Radiological Evaluation of Bone Regenerate After Mandibular Alveolar Ridge Distraction Osteogenesis Case Report

CLINICAL CASE Dent. Med. Probl. 2006, 43, 2, 299 304 ISSN 1644 387X Copyright by Silesian Piasts University of Medicine in Wrocław and Polish Stomatological Association RAFAŁ KOSZOWSKI, AGNIESZKA RACZKOWSKA SIOSTRZONEK Radiological Evaluation of Bone Regenerate After Mandibular Alveolar Ridge Distraction Osteogenesis Case Report Radiologiczna ocena regeneratu kostnego powstałego w wyniku osteogenezy dystrakcyjnej części zębodołowej żuchwy opis przypadku Department of Oral Surgery in Bytom Silesian Medical Academy in Katowice, Poland Abstract Distraction osteogenesis (DO) of mandibular and maxillary alveolar ridges is an alternative way for bone aug mentation prior to implant treatment. The authors performed radiological evaluation of a new bone formation with in distraction gap. Analysis of rentgenogrammes was performed before DO, after the end of activation and con solidation period, after implant placement and after implant loading with prosthesis. Digital radiodensitometric analysis of orthopantomogrammes was performed with Digora 2.1 software. Optical density changes were stated according to differences in 256 shades of gray scale in analyzed structures. Gradual increase of callus optical den sity has been observed from the end of activation period. Optical density comparable to starting values has been reached 2 months after implant placement. Between 2 and 4 months after implant placement decrease in density of bone structure was noted. After implant loading, bone density again had increased and was superior to initial value, measured at the beginning of the treatment (Dent. Med. Probl. 2006, 43, 2, 299 304). Key words: distraction osteogenesis, digital radiography, bone regeneration. Streszczenie Osteogeneza dystrakcyjna (OD) części zębodołowej żuchwy oraz wyrostków zębodołowych szczęk stanowi alter natywę dla zabiegów augmentacyjnych przed planowanym leczeniem implantologicznym. Autorzy dokonali radio logicznej oceny kościotworzenia w szczelinie dystrakcyjnej przedniego odcinka części zębodołowej żuchwy. Ana lizę rentgenogramów przeprowadzono przed rozpoczęciem OD, po zakończeniu aktywacji dystraktora, bezpośre dnio po zakończeniu okresu konsolidacji, po wprowadzeniu wszczepów oraz po obciążeniu wszczepów uzupełnieniem protetycznym. Do oceny regeneratu kostnego wykorzystano analizę densytometryczną zdjęć pan tomograficznych wykonanych techniką cyfrową aparatem Ortophos DS firmy Simens. Przeprowadzono ją stosu jąc program komputerowy DIGORA, wersja 2.1. Oceny gęstości optycznej obrazu dokonano w oparciu o zmianę barwy analizowanych struktur, przedstawionych w 256 odcieniach szarości. Po zakończeniu aktywacji dystrakto ra stwierdzono stopniowy wzrost gęstości optycznej obszaru w szczelinie dystrakcyjnej. Dwa miesiące po wpro wadzeniu wszczepów odnotowano wartości gęstości optycznej zbliżone do wartości wyjściowych (sprzed OD). W okresie 2 i 4 miesięcy po wprowadzeniu wszczepów zauważono zmniejszenie gęstości utkania kostnego. Po ob ciążeniu wszczepów uzupełnieniem protetycznym gęstość optyczna obrazu ponownie wzrosła i była wyższa niż wartość wyjściowa, mierzona przed rozpoczęciem leczenia (Dent. Med. Probl. 2006, 43, 2, 299 304). Słowa kluczowe: osteogeneza dystrakcyjna, radiografia cyfrowa, regeneracja kostna. Distraction osteogenesis (DO) is a new bone formation process localized between bone seg ments which are gradually separated. It is associ ated with distraction histiogenesis process in the surrounding soft tissues and covers creation of mucous membrane, muscles, ligaments, cartilage, vessels and nerves [1 6]. Mechanical movement of bone segments was

