Bone‐to‐Implant Contact Around Immediately Loaded Direct Laser Metal‐Forming Transitional Implants in Human Posterior Maxilla

Objective: Direct laser metal forming (DLMF) is a procedure in which a high‐power laser beam is directed onto a metal powder bed and programmed to fuse particles according to a computer‐aided design file, generating a thin metal layer. This histologic study evaluated the bone‐to‐implant contact (BIC%) around immediately loaded DLMF transitional implants retrieved after 2 months from posterior human maxillae. Methods: Twelve totally edentulous individuals (mean age, 66.14 ± 2.11 years) received DLMF transitional implants divided in twelve immediately loaded (IL) and twelve unloaded (UI) implants. These transitional implants were placed between conventional implants to support the interim complete maxillary denture during the healing period. After 8 weeks, the transitional implants and the surrounding tissue were removed and prepared for histomorphometric analysis. Results: Mature woven preexisting bone lined by newly formed bone in early stages of maturation were found around all retrieved implants. Histometric evaluation indicated that the mean BIC% was 45.20 ± 7.68% and 34.10 ± 7.85% for IL and UI, respectively (P <0.05). Conclusion: The present data obtained in humans showed that, although both IL and UI presented good BIC%, IL DLMF implants had a higher BIC% in the posterior maxilla.     

Comprehensive Analysis of Repair/Reinforcement Materials for Polymethyl Methacrylate Denture Bases: Mechanical and Dimensional Stability Characteristics

Fracture of complete denture is a common problem as acrylic resins hold inherent limitations. This necessitates affirmation of a selection criterion by evaluating the critical requirements of repair materials. The study intended to evaluate mechanical properties and dimensional stability of common denture base repair and reinforcement materials under standard experimental protocol. Seven types of denture reinforcement materials were chosen. Forty cuboidal samples were made in accordance with ISO 178 for three point bending test and divided to eight groups of five samples each. One group acted as control and samples of seven groups were sectioned and repaired with chosen materials. Five mechanical properties—fracture load, deflection, flexural strength, fracture toughness and elastic modulus were evaluated for all groups. Forty mandibular complete denture specimens were utilized for evaluating fracture load and deflection under loading. Dimensional stability after repair with seven different repair materials was analyzed in two planes (Linear and curvilinear) utilizing separate set of denture samples. Heat cure polymethyl methacrylate with polyethylene fiber was affirmed as material of choice based on this study as it accomplishes the most critical norms of requirement.     

牙周炎患者种植修复即刻负荷的临床应用及体会

目的:探讨牙周炎患者种植修复时采取即刻负荷的临床效果。方法:牙周炎患者6例,完善的牙周治疗后在下颌颏孔间植入四枚种植体,于术后48小时内用SynCone基台即刻负荷过渡义齿,并定期复诊检查。结果:术后随访12～40个月,植体无松动,无明显骨吸收,义齿使用良好,患者满意。结论:牙周炎患者经完善治疗后接受种植即刻负荷的修复方法,近期效果满意,远期效果需进一步观察。     

Displacement of Dental Implants in Trabecular Bone under a Static Lateral Load in Fresh Bovine Bone

Aim: The study aims to provide objective data for the displacement of titanium screw implants in trabecular bone specimens. One hundred Semados implants (Bego, Bremen, Germany) were inserted in bovine type IV bone specimens. All implants had a diameter of 3.75 mm; 50 implants had a length of 8.5 mm and 50 implants had a length of 15 mm. Insertion torque was determined at intervals of 10, 20, and 30 Ncm. Implants were loaded horizontally with 10, 20, and 30 N for 2 seconds. An indicator strip was attached to the implant abutment to allow direct observation of implant movement relative to the bone surface. Horizontal displacement was assessed with an accuracy of measurement of 10 µm. Seven implants got lost by visible loosening. Degree of displacement was subject to evaluation with all others. Those implants showed a mean displacement of 59 µm for 10 N (n = 100), 173 µm for 20 N (n = 99), and 211 µm for 30 N (n = 93). The mean displacement of 15‐mm implants (16, 37, 51 µm) was significantly lower compared with 8.5‐mm implants (103, 311, 396 µm) corresponding to 10, 20, and 30 N as lateral loads. Conclusions: Displacement of screw implants in trabecular bone can be detected and visualized using commercially available endoscopes with a high magnification. A lateral load of 20 N indicates a mean displacement of over 100 µm and therefore results in a critical displacement.     

