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.

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.

Bone Volume Dynamics and Implant Placement Torque in Horizontal Bone Defects Reconstructed with Autologous or Xenogeneic Block Bone: A Randomized, Controlled, Split-Mouth, Prospective Clinical Trial.

PURPOSE: The aim of this study was to evaluate volumetric stability of autologous and xenogeneic block grafts and primary stability of implants in maxillary grafted areas. MATERIALS AND METHODS: Each patient received one autologous block and xenogeneic block, both covered with a membrane. Bone thickness measurements clinically and tomographically were made before, immediately, and 6 months postoperatively. After 6 months, identical implants were placed in each grafted area, and primary stability was measured. RESULTS: Eight patients with anterior horizontal bone defects were selected. Clinical outcomes at 6 months postgrafting in the autologous block revealed a mean thickness of 7.4 ± 1.6 mm, with an initial mean measurement of 3.4 ± 1.7 mm and 2.6% resorption, whereas the mean in the xenogeneic block was 8.9 ± 1.5 mm, 3.3 ± 1.6 mm, and 7.3%, respectively. Tomographic evaluation of the thickness at 6 months postgrafting in the autologous block was a mean 7.8 ± 1.8 mm, with an initial mean of 3.7 ± 1.6 mm and resorption of 0%, while the mean in the xenogeneic block was 9.3 ± 1.6 mm, 3.6 ± 1.4 mm, and 2.1%, respectively. No significant difference in bone thickness was observed immediately or 6 months after the procedure. The mean implant placement torque was 32 ± 22 Ncm in the autologous block and 18 ± 9 Ncm in the xenogeneic block (P = .004). CONCLUSION: Xenogeneic block was shown to be a suitable alternative to reconstruct horizontal defects in the alveolar ridge that had undergone extensive resorption, though lower insertion torques were obtained during implant placement.

Retrospective Evaluation of the Influence of the Collar Surface Topography on Peri-implant Bone Preservation.

PURPOSE: To evaluate the influence of the collar surface topography on peri-implant marginal bone preservation. MATERIALS AND METHODS: A total of 156 patients who received at least one cylindrical implant of regular diameter with an external-hexagon platform in the posterior region of the maxilla or mandible were recalled to the office for a retrospective evaluation. Implantation sites and implant length information were recorded, and implants were divided according to the collar surface topography: machined (M) or rough (R) surface. Each implant was assessed by digital periapical radiography, using a sensor holder for the paralleling technique. The marginal bone remodeling was determined as the distance from the implant platform to the first bone-to-implant contact, and the known implant length was used to calibrate the images in the computer software. The follow-up measurements were compared with those obtained from the radiograph taken at the time of prosthetic loading to determine the late bone remodeling. An independent t test was used to compare data. RESULTS: From 138 patients who attended the recall, 242 implants (M = 126; R = 116) were evaluated with a mean follow-up period of 4.6 ± 0.9 years. Similar success rates were found in both groups (M = 95.0%; R = 95.9%). Late bone remodeling in the maxilla was not influenced by the implant collar (P = .504); however, lower marginal bone loss was observed in the R group (1.20 ± 0.52 mm) compared with the M group (1.58 ± 0.73 mm) in the mandible (P = .007). CONCLUSION: Although the implant collar design did not influence the success rate of dental implants, the rough collar design reduced the late marginal bone remodeling around external-hexagon implants in the mandible. The maxilla was not benefited by the rough collar design.

Influence of lip retraction on the cone beam computed tomography assessment of bone and gingival tissues of the anterior maxilla.

OBJECTIVE: To evaluate the influence of lip retraction on cone beam computed tomography (CBCT) assessment of bone and gingival tissues on the labial surface of the anterior maxilla. STUDY DESIGN: A retrospective study was conducted using measurements of bone and gingival tissues collected from 120 maxillary incisors. The thicknesses of the bone and gingival tissues of different regions were measured on CBCT images, with and without a lip retractor. The thicknesses of the gingival tissues obtained from CBCT were correlated with measurements performed by clinical probing. RESULTS: The thickness of bone in the more cervical region presented a higher mean value for exams performed with a lip retractor (P = .021). The thickness of bone found a significant correlation with the thickness of the gingiva (P ≤ .020) with a lip retractor in CBCT exams. The thickness of the gingival tissue obtained from CBCT scans with lip retraction found significant correlations with those obtained clinically (P ≤ .001). CONCLUSIONS: The use of lip retractors is a simple and reliable practice that allows the measurement of gingival tissues on CBCT images. This practice can exempt a patient from an invasive clinical procedure for measuring the thickness of the gingival tissue for implant cases of the anterior segment.

Assessment of mandibular posterior regional landmarks using cone-beam computed tomography in dental implant surgery.

The aim of this study has been to evaluate and correlate the anatomical features of the posterior mandibular region (submandibular fossa depth, bone height and thickness, and mandibular canal corticalization) to improve accident prevention and allow safe planning in implantology. Four parasagittal sections of cone-beam computed tomography (CBCT) from 100 patients were bilaterally analyzed. Linear measurements of the submandibular fossa depth, bone height and thickness were performed. The submandibular fossa was also classified into non-influential undercuts and influential undercuts for implant placement. Mandibular canal corticalization was also evaluated and classified according to the visualization. Data on patient age and gender were also collected. Forty-one scans (41%) were from male patients, and 59 (59%) were from female patients. Patient age ranged between 18 and 84 years, with an average age of 51.37 years. The submandibular fossa depth and implant bone thickness had a significant effect on the variability of the sample (46.1% and 22.3%, respectively). The submandibular fossa depth was quite variable, and the highest values were observed in the posterior regions. In 18.27% of the cases, the presence of the fossa directly influenced implant placement, considering a bone height of 10mm (standard implant). A significant correlation was observed between fossa depth and bone thickness. Thus, greater attention should be paid to thick ridges; although thick ridges are favorable, they may be associated with deeper submandibular fossae. The mandibular canal was the most influential anatomical structure in the premolar region due to the reduced bone height in this region and the greater difficulty in viewing the canal, and the submandibular fossa was the most influential structure in the molar region due to lower bone height leading up to the fossa and the greater fossa depth in this region. Therefore, CBCT is an important tool for assessing the mandibular region and planning for safe implant installation in the posterior mandible. Furthermore, comprehensive evaluation of the characteristics of this region is necessary, as the variables - submandibular fossa depth, bone height and thickness, and mandibular canal corticalization - are related and must be considered together when planning.

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.