augmentation may be successfully performed using a dedicated implant device designed according to residual bone height (RBH). The aim of this study was to evaluate whether a flapless surgical approach might negatively influence the outcome. A total of 40 consecutive patients (16 men and 24 women) were included in the study, 20 in each group (minimal flap/control versus flapless/study). Inclusion criteria were ≥ 3 mm RBH, ≥ 6 mm width of the residual alveolar ridge according to preoperative cone beam computerized tomography, and ≥ 8 mm buccopalatal keratinized gingiva for the flapless group. Primary outcome parameters included intraoperative membrane perforation. Secondary outcome parameters included postoperative infection, soft tissue healing, bone gain, and short-term dental implant survival. Mean RBH was 4.6 mm. No intraoperative membrane perforations and no postoperative infections were observed. Mean bone gain height was similar for both groups, at 11 mm. Soft tissue healing was observed within 2 months. In all cases, second-stage surgery allowed generation of at least 2 mm of keratinized gingiva buccally. All implants were osseointegrated at second-stage surgery. The use of a flapless approach to maxillary sinus augmentation using an implant device based on RBH yields predictable results.

Age-related new bone formation following the use of cancellous bone-block allografts for reconstruction of atrophic alveolar ridges

BACKGROUND

An age-related decrease in the number of osteogenic progenitor cells may compromise bone augmentation.

PURPOSE

Histomorphometrical assessment of age-related new bone formation, following atrophic alveolar ridge reconstruction, using cancellous bone-block allografts.

MATERIAL AND METHODS

Ninety-three consecutive patients (58 females and 35 males) were referred for implant-supported restoration of 122 severe atrophic alveolar ridges. Alveolar ridge deficiency locations were classified as anterior maxilla (n = 58), posterior maxilla (n= 32), and posterior mandible (n = 32). A bony deficiency of at least 3 mm horizontally and up to 3 mm vertically according to computerized tomography (CT) in the posterior mandible and anterior maxilla, served as inclusion criteria. In the posterior maxilla, a residual alveolar ridge up to 4 mm vertically according to CT served as inclusion criteria. Augmentation was performed by the use of cancellous bone-block allografts. Bone biopsies (9-month posterior maxilla, 4 months anterior maxilla and posterior mandible) of young (≤40 years) versus older (>40 years) patients were histomorphometrically evaluated.

RESULTS

In the posterior maxilla, no statistically significant histomorphometric differences were noted. While at the anterior maxilla and posterior mandible, statistically significant more newly formed bone was found in young versus older individuals, respectively (38.6% vs 19.8%, P = 0.04 and 69% vs 31%, P = .05).

CONCLUSION

New bone formation following residual alveolar ridge bone grafting is age-related. Longer bone consolidation and healing time may be recommended for older individuals.

Bone-to-Implant Contact and New Bone Formation Within Human Freeze-Dried Bone Blocks Grafted Over Rabbit Calvaria

PURPOSE

To assess the extent of osseointegration with rough-surface implants and new bone formation (NBF) within human freeze-dried bone blocks (h-FDB) grafted over rabbit calvaria.

MATERIALS AND METHODS

A total of 18 rectangular h-FDB blocks were stabilized bilaterally to the calvaria of nine New Zealand rabbits by two mini titanium screws each. A total of 18 rough-surface implants (5.0 × 6.0-mm) were placed, 9 simultaneously (immediate placement [IP]) on one side and 9 at 3 months after block grafting (delayed placement [DP]) on the contralateral side. At 12 weeks after the second surgical procedure, block biopsies were harvested and processed for histologic analysis. Morphometric measurements consisted of bone-to-implant contact (BIC) and the extent of NBF from the calvarial surface and outward into the block. A paired t test was applied for statistical analysis.

RESULTS

All h-FDB blocks were integrated, and the implants showed clinical stability. Histologically, the BIC was primarily between the apical end of the implants and the host rabbit calvaria. Bone growth between the implant threads was minimal and inconsistent among all animals. Morphometric measurements showed that the mean BIC of the IP and DP implants with the blocks was 10.50% ± 5.99% and 23.06% ± 9.58%, respectively (P < .001). NBF was observed primarily in the cancellous compartment of the block adjacent to the recipient calvarial bed. The extent of NBF into the block around the IP and DP implants was 9.95% ± 8.41% and 12.90% ± 11.07%, respectively (P = 0.2).

