Evaluation of the peri-implant tissues in the esthetic zone with prefabricated titanium or zirconia abutments: A randomized controlled clinical trial with a minimum follow-up of 7 years.

STATEMENT OF PROBLEM: Long-term clinical studies are lacking on the influence of the type of abutment, titanium or zirconia, on peri-implant tissues. PURPOSE: The purpose of this randomized clinical trial was to evaluate peri-implant tissues with titanium or zirconia abutments. MATERIAL AND METHODS: A total of 26 single-tooth implant-supported prostheses in 14 participants were analyzed. They received either a titanium abutment with a metal-ceramic crown (TAG) or a zirconia abutment with a ceramic crown (ZAG). Data were collected immediately, at 5 months, and at a minimum of 7 years after crown delivery. The success rate, plaque and bleeding indexes, bleeding on probing, white and pink esthetic scores, and the relationships of the gingival phenotype with the pink esthetic score were analyzed. Statistical analyses were conducted with the t test for paired and independent data (α=.05). RESULTS: The mean follow-up time was 95.2 ±2.6 months, showing an implant success rate of 96.7%. No statistically significant differences were found between TAG and ZAG among the time intervals evaluated for plaque or bleeding indexes (P>.05). A statistically significant difference was found for peri-implant probing depths in the mid-buccal sites between the groups at all the time intervals evaluated (TAG, P=.008; ZAG, P=.021): TAG showed an increase between 5 months (3.65 ±0.93 mm) and over 7 years (4.47 ±1.32 mm); and ZAG showed a reduction (5 months=5.22 ±1.71 mm; over 7 years=4.25 ±1.28 mm) in values. For the pink (PES) and white esthetic score (WES), ZAG (PES: immediately=6.33 ±1.41; 5 months=7.44 ±1.81; over 7 years=8.25 ±1.03; WES: immediately=7.67 ±1.50; over 7 years=8.38 ±0.74) showed higher mean values than TAG (PES: immediately=5.94 ±2.35; 5 months=6.53 ±2.15; over 7 years=7.44 ±1.81; WES: immediately=7.00 ±1.17; over 7 years=8.35 ±1.27) (P<.05). Statistically significant differences were found for gingival phenotype and for PES in TAG (P=.031), and the participants with thick phenotype showed higher PES in the 3 time intervals studied. CONCLUSIONS: Zirconia abutments exhibited better results than titanium abutments in terms of the peri-implant tissues. Moreover, in those with a thin phenotype, zirconia provided improved gingival esthetics.

Rehabilitation of Atrophic Maxilla With Immediate Loading of Extrasinus Zygomatic Implant.

ABSTRACT: The aim of this case series was to evaluate the long-term success rate of immediate occlusal loading of extrasinus zygomatic dental implants after a 3-year follow-up. The sample consisted of 31 patients (mean age of 64 years) with atrophic maxillae rehabilitated with 1 to 4 extrasinus zygomatic implants, placed unilaterally or bilaterally. All the patients received complete implant-supported dental prostheses with immediate loading by associating zygomatic implants with conventional implants. None of the procedures were associated with bone grafts. During the 3-year period of follow-up in the present study, all the patients attended clinical sessions and underwent radiographic exams every 6 months. In total 55 zygomatic and 69 conventional implants were placed, where 1 zygomatic and 2 conventional implants were lost, representing success rates of 98.18% and 97.20%, respectively. None of the studied patients had signs of sinusitis or changes in the maxillary sinuses. All the patients showed occlusal contact on natural antagonist teeth or implant-supported dental prostheses. Therefore, it was concluded that the use of exteriorized zygomatic implants with immediate loading represented a feasible option with high success rates for the treatment of atrophic maxilla.

Bone and gingival tissue thicknesses of maxillary anterior teeth with and without a metal post: a cone beam computed tomographic study.

