Theses and Dissertations (Maxillo-Facial and Oral Surgery)

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Lag screw effect on the biomechanical torsion stability in the I.S.I monocortical mandible angle system
(University of Pretoria, 2010-12-14) Jacobs, Frederick Julius; hpehlers@gmail.com; Ehlers, Hendrik Petrus
In a recent in vitro biomechanical stability study by F.J. Jacobs, a unique, patented inclined screw insertion (I.S.I.) mandibular angle, intra-oral trauma-plate was evaluated for torsion and compression stability and compared to conventional plating of simulated angle fractures in polyurethane mandibular replicas. This in vitro comparative pilot study is an extension of the above-mentioned study. Similar I.S.I. mini-plates with 45º inclined screw holes in quadrant 3 (Fig 1), were used but in the one sample 13mm-long lag screws were used to transect the fracture lines where in the other group non-lagging screws of similar length were used to fixate simulated mandibular angle fractures in polyurethane mandible replicas. A uniquely designed and manufactured jig, incorporated in a Zwick machine, was utilized to apply torsion forces within clinical relevant load values. The load-displacement values for torsion forces was determined and compared for the two groups. It was established that 5 lag screws significantly improved the torsion stability of the lag-plate group to that of the non-lag group. During the stability testing, two factors were identified, which had a critical influence on the compression generated by the lag screw between the fracture fragments. An adequate amount of bone must be maintained between the first screw hole, directly distal to the fracture line, and the fracture line. All screws must be inserted in the correct sequence in order to insure sufficient compression between the fracture fragments as a result of the lag-effect. AFRIKAANS : In `n onlangse in vitro studie deur F.J. Jacobs, is `n gepatenteerde, unieke geanguleerde miniplate, waarvan die skroefgate geanguleer is, die sg. Inklineerde Skroef Inplasing (I.S.I.) kaak-hoek, intra-orale traumaplaat geevalueer vir torsie en kompressie stabiliteit en vergelyk met konvensionele plate op gesimuleerde kaakhoek frakture in poli-uretaan mandibular replikas. In hierdie in vitro loodstudie, is I.S.I. miniplate met skroefgate wat teen 45º geanguleer is, gebruik in kombinasie met `n enkele 13mm lange grypskroef (“lag screw”) om gesimuleerde kaakhoek frakture in poli-uretaan mandibula replikas te fikseer. Deur gebruik te maak van `n spesiaal ontwerpte en vervaardigde monterings-apparaat wat binne in `n Zwick masjien geïnkorporeer word, is die I.S.I gefikseerde replikas onderwerp aan torsie kragte, binne klinies relevante ladingswaardes. Die verplasings en ladingswaardes is geregistreer en vergelyk met identiese I.S.I miniplate sonder `n grypskroef. Die loodstudie resultate het getoon dat die frakture wat gefikseerd is met die I.S.I. miniplaat-grypskroef kombinasie betekenisvol beter stabiliteit toon as die frakture wat met slegs die miniplaat, sonder `n grypskroef, gefikseerd is vir klinies relevante ladingsen verplasingswaardes. Tydens biomeganiese toetsing van die mandibula replikas, is twee faktore wat `n kardinale rol speel in die stabiliteit wat verkry word deur `n miniplaat grypskroef kombinasie te gebruik, geïdentifiseer. Voldoende hoeveelheid been tussen die eerste skroefgat, direk distaal van die fraktuurlyn, en die fraktuurlyn asook die korrekte volgorde waarin die skroewe geplaas word, moet gehandhaaf word om maksimale kompressie van die fragmente deur die grypskroef te verseker. Deur `n I.S.I miniplaat, met geanguleerde skroefgate van 45º, te kombineer met `n grypskroef, kan die stabiliteit van die gefikseerde mandibulere kaakhoek betekenisvol verbeter word en verleen dit meer stabiliteit wanneer vergelyk word met frakture gereduseer met `n I.S.I miniplaat sonder grypskroef plasing.
