ABSTRACT
Implantoplasty (IP) is used in dental implants with peri-implantitis and aims to remove threads and polish rough surfaces in order to prevent bacterial colonization. As a result of this procedure, implant strength might be compromised. We tested 20 tapered screw-shaped Ti6Al4V dental implants with a simulated bone loss of 50%. Ten implants underwent IP and 10 served as controls. Surface topography (Sa, Sz, Ssk, and Sdr) was analyzed with a confocal optical microscope. Subsequently, a minimum of four series of cyclic loads were applied with a servo-hydraulic mechanical testing machine (5 × 106 cycles at 15 Hz, between a maximal nominal value-starting at 529 N in the IP group and 735 N in the control group-and 10% of that force). We recorded the number of cycles until failure and the type of failure. Implant failure was analyzed by visual inspection and scanning electron microscopy. Open circuit potential and potenctiodynamic tests were carried out with high precision potentiostat using Hank's solution at 37 °C to evaluate the effect of the implantoplasty on the corrosion resistance. Implantoplasty significantly reduced the surface topography values (median) and interquartile range (IQR); Sa from 1.76 (IQR = 0.11) to 0.49 (IQR = 0.16), Sz from 20.98 (IQR = 8.14) to 8.19 (IQR = 4.16), Ssk from 0.01 (IQR = 0.34) to -0.74 (IQR = 0.53) and Sdr from 18.20 (IQR = 2.26) to 2.67 (IQR = 0.87). The fatigue limits of the control and implantoplasty groups were 551 N and 529 N, respectively. The scanning electron micrographs showed fatigue striations indicating fatigue failure. Besides, the fractographic analysis revealed a typical brittle intergranular fracture mechanism. The infinite life range of the dental implants evaluated was largely above the threshold of usual chewing forces. Implantoplasty seems to render a fairly smooth surface and has a limited impact on fatigue resistance. In addition, implantoplasty produces a decrease in the corrosion resistance of the implant. Corrosion current density from 0.019 µA/cm2 for as-received to 0.069 µA/cm2 in the interface smooth-roughened dental implant. These places between the machining and the rough area of the implant are the most susceptible, with the appearance of pitting.
ABSTRACT
BACKGROUND: The surgical extraction of the lower third molars is one of the most common procedures in oral surgery, and this surgical operation can cause intra- and postoperative complications such as pain, trismus, bleeding, infection, oedema, inferior alveolar nerve injuries, displacement of teeth to neighbouring spaces and mandibular fractures. The aim of this systematic review is to report the prevalence of mandibular fractures that occur intra- and postoperatively in patients who have undergone surgical removal of the lower third molar. MATERIAL AND METHODS: An electronic database search for articles published in Cochrane, PubMed (MEDLINE) and Scopus was conducted using the key words "Molar, Third"; "Mandibular Fractures"; "Molar Third, Removal"; "Molar Third, Complications"; "Dental Extractions, Complications"; "Mandibular Fractures, Third molar removal". The inclusion criteria were articles including at least 10 patients and were published in English in the last 10 years. The exclusion criteria were nonhuman studies and case reports. RESULTS: Postoperative mandibular fractures after 3MI occur more frequently in male patients between the ages of 40 and 60 and are caused by premature chewing force. The parameters that most frequently characterise mandibular fractures at the mandibular angle are deeply impacted lower third molars, Class II and III, B and C, according to the Pell & Gregory classification system, mesioangular according to the Winter's classification, and are located on the left mandibular side.. CONCLUSIONS: Mandibular fractures can be predicted with adequate preoperative planning for each case and identify the related risk factors for this complication. Key words:Molar, Third; Mandibular Fractures; Molar Third, Removal; Molar Third, Complications; Dental Extractions, Complications; Mandibular Fractures, Third molar removal.