300 R. KOSZOWSKI, A. RACZKOWSKA SIOSTRZONEK initially used in treatment of dislocated broken bones. Hippocrates was the first who discovered external apparatus for repositioning of fractured bones, which was further improved by Chauliac, Barton and Malgaigne. Lengthening of long bones was first performed by Codivilla in 1905. After oblique osteotomy of the femur, elongation of the bone was obtained due to application of external distraction device [6]. Significant contribution in the development of distraction technique was made by Ilizarow, who designed a new apparatus for long bone lengthen ing in 1951. He also introduced a new technique of osteotomy (corticotomy) and proposed 7 days latency period before segment movement [1, 6]. First osteodistraction of the mandible was per formed in 1927 by Rosenthal. After the osteotomy, intraoral tooth borne device was applied. Further evolution involved modification of distraction devices, its localization and way of fixation as well as techniques of osteotomy. Special input to cra niofacial distraction osteogenesis had Kazanjian, Crawford, Kole and McCarthy. This new method was widely introduced in correction of cranio maxillo facial developmental deformities [4, 6, 7]. Reduction in size of the devices allowed for its placement on small bones, including alveolar ridges of mandible and maxilla. First vertical dis traction osteogenesis of mandibular alveolar ridge was performed by Chin and Toth in 1996 [1, 6, 8]. Mechanism of the distraction osteogenesis is based on reparative callus formation under traction forces [9]. Treatment consists of five succeeding periods: osteotomy, latency, distraction, consolida tion and remodeling. Discontinuity of bone in duced haematoma and later cloth formation, where collection of osteoprogenitor cells takes place. During next 7 days (latency period) gradual growth of blood vessels and cell proliferation into the cloth is observed. The cloth is replaced by granular tissue and afterwards connective tissue. Beginning of distraction at this time leads to elon gation of soft callus which results in vessels elon gation, increase in tissue oxygenation and fibro blasts proliferation. Tissue formation is parallel to the applied traction forces. Between end of the dis traction period and removal of the distraction device the consolidation period takes place. It is characterized by new bone formation via membra nous and endochondral ossification. The last peri od remodeling lasts 12 months. During this time newly formed bone is reinforced by permanent bone with typical lamellar structure due to func tional loading application [3, 8 10]. During latency period radiographs show grad ual formation of reparative callus within osteoto my gap. After the end of distraction period radio logical examination demonstrates three zones of distraction regenerate. Between two trabecular bone zones adjacent to the residual bone segments a radiolucent fibrous zone is placed. At the con solidation period fibrous zone ossifies and pre sents as homogeneous area which mixes with sur rounding zones. Remodeling period leads to oblit eration of the border of normal bone structure and osteotomy gap. It also results in restoring of newly formed bone by parallel fibered lamellar bone [6]. The aim of the study was radiological evalua tion of bone formation within distraction gap of mandibular alveolar ridge. Case The study was performed on rentgenogram mes taken on 48 years old female patient, who had undergone distraction osteogenesis before implan tology treatment. The surgery was done in anteri or part of mandibular alveolar ridge where intrao ral distraction device TRACK 1.5 (KLS Martin) was used. After 7 days latency period, distraction was performed during next 7 days. 6mm elonga tion of bone fragment was obtained. After the end of consolidation period the distractor was removed. Implant treatment was implemented 4 weeks after the removal of the device. Two Brane mark implants (13 mm 3.75 mm) were placed in the region 32 and 42. 4 months after placement, the implants were exposed and healing screws were implemented. After 2 weeks healing period prosthetic treatment with complete, overdenture prosthesis supported on two implants connected with bar was performed. Evaluation of radiological signs of a new bone formation was performed on digital orthopanto mogrammes (taken by Orthophos DS, Siemens). Digital, densitometric analysis was based on DIG ORA 2.1 computer program. Optical density of radiological image within distraction defect was evaluated according to the changes in 256 shades of grey scale. Computer program allows for point, linear and zonal density profile assessment. The results are presented as maximum, minimum and mean value and also as a graph called histiogram. Numerical presentation of the results describes maximal and minimal optical density of all pixels gathered within examined area. The histiogram shows the number of pixels characterized by par ticular density value. Co ordinates of the pixels are shown on the monitor and are necessary in stan dardization of the results. Densitometric analysis was performed on orthpantomogrammes taken before the beginning of DO, after the end of activation period, after the