Impact of Pulsatile Perfusion on Clinical Outcomes of Neonates and Infants With Complex Pathologies Undergoing Cardiopulmonary Bypass Procedures

The aim of this clinical trial was to evaluate the pulsatile perfusion mode in pediatric patients who had complex cardiac pathologies according to Jenkins stratifications (category 4) undergoing cardiopulmonary bypass procedures (CPB). Patients with transposition of great arteries (TGA) and ventricular septal defect (VSD) were included in this clinical study. Eighty‐nine consecutive pediatric patients undergoing open heart surgery for repair of TGA‐VSD were prospectively entered into the study and were randomly assigned to either the pulsatile perfusion group (Group P, n = 58) or the nonpulsatile perfusion group (Group NP, n = 31). There were no differences between groups in terms of demographical and intraoperative parameters. The pulsatile group needed significantly less inotropic support (P < 0.05) and had lower lactate levels (P < 0.001), higher urine output (P < 0.01), and higher albumin levels (P < 0.05). In addition, the pulsatile group had less ICU (P < 0.01) and hospital stays (P < 0.001). We conclude that the use of pulsatile flow is a better option and should be considered for repair of the complex congenital heart defects.     

Comparison of benefit and safety between different loading dose of clopidogrel on elderly patients undergoing primary percutaneous cronary intervention for ST-segment elevation myocardial infarction

Background Despite the proven benefit of 600-mg loading dose of clopidogrel in patients with acute ST-segment elevation myocardial infarction (STEMI) who undergo primary percutaneous cronary intervention (PCI), there is still concern about its benefit and safety on elderly population. Methods Data of 172 consecutive elderly patients (≥75 years) with STEMI who underwent primary PCI at Guangdong Provincial Cardiovascular Institute from January 2008 to December 2011 were retrospectively collected. Patients were divided into 600-mg loading clopidogrel group and 300-mg clopidogrel group accoring to the loading dose of clopidogrel before primary percunaeous coronary intervention(PCI). Enzymatic myocardial infarction size estimated by peak creatine kinase-myocardial band (CK-MB) and patency of the infarct-related artery (IRA) were compared. Thirty-day major adverse cardiac events (MACEs), which consist of death, nonfatal myocardial infarction (MI), nonfatal stroke, target vessel revascularization (TVR) or stent thrombosis (ST) were compared to assess the efficacy of different loading dose. Bleeding information was compared as well to assess the safety of different pretreatment stragety before primary PCI. Results 96 patients were adminstered with 600-mg loading clopidogrel before primary PCI while 76 were administered with 300-mg. Patency of the IRA was significantly higher in patients administered with 600-mg loading clopidogrel therapy as compared with those who received 300-mg loading clopidogrel (94.8% vs. 85.5%, P = 0.038). 600-mg loading dose of clopidogrel was associated with lower incidence of 30-day MACEs compared with 300-mg loading dose of clopidogrel (8.3% vs. 19.7%, P = 0.029) while did not increase the risk of TIMI major (3.1% vs. 3.9%, P = 0.770) and minor bleeding (10.4% vs. 6.6%, P = 0.376). Conclusion 600-mg loading clopidogrel improves final patency of the IRA and clinical outcome as compared with 300-mg loading clopidogrel without increasing bleeding hazard.     

