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Defective osteogenesis of the stromal stem cells predisposes CD18-null mice to osteoporosis.

Osteogenesis by the bone marrow stromal stem cells (BMSSCs) supports continuous bone formation and the homeostasis of the bone marrow microenvironment. The mechanism that controls the proliferation and differentiation of BMSSCs is not fully understood. Here, we report that CD18, a surface protein present primarily on hematopoietic cells, but not on differentiated mesenchymal cells, is expressed by the stromal stem cells and plays a critical role in the osteogenic process. Constitutive expression of CD18 on BMSSCs using a retroviral promoter significantly enhances bone formation in vivo, whereas genetic inactivation of CD18 in mice leads to defective osteogenesis due to decreased expression of the osteogenic master regulator Runx2/Cbfa1. The defective osteogenesis of the CD18-null BMSSCs can be restored by expressing full-length, but not cytoplasmic domain-truncated, CD18. Radiographic analyses with dual-energy x-ray absorptiometry and 3D microcomputed tomography show that mice lacking CD18 have decreased bone mineral density and exhibit certain features of osteoporosis. Altogether, this work demonstrates that CD18 functions critically in the osteogenesis of BMSSCs, and thus lack of CD18 expression in the leukocyte adhesion deficiency patients may predispose them to osteoporosis.

Animals↗

Endoplasmic reticulum-mediated quality control of type I collagen production by cells from osteogenesis imperfecta patients with mutations in the pro alpha 1 (I) chain carboxyl-terminal propeptide which impair subunit assembly.

A heterozygous single base change in exon 49 of COL1A1, which converted the codon for pro alpha 1(I) carboxyl-terminal propeptide residue 94 from tryptophan (TGG) to cysteine (TGT) was identified in a baby with lethal osteogenesis imperfecta (OI64). The C-propeptide mutations in OI64 and in another lethal osteogenesis imperfecta cell strain (OI26), which has a frameshift mutation altering the sequence of the carboxyl-terminal half of the propeptide (Bateman, J. F., Lamande, S. R., Dahl, H.-H. M., Chan, D., Mascara, T. and Cole, W. G. (1989) J. Biol. Chem. 264, 10960-10964), disturbed procollagen folding and retarded the formation of disulfide-linked trimers. Although assembly was delayed, the presence of slowly migrating, overmodified alpha 1(I) and alpha 2(I) chains indicated that mutant pro alpha 1(I) could associate with normal pro alpha 1(I) and pro alpha 2(I) to form pepsin-resistant triple-helical molecules, a proportion of which were secreted. Further evidence of the aberrant folding of mutant procollagen in OI64 and OI26 was provided by experiments demonstrating that the endoplasmic reticulum resident molecular chaperone BiP, which binds to malfolded proteins, was specifically bound to type I procollagen and was coimmunoprecipitated in the osteogenesis imperfecta cells but not control cells. Experiments with brefeldin A, which inhibits protein export from the endoplasmic reticulum, demonstrated that unassembled mutant pro alpha 1(I) chains were selectively degraded within the endoplasmic reticulum resulting in reduced collagen production by the osteogenesis imperfecta cells. This biosynthetic deficiency was reflected in the inability of OI64 and OI26 cells to produce a substantial in vitro collagenous matrix when grown in the continuous presence of ascorbic acid to allow collagen matrix formation. Both these carboxyl-terminal propeptide mutants showed a marked reduction in collagen accumulation to 20% (or less) of control cultures, comparable to the reduced collagen content of tissues from OI26.

Base Sequence↗

Musculo-skeletal problems associated with pregnancy in women with osteogenesis imperfecta.

Having seen a number of women with osteogenesis imperfecta who developed severe back pain during or just after pregnancy, we wished to determine the likelihood of this and other musculoskeletal problems in pregnancy. We interviewed by telephone 100 women with osteogenesis imperfecta who had, between them, 213 pregnancies between 1957 and 1998. For each pregnancy we recorded the Sillence type for the osteogenesis imperfecta, the mode of delivery and the musculo-skeletal complications. The most common problem was back pain, which was severe in or after 28 pregnancies (13.1%). There was no identifiable relationship to the type of osteogenesis imperfecta or to the mode of delivery. In many cases the back pain could be related to crush fractures of vertebrae. Other problems identified included spinal deformity, non-vertebral fractures, disc problems and ligament problems. We suggest that it may be appropriate to advise the avoidance of long periods of breast feeding in women with OI, particularly in those who have vertebral fractures.

