Effect of butyrate, a bacterial by-product, on the viability and ICAM-1 expression/production of human vascular endothelial cells: Role in infectious pulpal/periapical diseases.

AIM: To investigate the effects of butyric acid (BA), a metabolic product generated by pulp and root canal pathogens, on the viability and intercellular adhesion molecule-1 (ICAM-1) production of endothelial cells, which are crucial to angiogenesis and pulpal/periapical wound healing. METHODOLOGY: Endothelial cells were exposed to butyrate with/without inhibitors. Cell viability, apoptosis and reactive oxygen species (ROS) were evaluated using an MTT assay, PI/annexin V and DCF fluorescence flow cytometry respectively. RNA and protein expression was determined using a polymerase chain reaction assay and Western blotting or immunofluorescent staining. Soluble ICAM-1 (sICAM-1) was measured using an enzyme-linked immunosorbent assay. The quantitative results were expressed as mean ± standard error (SE) of the mean. The data were analysed using a paired Student's t-test where necessary. A p-value ≤0.05 was considered to indicate a statistically significant difference between groups. RESULTS: Butyrate (>4 mM) inhibited cell viability and induced cellular apoptosis and necrosis. It inhibited cyclin B1 but stimulated p21 and p27 expression. Butyrate stimulated ROS production and hemeoxygenase-1 (HO-1) expression as well as activated the Ac-H3, p-ATM, p-ATR, p-Chk1, p-Chk2, p-p38 and p-Akt expression of endothelial cells. Butyrate stimulated ICAM-1 mRNA/protein expression and significant sICAM-1 production (p < .05). Superoxide dismutase, 5z-7oxozeaenol, SB203580 and compound C (p <  .05), but not ZnPP, CGK733, AZD7762 or LY294002, attenuated butyrate cytotoxicity to endothelial cells. Notably, little effect on butyrate-stimulated sICAM-1 secretion was found. Valproic acid, phenylbutyrate and trichostatin (three histone deacetylase inhibitors) significantly induced sICAM-1 production (p < .05). CONCLUSION: Butyric acid inhibited proliferation, induced apoptosis, stimulated ROS and HO-1 production and increased ICAM-1 mRNA expression and protein synthesis in endothelial cells. Cell viability affected by BA was diminished by some inhibitors; however, the increased sICAM-1 secretion by BA was not affected by any of the tested inhibitors. These results facilitate understanding of the pathogenesis, prevention and treatment of pulpal/periapical diseases.

Accuracy of mechanical torque-limiting devices for implant screw tightening: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: A consensus is lacking on the accuracy of torque value on different types of mechanical torque-limiting devices. PURPOSE: The purpose of this systematic review and meta-analysis was to determine the accuracy of unused mechanical torque-limiting devices. MATERIAL AND METHODS: Electronic searches were conducted until October 2021 in 6 electronic databases. Relevant articles were manually screened in 5 journals from January 2000 to October 2021. Two reviewers screened titles, abstracts, and full texts and extracted the data independently. A meta-analysis was conducted to evaluate the weighted mean difference in torque value deviation from target torque between spring-style and friction-style devices as a primary outcome. Deviations of output torque value from target value in spring-style or friction-style devices were also analyzed as a secondary outcome. RESULTS: A total of 11 595 articles were identified, and 16 articles were included for final statistical analysis. Meta-analysis of the included articles showed that torque value deviation in the spring-style was significantly lower than in the friction-style devices (-0.99 Ncm, 95% confidence interval [CI]: [-1.89, -0.09], P=.030). Deviations of output torque value from target value was -0.54 Ncm in the spring-style group (CI: [-1.23, 0.15], P=.122) and -0.18 Ncm in the friction-style group (95% CI: [-1.40, 1.04], P=.770). Meta-regression analysis indicated that target value was significantly associated with the mean deviation from target value only in the spring-style group. High heterogeneity was found, suggesting more studies with standardized research design are required. CONCLUSIONS: Both spring- and friction-style mechanical torque-limiting devices can produce relatively accurate torque values; however, unused spring-type devices tend to have lower deviation from target torque value than unused friction-type devices.

Guided implant surgery risks and their prevention.