CONCLUSION

In this model, a significantly lower BIC was demonstrated when implants were placed simultaneously with h-FDB block grafting compared to those placed in a two-stage mode. However, both techniques showed limited osseointegration.

Volumetric Stability of Fresh Frozen Bone Blocks in Atrophic Posterior Mandible Augmentation

Fresh frozen bone allografts (FFB) have become an alternative for bone augmentation in the past decades, especially because of the absence of recent reports of disease transmission or immunologic reactions when it is used. The aim of this prospective controlled study is to evaluate volumetric changes of newly created bone following reconstruction of the atrophic posterior mandible. Twenty consecutive patients presenting for reconstruction of posterior mandibular alveolar bone ridge width ≤6.0 mm and/or height ≤6.0 who met all inclusion and exclusion criteria were included. FFB blocks were used. The main outcome variable investigated was bone volume dynamics. Vertical, horizontal, and 3-dimensional bone gain data were measured from computerized tomography scans. The main predictor variable was time evaluated at 3 points: immediately after surgery (T1), at implant placement (T2), and 1 year after functional loading (T3). Secondary outcome parameters evaluated were implant survival, histologic findings, and microtomographic morphometry. The study included 28 hemi-mandibles, 50 FFB bone blocks, and 15 female and 5 male patients (mean age, 51.8 years). Block and implant survival rates were 100% and 96%, respectively, after 31.75 months of follow-up. Vertical and horizontal bone gain at T2 was 5.15 and 6.42 mm, respectively. Volumetric resorption was 31% at T2, followed by an additional 10% reduction at T3. Histologic evaluation showed newly formed vital bone in intimate contact with the remaining FFB. Microtomography revealed 31.8% newly formed bone, 14.5% remaining grafted bone, and 53.7% connective tissue and bone marrow. Thus, FFB blocks may lead to new bone formation and consolidation, with satisfactory volumetric bone maintenance, allowing implant-supported rehabilitation with high success rates.

[Establishing adequate periimplant zone of keratinized mucosa to enhance periimplant health]

The presence of an adequate zone of keratinized mucosa (KM) for maintaining gingival health associated with natural teeth is usually described as the presence of 1-2 mm of attached gingiva (AG). Dental implants without KM measuring 2 mm or more, exposed to high levels of bacterial plaque, have shown higher scores of plaque accumulation, peri-implant 'mucosal inflammation', bleeding on probing, peri-implantitis, alveolar bone loss and recession. In a recent study the effects of KM width on peri-implant tissue health was assessed. Significant improvements in clinical and immunological parameters were noted after increasing KM width by the use of free gingival graft (FGG) surgery. A recent systematic review evaluated the efficacy of various techniques and biomaterials adopted in periimplant KM augmentation. Free gingival graft, connective tissue graft, acellular dermal matrix and collagen matrix were used for KM augmentation. Improvements in KM width were reported in all studies. A definitive conclusion could not be achieved owing to the lack of well-designed studies and appropriate methods of studying soft tissue. The establishment of universal surgical guidelines and measurement systems is imperative in the future. The present manuscript will describe the clinical use of FGG for establishing adequate periimplant zone of KM to enhance periimplant health.

Maxillary Sinus Grafting with Autograft Versus Fresh-Frozen Allograft: A Split-Mouth Evaluation of Bone Volume Dynamics

PURPOSE

To compare volumetric changes after sinus augmentation of completely edentulous maxillae with either autogenous or allogeneic fresh-frozen bone particles.

MATERIALS AND METHODS

This split-mouth study in patients who required bilateral sinus grafting used autograft particles for one sinus and allograft particles for the contralateral sinus. The grafted sinuses were left to heal for 6 months prior to implant insertion. All patients underwent four computed tomography scans: prior to augmentation and 1 week, 6 months, and 12 months after grafting. Computer software was used to analyze bone graft volume in each scan.

RESULTS

Fifteen patients (8 men, 7 women) with a mean age of 54 ± 5 years (range, 48 to 60 years) took part and underwent 30 sinus augmentation procedures. Mean autograft and allograft volumes were not statistically significantly different at each time point (1 week: 2.01 ± 0.43 cm³ vs 2.46 ± 0.79 cm³; 6 months: 1.53 ± 0.49 cm³ vs 1.75 ± 0.64 cm³; and 12 months: 1.38 ± 0.43 cm³ vs 1.59 ± 0.56 cm³, respectively). Mean volumetric reductions of 31.35% and 35.36% (23.9% and 29.9% in the 6 months prior to implant insertion, followed by an additional 9% and 9% in the following 6 months), relative to 1 week postgrafting, were noted for the autograft and allograft groups, respectively, after 12 months.