Detection of changes of scar thickness under mechanical loading using ultrasonic measurement

The intervention of pressure therapy on management of hypertrophic scar (HS) after burn is based on the theoretical assumption that the mechanical force added onto the scar tissue will reduce the growth of myofibroblasts which create the collagen clusters and the interstitial space, and to realign fibrous tissues, thus reducing the thickness of HS. In this experimental study, a high frequency ultrasound imaging system (12 MHz) was applied to measure the real time changes of thickness of the post burn HS under a mechanical loading system with similar pressure generated to the scar tissue. The validity of the ultrasound system in measurement of the changes of scar thickness underneath the tissue was tested on the porcine skin in vitro followed by measurement of human skin in vivo. Results showed that the ultrasound measurement of thickness had both good validity (r² = 0.98, p < 0.0001) and good intra-rater reliability (ICC = 0.89). Then, the system was used to test the thickness of 14 human HS samples in vivo among 7 subjects. External loading force with similar pressure range (10–45 mmHg) was then applied to these scar samples via ultrasound probe with rectangular contacting area at 4 cm² and each loading force was maintained unchange for 2 min over the scar tissue. The real time scar thickness was documented. Results showed that the mean scar thickness was found to be significantly decreased when the loading force applied was increased from 5 to 35 mmHg (with 10 mmHg interval) (p < 0.001). A significant negative correlation between the pressure level and scar thickness was observed (r² = 0.96, p = 0.005). The decline of thickness was found more significant between 0 mmHg and 15 mmHg. The findings were in line with the postulate that pressure therapy is effective in reducing the thickness of HS. A long term followup study should be administered to determine the prolonged effect of pressure intervention.     

Immediate loading of mandibular overdentures supported by unsplinted direct laser metal-forming implants: results from a 1-year prospective study

Background: At present, only some studies have dealt with immediate loading of unsplinted implants supporting mandibular overdentures. The aim of this prospective study is to evaluate treatment outcomes of mandibular overdentures supported by four one‐piece, unsplinted, immediately loaded, direct laser metal‐forming (DLMF) implants by assessing implant survival rate, implant success, marginal bone loss, and prosthetic complications. Methods: A total of 96 one‐piece DLMF implants were inserted in the edentulous mandible of 24 patients. Four implants were placed in each edentulous mandible. Immediately after implant placement, a mandibular overdenture was connected to the implants. At 1‐year follow‐up, clinical, radiographic, and prosthetic parameters were assessed. Success criteria included absence of pain, suppuration, and implant mobility; absence of continuous peri‐implant radiolucency; and distance between the implant shoulder and the first visible bone contact <1.5 mm. Results: After a 1‐year loading time, the overall implant survival rate was 98.9%, with only one implant lost. Among the surviving 95 implants, two did not fulfill the success criteria; therefore, the implant success rate was 97.8%. The mean distance between the implant shoulder and the first visible bone contact was 0.28 ± 0.30 mm (95% confidence interval, 0.24 to 0.32). Some prosthetic complications were reported. Conclusion: Based on the present results and within the limits of this study, the immediate loading of four unsplinted DLMF implants by means of ball attachment–supported mandibular overdentures seems to represent a safe and successful procedure.     

Impact of excessive occlusal load on successfully‐osseointegrated dental implants: a literature review

The aim of the present study was to review the available evidence on the response of the peri‐implant bone when subjected to excessive occlusal forces. The search strategy included papers published in English in the Medline database and the Wiley Online Library from January 1991 to December 2011. Experimental or review papers reporting the conditions of the peri‐implant bone of dental implants submitted to excessive occlusal loading in the presence of a controlled oral hygiene regime were eligible for inclusion. The knowledge regarding the response of the peri‐implant bone when the dental implant is excessively loaded is limited, and the level of evidence is poor. With animal experimental studies showing conflicting results, it is unclear whether occlusal overload might cause marginal bone loss or total loss of osseointegration to already osseointegrated dental implants when the applied load exceeds the biologically‐acceptable limit. This biological limit is also unknown. Furthermore, higher remodeling activity of the peri‐implant bone is found around implants subjected to high loading forces.