Adolescent↗

Mid-tibial distraction osteogenesis redistributes bone blood flow: a microsphere study in rabbits.

BACKGROUND: Distraction osteogenesis can be used for the treatment of osteomyelitis and nonunion, conditions thought to benefit from increased blood flow in the bone tissue of the distracted limb. We have questioned whether such an increase occurs, and investigated the spatial distribution of bone blood flow after distraction osteogenesis. METHODS: The tibiae of 8 rabbits were lengthened 10 mm by a standard midtibial distraction osteogenesis procedure. 2 weeks into the consolidation phase, the bone and soft tissue blood flow of the distracted and the contralateral extremity were measured using radioactive microspheres. RESULTS: The absolute bone blood flow of the distracted tibia was 4% lower than that of the non-distracted side, representing a 41% decrease in the proximal metaphysis, a smaller decrease in the proximal epiphysis, distal metaphysis and distal epiphysis, and an increase in the diaphysis. INTERPRETATION: Mid-tibial distraction osteogenesis redistributed the bone blood flow of the distracted tibia, but absolute tibial blood flow did not increase. Our results do not confirm previous research in this field.

Animals↗

Coronal suture response to distraction osteogenesis in rabbits with delayed-onset craniosynostosis.

Recent studies have identified a subpopulation of persons with craniosynostosis who exhibit progressive or delayed-onset synostosis and mild cranial vault deformities. These persons may be good candidates for nonextirpation distraction osteogenesis. The present studies were designed to determine force-displacement parameters and assess the effects of distraction osteogenesis on coronal suture growth and morphologic characteristics in a rabbit model with congenital, delayed-onset craniosynostosis. Data were collected from a total of 178 rabbits: 71 normal controls; 16 normal controls with distraction; 72 with delayed-onset coronal suture synostosis; and 19 with delayed-onset coronal suture synostosis and distraction. At 10 days of age, all rabbits had amalgam markers placed on both sides of the coronal suture. In the force-displacement study, force-displacement distractors were placed across the coronal suture and distracted acutely for 1.0 mm at 42 days of age. Force-displacement curves for the coronal suture were best described by a third-order polynomial regression equation for both normal and synostosed groups. Significant differences (P < 0.05) were found in the mean force necessary to distract a normal suture 1 mm in distance (13.72 kg) compared with a suture with delayed-onset synostosis (48.39 kg). A significant (P < 0.05) relationship was also found between the extent of synostosis and the distractive force in rabbits with delayed-onset synostosis. In the distraction study, internal distractors were fixed across the coronal suture at 25 days of age and percutaneously and intermittently activated at an average of 0.11 mm/day for 42 days (4.54 mm total). Serial radiographs were taken at 10, 25, 42, and 84 days of age. Results revealed that rabbits with delayed-onset synostosis and distraction had significantly (P < 0.01) more coronal suture growth rates compared with rabbits with delayed-onset synostosis and no distraction. Coronal sutures were harvested at 84 days of age for qualitative histologic examination. Normal, distracted coronal sutures showed widened sutural ligaments and thin, active osteogenic fronts. In contrast, distracted coronal sutures from rabbits with delayed-onset synostosis showed narrowed sutural ligaments, thickened and blunt osteogenic fronts, and increased collagen and bony matrix deposition compared with controls. Results suggest that distraction osteogenesis without corticotomy may be a treatment alternative in persons with progressive, delayed-onset synostosis. However, these preliminary data also suggest that distractive forces may accelerate or stimulate osteogenesis differentially in persons with craniosynostosis, possibly through an underlying genetic disorder of bone and cytokine regulation. These differential osteogenic responses to distraction, if validated clinically, will need to be taken into account when planning distraction rate and rhythm protocols for patients with craniosynostosis.

Age of Onset↗

Spring-mediated mandibular distraction osteogenesis.