Ideal implant placement may reduce surgical complications, such as nerve injury and lingual cortical plate perforation, and minimize the likelihood of functional and prosthetic compromises. Guided implant surgery (GIS) has been used as the means to achieve ideal implant placement. GIS refers to the process of digital planning, custom-guide fabrication, and implant placement using the custom guide and an implant system-specific guided surgery kit. GIS includes numerous additional steps beyond the initial prosthetic diagnosis, treatment planning, and fabrication of surgical guide. Substantial errors can occur at each of these individual steps and can accumulate, significantly impacting the final accuracy of the process with potentially disastrous deviations from proper implant placement. Pertinent overall strategies to reduce or eliminate these risks can be summarized as follows: complete understanding of the possible risks is fundamental; knowledge of the systems and tools used is essential; consistent verification of both diagnostic and surgical procedures after each step is crucial; proper training and surgical experience are critical. This review article summarizes information on the accuracy and efficacy of GIS, provides insight on the potential risks and problems associated with each procedural step, and offers clinically relevant recommendations to minimize or eliminate these risks.

Strain analysis of 9 different abutments for cement-retained crowns on an internal hexagonal implant.

STATEMENT OF PROBLEM: Many aftermarket abutments for cement-retained crowns are available for the tapered screw-vent implant. Aftermarket abutments vary widely, from stock to custom abutments and in materials such as zirconia, titanium, or a combination of the two. How these aftermarket abutments perform under occlusal loads with regard to strain distribution is not clear. PURPOSE: The purpose of this in vitro study was to measure and compare the different strains placed upon the bone around implants by 9 different abutments for cement-retained crowns on an implant with an internal hexagonal platform. MATERIAL AND METHODS: Nine 4.1×11.5-mm tapered screw-vent implants were placed into a 305×51×8-mm resin block for strain measurements. Five abutment specimens of each of the 9 different abutments (N=45) were evaluated with 1 of the 9 implants. Monolithic zirconia crowns were then fabricated for each of the 9 different abutments, the crowns were cyclically loaded (maximum force 225 N) at 30 degrees, twice at a frequency of 2 Hz, and the strain was measured and recorded. The strain to the resin block was determined using a 3-dimensional digital image correlation (3D DIC) technique. Commercial image correlation software was used to analyze the strain around the implants. Data for maximal and minimal principal strains were compared using analysis of variance with a Tukey-Kramer post hoc test (α=.05). RESULTS: Strain measurements showed no significant differences among any of the abutments for minimal (compression) principal strains (P>.05). For maximal (tensile) principal strains, the zirconia abutment showed the highest, and the patient-specific abutment showed the second-highest strain around the implant, with the zirconia being significantly greater than all abutments, with the exception of the patient-specific abutment, and the patient-specific abutment being significantly greater than the straight contoured abutment in titanium and also zirconia (P<.05). CONCLUSIONS: The name brand patient specific titanium and Atlantis zirconia abutments conferred the most tensile strain to the implants. When selecting an abutment for a cement-retained crown on a tapered screw-vent implant, practitioners should consider the abutment material and the manufacturer of the abutment because not all abutments that fit in an individual implant transmit the strains in the same way.

The Effect of Platform Switching on Periimplant Crevicular Fluid Content During Early Wound Healing.

PURPOSE: The objective of this study was to investigate the soft tissue response and periimplant crevicular fluid (PICF) content around platform-switched (PS) and platform-matched (PM) implants during early healing. MATERIALS AND METHODS: Nonsmokers treatment planned to receive a single implant in 2 quadrants were recruited. Two-stage implant placement protocol with 1 PM and 1 PS implant was implemented. Periimplant probing depths (PDs), modified sulcus bleeding index, and plaque indices were recorded, and PICF was collected at 1, 2, 4, and 6 weeks after abutment connection. RESULTS: PD readings were higher at week 1 than at week 6 for both groups (P = 0.0005). PD was statistically deeper in PM than in PS at week 1 (P = 0.03). There was a time-dependent decrease in total PICF volume for both groups. This decrease was statistically significant for PS (P = 0.0005), with no differences between the 2 groups at any time (P > 0.05). The decrease observed in both PM and PS for PICF interleukin 6 and macrophage inflammatory protein-1ß, and in PS for tumor necrosis factor-α (TNF-α) was statistically significant (P ≤ 0.03). TNF-α was statistically higher in PS than in PM at week 1 (P = 0.005). CONCLUSION: Within the limits of this study, it seems that periimplant soft tissue response around PM and PS implants is mostly similar during the early healing period.