The objective of this retrospective study was to evaluate buccal bone and gingival thickness measurements obtained from cone beam computed tomographic (CBCT) images of maxillary anterior teeth with and without metal posts. A convenience sample of 71 CBCT images of healthy maxillary anterior teeth and 61 CBCT images of maxillary anterior teeth with a metal post were selected from a database. Eight tomographic measurements (4 bone thicknesses and 4 gingival thicknesses) were performed in the parasagittal section of each tooth, perpendicular to the tooth axis. The Mann-Whitney U test was used to compare these thicknesses, and the Spearman correlation coefficient was calculated for correlation of age with sex. Statistically significant differences were observed for almost all measurements (P < 0.05); the CBCT images of teeth with metal posts displayed lower bone thickness values and higher gingival thickness values. No statistically significant correlations were observed between the thickness measurements and age. However, significantly higher bone thickness values were observed in men (P < 0.05). Cone beam computed tomographic images of teeth with metal posts showed differences in mean bone and gingival measurements compared to teeth without metal posts, suggesting a possible interference of metal artifacts.

Artifacts caused by titanium implants in CBCT images of the mandible: an experimental study.

This study evaluated the quantity of metal artifacts produced by dental implants placed in different mandibular regions using various cone beam computed tomography (CBCT) protocols. Titanium implants were placed in 4 regions (incisor, canine, premolar, and molar) of an artificial mandible and subjected to CBCT examinations with the mandibular model placed in different positions within the field of view (FOV) and imaged with different FOV and voxel sizes. An axial section of the cervical region of each implant was selected for artifact quantification. The artifacts were measured by normalizing the actual standard deviation (ASD) of the voxel values. Kruskal-Wallis and Student-Newman-Keuls tests were used to compare the tooth regions and the different positions of the mandible. The Wilcoxon test was used to compare changes in FOV and voxel size. The intraobserver agreement was calculated using the intraclass correlation coefficient. The significance level was 5%. The incisor region showed significantly more artifacts than other regions (P = 0.0315). No statistically significant difference was found when the position of the mandible varied within the FOV (P = 0.7418). Smaller FOV and smaller voxels produced more artifacts (P < 0.0001). The quantity of metal artifacts was affected by FOV and voxel size as well as by anatomical region. Variation of the mandible location within the FOV did not affect the artifacts as defined by the normalized ASD of the voxel values.

Fatigue Behavior of Different CAD/CAM Materials for Monolithic, Implant-Supported Molar Crowns.

PURPOSE: To evaluate the fracture resistance after the thermal and mechanical fatigue of feldspathic, lithium disilicate, and resin-modified CAD/CAM monolithic crowns cemented onto a universal post abutment. MATERIALS AND METHODS: A right second mandibular molar was designed in CAD/CAM software, and 30 crowns were machined using three different materials (n = 10): feldspathic ceramic, finished only with a glaze cycle (G1); lithium disilicate, sintered and finished with a glaze cycle (G2); and resin, modified by nanoceramic and finished with rubber (G3). All crowns were cemented under a constant 50 N load, the excess cement was removed, and the crowns were light-cured for 30 seconds. After being immersed in deionized water for 7 days, the crowns were submitted to thermal cycling, which consisted of varying the temperature from 2 to 50°C for 350,000 cycles, and mechanical cycling in a fatigue simulator, where a 250 N load was applied for 1,000,000 cycles at 2 Hz. The resistance of each crown was verified in a compression-to-failure test at 1 mm/min in a universal test machine. The groups were compared using one-way ANOVA with a Bonferroni post hoc test and Weibull statistics. RESULTS: The resin-modified group was the least resistant group (1755 ± 124 N), followed by the feldspathic (2147 ± 412 N) and lithium disilicate groups (2804 ± 303 N). The Weibull statistics demonstrated that lithium disilicate is the most reliable material and has the lowest fracture probability. CONCLUSIONS: It was possible to conclude that all of the tested CAD/CAM materials can be used as monolithic, implant-supported molar crowns.

Influence of crown-to-implant ratio on stress around single short-wide implants: a photoelastic stress analysis.