Radiological Evaluation of Bone Regenerate after Mandibular Alveolar Ridge Distraction Osteogenesis 301 Fig. 1. Location of horizontal measuring lines Ryc. 1. Przebieg poziomych linii pomiarowych Fig. 2. Location of vertical measuring line Ryc. 2. Przebieg pionowej linii pomiarowej end of consolidation period (directly before implant insertion), 2 and 4 months after implant placement and 5 months after implant loading (9 months after implant placement). Changes in optical density within distraction defect were evaluated along horizontal and verti cal sections. Results of the measurements were compared with initial values stated before begin ning of the distraction. Linear density profile was assessed along two horizontal sections :G 1 pointed out by points g 1 (1320, 1204) and g 1 (1480, 1216), G 2 pointed out by points g 2 (1532, 1220) and g 2 (1652, 1216) (fig. 1). Vertical linear den sity profile was assessed along section G 3 pointed out by points g 3 (1480, 1020) and g 3 (1480, 1152) (fig. 2). Evaluation of optical density within distrac tion gap along horizontal lines are shown in the table 1. Before beginning of the treatment the mean value of bone density measured in the area of planned surgery were as follows: G 1 103.47, G 2 125.95. After the end of activation period, gradual increase of optical density within distrac tion defect was stated. Optical density similar to initial one (before DO) was obtained 2 months after implant placement, with mean values :G 1 133.93, G 2 121.61. It has been stated, that between 2 nd and 4 th month after implant insertion, the mean bone den sity has decreased up to 20 units. After implant loading, optical density increased and was superi or to initial value (measured before beginning of the treatment). Evaluation of optical density within distrac tion gap along vertical line is shown in the table 2. Continuous increase of bone density, except the period between 2 nd and 4 th month after implant placement was stated. At this time decrease of minimum, maximum and mean value of density was observed. Table 1. Evaluation of optical density within distraction gap along horizontal lines Tabela 1. Ocena gęstości optycznej w szczelinie dystrakcyjnej wzdłuż wyznaczonych odcinków poziomych Density G 1 G 2 (Gęstość) Min. Max. Mean M. dev. Min. Max. Mean M. dev. Before OD 61 129 103.47 13.36 107 147 125.95 8.46 (Przed rozpoczęciem OD) After activation 48 101 62.43 12.23 53 106 70.16 13.62 (Po zakończeniu aktywacji) After consolidation period 77 153 110.64 18.91 58 110 91.03 7.54 (Po zakończeniu okresu konsolidacji) 2 months after implant placement 117 143 133.93 6.94 117 126 121.61 2.0 (2 miesiące po wprowadzeniu wszczepów) 4 months after implant placement 105 125 114.18 6.68 96 107 100.6 2.98 (4 miesiące po wprowadzeniu wszczepów) 9 months after implant placement 121 149 134.89 8.15 90 118 107.64 7.44 (9 miesięcy po wprowadzeniu wszczepów) Min. gęstość minimalna, Max. gęstość maksymalna, Mean średnia wartość gęstości, M. dev. średnie odchylenie wartości gęstości.

302 R. KOSZOWSKI, A. RACZKOWSKA SIOSTRZONEK Table 2. Evaluation of optical density within distraction gap along vertical line. Tabela 2. Ocena gęstości optycznej w szczelinie dystrakcyjnej wzdłuż wyznaczonego odcinka pionowego Stage After activation After consolidation 2 months after 4 months after 9 months after of treatment (Po zakończeniu period implant placement impant placement implant placement (Etap leczenia) aktywacji) (Po zakończeniu (2 miesiące po (4 miesiące po (9 miesięcy po Density okresu konsolidacji) wprowadzeniu wprowadzeniu wprowadzeniu (Gęstość) wszczepów) wszczepów) wszczepów) Min. 87 93 81 58 67 Max. 103 126 140 124 126 Mean 95.20 107.81 119.77 100.14 107.5 M. dev 3.66 11.23 8.23 15.75 9.55 Min. gęstość minimalna, Max. gęstość maksymalna, Mean średnia wartość gęstości, M. dev. średnie odchylenie wartości gęstości. Discussion Distraction osteogenesis becomes more and more popular method of preparation of mandibular and maxillary alveolar ridges before implant appli cation. This method allows for enlarging of bone and in some cases is an alternative for augmenta tive procedures, which