Successful performance of distraction osteogenesis requires rigorous patient compliance with a daily activation regimen of a percutaneous screw. Previous clinical studies have found that failure of patient compliance with this regimen is the most common complication leading to technical failure of the distraction process. The authors have developed an internalized spring-mediated device for mandibular distraction osteogenesis that can potentially abrogate the risks associated with patient compliance by allowing for automated distraction across an osteotomy. Twenty adult New Zealand White rabbits underwent unilateral mandibular osteotomy. A segment of nickel-titanium shape memory alloy reinforced at both ends with a pinball was fashioned into an inferiorly based arc and secured to the mandible with stainless steel wire. On postoperative day 12, spring activation commenced by cutting a wire binding the two pinballs to one another. Animals were observed for 6 weeks before they were killed. Radiographic studies and decalcified histologic analysis were performed on extracted mandibles. Temperature- and displacement-dependent properties of the shape memory alloy were also examined. Five animals were excluded from the study due to infection, nonunion, or device failure. A mean distraction of 1.2 mm in the distracted hemimandible relative to the nonoperated hemimandible was found (P <.001, two-tailed paired t test). The maximum distraction achieved in an experimental specimen using the spring distractor was 3.7 mm. There were no other histologic or radiographic differences found between study specimens and specimens subjected to traditional distraction methods. Biomechanical testing of the shape memory alloy revealed a temperature-dependent increase in force at body temperature compared with room temperature and a reduction in force with increased displacement of the spring. This study demonstrates the feasibility of spring-mediated distraction osteogenesis across an osteotomy. As the field of distraction osteogenesis matures, the next level of sophistication in the clinical development of devices will incorporate technology that permits fully internalized and automated distraction to occur.

Alloys↗

Unilateral mandibular ramus elongation by intraoral distraction osteogenesis.

Successful correction of facial asymmetry by mandibular distraction osteogenesis relies on mastering vector control. Lack of necessary vector control continues to compromise the treatment modality. The purpose of this study was to describe a new simplified method for vector transfer and to evaluate this method according to the outcome and the efficacy of distraction osteogenesis in the correction of unilateral mandibular hypoplasia and asymmetry. Twenty-seven patients with unilateral hypoplasia of the mandibular ramus underwent unilateral mandibular distraction osteogenesis with intraoral distraction devices. Posterior-anterior and lateral cephalograms were analyzed by digitalization. Changes in sagittal, vertical, and transversal linear and angular dimensions after the distraction treatment were evaluated by measurements performed on headfilms taken before and after surgery. Means and variances were calculated for selected cephalometric variables for each time point. The differences between the control and the treatment side were calculated, statistically described, and compared with a paired Student t test. Correction of the mandibular asymmetry, chin position, and the canting of the occlusal plane was obtained in all patients clinically, as well as radiographically, by the use of intraoral unidirectional distraction osteogenesis.

Adolescent↗

Advances in osteogenesis imperfecta.

Considerable progress has been made in many aspects of osteogenesis imperfecta. The international Sillence classification of osteogenesis imperfecta is being expanded to include a greater range of subgroups of patients. Attempts are being made to identify the genes causing forms of osteogenesis imperfecta and related syndromes that are not caused by mutations of the Type I collagen genes. In medium-term studies, bisphosphonate treatment has been shown to be the first method of treatment to improve the clinical course of the disease significantly. Somatic cell therapy, using allogeneic bone marrow and mesenchymal stromal cell transplantation, are in their early phases of development for use in humans with osteogenesis imperfecta. Somatic gene therapy, which aims to inactivate the mutation, is being evaluated in laboratory and animal studies.

Collagen↗

Lengthening of muscle during distraction osteogenesis.

Chronic lengthening of immobilized, neurally intact muscle leads to the addition of sarcomeres in series. Confirmation of a similar adaptation during distraction osteogenesis is crucial for providing a rationale for a successful outcome of the intervention. When distraction osteogenesis (at < or = 1.4 mm/day) is done in skeletally immature animals, muscle adapts by creating a longer and functionally intact muscle. This is achieved through muscle growth, the proliferation of myogenic cells ultimately leading to serial addition of sarcomeres. When distraction osteogenesis is done in skeletally mature animals, however, the same distraction regimen leads to a lengthened muscle that has significant fibrosis and weakness, the latter possibly a result of partial denervation. Despite a modest but significant elevation of local insulinlike growth factor-1 in the lengthened muscles from adult animals, muscle growth is not adequate and leads to a loss of function. In adult animals, the distraction osteogenesis-induced increase in insulinlike growth factor-1 is insufficient to facilitate muscle growth during lengthening. Muscle can be targeted for future therapeutic use of insulinlike growth factor-1; however, such a therapy also may lead to increased fibrosis.

Adaptation, Physiological↗

Craniofacial distraction osteogenesis: a review of 3278 cases.