PURPOSE: The aim of this study was to evaluate the photoelastic fringe patterns around two short-wide implants supporting single crowns with different crown-to-implant (C/I) ratios. MATERIALS AND METHODS: External hexagon (EH) cylindrical implants (5 × 7 mm) or Morse Taper (MT) conical implants (5 × 6 mm) were embedded individually into photoelastic resin blocks. Each implant received a single metal-ceramic crown, with a C/I ratio of 1:1 or 2:1 (n = 10). Each set was positioned in a polariscope and submitted to a 0.5 kgf compressive load, applied axially or obliquely (30°). The polariscope images were digitally recorded, and based on isoclinal and isochromatic fringes, the shear stress was calculated at 5 predetermined points around each implant. Data were analyzed by two-way ANOVA (α = 0.05). RESULTS: Under axial loading, the stress was concentrated at the crestal region, and there were no differences between C/I ratio or implant types. In contrast, under oblique loading, EH implants showed lower stress values than the MT group and the 2:1 C/I ratio showed higher stress concentration for both implant types (p < 0.05). Moreover, MT implants showed stress distribution through a higher area than the EH implant did, with a tendency to direct the stress toward the implant's apex under oblique loading. CONCLUSION: MT conical short-wide implants showed higher stress values that were distributed through a higher area directed to the implant apex. The C/I ratio influences the stress distribution only under oblique loading.

Effect of platform connection and abutment material on stress distribution in single anterior implant-supported restorations: a nonlinear 3-dimensional finite element analysis.

STATEMENT OF PROBLEM: Although various abutment connections and materials have recently been introduced, insufficient data exist regarding the effect of stress distribution on their mechanical performance. PURPOSE: The purpose of this study was to investigate the effect of different abutment materials and platform connections on stress distribution in single anterior implant-supported restorations with the finite element method. MATERIAL AND METHODS: Nine experimental groups were modeled from the combination of 3 platform connections (external hexagon, internal hexagon, and Morse tapered) and 3 abutment materials (titanium, zirconia, and hybrid) as follows: external hexagon-titanium, external hexagon-zirconia, external hexagon-hybrid, internal hexagon-titanium, internal hexagon-zirconia, internal hexagon-hybrid, Morse tapered-titanium, Morse tapered-zirconia, and Morse tapered-hybrid. Finite element models consisted of a 4×13-mm implant, anatomic abutment, and lithium disilicate central incisor crown cemented over the abutment. The 49 N occlusal loading was applied in 6 steps to simulate the incisal guidance. Equivalent von Mises stress (σvM) was used for both the qualitative and quantitative evaluation of the implant and abutment in all the groups and the maximum (σmax) and minimum (σmin) principal stresses for the numerical comparison of the zirconia parts. RESULTS: The highest abutment σvM occurred in the Morse-tapered groups and the lowest in the external hexagon-hybrid, internal hexagon-titanium, and internal hexagon-hybrid groups. The σmax and σmin values were lower in the hybrid groups than in the zirconia groups. The stress distribution concentrated in the abutment-implant interface in all the groups, regardless of the platform connection or abutment material. CONCLUSIONS: The platform connection influenced the stress on abutments more than the abutment material. The stress values for implants were similar among different platform connections, but greater stress concentrations were observed in internal connections.

Influence of the veneer-framework interface on the mechanical behavior of ceramic veneers: a nonlinear finite element analysis.

STATEMENT OF PROBLEM: The chipping of ceramic veneers is a common problem for zirconia-based restorations and is due to the weak interface between both structures. PURPOSE: The purpose of this study was to evaluate the mechanical behavior of ceramic veneers on zirconia and metal frameworks under 2 different bond-integrity conditions. MATERIAL AND METHODS: The groups were created to simulate framework-veneer bond integrity with the crowns partially debonded (frictional coefficient, 0.3) or completely bonded as follows: crown with a silver-palladium framework cemented onto a natural tooth, ceramic crown with a zirconia framework cemented onto a natural tooth, crown with a silver-palladium framework cemented onto a Morse taper implant, and ceramic crown with a zirconia framework cemented onto a Morse taper implant. The test loads were 49 N applied to the palatal surface at 45 degrees to the long axis of the crown and 25.5 N applied perpendicular to the incisal edge of the crown. The maximum principal stress, shear stress, and deformation values were calculated for the ceramic veneer; and the von Mises stress was determined for the framework. RESULTS: Veneers with partial debonding to the framework (frictional coefficient, 0.3) had greater stress concentrations in all structures compared with the completely bonded veneers. The metal ceramic crowns experienced lower stress values than ceramic crowns in models that simulate a perfect bond between the ceramic and the framework. Frameworks cemented to a tooth exhibited greater stress values than frameworks cemented to implants, regardless of the material used. CONCLUSION: Incomplete bonding between the ceramic veneer and the prosthetic framework affects the mechanical performance of the ceramic veneer, which makes it susceptible to failure, independent of the framework material or complete crown support.