Accuracy of mechanical torque-limiting devices for dental implants.

STATEMENT OF PROBLEM: A common complication in implant dentistry is unintentional implant screw loosening. The critical factor in the prevention of screw loosening is the delivery of the appropriate target torque value. Mechanical torque-limiting devices (MTLDs) are the most frequently recommended devices by the implant manufacturers to deliver the target torque value to the screw. Two types of MTLDs are available: friction-style and spring-style. Limited information is available regarding the influence of device type on the accuracy of MTLDs. PURPOSE: The purpose of this study was to determine and compare the accuracy of spring-style and friction-style MTLDs. MATERIAL AND METHODS: Five MTLDs from 6 different dental implant manufacturers (Astra Tech/Dentsply, Zimmer Dental, Biohorizons, Biomet 3i, Straumann [ITI], and Nobel Biocare) (n=5 per manufacturer) were selected to determine their accuracy in delivering target torque values preset by their manufacturers. All torque-limiting devices were new and there were 3 manufacturers for the friction-style and 3 manufacturers for the spring-style. The procedure of target torque measurement was performed 10 times for each device and a digital torque gauge (Chatillon Model DFS2-R-ND; Ametek) was used to record the measurements. Statistical analysis used nonparametric tests to determine the accuracy of the MTLDs in delivering target torque values and Bonferroni post hoc tests were used to assess pairwise comparisons. RESULTS: Median absolute difference between delivered torque values and target torque values of friction-style and spring-style MTLDs were not significantly different (P>.05). Accuracy of Astra Tech and Zimmer Dental friction-style torque-limiting devices were significantly different than Biohorizons torque-limiting devices (P<.05). CONCLUSIONS: There is no difference between the accuracy of new friction-style MTLDs and new spring-style MTLDs. All MTLDs fell within ±10% of the target torque value. Astra Tech and Zimmer Dental friction-style torque-limiting devices were significantly more accurate than Biohorizons (C) torque-limiting devices (P<.05); however, all the torque-limiting devices fell within ±10% of the target torque value preset by the manufacturers.

Effects of a new implant abutment design on peri-implant soft tissues.

The purpose of this study was to assess the effects of a modified implant abutment design on peri-implant soft and hard tissues in dogs. Three months after extraction of mandibular premolar teeth, 3 dental implants were placed in each side of the jaw using a 1-stage approach. Implants on one side of the mandible received standard abutments (control), and implants on the contralateral side received modified, patented, grooved abutments (test). Two months after implant placement, animals were euthanized and specimens were prepared for histologic and histomorphometric assessment. The linear distance (in micrometers) was measured from the implant shoulder (IS) to the following landmarks: gingival margin (GM; distance IS-GM), most apical position of the junctional epithelium (JE; distance IS-JE), and bone crest (BC; distance IS-BC). Percent of bone-to-implant contact was also measured. Histologic assessment revealed that all implants were osseointegrated and that interimplant gingival fibers between test abutments appeared to be more numerous and organized than control abutments. The IS-GM and IS-JE distances in test implants were greater than the corresponding distances in control implants (P = .024 and P = .015, respectively), whereas crestal bone loss (IS-BC) was greater for control implants than test implants (P = .037). There were no differences between control and test implants in bone-to-implant contact (P = .69), which averaged close to 50%. These results suggest that the modified groove design incorporated in standard abutments confers both soft and hard tissue benefits.

Do X-linked diseases affect periodontal health?

Genetic factors play an important etiologic role in destructive periodontal diseases. There have been reports that sex chromosomes, especially disorders associated with the X chromosome, affect periodontal health. Although numerous X-linked diseases have been reported to be associated with various periodontal diseases, the association of gingivitis and/or periodontitis with these genetic syndromes should be considered tenuous and raises the question of whether the periodontal manifestation truly arises from an underlying X-linked genetic etiology. A brief overview of genetics in relation to sex chromosomes and putative X-linked genetic periodontal diseases is given.

