Application of the break-even point to express the bone dynamics around implants.

PURPOSE: The aim of this study was to apply the break-even point concept to express the dynamics of bone formation and resorption around implants. METHODS: Published data on new bone and parent bone densities around implants from one human and three dog studies were selected and used for analysis. The break-even point (BEP) of the bone density (BD) was assessed. The BEP is the point at which, in a graph, the lines representing the formation of new bone and resorption of old bone intersect. BEP is expressed in time (x; days) of occurrence and percentage of bone (y; %) at which the break-even point occurs and illustrates the grade of bone modeling. The sooner the occurrence, the faster the bone formation in relation to the resorption of the old bone. RESULTS: In the marrow and cortical compartments, BEP of bone density occurred after 7.9 days (BD% 24.5%) and >30 days, respectively. Different surfaces presented similar BEP, ranging between 9.7 and 11.2 days (BD% 19.1-22.5%). BEP at implants installed in the human maxilla occurred after 29-30.4 days (BD% 28.3-29.6%). CONCLUSION: The present study showed that the parameters used to express the break-even point can provide information on the influence of the model used, surface characteristics, and bone quality on bone modeling/remodeling around implants.

Influence of one-step professional mechanical tooth cleaning pastes on surface roughness and morphological features of tooth substrates and restoratives.

PURPOSE: This study investigated the influence of professional mechanical tooth cleaning (PMTC) pastes on the surface texture of different subject materials. METHODS: Two one-step PMTC pastes, Clinpro Cleaning Paste for PMTC (CP) and PRG Pro-Care Gel (PG), and multiple-step PMTC pastes, Merssage Regular (MR), Merssagge Fine (MF), and Merssage Plus (MP), were used. For comparison, PMTC was performed using distilled water without paste (DW). The subjected materials used were bovine enamel (ENA) and dentin (DEN), a resin composite (FSU), and lithium disilicate (IEC). The prepared specimens were polished using a #2000-grit silicon carbide paper. PMTC was performed using a brush at 1,000 rpm for 15 s. RESULTS: The surface roughness (Ra) values of the specimens before and after PMTC were measured by laser scanning microscopy. The Knoop hardness number (KHN) of the subjected material was obtained. The types of PMTC pastes and subject materials had a significant influence on the Ra values and KHN. For the majority of subject materials, the descending order of Ra values after PMTC was MR > MF > CP > PG > MP > DW. The descending order of KHN of the materials was IEC > ENA > FSU > DEN. CONCLUSION: Although one-step PMTC pastes appeared to be effective, it is important to consider the subject material during PMTC.

The Influence on Healing of Bony Window Elevated Inward in the Sinus Cavity as Cortical Bone Graft: A Histomorphometric Study in Rabbit Model.

PURPOSE: To evaluate the influence on healing of the bony window elevated inward in the sinus cavity as a cortical bone graft. MATERIALS AND METHODS: Eighteen rabbits were included in the experiment. At the test sites (bony window), the antrostomy was prepared and the remaining bony window was elevated together with the sinus mucosa. At the control sites, the bony window was gently detached before the sinus mucosa elevation and discarded. The space obtained was grafted with deproteinized bovine bone mineral (DBBM). A collagen membrane was positioned on the antrostomy at both sides. The rabbits were euthanized after 2, 4, and 8 weeks in groups of six each. Histologic analyses in different regions of the elevated space were carried out, and a Wilcoxon test was used to estimate differences. Microcomputed tomography (microCT) analyses were also performed. RESULTS: After 2 weeks of healing, higher proportions of new bone were found in the test group compared with the control group due to the higher amount of bone formed in the region subjacent to the sinus mucosa. In this region, higher amounts of new bone were also found in the test group after 4 (P = .028) and 8 weeks of healing (P = .345). After 8 weeks of healing, the percentage of new bone was higher at the control sites compared with the test sites, with the proportions being 25.4% ± 3.2% and 21.3% ± 6.1%, respectively. In this period of evaluation, the bony window contributed with 20.1% ± 5.3% of vital bone in the test group. A fraction of 60.4% ± 10.8% of its surface was surrounded by new bone. In the microCT analysis, after 8 weeks of healing, fractions of 22.3% ± 1.6% and 22.2% ± 0.7% of bone were found in the test and control groups, respectively. CONCLUSION: The presence of the bony window positively influenced the healing in the elevated space, especially in the submucosa region. The bony window was vital and incorporated into newly formed bone.

Bone healing at non-submerged implants installed with different insertion torques: a split-mouth histomorphometric randomized controlled trial.

OBJECTIVES: To evaluate histomorphometrically the healing at implants installed with standard or very low insertion torque values MATERIAL AND METHODS: Twelve volunteer patients were recruited, and two screw-shaped titanium devices were installed in the distal segments of the mandible using insertion torque values of either < 10 Ncm or ~ 30 Ncm. The implants were left to heal in a non-submerged fashion. After 8 weeks, biopsies were retrieved, and ground sections were prepared for histological evaluation. RESULTS: Histological slides from 11 patients were available for (n = 11). The new bone in contact with the implant surface was 39.3 ± 18.5% and 49.4 ± 9.4% at the < 10 and ~ 30 Ncm sites, respectively. Considering the pre-existing old bone, the total mineralized bone was 46.8 ± 22.1% at the < 10 Ncm sites and 57.0 ± 14.1% at the ~ 30 Ncm. No statistically significant differences were found. New bone density and total mineralized bone density were 36.6 ± 8.1% and 53.0 ± 13.5% at the < 10 Ncm sites and 35.9 ± 10.0% and 52.2 ± 16.0% at the ~ 30 Ncm sites, respectively. No statistically significant differences were disclosed. CONCLUSION: From the data of the present study, it can be concluded that a trend of higher osseointegration was observed at the ~ 30 Ncm compared to the < 10 Ncm torque group. Nevertheless, it can be concluded that an implant installed with a very low torque may achieve a good integration. TRIAL REGISTRATION: ClinicalTrials.gov NCT04017156; trial retrospectively registered on 12 July 2019.