Immediate implant placement, reconstruction of compromised sockets, and repair of gingival recession with a triple graft from the maxillary tuberosity: a variation of the immediate dentoalveolar restoration technique.

Immediate implant placement into compromised sockets is challenging for clinicians. The 3-dimensional implant position, status of the buccal bone wall, and regeneration of the soft tissue contours all affect adequate esthetic and functional results. This clinical report presents a treatment protocol (a variation of the immediate dentoalveolar restoration concept) consisting of immediate implantation and the reconstruction of the buccal bone wall and gingival recession in a single procedure with a triple graft (cancellous and cortical bone and soft tissue graft).

Assessing peri-implant bone microarchitecture: conventional vs. osseodensification drilling - ex vivo analysis.

The aim was to evaluate primary implant stability and bone microarchitecture in two drilling situations, by comparing the conventional technique (CT) and osseodensification (OD) (Versah Burs - Jackson - Mississippi - USA). The implant insertion torque (IT), implant stability quotient (ISQ), and the peri-implant trabecular microstructure were assessed on bone fragments obtained from pig's tibia (n=12), divided between CT (n=6) and OD (n=6). After the drilling procedure, the implants were installed (3.5x8.5 mm, Epikut - SIN - São Paulo - Brazil). The IT and ISQ were measured using a digital torque wrench and resonance frequency analysis. Then, the bone fragments containing the implants were removed with a trephine and analyzed by Microtomography (µCT, 8.0 µm). The comparison between groups was performed using the unpaired t-test (α=0.05). The results revealed that OD promotes a higher insertion torque (CT: 7.67±2.44 Ncm; OD: 19.78±5.26 Ncm) (p=0.0005), although ISQ was not different (CT: 61.33±4.66; OD: 63.25±4.58) (p=0.48). There was a significant increase in peri-implant bone volume (CT: 23.17±3.39 mm3; OD: 32.01±5.75 mm3) (p=0.008), and trabecular parameters: separation (CT: 0.4357±0.03 mm; OD: 0.3865±0.04 mm) (p=0.0449), number (CT: 1.626±0.18 1/mm; OD: 1.946±0.13 1/mm) (p=0.007), and thickness (CT: 0.1130±0.009 mm; OD: 0.1328±0.015 mm) (p=0.02). Structure model index (SMI) data demonstrate no significant differences between groups (CT: 1.7±0.2; OD: 1.4±0.4) (p=0.12). In conclusion, OD increases the insertion torque values and promotes beneficial changes regarding bone microarchitecture compared with CT, revealing more peri-implant bone volume with consequent higher primary stability.

Microbiological analysis of bacterial sealing of internal conical implants with different taper angles.