The effect of innovative screw angled mini-plates on biomechanical stability of mono-cortical fixation : an in vitro model
(University of Pretoria, 2009-10-08) Butow, Kurt-Wilhelm; fjjacobs@medic.up.ac.za; Jacobs, Frederick Julius
There is no evidence in the literature of biomechanical stability characteristics comparing conventional rectangular screw placement with that of an angled mono-cortical screw plating system where standard 2mm diameter screws are applied at angles more acute than conventional 90° screws, through plate holes machined (cut) for a definite specific screw angle placement P. Angled screws will have an obvious clinical advantage of direct line of vision insertion, through an intra-oral route without the disadvantage of trans-buccal (cutaneous) approach required for conventional 90° rectangular screw application. Angled screw application will result in the prevention of possible, less post-operative swelling, nerve fall out (motor and/or sensory), haematoma, false aneurysm and scarring as unwanted clinical complications associated with trans-buccal extra-oral surgical technique. Intra-oral angled screw application will result in definitive cost saving due to less operating time required. Post-treatment removal of angled screws is uncomplicated, requiring only intra-oral surgical approach, without trochar use or skin incisions for screwdriver application. By determining angle displacement values at certain clinical relevant force values for both compression/tension and torsion, preference can be established for ideal angle(s) of screw application in a plating system. An own unique, designed and manufactured, jig and inclined screw insertion (ISI) plates were implemented during the biomechanical evaluation of stability at different screw angle applications in a Zwick machine. For the purpose of this biomechanical comparative investigation an inclined screw insertion (ISI) plate was manufactured with 90°, 75°, 60° and 45° angled plate holes orientated in line with the long-axis (quadrant 3) of the distal section of the plates and diagonal across (quadrant 1) in the proximal section of the plates. Screws with an ISI angle of 30° in any quadrant application resulted in lifting the plate from the bone surface and caused cortical bone destruction during pilot drilling. The results for mono-cortical 7mm screw placement proved superior in biomechanical stability during tension/compression - forces for screw insertion angles of 60° and 45°, when compared to conventional 90° rectangular screw placement. Screws inserted at an angle of 75° demonstrated no improvement in compression/tension stability when compared with 90°.Torsion force stability for all of the 75°, 60° and 45° inclined screw insertion (ISI) systems proved more stable compared to conventional 90° screw angle plates. It is concluded that angled monocortical screw placement between angles 60° and 45° has clinical significance as far as stability, intra-oral surgical technique and time-cost factor is concerned. The results of this biomechanical behaviour investigation of ISI, evolved new terminology such as screw-tip shifting, screw-tip travel, lag potential and clinical significance for the range of screw angle placement. Angled orientation to the plate design and plate geometry is also defined in terms of tension line distribution in the anatomical region for application in the mandible. An unique quadrant description for ISI is described for future communication. An international patent, based on the ISI principle, has been registered for monocortical six-hole plates of firstly different geometric designs to conform to specific anatomical topographic sites in the mandible and secondly specific screw plate-holes angled at 60° in different orientation to the plate (Patent:PCT/EP 2006/006365), (Addendum 6). A specific L-shaped, mandibular angle plate with screw holes at a 60° angle where orientation shifts from in-line with the long-axis of the plate in the distal three plate holes to diagonal orientation in the proximal section of the plate, is designed and manufactured by Stryker/Leibinger as an example of such a patent plate. It is recommended that a smart-lock plate with plate holes at 55° angles be manufactured to allow screw angle placements of 65° - 45° in different angle orientations. Pilot hole drilling and ISI can be performed without the use of a drill-guide.