Use of TiBrush for surface decontamination at peri-implantitis sites in dogs: Radiographic and histological outcomes.

AIM: The aim of the present study was to evaluate the efficacy on the healing of mechanical decontamination of infected implant surfaces performed with a titanium brush. METHODS: Mandibular premolars and first molars were extracted bilaterally in six dogs. After 3 months, two unsubmerged implants were installed on both sides of the mandible. Three months later, peri-implantitis was induced with ligatures for 3 months and then removed. After 1 month, surgical mechanical decontamination of the surfaces was performed either with a rotatory titanium brush or gauzes soaked in saline. Five month later, biopsies were retrieved. Evaluations on X-rays taken of the mesiodistal plane and on histological slides prepared in a buccal-lingual plane were performed. RESULTS: After the induction of peri-implantitis, a mean marginal bone loss of 2.6 ± 0.6 mm and 1.9 ± 1.0 mm was observed in the brush and gauze groups by X-ray, respectively. Five months after treatment, a mean gain of marginal bone of 0.6 mm was obtained in both groups. The mean closures of the vertical and horizontal defects were 0.6 mm and 0.6 mm for the brush group, and 0.8 mm and 0.5 mm for the gauze group, respectively. Histologically, a loss of attachment at the buccal aspect of 2.2 ± 0.9 mm in the brush group and of 2.3 ± 0.5 mm in the gauze group was found. No statistically-significant differences were found after the treatment. CONCLUSIONS: Mechanical implant surface decontamination performed with a rotatory titanium brush resulted in a marginal bone level gain, yielding a low content of inflammatory infiltrate close to the marginal bone.

Marginal soft tissue stability around conical abutments inserted with the one abutment-one time protocol after 5 years of prosthetic loading.

BACKGROUND: Soft tissue stability is crucial to obtain and maintain optimal esthetic results. PURPOSE: This study aimed to investigate, over 5 years, the soft tissue response using a conical abutment together with the "one-abutment one-time" (OA-OT) protocol in the restoration of implants inserted in the anterior esthetic area. MATERIAL AND METHODS: From January 2011 to January 2012, all consecutive patients requiring an implant n the maxillary area between canines were enrolled. After submerged healing and osseointegration, a definitive abutment with a provisional crown was inserted. After 1 month, the definitive crown was delivered (Tdef). Analog impressions were taken before tooth extraction (T0), at implant insertion Timpl, and Tdef, and at 12 months (T1) and 60 months (T5). Casts were scanned and superimposed using a dedicated software. Differences in vertical height of soft tissue margins between the digitized model casts were calculated and paired sample t test was conducted to compare results. To detect the potential role of biotype, groups (thick vs. thin) were compared by analysis of variance with general linear model. RESULTS: Twenty-five patients were enrolled. Three patients dropped out. At the 60-month, 22 patients (12 men and 10 women with mean age of 68.3 ± 11 years) concluded the study follow-up. Horizontal changes demonstrated gain of 1.06 mm at Timpl, 0.94 mm at Tdef, 0.92 mm at T1 and 0.97 mm at T5 compared to T0. Vertical changes demonstrated gain of 0.84 mm at Timpl, 0.11 mm at Tdef, 0.29 mm at T1 and 0.59 mm at T5 compared to T0. The analysis of variance showed a significant better performance of thick biotype in soft tissue horizontal width (P = .022). No statistical differences were noticed for vertical width (P = .111). CONCLUSIONS: The use of a conical abutment together with the OA-OT approach allowed longitudinal stable soft tissue dimensions.

Five-year cohort prospective study on single implants in the esthetic area restored using one-abutment/one-time prosthetic approach.

PURPOSE: This study was aimed to investigate, over 5 years, bone response to "one-abutment onetime" (OA-OT) protocol in the restoration of implants inserted in the anterior maxilla. Additionally, influence of soft tissue biotype in the bone remodeling was investigated. MATERIALS AND METHODS: From January 2011 to January 2012, all consecutive patients presented with a hopeless tooth in the maxillary area between canines were enrolled. Post-extraction ridge preservation was performed. After 6 months, implant was midcrestaly inserted and intraoperative impression was taken. Two months thereafter an immediate definitive abutment with a provisional crown was inserted. At final crown connection, patients underwent a standardized periapical radiograph (T0). At 12 (T1), 24 (T2), 36 (T3), 48 (T4), and 60 (T5) months, radiographic follow-up and clinical control were carried out. Independent sample t-test was conducted to compare bone loss at different times. To detect the potential role of biotype, groups (thick TK vs thin TH) were compared by analysis of variance with general linear model. RESULTS: Twenty-five patients were enrolled, but only 22 patients concluded the study. The radiographic analysis showed a stable longitudinal condition of bone levels after the first-year significant increasing (0.17 ± 0.25mm, 0.33 ± 0.25mm, 0.28 ± 0.27mm, 0.25 ± 0.26mm, 0.31 ± 0.35mm, and 0.31 ± 0.29mm, respectively at T1, T2, T3, T4, and T5). No statistical significant differences in bone loss among the two groups TH vs TK over the time (P = 0.952) were demonstrated. CONCLUSION: Results showed that the OA-OT approach allow to obtain stable bone levels.