CONCLUSION

On the basis of this split-mouth study of 15 patients, there was no statistically significant volumetric difference after 12 months between the use of autograft or allografts for sinus augmentation. Fresh-frozen bone allograft may serve as an alternative that avoids the morbidity associated with autograft harvesting.

Reliability of retrievable cemented implant-supported prostheses

STATEMENT OF PROBLEM

One of the disadvantages of a cemented implant restoration is the potential difficulty of retrieving it. The restoration may be destroyed during removal.

PURPOSE

The purpose of this retrospective clinical study was to assess the long-term survival rates of cemented posterior metal ceramic implant-supported prostheses (ISPs) with a metal screw access hole.

MATERIAL AND METHODS

During a 12-year period, 274 cemented ISPs with an abutment screw access hole in the metal framework were assessed and served as the study group, and 119 conventional cemented ISPs (without access hole) served as the control group. Participants were followed every 6 months in the first year and once a year subsequently. Ceramic fracture, screw loosening, and refabrication were the prosthetic outcome parameters evaluated at the recall. The Pearson Chi square and Fisher exact test were used to compare the outcome parameters between the control and study groups.

RESULTS

A total of 1005 implants and 393 ISPs were evaluated. Ceramic fracture occurred in 6.6% of the ISPs (6.2% test and 7.6% control). Screw loosening occurred in 3.28% of the test group and 3.36% of the control group. Refabrication of ISPs was done in 2.79% of all restorations, (1.45% test and 6.72% control [P=.012]).

CONCLUSIONS

Within the limits of this study, preparing cemented ISPs with a screw access hole in the metal framework improves ISP survival rates over time and lowers the cost of maintenance without increasing the risk for porcelain fracture or screw loosening.

Evaluation of a topical herbal patch for soft tissue wound healing: an animal study

Aim

This study evaluated the effects of a topical herbal patch (PerioPatch®) for gingival wound healing in a rat model.

Materials and Methods

A mid‐crestal incision was performed on each side of the edentulous anterior maxilla in 48, 6‐month‐old, Wistar rats. Full‐thickness flaps were raised, repositioned and sutured. Four experimental groups were established: herbal patch, placebo patch, no patch and no patch and no surgery. Patches were placed immediately after surgery and replaced every 12 h for the following 3 days. Half of the animals were killed after 5 and the remaining ones after 12 days. Tissue blocks were retrieved and processed for histological and immunohistochemical evaluation. Epithelial gap, collagen contents, amount of macrophages, cellular proliferation and vascular contents were evaluated in the central incision area. Statistical analysis consisted of two‐way anova.

Results

The herbal patch group presented the smallest epithelial gap at 12 days, the highest collagen content both at 5 and 12 days, a larger number of proliferating cells at day 5 and more numerous blood vessels at day 12. Macrophage number was similar in all groups.

Conclusion

Herbal patch improved wound healing in this animal model.

Maxillary sinus grafting with autograft vs. fresh frozen allograft: a split-mouth histomorphometric study

BACKGROUND

Surgical techniques as sinus floor augmentation have made it possible to increase the bone volume of the posterior maxilla so that implant placement may be feasible. A large variety of bone grafting materials have been utilized for sinus floor augmentation. A good alternative is allograft. Fresh frozen bone is harvested from live or cadaveric donors and then immediately frozen and stored at -80 °C. To date, studies about the effect of fresh frozen bone are scarce.

OBJECTIVE

Evaluation of new bone formation, following maxillary sinus grafting with autograft vs. fresh frozen allograft.

MATERIALS AND METHODS

A split-mouth edentulous design including 15 patients was used. Sinus floor augmentation was carried out using either autogenous bone harvested from the ramus area or fresh frozen bone from allogeneic femoral heads. The choice was determined randomly, using a randomized table. The grafted sinus was left to heal for 6 months. Biopsies were harvested from the lateral wall. The biopsies were used for bone histology and histomorphometric analysis. After collection of the biopsy, dental implants were placed. After a healing period of 6 months, the implants were loaded.

RESULTS

Implant survival, histology, and histomorphometry of sinuses grafted with autogenous or fresh frozen bone were similar. The new bone formation took place predominantly around and in-between particles.

CONCLUSIONS

The findings of the present study support the use of fresh frozen bone allografts for sinus floor augmentation.