The present study evaluated the effect of the taper angle of different internal conical connection implants and cyclic loading on the implant-abutment bacterial seal. A total of 96 implant-abutment sets were divided into eight groups. Four groups of different taper degrees with cyclic mechanical loading of 500,000 cycles per sample, with a 120-N load at 2 Hz before analysis [16DC (16-degree, cycled), 11.5DC (11.5-degree, cycled), 3DC (3- degree, cycled) and 4DC (4- degree, cycled)] were compared to four control groups without cyclic loading [16D (16-degree), 11.5D (11.5-degree), 3D (3-degree), and 4D (4-degree)]. Microbiological analysis was performed by immersing all samples in a suspension containing Escherichia coli and incubating them at 37°C. After 14 days, the presence of bacterial seals was evaluated. Fisher-Freeman-Halton exact tests and binomial tests were performed (5% significance level). The groups showed significant differences in bacterial seal, and mechanical load cycling improved the bacterial seal in the 3DC group. In all other groups, no significant differences in bacterial seal were found between cycled and uncycled samples. To conclude, the internal conical connection with a 3-degree taper angle showed better results than the other connection with different angles when subjected to load cycling. However, none of the angles tested were fully effective in sealing the implant-abutment interface.

A Comparative Histomorphometric Analysis of Two Biomaterials for Maxillary Sinus Augmentation: A Randomized Clinical, Crossover, and Split-Mouth Study.

Introduction: Considering oral rehabilitation with dental implants, many studies have aimed at improving bone regeneration through the use of biomaterials. Objective: This study aimed at comparing bone neoformation in patients undergoing bilateral maxillary sinus surgery with two bovine biomaterials. Materials and Methods: This is a randomized, blinded, clinical crossover, and divided mouth study. Ten participants with an indication of maxillary sinus enlargement were selected and underwent surgical treatment with Bio-Oss® graft biomaterial (graft 1) on one side and Lumina-Porous® graft biomaterial (graft 2) on the other. The samples were collected after nine months and fixed and then decalcified in 10% ethylenediamine tetra-acetic acid (EDTA) solution for 30 days to process and make histological slides. Connective and bone tissue were further analyzed to identify the amount of newly formed bone. Results: The graft 1 group had a greater formation of vital mineralized tissue when compared to the graft 2 group (p = 0.01). For nonvital mineralized tissue and amount of connective tissue, there was no statistical difference (p = 0.21 and p = 0.09, respectively). The medullary spaces were larger in the graft 2 group. The group treated with graft 1 presented a higher percentage of osteoclasts and viable osteocytes compared to the graft 2 group (p = 0.014 and p = 0.027, respectively). Conclusion: Every day, new alternative biomaterials are offered as an option in oral rehabilitation. In this study, both treatments induced bone neoformation after 9 months; however, the group treated with Bio-Oss® showed a higher percentage of vital mineralized bone tissue.

Corticosteroids or cyclooxygenase 2-selective inhibitor medication for the management of pain and swelling after third-molar surgery.

The dental-impaction pain model is the most commonly used and widely accepted acute pain model for assessing the analgesic effect of drugs in humans. The aim of this randomized crossover clinical trial was to observe and compare the anti-inflammatory effects of corticosteroid and nonsteroidal cyclooxygenase 2-selective inhibitor medication on pain, swelling, and trismus after third-molar surgery. For this, 50 adult subjects, 25 male and 25 female, with ages ranging between 18 and 29 years (mean, 22.5 years) and no local or systemic problems, presenting bilateral impacted lower third molars in similar position with surgical extraction indicated were selected. The subjects were submitted to 1 surgical procedure for each side with interval of 3 weeks between each procedure, in which they were given 120 mg etoricoxib, nonsteroidal anti-inflammatory (group 1), or 4 mg dexamethasone, corticosteroid anti-inflammatory (group 2), 1 hour before the procedures. Data were registered at preoperative baseline and 24 and 48 hours postoperatively. Postoperative pain was evaluated using a visual analog scale, and the degree of swelling was evaluated through facial reference points' variation. The presence of trismus was analyzed through measurement of the interincisal distance. These assessments were obtained before the operation and at 24 and 48 hours after the surgeries. There was no statistically significant difference between anti-inflammatory treatments. However, at 48 hours, the facial swelling increased in both groups despite trismus reduction. The effects of nonsteroidal and steroidal anti-inflammatory drugs were similar for pain, swelling, and trismus.

Biomechanical behavior of atrophic maxillary restorations using the all-on-four concept and long trans-sinus implants: A finite element analysis.