need autogenous bone grafts or/and bone substitutes [3, 5, 11 13]. Proper indications and suitable surgery plan ning according to the gold standards are essential to obtain good results of the treatment [1, 6, 8]. Post operation radiological control of the bone regenerate within distraction zone is necessary to evaluate bone mineralization level, to discover abnormality in osteogenesis process and to make a decision of implant placement [2, 6, 11]. Radio logical evaluation of bone regeneration during dis traction osteogenesis is also used in orthopeadics, in case of limbs elongation. Radiological examina tion plays crucial role in decision making of removal of external fixator [14 17]. The need of standardization and objectivization of the results of radiological examination taken during DO is emphasized [18, 19]. Computer analysis of the ra diological images gives such possibility [20 22]. The authors used computer program Digora 2.1 to establish optical density of the image. Optical density changes were stated according to evaluation of gray scale assigned to each pixel of the roentgenogram. Roentgenograms were taken in the digital technique, which gave possibility to stan dardize conditions of the examination [23]. Similar method of radiological evaluation of a bone regen eration during limb lengthening was described by Tęsiorowski et al. Small changes in formation of a new bone may not be detectable by the human eye therefore the authors implemented optical density measurement of radiological pictures. The results were documented as diagrams of changes in grey scale along lines drawn parallel and perpendicular ly to the long axis of elongated extremities [18]. In the described study optical density mea surement were done along lines drawn parallel and perpendicularly to the distraction gap. Gaggl et al. discovered, that during consolidation peri od, gradual increase of bone density is observed within distraction zone [11]. Three months after the end of the distraction, intensity of bone shade in bone regeneration was similar to the sur rounding bone. Lamellar structure of the newly formed bone was observed after the six months [6, 11]. Own observations confirmed gradual increase in intensity of optical density within distraction gap during consolidation period. After the end of consolidation, decrease in optical density of newly formed bone was found. This disadvantageous process was eliminated after implant loading and renewed increase of optical density in bone regen eration was observed. Hence the implants should be loaded immediately after the end of osseointe gration. According to principles of alveolar ridges DO, dental implants are placed 4 8 weeks after the end of consolidation process [6]. Such procedure was implemented in described case. Oda et al described histomorphometric evalu ation of implants placed immediately after the end of the distraction. They found better implant osseointegration 12 weeks after bone elongation in comparison to 8 weeks period [6]. Therefore the authors suggests that implants inserted immediate ly after the end of active period of distraction should be loaded not before 12 weeks post implan tation [2, 24]. Final assessment of bone regeneration within distraction gap needs longer time for observations and larger number of cases. The results will allow for introducing optimal principles of implant and prosthetic treatment in patients after DO. It will also be helpful in comparison of DO and clas sical augmentation techniques in treatment of atrophied mandibular and maxillary alveolar ridges.

Radiological Evaluation of Bone Regenerate after Mandibular Alveolar Ridge Distraction Osteogenesis 303 The authors conclude that during consolida tion period constant increase in optical density of bone regeneration is observed. Decrease in optical density of bone regenerate is observed after the end of consolidation period. Regrowth of the den sity is found after implant loading. Final assess ment of bone regenerate within distraction gap needs longer time of observations. References [1] KOSZOWSKI R., POGORZELSKA STRONCZAK B., RACZKOWSKA SIOSTRZONEK A.: Osteogeneza dystrakcyjna części zębodołowej żuchwy doniesienie wstępne. Implantoprotetyka 2003, 4, 2, 21 25. [2] R. KOSZOWSKI, B. POGORZELSKA STRONCZAK, M. DIJAKIEWICZ, A. RACZKOWSKA SIOSTRZONEK, T. MORAWIEC, V. SZYCIK: