| Abstract | Cilj istraživanja bio je termografski usporediti nove metode osteotomije, napravljene pomoću visokoenergetskog lasera u kontaktnom i beskontaktnom načinu rada i piezoelektričnog uređaja, s mehaničkim instrumentima za osteotomiju. Pomoću SEM i 3D SEM elektronske mikroskopije i laser profilometrije istražiti utjecaj vrste osteotomije na koštano cijeljenje. Istraživanje je provedeno na in vivo životinjskom modelu Wistar štakora. Životinje su bile nasumično podijeljene u četiri skupine po šest životinja prema planiranom vremenu žrtvovanja: prva je skupina bila žrtvovana neposredno nakon završetka osteotomije, druga nakon 7 dana, treća nakon 14 dana i četvrta nakon 21 dan od kirurškog zahvata. Na svakoj tibiji životinje bile su napravljene dvije osteotomije, ukupno četiri na obje tibije, uvijek s istim redoslijedom. Osteotomije su bile napravljene pomoću kirurškog svrdla, piezoelektričnog uređaja, Er:YAG lasera u kontaktnom i beskontaktnom načinu rada. Prilikom izvođenja svih osteotomija pomoću
infracrvene termokamere zabilježena je promjena temperature. Izgled osteotomije neposredno nakon okončanja kirurškog zahvata i procjena dinamike cijeljenja analizirani su laser profilometrijom i SEM i 3D SEM tehnikom. Termografska analiza pokazala je da je prosječna vrijednost promjene temperature za skupinu laser u beskontaktnom načinu rada iznosila 53,27 °C, za laser u kontaktnom načinu rada 2,0 °C. Kod skupine piezoelektričnog uređaja i kirurškog svrdla nije došlo do porasta temperature za vrijeme osteotomije. SEM i 3D SEM analizom utvrđeno je najbrže cijeljenje u skupini piezoelektričnog uređaja, dok je ono bilo usporeno u skupini laserskog uređaja u kontaktnom i beskontaktnom načinu rada. Nakon 3 tjedna došlo je do izjednačenja dinamike cijeljenja. Lasersko profilometrijski utvrđena je razlika u brzini cijeljenja nakon prvog tjedna od kirurškog zahvata između skupine piezoelektričnog uređaja i skupine kontaktnog lasera, dinamika cijeljenja bila je ubrzana kod piezoelektrične skupine. Zabilježeni porast temperature u skupini beskontaktnog laserskog uređaja koji je bio iznad granice termičkog oštećenja nije uzrokovao trajne i ireverzibilne posljedice na koštano cijeljenje. Nakon početnog usporednog ciljanja opaženog unutar skupina laserskog uređaja, došlo je do izjednačenja u dinamici cijeljenja nakon 3 tjedna od osteotomije unutar sve četiri skupine. |
| Abstract (english) | Aim: The aim was to termographically compare new methods of osteotomy, performed with the piezosurgical device and high-energy laser in contact and non-contact mode, with mechanical osteotomy instruments. The influence of different types of osteotomy tool on bone healing was assessed with SEM and 3D SEM and the laser profilometry analysis.
Materials and methods: The research was conducted on the in vitro animal model on Wistar rats. The animals were randomly divided into four groups, each group consisting of six animals, according to the time when animals were sacrificed: the first group was sacrificed immediately after the surgery, the second group after one week, the third group after two weeks and the fourth group three weeks after the surgery. After general anaesthesia application by an
intraperitoneal injection, the animals were placed in dorsal decubitus position and hair removal and disinfection of the surgical site were performed. The tibial bone was exposed by gentle reflection of the dermo-periosteal flap. The osteotomies were always performed in the same sequence: the right distal part of the tibia with by a contact Er:YAG laser, the right proximal part by the piezosurgery unit, the left proximal part by surgical drill and left distal part digitally controlled non-contact Er:YAG laser. The osteotomies were 5 mm apart from each other, approximately 2 mm deep with a diameter ranging between 1.0-2.0 mm. All osteotomies were performed with copious irrigation. For each osteotomy, the base temperature and maximum temperature were recorded using an infrared thermographic camera and the mean temperature
was calculated. The appearance of the osteotomy site and the dynamics of bone healing were assessed with the SEM and 3D-SEM analysis for each group, immediately after the osteotomy procedure and after the first, second and third week. The remnants of the soft tissue were detached from the bone samples collected from the sacrificed animals and prepared for SEM analysis. The 3D stereo-photographs were created by taking two stereo-pair photographs under different angels, with a separation of 7°, one for each eye. A red filter and photography with - 3.5° was used for the left eye, and a green filter and a photography with +3.5° for the right eye. Laser profilometry was used to measure the defect volume immediately after the osteotomy procedure, and after the first, second and third week. The samples were prepared by being dried with compressed air and sprayed with a thin layer of a white powder to decrease the measurement noise and accompanying artifacts. The rate of bone healing was analyzed by measuring the volume reduction rate during the time points.
Results: There was a significant difference in temperature change between all the techniques. A t-test for paired samples was used to determine techniques that differed from each other. Multiple comparison showed a difference among all the techniques, except between piezosurgery and surgical drill. The largest temperature change of 53.3° C was detected for the
non-contact laser, followed by 2.0° C for the laser contact group. No temperature change was detected for the piezosurgery while a negative temperature change was detected for the surgical drill. Mean maximum temperature (Tmax) was 29.9 ± 0.5 °C (ΔT=1.9 ± 0.3 °C) for contact Er:YAG laser, 79.1 ± 4.6 °C (ΔT= 49.1 ± 4.4 °C) for non-contact Er:YAG laser, 29.1 ± 0.2 °C (ΔT= -0.2 ± 0.3 °C) for piezosurgery and 27.3 ± 0.4 °C (ΔT= - 0.9 ± 0.4 °C) for surgical drill. SEM and 3D SEM analysis in the surgical drill group determined the presence of a blood clot immediately after the surgical procedure. Furthermore, the presence of bone debris was also evident on the cavity walls. During the first week bone formation was evident at the bottom of the defect, while during the second week the newly formed bone completely fulfilled the osteotomy defect. After the third week the bone formation extended beyond the perimeter of the original defect. Similar healing pattern was detected in the piezoelectric group: immediately after the osteotomy a blood clot was present, which was substituted by new bone completely filling the defect by the end of the third week. The osteotomies prepared with contact mode Er:YAG laser and non-contact mode exhibited similar healing pattern. Immediate after the surgical procedure, displayed a bone defect filled with a retracted blood clot and clean cavity walls deprived of bone debris accumulation. A delay in the bone healing process was observed during the initial stages of bone healing. After the third week complete fill of the defect by
newly formed bone was present. A visible rim around the circumference of the defect was present. The rim was more pronounced in the laser non-contact group. The rim is likely to have been created as a consequence of thermal injury during laser irradiation of the bone. The laser profilometry analysis determined a difference in the healing dynamics after the first week, between the piezoelectric and contact laser group. In the later time intervals, there was no difference in the healing dynamics.
Conclusion: During the non-contact laser ablation of the bone high temperature elevation were recorded. The amount of the recorded temperature elevation was above the threshold values for the heat induced bone tissue injury. Despite the initial delay in the dynamics of bone haling observed in both laser groups, after the third week, the amount of bone formation and restitution rate of the defects were similar in all of the tested groups. |