Bone ingrowth and initial stability of titanium and porous tantalum dental implants: a pilot canine study.

PURPOSE: To investigate if a dental implant system with a midsection covered by 3-dimensionally porous tantalum material would exhibit stability comparable with a traditional threaded titanium alloy implant system and whether bone would grow into the porous section. METHODS: Three experimental and 3 control implants were placed in the individual mandibles of 8 dogs. Resonance frequency analysis assessed implant stability at 0, 2, 4, 8, and 12 weeks of healing. Histomorphometric and backscattered scanning electron microscopic analyses examined the presence of bone ingrowth into the experimental implant's porous section and bone-to-implant contact along the titanium surfaces of both implants. RESULTS: Implant stability did not significantly differ during 0 to 12 weeks of healing. Progressive tissue mineralization developed inside porous sections from weeks 2 to 12. Porous implants exhibited a combination of progressive osseointegration along their titanium surfaces and bone ingrowth inside their porous tantalum sections. CONCLUSIONS: Cortical and apical implant threads, combined with the porous section, were able to stabilize the experimental implant to the same degree as the fully threaded control implant.

Immediate Implant Placement and Provisionalization in the Esthetic Zone: A 6.5-Year Follow-Up and Literature Review.

The success of dental implant therapy in the esthetic zone requires not only functional osseointegration but also a satisfactory esthetic outcome. To establish harmony, balance, and continuity of gingival architecture between an implant restoration and the adjacent natural dentition is challenging. Immediate implant placement and provisionalization following tooth extraction have been documented as a predictable treatment modality, with fewer surgical interventions needed, to replace a missing tooth in the esthetic zone. This case report illustrates immediate implant placement and provisionalization to replace a failing maxillary right central incisor while maintaining optimal gingival esthetics. The maxillary right central incisor was extracted without flap elevation to minimize soft and hard tissue trauma. Immediately afterwards, the implant was installed using a surgical stent and restored with a provisional crown that had no occlusal contacts. During healing, no significant adverse effects were observed clinically or radiographically. This proposed treatment modality provided the patient with immediate esthetics, function, and comfort without any complications during a follow-up period of 6.5 years.

Development of a decellularized porcine bone graft by supercritical carbon dioxide extraction technology for bone regeneration.

A series of novel decellularized porcine collagen bone graft (DPB) materials in a variety of shapes and sizes were developed by the supercritical carbon dioxide (SCCO2 ) extraction technique. The complete decellularization of DPB was confirmed by hematoxylin and eosin staining, 4,6-diamidino-2-phenylindole (DAPI) staining, and residual DNA analysis. The native intact collagen remained in the DPB after the SCCO2 process was confirmed by Masson trichrome staining. The physicochemical characteristics of DPB were investigated by scanning electron microscopy and x-ray diffraction. The cytotoxicity and biocompatibility tests according to ISO10993 and its efficacy for bone regeneration in osteochondral defects in rabbits were evaluated. The rabbit pyrogen test confirmed DPB was non-toxic. In vitro and in vivo biocompatibility tests of the DPB did not show any toxic or mutagenic effects. The bone regeneration potential of the DPB presented no significant histological differences compared to commercially available deproteinized bovine bone. In conclusion, DPB produced by SCCO2 exhibited similar chemical characteristics to human bone, no toxicity, good biocompatibility, and enhanced bone regeneration in rabbits comparable to that of deproteinized bovine bone. Results from this study could shed light on the potential application of the SCCO2 extraction technique to generate a native decellularized scaffold for bone tissue regeneration in human clinical trials.

Evaluating the bone-regenerative role of the decellularized porcine bone xenograft in a canine extraction socket model.

