Libros

Purpose: To compare bone substitutes composed of glycated collagen with synthetic micro-sized (1 to 10 μm) hydroxyapatite (OB) vs non–cross-linked collagen matrix with large-particle (250 to 1,000 μm) bovine-derived hydroxyapatite (BOC). Materials and Methods: The P1 to P4 premolars were bilaterally extracted from the mandibles of 19 Beagle dogs. After 21 days, osteotomies were created in each dog that received OB or BOC and were covered with a collagen membrane or were left untreated. The animals were randomly divided into three groups based on sacrifice time (4, 12, or 24 weeks). The right and left hemimandibles were trimmed to facilitate imaging and histology, and all tissues were placed in 10% neutral-buffered formalin. Microcomputed tomography (MicroCT 40 Scanner, Scanco) was used to analyze bone sections. Bone volume, residual material volume, and bone mineral density were determined for each treatment site (OB and BOC) based on a volume of interest that encompassed the original defect. Additionally, blinded histopathologic assessment (based on the ISO 10993-6 scoring system) and histomorphometry were performed on sections ground to < 100 μm thick and stained with Stevenel’s blue. Results: No clinical side effects were noted. No statistical differences were observed for OB vs BOC regarding the mineral volume percentage. Compared to OB, BOC had significantly higher mean mineralization densities at 12 weeks (P < .01), but this difference did not extend to 24 weeks. For residual grafting material, bone maturation, alveolar ridge restoration, and inflammatory response, OB showed a residual amount of bone graft and no statistical differences compared to BOC. Conclusion: Both OB and BOC represent valid treatment options for critically sized bone defects. Both bone fillers outperformed the sham-operated, ungrafted (empty) control, demonstrating statistically improved bone growth and ridge restoration. Palabras clave: bone grafting, collagen membrane, ridge augmentation, collagen scaffold

Purpose: To compare glycated multilayered membranes (OV) to a commercially available thin-layer membrane (OP) in a lateral ridge augmentation model in dogs. Materials and Methods: This was designed as a three-arm study, where one negative control (empty defect) was compared to two test arms: alveolar bone defects grafted with a mixture of 90% deproteinized bovine bone mineral and 10% porcine collagen, then covered with either a thick- (OV) or thin-layered (OP) membrane. Animals were randomly divided into three groups corresponding to the final sacrifice times of 4 weeks, 12 weeks, and 24 weeks. Sections underwent microCT, histology, histopathology, and histomorphometry. Results: No statistical differences were observed for OV compared to OP regarding the percentage of mineral volume and mean mineral density, amount of bone maturation, percentage of bone graft and membrane remaining in the grafted area, alveolar ridge width measurements, membrane mineralization, or ossification. Test groups presented significantly higher values compared to the empty control for all the endpoints. Conclusions: Within its limitations, this in vivo study highlighted that multilayered thick glycated membranes can serve as effective occlusive barriers for up to 6 months. Palabras clave: bone grafting, collagen membrane, ridge augmentation

Purpose: To monitor the early bone reaction in a canine model to a conventional sandblasted and dual acid-etched implant surface (ABT), a nanostructured hydrophilic surface (Nano), a dry salt–bioactivated ultra-hydrophilic surface (Hydro), and a bioactivated nanosurface obtained from the addition of dry salts to the Nano surface (Nano-Active). Materials and Methods: ABT, Nano, Hydro, and Nano-Active implants were placed in 12 dogs. A randomized split-mouth design was adopted. One implant of each type was placed in the mandible 3 months after tooth extraction in healed sites at the first molar region bilaterally. In the same session, the third and fourth premolars were extracted bilaterally and one implant of each type was immediately placed into the extraction socket. The dogs were euthanized at 14 and 28 days following surgery, and the peri-implant bone reaction was assessed histologically using Stevenel’s blue and alizarin red in nondecalcified sections. Results: The postoperative healing was uneventful. The 14-day histologic analysis reported nonsignificant results in terms of difference between the groups, while significant results were found 28 days after surgery. In fact, a significantly higher rate of new bone around the implant was reported in the Nano-Active compared to the Nano groups (51.0% ± 10.2% vs 36.0% ± 10.2%) and Hydro compared to the Nano groups (47.3% ± 10.7% vs 36.0% ± 10.2%). Conclusion: The results obtained indicate that new bone formed after 4 weeks demonstrated a tendency for dry salt– treated bioactivated surfaces to improve bone deposition in the interface in the early stages of healing; however, due to the limited number of dogs, the results failed to show a statistical significance. A study with a significantly larger group of animals should be performed in order to challenge the assumption that ultra-hydrophilic–surface implants might show higher bone-implant contact in immediate postextraction replacement. Palabras clave: bioactivated implant surface, histology, histomorphometric, nanosurface, salt-bioactivated surface, surface