The nascent field of craniofacial distraction osteogenesis has not yet been subjected to a rigorous evaluation of techniques and outcomes. Consequently, many of the standard approaches to distraction have been borrowed from the experience with long bones in orthopedic surgery. The ideal "latency period" of neutral fixation, rate and rhythm of distraction, and consolidation period have not yet been determined for the human facial skeleton. In addition, because the individual craniofacial surgeon's experience with distraction has generally been small, outcomes and meaningful complication rates have not yet been published. In this study, a four-page questionnaire was sent to 2476 craniofacial and oral/maxillofacial surgeons throughout the world, asking about their experiences with distraction osteogenesis. Information about the types of cases, indications for surgery, surgical techniques, postoperative management, outcomes, and complications were tabulated. Of 274 respondents (response rate, 11.4 percent), 148 indicated that they used distraction in their surgical practice. One hundred forty-five completed surveys were entered into a database that provided information about 3278 craniofacial distraction cases. Statistical analyses were performed comparing the rates of premature consolidation, fibrous nonunion, and nerve injury, on the basis of the use of a latency period and different rates and rhythms of distraction. In addition, the rates of all complications were determined and compared on the basis of the number of distraction cases performed per surgeon. The results of the study clearly show a wide variation in the surgical practice of craniofacial distraction osteogenesis. Although the cumulative complication rate was found to be 35.6 percent, there is a pronounced learning curve, with far fewer complications occurring among more experienced surgeons (p < 0.001). The presence of inferior alveolar nerve injury as a result of mandibular distraction was much lower for respondents whose distraction regimens consisted of no more than 1 mm of distraction per day (19.5 percent versus 2.4 percent; p < 0.001). No evidence was found to support the use of a latency period or to divide the daily distraction regimen into more than one session per day. Conclusions could not be drawn from this study regarding the length of the consolidation period. Overall, the surgeon-reported outcomes are comparable with those published for other craniofacial procedures, despite the higher incidence of complications. Although conclusions made on the basis of a subjective questionnaire need to be interpreted cautiously, this study has strength in the large numbers of cases reviewed. Because of the anonymity of responses, it has been assumed that surgeons who responded to the survey reported accurate numbers of complications and successful outcomes. Finally, additional clinical and animal studies that will be of benefit in advancing the field of craniofacial distraction osteogenesis are outlined.

Craniofacial Abnormalities↗

Transport distraction osteogenesis: a new method to heal adult calvarial defects.

Popularized by Gavril Ilizarov in the 1960s, monofocal distraction osteogenesis has become a well-established method of endogenous bone engineering. This revolutionary surgical technique has significantly augmented the available reconstructive orthopedic and craniomaxillofacial procedures. Bifocal distraction osteogenesis, or bone transportation, is a modification of monofocal distraction that involves moving a free segment of living bone to fill an intercalary bone defect. Bifocal distraction has been applied successfully to reconstruct complex mandibular and long bone defects. Because traumatic or postsurgical calvarial defects do not spontaneously heal in humans older than 18 to 24 months of age, we hypothesized that bifocal distraction osteogenesis could be applied to the skull to close critical size calvarial defects. Critical size (15 x 15 mm) calvarial defects were created in eight New Zealand White rabbits. Next, a 15-mm x 10-mm calvarial box osteotomy was created just anterior to the skull defect. This osteotomy created a free bone segment that could be transported. A custom-made transport distraction device was fixed into place and the skin incision was closed. After a 4-day latency period, the distraction device was activated (0.5 mm once daily for 30 days) in seven animals; the distraction device in one animal was not activated and served as a control. All animals underwent 30 days of consolidation and were then killed. Radiographs and computed tomographic scans were performed at the following time points: end of latency period (postoperative day 4), mid-distraction (postoperative day 19), and end of consolidation period (postoperative day 64). Gross and histologic analysis was performed to evaluate the quality of the bony regenerate. The control animal healed with a fibrous union. Complete closure of the skull defects was observed in five of seven rabbits at the end of the consolidation period. One animal was removed from the study because of an early loosening of the distraction device, and one was removed because of device failure. Of the remaining five animals that completed the distraction protocol, radiographs and computerized tomographic scans showed successful ossification in all five rabbits at the end of the consolidation period. This study suggests that transport distraction osteogenesis is a promising technique that may be applied to a variety of commonly encountered craniofacial problems such as nonhealing calvarial defects.

Age Factors↗

Spondylolisthesis in osteogenesis imperfecta due to pedicle elongation: report of two cases.