OBJECTIVE: To evaluate the efficacy of a novel decellularized porcine bone xenograft, produced by supercritical carbon dioxide extraction technology, on alveolar socket healing after tooth extraction compared to a commercially available deproteinized bovine bone (Bio-Oss®). MATERIALS AND METHODS: Nine dogs (about 18 months old and weighing between 20 kg and 30 kg) underwent extractions of lower second to fourth premolars, bilaterally. The dogs were randomly selected and allocated to the following groups: Group 1: control unfilled socket; Group 2: socket filled with decellularized porcine bone xenograft (ABCcolla®) and covered by a commercially available porcine collagen membrane (Bio-Gide®); Group 3: socket filled with Bio-Oss® and covered by Bio-Gide® membrane. One dogs from each group was sacrificed at 4-, 12-, and 24-week to evaluate the socket healing after tooth extraction. The mandible bone blocks were processed without decalcification and specimens were embedded in methyl methacrylate and subjected to histopathology analyses to evaluate the bone regeneration in the extraction sockets. RESULTS: At 24-week after socket healing, ABCcolla® treated defects demonstrated significantly higher histopathology score in new bone formation and bone bridging, but significantly lower score in fluorescent labeling than those of the Bio-Oss®. In the microphotographic examination, decellularized porcine bone xenograft showed similar characteristics of new bone formation to that of Bio-Oss®. However, there was significantly less remnant implant materials in the decellularized porcine bone xenograft compared to the Bio-Oss® group at 24-week. Thus, the decellularized porcine bone graft seems to have promising bone regeneration properties similar to that of Bio-Oss® with less remnant grafted material in a canine tooth extraction socket model. CONCLUSIONS: Within the limits of the study, we concluded that ABCcolla® treated defects demonstrated significantly more new bone formation and better bone bridging, but less amount of fluorescent labeling than those of the Bio-Oss® group. However, clinical studies in humans are recommended to confirm these findings.

Soft tissue healing around platform-switching and platform-matching single implants: A randomized clinical trial.

BACKGROUND: Implants with platform-switching (PS) design have been demonstrated to reduce marginal bone loss. However, the influence on peri-implant soft tissue healing is unclear. This study was designed to investigate its effect on peri-implant soft tissue healing after implant uncovery. METHODS: Non-smokers needing two implants in different quadrants were recruited in this study. For each individual, one PS and one platform-matching (PM) implants were placed using two-stage protocol. Following 2 to 8 months of healing, all implants were uncovered and connected to the corresponding healing abutments. Clinical measurements and peri-implant crevicular fluid (PICF) were taken at 1-, 2-, 4-, and 6-week after 2nd stage surgery. The cytokine concentrations in PICF were analyzed. Peri-implant mucosa (1 × 2 × 2 mm) was harvested around the healing abutment for the analysis of gene expression at uncovery and 6-week post-uncovery. RESULTS: Eighteen participants (nine males; 51.7 ± 14.9 years) were recruited. Compared to PM, PS showed significantly lower probing depth (PD) at 1- and 2-week as well as modified sulcus bleeding index (mSBI) at 1-, 4-, and 6-week (P < 0.05). Over time, a decrease in osteoprotegerin and interleukin-1ß concentrations in PICF along with an increase in receptor activator of unclear factor kappa-B ligand, periostin, and peroxidasin gene expressions in peri-implant mucosa were noted within both groups (P < 0.05) without significant intergroup differences. CONCLUSION: Within the limits, implants with PS design rendered significant benefits over PM design in PD and mSBI reduction during a 6-week healing. However, molecular changes within PICF and peri-implant mucosa as a response to PM and PS appear negligible.

Protracted benign paroxysmal positional vertigo following osteotome sinus floor elevation: a case report.

Benign paroxysmal positional vertigo (BPPV) is a relatively rare condition characterized by onset of rotation dizziness triggered by head movements or change in posture. BPPV etiology includes head injury, infection, vascular disorders, surgical trauma, and idiopathic events. This report presents a case of protracted BPPV following osteotome sinus floor elevation and simultaneous implant placement. A 49-year-old female suffered intense vertigo and nausea immediately after implant placement using an osteotome sinus floor elevation procedure, especially when changing head position while sitting upright. Despite antivertigo medications, the condition did not improve. Following referral to a neurotologist, BPPV contralateral to the operation site was diagnosed 14 days after the osteotome sinus floor elevation procedure. The Epley's maneuver was then applied and, gradually, symptoms of BPPV disappeared 3 months after the implant surgery. No recurrence of BPPV was observed during further 3-month follow-up. Prevention and management of osteotome sinus floor elevation-related BPPV are reviewed in this report.