Purpose: To retrospectively evaluate the survival rate and technical and biologic complications of feather-edge zirconia and metal-ceramic implant restorations cemented on conical titanium abutments. Materials and methods: Patients rehabilitated with implant-supported single crowns or fixed dental prostheses (FDPs) were divided into four groups: ZR-TL = tissue-level implant with a convergent collar and zirconia restoration; ZR-BL = bone-level implant and zirconia restoration; MC-TL = tissue-level implant with a convergent collar and metal-ceramic restoration; MC-BL = bone-level implant and metal-ceramic restoration. All of the restorations were cemented onto conical titanium abutments and had feather-edge margins, following the biologically oriented preparation technique (BOPT). Crown-level survival rates, technical and biologic complications, and bone resorption were registered. Chi-square test was performed to analyze all evaluated parameters among the groups. Nonparametric Mann-Whitney test was performed to analyze changes in bone level. Results: A total of 85 patients (133 implants, 66 single crowns, and 28 FDPs) were included in the present study with a mean follow-up time of 4.98 years. The overall survival rate was 98.2% for zirconia and 97.5% for metal-ceramic restorations at the crown level. No significant differences were found between the zirconia (ZR-BL and ZR-TL) and the metal-ceramic (MC-BL and MC-TL) groups for technical complications (P > .05). Bone resorption was 0.33 (0.37) mm in MC-TL; 0.61 (0.52) mm in MC-BL; 0.39 (0.51) mm in ZR-TL; and 0.77 (0.64) mm in ZR-BL, showing significantly greater bone loss in bone-level implants (P = .011). Conclusion: Zirconia implant restorations with feather-edge margins seem to be a viable alternative in cases of both tissue-level and bone-level implants.

Purpose: After tooth extraction, a modeling and remodeling phase of bone and soft tissues occurs. It has been fully demonstrated that bone resorption as high as 50% can take place regarding ridge width and a variable amount concerning ridge height, making it difficult to perform implant surgery. Materials and methods: Active members of the Italian Academy of Osseointegration (IAO) participated in this Consensus Conference, and three systematic reviews were conducted before the meeting to provide guidelines on alveolar ridge preservation procedures. The systematic reviews covered the following topics: (1) What material best preserves the dimensions of the ridge horizontally and vertically?; (2) what material favors the formation of the highest quantity of new bone?; (3) which technique would best seal the socket?; and (4) what effect does alveolar ridge preservation have on soft tissues? Results: The main conclusions reached by the assembly were that alveolar ridge preservation is advisable after dental extraction, particularly in esthetic areas, in proximity of anatomical structures (ie, maxillary sinus, inferior alveolar nerve, and mental foramen), whenever the treatment plan requires delayed placement, and whenever patients ask to postpone implant insertion for various reasons. Socket debridement is advised before the use of a "regenerative material," and xenograft is considered the gold standard material to maintain ridge dimensions. Another indication is antibiotic therapy, which is recommended in the case of alveolar ridge preservation (amoxicillin 2 g 1 hour before the intervention and 1 g every 12 hours for 6 days). A membrane or autologous soft tissue should be used to seal the socket and protect the regenerative material, and the indicated reentry time (implant insertion) is 4 to 6 months. Conclusion: This Consensus Conference agreed that the adoption of alveolar ridge preservation can effectively prevent physiologic bone loss, especially in esthetic areas. It is recommended to cover the xenograft material with a membrane or autologous soft tissue, and antibiotic therapy is advisable. Palabras clave: antibiotics, bone regeneration, dental implants, postextraction site, surgery