A preliminary investigative system to disciplinary inquiries of the Health Professions Council of South Africa, with specific reference to Maxillo-Facial and Oral Surgery
(University of Pretoria, 2006-09-09) Carstens, Pieter Albert, 1960-; Butow, Kurt-Wilhelm; frikkie@shisas.co.za; Redelinghuys, Izak Frederik
The purpose of this study was to evaluate the effectiveness of the committee of preliminary inquiry (in the context of professional conduct committees) of the Health Professions Council of South Africa, with specific reference to maxillo-facial and oral surgery. An evaluation was done of cases that were referred by the committee for preliminary inquiry to this specific professional conduct committee of the Medical and Dental Professions Board. Where necessary, these cases were supplemented by relevant cases from other professional conduct committees. In order to achieve this goal, a comprehensive literature study was conducted on the broad concept of medical and dental misconduct and negligence. Specific attention was paid to the issues of expert testimony and witnesses and consent. Furthermore, a study was conducted to determine the legal framework in which these committees are supposed to function. In the cases where inquiries into the complaints against the registered practitioners followed, a detailed evaluation of the so-called legal process was done, as well as the findings in each case (in the context of the professional conduct committees). The results of this study have shown that the investigative system of the committee for preliminary inquiry preceding professional conduct inquiries into complaints against registered practitioners has certain shortcomings, especially in the more complex cases. The following proposals have been made (in order of most importance): 1. Both the committee for preliminary inquiry and professional conduct committee must abide by the rules of natural justice, as pertained in the Constitution of the Republic of South Africa. 2. Establishment of a Forum of Expert Witnesses that will evaluate all cases of alleged professional misconduct and negligence pertaining to the field of maxillo-facial and oral surgery, after it was evaluated and referred by the Ombudsman. 3. Appointment of a maxillo-facial and oral surgeon as Ombudsman to evaluate all cases brought before the committee for preliminary inquiry pertaining to the field of maxillo-facial and oral surgery. 4. Acceptance of the proposed test of medical negligence, i.e. the ‘reasonable person’s test’, subjected to that of the ‘reasonable specialist’ as standard for evaluation of cases of alleged negligence in maxillo-facial and oral surgery. 5. The proposed patient’s consent form serves as an example of a legitimate patient consent form. It follows that the legal requirements, especially in cases of extensions and deviations of medical interventions, must be adhered to. 6. It is advisable to belong to an organisation providing indemnity cover (such as Medical/Dental Protection Society) in order to receive proper assistance in the handling of these cases of alleged unprofessional/disgraceful conduct. The recommendations consequential to this study would provide a more streamlined, cost- and time effective investigative system to investigate claims of unprofessional conduct for possible further disciplinary action.
Brandsonewydte na CO2 laserchirurgie (Afrikaans)
(University of Pretoria, 2006-07-28) Butow, Kurt-Wilhelm; upetd@up.ac.za; Koepp, Werner Gerhard
Please read the abstract in the section 00front of this document
The effect of a topical combined anti-inflammatory antibiotic preparation on the outcome of third molar surgery
(University of Pretoria, 2007-01-05) Butow, Kurt-Wilhelm; upetd@up.ac.za; Van Eeden, Simon Peter
Third molar surgery may be associated with a number of complications the most common of which are postoperative pain, swelling and trismus, and dry socket formation. The appearance of these post-operative sequelae is intimately related to the manifestations of inflammation in response to tissue injury. There is significant post-operative morbidity associated with these complications and it was thus the objective of this study to - investigate the effect of a combined antibiotic/anti-inflammatory intrasocket medication on post-operative pain, swelling and dry socket formation. The medication chosen for the study was Covomycin D®. Covomycin D® is a commercially prepared opthalmological preparation - each 1 millilitre contains 2 mg chloramphenicol, 5 mg neomycin sulphate and 0,5 mg dexamethasone. Nineteen subjects were included in the study after fullfilling certain criteria. All subjects were operated under general anaesthesia by the same surgeon. The patients were blinded to the side of the medication and were asked to complete a pain visual analogue scale and note the side of the worst swelling in the post¬operative period. All patients were followed up in the first week following surgery by an independent oral and maxillofacial surgeon who was also blinded to the side on which the medication was placed. The results showed a significant difference (p<0.6) in the pain experienced on the non-medicated compared to the medicated side on day one in eleven of the nineteen patients (57.9%). When the data was analysed over the six day postoperative period sixteen of the nineteen patients (84.2%) had significantly less pain on the medicated side compared to the non-medicated side (p<0.6). The swelling was reported as being worse on the non-medicated side in fourteen out of the nineteen patients (73.7%). Dry socket occurred in three out of nineteen patients or three out of thirty eight surgical extraction sites; an overall incidence of 7.9% or an incidence of 0% for the medicated side and an incidence of 15.8% on the non-medicated side i.e. all the dry sockets occurred on the non-medicated side. In conclusion, this double-blinded prospectve study, showed that the use of a combined antibiotic/anti-inflammatory intrasocket medication favourably influences the common adverse post-operative sequelae following the removal of lower third molars.

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