STUDY DESIGN: Two cases of spondylolisthesis due to severe elongation of pedicles in osteogenesis imperfecta are reported. OBJECTIVE: To describe an unusual type of spondylolisthesis and its successful management. SUMMARY OF BACKGROUND DATA: Spondylolisthesis is known to occur in osteogenesis imperfecta. Reports in the literature are few. Pedicle elongation resulting in spondylolisthesis has only been reported once. There is no report of a successful treatment of this type of spondylolisthesis resulting from pedicle elongation. METHOD: Two adolescent girls suffering from osteogenesis imperfecta presented with lower back pain and thoracic scoliosis. One of them had high-grade spondylolisthesis of L3-L4, L4-L5, and L5-S1, with a thoracic scoliosis. She was treated with anterior interbody fusion L3 to sacrum without instrumentation. Later, progression of her scoliosis required combined anterior and posterior instrumented fusion T1 to L1. The other girl presented with L5 spondylolisthesis and thoracic scoliosis. She has back pain as well as neurologic symptoms in her legs and is waiting for surgery. RESULTS: At the 3-year follow-up the operated patient is symptom-free from her spine and there has been no progression of either deformity. CONCLUSION: High-grade spondylolisthesis due to elongation of pedicle in osteogenesis imperfecta is uncommon. Anterior interbody fusion of all the involved motion segments has produced good pain relief and arrested deformity progression at the 3-year follow-up.

Adolescent↗

Distraction osteogenesis of the mandible.

PURPOSE OF REVIEW: Airway obstruction and craniofacial deformities resulting from mandibular deficiency are challenging and complex clinical problems. Mandibular distraction osteogenesis is playing a rapidly expanding role in the treatment of these children and has supplanted traditional management techniques in many centers. Several recent studies have reviewed clinical experience, described technical refinements, and addressed issues in patient selection and preoperative workup. RECENT FINDINGS: The extension of mandibular distraction osteogenesis to newborns with Pierre Robin sequence or craniofacial syndromes associated with micrognathia and airway obstruction has radically altered treatment protocols at several institutions. Early bilateral mandibular distraction has obviated tracheostomy in most newborns, with low operative morbidity. In addition, early decannulation and resolution of obstruction has occurred when mandibular distraction osteogenesis was applied to selected micrognathic children. Some of these patients were tracheotomized and others presented with severe obstructive symptoms. Studies have described success with external and internal distraction techniques. Recent publications have also demonstrated the surgeon's ability to mold the regenerate safely, the dynamic characteristics of the consolidation phase, and success with secondary and tertiary distraction. SUMMARY: After 15 years of clinical use in children for craniofacial deformities, recent advances in distraction osteogenesis have obviated tracheostomy in most newborns with micrognathia and severe airway obstruction. Applications of this technique to children with airway issues related to micrognathia or retrognathia have been rapidly expanding. In addition, refinements in distraction technique have advanced treatment of nonairway-related mandibular deformities.

Airway Obstruction↗

Guided tissue regeneration enhances bone formation in a rat model of failed osteogenesis.

BACKGROUND: Guided tissue regeneration is a technique that uses barrier materials to enhance tissue regeneration. Although previously demonstrated to be an effective way of enhancing craniofacial osteogenesis in several animal models, the ability of guided tissue regeneration to augment bone formation in the context of distraction osteogenesis is unknown. In the current study, the authors applied the principle of guided tissue regeneration to their rat mandibular distraction osteogenesis model in an attempt to enhance bone regeneration. METHODS: Twelve (n = 6 per group) adult Sprague-Dawley rats underwent routine gradual distraction (5 days' latency, 4-mm distraction over 8 days, 4 to 6 weeks of consolidation) and acute distraction (immediate lengthening to 4 mm, 6 to 8 weeks of consolidation). An additional 10 animals underwent acute distraction followed by application of bioabsorbable Gore Resolut XT membranes (acute distraction plus guided tissue regeneration). Membranes were completely wrapped around the distraction gap. Animals were killed 6 and 8 weeks postoperatively and mandibles analyzed radiographically and histologically. RESULTS: Quantitative histomorphometric analyses were performed to compare relative bone formation between all three groups. Gradual distraction mandibles achieved bony union by 6 weeks with 86 percent bone formation, which increased to 98 percent by 8 weeks. Acute distraction mandibles healed with a fibrous nonunion and only 37 percent bone formation by 8 weeks. In contrast, acute distraction plus guided tissue regeneration-treated mandibles formed significantly more bone than acute distraction mandibles by 6 weeks (57 percent) and achieved bony bridging by 8 weeks, with 88 percent new bone formation. CONCLUSION: The authors' data demonstrate that guided tissue regeneration can significantly enhance bone formation in a fibrous nonunion model of mandibular distraction osteogenesis.

Animals↗

Three-dimensional finite element analysis of the mandible and temporomandibular joint on simulated occlusal forces before and after vertical ramus elongation by distraction osteogenesis.