Purpose: Bone graft materials and soft tissue allografts are widely used in clinical practice to counteract physiologic postextraction site tridimensional shrinkage. The aim of this study was to test if plasma of argon treatment could have a bioactivation effect on hard and soft tissue scaffolds in clinical usage. Materials and methods: Forty-eight bovine bone matrix and porcine collagen samples were subdivided into two groups (test and control) of 12 samples each. The test group was treated with argon plasma (10 W, 1 bar for 12 minutes), while the control group was left untreated. Immediate cell adhesion and a proliferation assay at 72 hours were performed in the perfusion chamber of a bioreactor. Additionally, micro-CT analysis was performed on the treated and untreated scaffolds, before and after soaking in cell culture medium (four samples). Results: Osteoblasts seeded on plasma-treated bone matrix significantly increased the adhesion level compared with the untreated sample (43,144.3 ± 12,442.9 vs 21,736 ± 77,27.1; P = .0083). However, 3-day proliferation tests could not achieve significant differences between groups (105,715.5 ± 21,751.5 vs 107,108.6 ± 19,343.4; P = .998). No differences were measured on fibroblast adhesion on the collagen matrix in both conditions. Plasma of argon treatment and soaking in cell culture medium did not affect the bone matrix samples. The structure of collagen matrix samples was unaltered after plasma treatment, but became enlarged after soaking. Conclusion: Plasma of argon may be useful to biofunctionalize bone grafts, although benefits seemed to disappear after 3 days. No biologic response was detected on collagen matrix scaffolds. In vivo studies are needed to draw final clinical conclusions. Palabras clave: biomaterials, bone graft, bone substitute, guided bone regeneration, surface

Purpose: To evaluate the trueness of two intraoral scanners in different clinical situations and considering operator experience. Materials and methods: Two intraoral scanner systems were used to perform a total of 120 digital impressions of three master casts reproducing three scenarios (single implant, two implants, and four implants [full-arch]). Two operators, one experienced and one unexperienced, were selected. Results: No differences were found between the two operators. A statistically significant correlation was found with regard to the scanning system used and the clinical scenario analyzed. Conclusions: Within the limits of this preliminary report, operator experience seems not able to significantly influence the trueness of a digital impression; however, imprecision increased in the full-arch cases for both operators. The twoimplant scenario presented similar trueness values for both scanner systems.

Purpose: Beneficial aspects of short and ultrashort antibiotic administration protocols could be clinically correlated to the reduced side effects on the gastrointestinal microflora. The aim of this Consensus Conference was to establish the necessity of an antibiotic prophylaxis and its dosage to reduce the risk of early implant failure in healthy (ASA 1 or 2), periodontally healthy patients, undergoing basic dental implant surgery (straightforward cases). Additionally, the need for an antiseptic protocol, used before and after the implant surgery, was evaluated. Materials and Methods: Active members of the Italian Academy of Osseointegration (IAO), together with several worldwide-recognized key opinion experts in the field of microbiology, implant dentistry, and infectious diseases, were participants at this Consensus Conference. Two systematic reviews were carried out, before the Consensus Conference, and their results discussed in order to give guidelines on the administration of an antibiotic/antiseptic prophylaxis in implant surgery. The systematic reviews covered the following topics: (1) the use of antibiotics to reduce both implant failure rate and peri-implant infections in healthy patients and (2) the use of chlorhexidine compositions capable of reducing complications in patients undergoing surgical interventions. Results: The main statements reached by the assembly were as follows: (1) Rinsing with chlorhexidine is highly recommended before and after implant surgery to minimize the bacterial load. (2) A single dose of antibiotics in straightforward cases is recommended. (3) In complex cases (long surgical time, regeneration procedures), it is advisable to continue the antibiotic administration. Conclusion: This Consensus Conference advocates the administration of a unique dose of antibiotics in straightforward implant cases combined with the use of chlorhexidine. Palabras clave: antibiotics, dental implants, surgery