Osteogeneza dystrakcyjna części zębodołowej żuchwy jako zabieg przygotowujący do leczenia implan toprotetycznego. Implantoprotetyka 2004, 4, 21 24. [3] LEHRHAUPT N. B.: Alveolar Distraction: a possible new alternative to bone grafting. Int. J. Periodontics Restorative Dent. 2001, 21, 121 125. [4] MCCARTHY J. G., SCHREIBER J., KARP N. S.: Lengthening of the human mandible by gradual distraction. Plast. Reconstr. Surg. 1992, 89, 1 8. [5] MCNAMARA J.A., TROTMAN C. A.: Distraction osteogenesis and tissue engineering. The University of Michigan, An Arbor, Michigan 1997. [6] SAMCHUKOV M. L., COPE J. B., CHARKASIN A. M.: Craniofacial distraction osteogenesis. Mosby Inc., St. Louis 2001. [7] KOWALCZYK R., SPORNIAK TUTAK K., SILUK J.: Zastosowanie wewnątrzustnych dystraktorów kostnych w leczeniu wad rozwojowych żuchwy doniesienie wstępne. Czas. Stomat. 2002, 55, 36 43. [8] LAZAR F., HIDDING J., ZOLLER J.: Praimplantologische Distractionsosteogenese. Moglichkeiten und Grenzen. Implant. J. 2000, 4, 18 26. [9] BLOCK M. S., CHANG A., CRAWFORD A.: Mandibular alveolar ridge augmentation in the dog using distraction osteogenesis. J. Oral Maxillofac Surg. 1996, 54, 309 314. [10] HENKEL K. O., MA L., LENZ J. H., JONAS L., GUNDLACH K. K. H.: Closure of vertical alveolar bone defects with guided horizontal distraction osteogenesis: an experimental study in pigs and first clinical results. J. Cranio. Maxillofac Surg. 2001, 29, 249 253. [11] GAGGL A., SCHULTES G., KARCHER H.: Distraction implants a new possibility for augmentative treatment of the edentulous atrophic mandible: case report. Br. J. Oral Maxillofac. Surg. 1999, 37, 481 485. [12] TRIACA A., ANTONINI M., MINORETTI R., MERZ B. R.: Segmental distraction osteogenesis of the anterior alveolar process. J. Oral Maxillofac. Surg. 2001, 59, 26 34. [13] UEDA M., TOHNAI I., NAKAI H.: Tissue engineering research in oral implant surgery. Artificial Organs 2001, 25, 164 171. [14] BLANE C. E., HERZENBERG J. E., DIPIETRO M. A.: Radiographic imaging for Ilizarov limb lenghteninig in children. Pediatr. Radiol. 1991, 21, 117 120. [15] HAMANISHI C., YASUWAKI Y., KIKUCHI H., TANAKA S., TAMURA K.: Classification of the callus in limb lenghten ing. Radiographic study of 35 limbs. Acta Othop. Scand. 1992, 63, 430 433. [16] MINTY I., MAFFULLI N., HUGHES T. H., SHAW D. G., FIXSEN J. A.: Radiographic features of limb lengthening in children. Radiol. 1994, 35, 555 559. [17] YOUNG J. W., KOSTURBIAK I. S., RESNIK C. S., PALEY D.: Sonographic evaluation of bone production at the dis traction site in Ilizarow limb lenghtening procedures. Am. J. Radiol. 1990, 154, 125 128. [18] TĘSIOROWSKI M., KĄCKI W., JASIEWICZ B., ZARZYCKA M., WOJNAR L.: Analiza komputerowa kości i regeneratu na zdjęciach rentgenowskich w czasie wydłużania kończyn doniesienie wstępne. Chir. Narz. Ruchu Ortop. Pol. 2001, 66, 73 78. [19] WOJNAR L., TĘSIOROWSKI M., GĄDEK A., ZARZYCKA M., JASIEWICZ B., KĄCKI W: Zastosowanie kliniczne iloś ciowej oceny regeneratu kostnego na zdjęciach rentgenowskich. Prz. Lek. 2002, 59, 4 suppl. 120 122. [20] CZERWIŃSKI E.: Ilościowa ocena zmian występujących pod wpływem fluoru w kości korowej i gąbczastej oraz ich znaczenie diagnostyczne. Rozprawa habilitacyjna, Kraków 1994. [21] SŁOMCZYKOWSKI M., KMIECIAK M., WOLF L., KOŁODZIEJCZYK K.: Metoda cyfrowej oceny radiogramów kości. Chir. Narz. Ruchu Ortop. Pol. 1995, 60, 211 215. [22] WOJNAR L., CZERWIŃSKI E., KUKIEŁKA R.: Pomiar szerokości szpary stawowej z zastosowaniem komputerowej analizy obrazu. Chir. Narz. Ruchu Ortop. Pol. 1998, (supl. 3), 63. [23] KOSZOWSKI R., RACZKOWSKA SIOSTRZONEK A., MORAWIEC T.: Standaryzowana metodyka oceny zmian osteolitycznych żuchwy przy zastosowaniu cyfrowej analizy radiodensytometrycznej. Acta Bio Optica Infor. Med. 2003, 9, 123 129. [24] KIMOTO K., GARRETT N. R.: Effect of mandibular ridge height on masticatory performance with mandibular con ventional and implant assisted overdentures. Int. J. Oral. Maxillofac. Implants 2003, 18, 523 530.

304 R. KOSZOWSKI, A. RACZKOWSKA SIOSTRZONEK Address for correspondence: Rafał Koszowski Department of Oral Surgery in Bytom Silesian Medical Academy in Katowice Akademicki 17 41 902 Bytom Poland e mail: chirstom@slam.katowice.pl Received: 4.05.2006 Revised: 7.06.2006 Accepted: 7.06.2006 Praca wpłynęła do Redakcji: 4.05.2006 r. Po recenzji: 7.06.2006 r. Zaakceptowano do druku: 7.06.2006 r.