Immediate mechanical stability of threaded and porous implant systems.

BACKGROUND: Primary stability of a dental implant system is an essential factor to maintain its long-term success. Thus, the objective of this study was to examine whether primary stability is different between threaded and porous dental implant systems placed in artificial bone blocks and human cadaveric mandibular bone. MATERIALS AND METHODS: Forty-two threaded and 42 highly porous dental implants were placed in artificial polyurethane bone foams with 7 different thicknesses (3.5 to 12mm). In addition, 11 threaded and 11 porous implants were installed in 8 edentulous mandibles of human cadavers. Implant stability quotient values, insertion torque, static and dynamic stiffness, and viscoelastic tan δ of each implant system were measured. Mean gray values were obtained at the implantation sites in the human mandible. FINDINGS: The porous implant group had substantially lower implant stability quotient values and insertion torque values than the threaded implant group that were equal or >5.5mm in thickness of the artificial bone block (p<0.026) with the exception of 8.5mm thickness, while static and dynamic stiffness values were not different between the two implant groups greater than 5.5mm in thickness (p>0.132). Static and dynamic stiffness values of the porous group were significantly greater than the thread group in the human mandibular bone (p<0.015). INTERPRETATION: The porous layer supports axial loading better than lateral and shear loading of the dental implant system. This result indicates that trabecular shaped architecture of the porous layer may provide sufficient anchorage compromising reduction of the axial primary stability of the porous implant system to be comparable with the threaded implant system.

Soft Tissue Volume Augmentation Using Connective Tissue Grafts via Apical Pouch: Technical Considerations and Case Reports.

The success of dental implant therapy in the esthetic zone requires not only functional osseointegration but also favorable esthetic results. The greatest challenge in the esthetic zone is to establish harmony, balance, and continuity of gingival form between implant restorations and the adjacent natural teeth. In the esthetic zone, a localized ridge defect or loss of a peri-implant papilla is common and can be corrected via soft tissue augmentation. This case report describes a novel surgical technique using connective tissue grafts via an apical pouch to increase soft tissue volume over an alveolar ridge defect or around natural teeth or implants in the maxillary anterior area. The described surgical technique successfully achieved the desirable esthetic outcomes in the reported cases.

Dental implant bioactive surface modifications and their effects on osseointegration: a review.

BACKGROUND: The purpose of this article is to review and update the current developments of biologically active dental implant surfaces and their effect on osseointegration. METHODS: PubMed was searched for entries from January 2006 to January 2016. Only in-vivo studies that evaluated the effects of biomolecular coatings on titanium dental implants inserted into the bone of animals or humans were included. RESULTS: Thirty four non-review studies provided data and observations were included in this review. Within the criteria, four categories of biomolecular coatings were evaluated. The potential biomolecules include bone morphogenetic proteins in 8 articles, other growth factors in 8 articles, peptides in 5 articles, and extracellular matrix in 13 articles. Most articles had a healing period of 1 to 3 months and the longest time of study was 6 months. In addition, all studies comprised of implants inserted in animals except for one, which evaluated implants placed in both animals and humans. The results indicate that dental implant surface modification with biological molecules seem to improve performance as demonstrated by histomorphometric analysis (such as percentage of bone-to-implant contact and peri-implant bone density) and biomechanical testing (such as removal torque, push-out/pull-out tests, and resonance frequency analysis). CONCLUSIONS: Bioactive surface modifications on implant surfaces do not always offer a beneficial effect on osseointegration. Nevertheless, surface modifications of titanium dental implants with biomolecular coatings seem to promote peri-implant bone formation, resulting in enhanced osseointegration during the early stages of healing. However, long-term clinical studies are needed to validate this result. In addition, clinicians must keep in mind that results from animal experiments need not necessarily reflect the human clinical reality.

Associations of Resonance Frequency Analysis with Dynamic Mechanical Analysis of Dental Implant Systems.