Background. Maxillary bone atrophy with a considerable amount of pneumatization and anterior expansion of the maxillary sinus might be a situation limiting oral rehabilitation with osseointegrated implants. Therefore, the present study aimed to biomechanically evaluate two rehabilitation techniques for maxillary bone atrophy: all-on-four and long trans-sinus implants. Methods. Two three-dimensional models consisting of atrophic maxilla with four implants were simulated. In the M1 model, two axially inserted anterior implants and two tilted implants, 15 mm in length, placed tangential to the maxillary sinus's anterior wall were used. In the M2 model, two axially inserted anterior implants and two trans-sinus tilted implants, 24 mm in length, were used. For the finite element analysis (FEA), an axial load of 100 N was applied on the entire extension of the prosthesis, simulating a rehabilitation with immediate loading. The peri-implant bone and the infrastructure were analyzed according to the Mohr-Coulomb and Rankine criteria, respectively. Results. The results were similar when the stresses on peri-implant bone were compared: 0.139 and 0.149 for models 1 and 2, respectively. The tension values were lower in the model with trans-sinus implants (27.99 MPa). Conclusion. It was concluded that the two techniques exhibited similar biomechanical behavior, suggesting that the use of long trans-sinus implants could be a new option for atrophic maxilla rehabilitation.

Clinical, Tomographic, and Histologic Evaluation of an Autogenous Bone Graft Harvested from the Maxillary Tuberosity for Guided Bone Regeneration: Case Report with a 4-Year Follow-up.

This report presents a case in which autogenous bone grafts were harvested from the maxillary tuberosity for guided bone regeneration and dental implant placement, with long-term follow-ups and assessment at the clinical, tomographic, and histologic levels. Particulate and block autogenous bone grafts were covered with a resorbable collagen membrane. Advanced bone remodeling and good bone quality, enabling dental implant placement, were observed after a short healing time (3 months). The differences in buccal bone plate thickness in the grafted area between the period immediately after implant placement and 4 years thereafter ranged from +0.879 mm to -0.001 mm. The implants osseointegrated uneventfully, and alveolar bone regeneration remained stable with a satisfactory result after 4 years.

Immediate three-dimensional changes in the oropharynx after different mandibular advancements in counterclockwise rotation orthognathic planning.

BACKGROUND: A retrospective cohort study was performed to evaluate the immediate effect on the oropharynx dimensions from different mandibular advancements in patients undergone counterclockwise rotation (CCW) of the maxillomandibular complex. MATERIAL AND METHODS: 138 CBCT images of patients, who had undergone orthognathic surgery, were identified from Dolphin Imaging archive according to pre- (T0) and post-operative (T1) times. Each pre-operative CBCT image was selected considering retrognathic mandible. Superimpositions of CBCT images were performed to measure mandibular advancement at B point in millimeters (mm) and divided into three groups: G1 (< 5 mm), G2 (between 5 and 10 mm) and G3 (> 10 mm). For evaluating oropharynx dimension at T0 and T1 for each group, medial sagittal area (MSA), volume, and minimum cross-sectional axial area (CSA) were measured on Dolphin Imaging. Pearson correlation verified reliability of method. Paired t-test were applied to compare values of measurements between T0 and T1 (p ≤ 0.05). RESULTS: 88 CBCT images were included. Method was reliable (r ≥ 0.93). According to MSA, volume and CSA values from G1, there was no significant difference between T0 and T1. CSA values presented significant difference comparing T0 and T1 in G2 (p ≤ 0.05). In subjects of G3, measurements increased in T1 significantly affecting oropharynx dimension. CONCLUSIONS: MSA, volume and CSA values showed a significant increase affecting upper airway in advancements higher than 10 mm. Mandibular advancement range showed different effects in the airway space and should be considered to achieve favorable post-operative results in the oropharynx dimensions. Key words:Retrognathia, orthognathic surgery, three-dimensional imaging, oropharynx, airway.

Influence of Surface Treatment of Lithium Disilicate on Roughness and Bond Strength.