Distraction osteogenesis has recently become a mainstay for treatment of mandibular hypoplasia. Thorough knowledge about changes in the temporomandibular joint (TMJ) and the surrounding parts of the mandible and the skull after mandibular distraction is still lacking. The purpose of the current study was to investigate the stress distribution in the mandible and the TMJ before and after skeletal correction by intraoral unilateral vertical mandibular ramus distraction, using a finite element (FE) model. The FE models were based on computed tomography scans and magnetic resonance imaging scans of a patient with unilateral hypoplasia of the right mandibular ramus caused by juvenile idiopathic arthritis. The character of stress distribution in the mandible and TMJ before and after skeletal correction by 15 mm of vertical distraction of the mandibular ramus was analyzed quantitatively and compared during centric occlusion. Before the distraction osteogenesis treatment, the condyles, articular discs, and glenoid fossa regions are loaded with a different stress pattern. The affected right condyle, disc, and fossa are loaded diffusely and externally in comparison with the anterior and with centralized loading on the normal left side. After unilateral mandibular distraction osteogenesis, the load became more centric and symmetrical. The results suggest that correction of the mandibular deformity by distraction osteogenesis tends to normalize the stress patterns in the TMJ.

Arthritis, Juvenile↗

Frontal ostium neo-osteogenesis and restenosis after modified endoscopic Lothrop procedure in an animal model.

All patients who undergo a modified endoscopic Lothrop procedure have postoperative narrowing of the enlarged frontal ostium. The aim of this study is to evaluate neo-osteogenesis and restenosis of the frontal ostium and its effect on mucociliary clearance. Fourteen sheep underwent an endoscopic modified Lothrop procedure. Pre- and postoperative nuclear medicine gamma scintigraphy of the frontal sinuses was performed. The sizes of the frontal ostia were measured and biopsies taken from the bone of the frontal ostium. Histological evidence of new bone formation was found in 56% of biopsies. The average preoperative mucociliary clearance half times (T1/2) at 15 and 30 min were 70 and 74 min, respectively, and postoperatively were 50 and 67 min. There was a non-significant trend towards poorer clearance in sinuses with neo-osteogenesis. The average size of the frontal ostium decreased by 28%. There was no relationship between the size of the ostium and neo-osteogenesis. Neo-osteogenesis was seen in 56% of biopsies with a 28% reduction in size of the frontal ostium after 224 days. Mucociliary clearance did not alter significantly.

Animals↗

Reduced strength of skin in osteogenesis imperfecta.

The biochemical properties and ratio collagen type I/type III of skin biopsies from nine patients with osteogenesis imperfecta and nine age- and sex-matched controls were studied. Four of six patients with osteogenesis imperfecta Sillence type I had pronounced reductions in skin tensile strength, decreased ratios of collagen type I/type III, primarily accomplished by reduced amounts of collagen type I, moderate or no disability. The three patients with osteogenesis imperfecta Sillence type III had severe skeletal deformities, but normal skin tensile strength, and ratios of collagen type I/type III within the normal range. These observations may be explained as resulting from various structural defects in the type I collagen of patients with osteogenesis imperfecta.

Adult↗

Discrimination of morphological findings in dentine from osteogenesis imperfecta patients using combinations of polarized light microscopy, microradiography and scanning electron microscopy.

OBJECTIVES: The aim of this study was to investigate the morphological appearance of dentine in teeth from individuals with osteogenesis imperfecta type I, III and IV using different histological techniques, and to correlate morphological findings to different types of osteogenesis imperfecta. SAMPLE AND METHODS: Extracted or exfoliated primary and permanent teeth were collected from 15 patients with the osteogenesis imperfecta diagnoses I, III or IV, with or without the additional diagnosis dentinogenesis imperfecta. Ground and decalcified sections were prepared from the teeth. Histo-morphological studies of the dentine were performed utilizing light and polarized light microscopy, microradiography and scanning electron microscopy. RESULTS: Characteristic findings were irregular tubules, remnants of capillary inclusions and obliterated pulps. All types of osteogenesis imperfecta exhibited similar types of dentine aberrations, but patients with type III or IV had a higher frequency of aberrations when compared to type I. CONCLUSIONS: The combination of either polarized light microscopy or micro-radiography, together with scanning electron microscopy, gave the most amount of morphological information from dentine samples. In addition, aberrations in dentine structure were more clearly observable. Light microscopy was not critical for the analyses.

Adolescent↗