BACKGROUND: Resonance frequency analysis (RFA) has been introduced as a noninvasive method to clinically estimate the stability of dental implant systems. PURPOSE: The objective of this study was to examine whether implant stability quotient (ISQ) values of RFA can account for mechanical stability of the dental implant system, which is assessed using dynamic mechanical analysis (DMA). MATERIALS AND METHODS: Fifty-seven screw-type titanium dental implants were placed in artificial polyurethane foams with seven different thicknesses (3.5 to 12 mm) and eight edentulous mandibles of human cadavers (four men and four women, 79.11 ± 13.48 years). After the ISQ values, insertion torque, and static stiffness of each implant system were measured, the DMA was performed to assess dynamic stiffness and viscoelastic tan δ. RESULTS: The ISQ value had strong positive correlations with thickness, insertion torque, static and dynamic stiffness, and a negative correlation with tan δ of implant systems in artificial bone blocks (r = 0.769 to 0.992, p < .043). However, the ISQ value was correlated with only the insertion torque of implant systems in human mandibles (p < .049). CONCLUSION: The ISQ values could reflect mechanical stability of the dental implant system under the controlled condition of homogeneous density in simple dimensions.

Three-Dimensional Displacement of Nine Different Abutments for an Implant with an Internal Hexagon Platform.

PURPOSE: Clinicians need to know whether there are any differences among the many abutment options available for restoring a particular implant. This study aims to compare nine abutments for one implant system for positional changes between hand tightening and torqueing. MATERIALS AND METHODS: Nine Tapered Screw-Vent (TSV) implants were placed into a resin block. Five specimens of nine different abutments (n = 45) were tried in one of the nine implants. Initially, the abutments were torqued to 20 Ncm to represent hand tightening. Abutments were tightened to 30 Ncm using a torque driver as recommended by the manufacturer for final seating. Images were recorded in 12-second intervals for approximately 10 minutes after the torque was applied. The spatial relationship of the abutments to the resin block was determined using three-dimensional digital image correlation. Commercial image correlation software was used to analyze the displacements. Mean displacements for the nine different abutments were calculated in all three dimensions and for overall displacement in space. A t test with a step-down Bonferroni correction was used for a pairwise comparison of each abutment's mean displacements to the other abutments to determine statistical differences (α = .05). RESULTS: The Atlantis titanium, Inclusive titanium, and Legacy zirconia abutments showed mean displacements that were statistically significantly higher than other abutments in the horizontal direction. The overall three-dimensional displacement of the Atlantis titanium abutment after an applied 30-Ncm torque was significantly higher than that of six of the other eight abutments (P < .0144). CONCLUSION: Within the limitations of this in vitro study, the Zimmer PSA demonstrated less displacement between hand tightening and torqueing than the Atlantis titanium or Inclusive titanium abutments when used to restore a TSV implant.

Fixation tack penetration into the maxillary sinus: A case report of a guided bone regeneration procedure complication.

BACKGROUND: Guided bone regeneration (GBR) is an established and predictable procedure used to obtain adequate alveolar bone for the placement of dental implants. Anatomical challenges, such as the proximity of the maxillary sinus, may lead to complications during a GBR procedure. The purpose of this report is to present a unique and hitherto unreported complication of a GBR procedure, i.e., the penetration of a titanium fixation tack into the maxillary sinus. CASE REPORT: A unique GBR is presented, where a titanium tack penetrated the maxillary sinus with subsequent migration and loss. Attempts to locate the tack visually during the procedure were unsuccessful. The GBR procedure was aborted and dental radiographs were immediately obtained. The patient was completely asymptomatic during the healing period. Eight weeks later a cone beam computed tomography revealed a non-inflamed sinus with no pathology evident. However, the tack could not be visualized. An otolaryngology consultation was requested and the ensuing sinus endoscopy did not reveal any evidence of the penetrated tack. It is thought that the loose tack migrated completely out of the sinus through the nasal passage. CONCLUSIONS: The use of a pre-operative cone beam computed tomography (CBCT) would have allowed the clinician to assess the exact thickness of the lateral wall of the maxillary sinus and better determine the ideal placement location and/or the feasibility of using a fixation tack in the posterior upper jaw.