PURPOSE: To evaluate the effect of different concentrations of hydrofluoric acid (HF) on the surface roughness of a ceramic reinforced by lithium disilicate and on the bond strength formed between the ceramic and self-adhesive resin cement. MATERIALS AND METHODS: A total of 100 disks of IPS e.max Press ceramic (Ivoclar Vivadent) reinforced by lithium disilicate were prepared as follows: group 1 remained untreated (control group); in groups 5-20, 5-40, and 5-60, the surfaces were etched with 5% HF for 20, 40, and 60 seconds, respectively; in groups 10-20, 10-40, and 10-60, the surfaces were etched with 10% HF for 20, 40, and 60 seconds, respectively; and in groups 10-20P, 10-40P, and 10-60P, the surfaces were etched with 10% HF for 20, 40, and 60 seconds, respectively, followed by treatment with 37% phosphoric acid for 5 seconds. Surface roughness and bond strength were analyzed with confocal microscopy and microshear testing, respectively. The values obtained were statistically analyzed using paired t test and two-way ANOVA followed by Tukey post hoc test at a 5% significance level. RESULTS: Surface roughness was influenced by the concentration and exposure time of acid applied (P < .05) and by the combination of these two factors (P < .05). Treatment with 10% HF for 40 seconds (group 10-40) achieved the highest roughness value. In contrast, bond strength was affected only by the acid exposure time (P < .05). CONCLUSION: Conditioning of lithium disilicate ceramics can change the surface morphology, thereby affecting bond strength with resin cement.

Neurosensory Function and Implant Survival Rate Following Implant Placement With or Without an Interposed Bone Graft Between the Implant and Nerve: Prospective Clinical Trial.

PURPOSE: This prospective clinical study evaluated the influence of an interposed bone graft with inferior alveolar nerve lateralization in terms of rates of sensory disturbance, mean sensation recovery time, and survival rates for placement of osseointegrated implants. MATERIALS AND METHODS: Patients with an atrophic posterior mandible were enrolled in this study and randomized into two groups: bone graft group (a bone graft was placed between the implant and inferior alveolar nerve after lateralization) and control group (implants were placed in direct contact with the inferior alveolar nerve after lateralization). Neurosensory disturbances were evaluated via questionnaire 1 week after surgery and at the end of each month during the first year after surgery. RESULTS: Eighty-two implants were placed, with a survival rate of 97.56%. Two implants were removed due to mandibular fracture. All patients reported initial sensory disturbances arising from the surgical procedure. In the control group, the mean time for recovery from sensory disturbance was 3.95 ± 2.33 months, compared with 4.11 ± 4.68 months in the bone graft group (P = .587). CONCLUSION: The interposition of a bone graft between implants and the inferior alveolar nerve after lateralization did not prevent sensory disturbances and did not influence the sensation recovery time or implant survival rates.

Marginal Bone Remodeling Around Dental Implants with Hexagon External Connection After 10 Years: A Case Series with 10 to 19 Years of Function.

Peri-implant bone remodeling occurs in all osseointegrated implants and can be defined as an adaptive process of bone around the implant in response to functional loading. This retrospective study evaluated the marginal bone remodeling around dental implants with external hexagonal connections in function for more than 10 years. The sample consisted of 17 implants placed in the posterior region of the mandible to replace one or several teeth. For all cases, the initial periapical radiograph was assessed together with a subsequent follow-up periapical radiograph. Image analysis was performed using ImageJ software to establish the initial bone measurements and subsequent bone loss. The data were statistically analyzed using paired t test at a significance level of 5%. There was significant bone remodeling when the baseline and follow-up were compared (P < .001). The mean values of peri-implant bone remodeling on the mesial aspect were 0.90 ± 0.63 mm vertically and 1.17 ± 0.60 mm horizontally. The distal aspect of the implants showed 1.01 ± 0.82 mm and 1.06 ± 0.75 mm of marginal bone remodeling vertically and horizontally, respectively. Within the limitations of this study, marginal bone remodeling was visible, and bone levels around the external hexagon implants remain stable after 10 years of function.