Purpose: This systematic review aimed to assess the effect of chlorhexidine (CHX) in preventing complications after extractive, implant, and periodontal surgery. Materials and Methods: The PICO question set for this systematic review was: “Is the use of chlorhexidine formulations able to prevent complications (safety) in patients undergoing procedures of either oral surgery, dental implantology, or periodontology compared to treatment procedures in patients without a chlorhexidine prescription?” Once inclusion and exclusion criteria were established, a search was carried out independently by two researchers on PubMed/MEDLINE, Scopus, and Web of Science. The primary outcomes investigated were the rate of alveolar osteitis and bacteremia after surgical procedures in oral surgery. Meta-analysis and trial sequential analysis (TSA) were performed in order to evaluate the findings. Results: After the selection, the 32 studies that fully met the eligibility criteria were considered in this systematic review. A meta-analysis was only possible for data obtained from studies related to extractive surgery. Meta-analysis and TSA showed a statistically significant decrease in the rate of alveolar osteitis after tooth extraction when CHX was employed compared with placebo treatments or treatments not using CHX (RR = 0.49; 95% CI: [0.40, 0.60], P < .001; I2 = 8%). Focusing on the rate of bacteremia, meta-analysis and TSA showed how the employment of CHX (RR = 0.87; 95% CI: [0.79, 0.96], P = .004; I2 = 4%) decreases the rate of bacteremia after extractive surgery. Data from the literature seem to lack in the evaluation of CHX use for the reduction of complications in periodontology and implant dentistry. Conclusion: This systematic review showed with a good power of evidence that CHX employment reduces alveolar osteitis and bacteremia rates after dental extractions. Palabras clave: chlorhexidine, complication, efficacy, prevention, systematic review, TSA

Purpose: This 3-year study aimed to evaluate hard and soft tissue modification around a two-piece implant characterized by a transmucosal hyperbolic neck in healthy consecutive patients with a need for single-tooth replacement. Materials and Methods: Two-piece implants (n = 66) were placed with a flapless technique in 56 patients (27 men; 29 women; mean age 55 ± 9 years): 16 immediately after root extraction (immediate group), 20 after 8 to 12 weeks (early group), and 30 after 10 or more months (delayed group). The transmucosal hyperbolic neck was exposed 1 to 1.5 mm above gingival level. Customized abutments were positioned 3 months later with the implant-abutment connection located approximately 1 to 1.5 mm above soft tissue level. Provisional cemented resin crowns were designed with the finishing line at the hyperbolic neck and then positioned to avoid excessive compression of soft tissue, to guide gingival contours. Twenty days later, a definitive metal-ceramic crown was cemented. In all patients, the gingival biotype (thin or thick) was also evaluated. The primary outcomes were as follows: 36-month implant survival rate, peri-implant marginal bone level (MBL, in mm) changes observed in single-blind on radiographs at 1, 3, 6, 12, 24, and 36 months (T₁, T₃, T₆, T₁₂, T₂₄, and T₃₆), and pink esthetic score (PES) at T₆, T₁₂, and T₃₆ to analyze soft tissue adaptation after loading and crown application. The secondary outcomes were as follows: plaque score and bleeding on probing (BOP). Linear regression models and multilevel mixed logistic regression were used to detect any statistical difference of MBL according to operative parameters. Kruskal-Wallis one-way analysis of variance (ANOVA) on ranks was performed to assess statistical differences of PES at T₆, T₁₂, and T₃₆. Results: The survival rate was 100%. The dropout rate was 1.79%. No infections, mucositis, or peri-implantitis were reported. Implants placed in thick-biotype tissues showed a statistically different lower bone loss at 36 months with respect to the thin biotype (P .05). At 36 months, the early group showed lower bone loss compared with the delayed group (P .05). Multilevel mixed logistic regression revealed that gingival biotype was the parameter that was most related to MBL variations (P = .025). The PES value (mean ± SD) at T₆ was 10.76 ± 1.19 (median: 11; range: 8 to 13; IQR: 10 to 12). The values statistically increased at T₁₂ and T₃₆, where the mean values were 11.76 ± 1.10 (median: 12; range: 9 to 13; IQR: 11 to 12) and 11.83 ± 1.03 (median: 12; range: 9 to 14; IQR: 11 to 13). Conclusion: MBL and soft tissue clinical parameters measured around two-piece hyperbolic-neck implants were stable during the 3-year follow-up and free from complications. The exposure of the hyperbolic neck for 1.0 to 1.5 mm allowed a flapless one-stage surgery, which supported fast adaptation of the soft tissues, evidenced by high PES values and low percentages of BOP. The results from the study imply a new simple approach in the clinical management of gingival and bone tissue. Palabras clave: flapless procedure, hyperbolic neck, prospective cohort study, single implant, transmucosal placement