Assessing peri-implant bone microarchitecture: conventional vs. osseodensification drilling - ex vivo analysis

Abstract: The aim was to evaluate primary implant stability and bone microarchitecture in two drilling situations, by comparing the conventional technique (CT) and osseodensification (OD) (Versah Burs - Jackson - Mississippi - USA). The implant insertion torque (IT), implant stability quotient (ISQ), and the peri-implant trabecular microstructure were assessed on bone fragments obtained from pig's tibia (n=12), divided between CT (n=6) and OD (n=6). After the drilling procedure, the implants were installed (3.5x8.5 mm, Epikut - SIN - São Paulo - Brazil). The IT and ISQ were measured using a digital torque wrench and resonance frequency analysis. Then, the bone fragments containing the implants were removed with a trephine and analyzed by Microtomography (µCT, 8.0 µm). The comparison between groups was performed using the unpaired t-test (α=0.05). The results revealed that OD promotes a higher insertion torque (CT: 7.67±2.44 Ncm; OD: 19.78±5.26 Ncm) (p=0.0005), although ISQ was not different (CT: 61.33±4.66; OD: 63.25±4.58) (p=0.48). There was a significant increase in peri-implant bone volume (CT: 23.17±3.39 mm3; OD: 32.01±5.75 mm3) (p=0.008), and trabecular parameters: separation (CT: 0.4357±0.03 mm; OD: 0.3865±0.04 mm) (p=0.0449), number (CT: 1.626±0.18 1/mm; OD: 1.946±0.13 1/mm) (p=0.007), and thickness (CT: 0.1130±0.009 mm; OD: 0.1328±0.015 mm) (p=0.02). Structure model index (SMI) data demonstrate no significant differences between groups (CT: 1.7±0.2; OD: 1.4±0.4) (p=0.12). In conclusion, OD increases the insertion torque values and promotes beneficial changes regarding bone microarchitecture compared with CT, revealing more peri-implant bone volume with consequent higher primary stability.

Resumo O objetivo deste estudo foi avaliar a estabilidade de implante e a microarquitetura óssea em duas técnicas de fresagem, comparando a técnica convencional (CT) e a osseodensificação (OD) (Versah Burs - Jackson - Mississippi - EUA). O torque de inserção do implante (IT), quociente de estabilidade primária (ISQ) e a estrutura trabecular peri-implantar foram avaliados em fragmentos ósseos obtidos de tíbia de porco (n=12), divididos entre CT (n=6) e OD (n=6). Após o procedimento de fresagem, foram instalados implantes (3,5x8,5 mm, Epikut - SIN - São Paulo - Brasil). O IT e o ISQ foram aferidos por meio de um torquimetro digital e análise de frequência de ressonância. Em seguida, os fragmentos ósseos contendo os implantes foram removidos com trefina e analisados ​​por microtomografia computadorizada (µCT, 8,0 µm). A comparação entre os grupos foi realizada por meio do teste-t não-pareado (α=0.05). Os resultados revelaram que a OD promove maior torque de inserção (CT: 7,67 ± 2,44º Ncm; OD: 19,78 ± 5,26 Ncm) (p=0,0005), embora a estabilidade primária não tenha sido diferente (CT: 61.33 ± 4.66; OD:63.25 ± 4.58) (p=0,48). Houve um aumento significativo no volume ósseo peri-implantar (CT: 23,17±3,39 mm3; OD: 32,01±5,75 mm3) (p=0,0089) e parâmetros trabeculares: separação (CT: 0,4357 ± 0,03 mm; OD: 0,3865 ± 0,04 mm) (p=0,0449), número (CT: 1,626 ± 0,18 1/mm; OD: 1,946 ± 0,13 1/mm) (p=0,007) e espessura (CT: 0,1130 ± 0,009 mm; OD: 0,1328 ± 0,015 mm) (p=0,02) O índice de modelo estrutural (SMI) não demostrou diferença estatisticamente significativa (p=0.1228). Concluindo, OD apresenta maiores valores de torque de inserção e promove mudanças benéficas na microarquitetura óssea em comparação com a TC, revelando maior volume ósseo peri-implantar.