Contralateral Jaw Research Articles

Periodontal Repair in Dogs: Evaluation of a Bioabsorbable Space-Providing Macro-Porous Membrane with Recombinant Human Bone Morphogenetic Protein-2.

Recombinant human bone morphogenetic protein-2 (rhBMP-2) technologies have been shown to significantly support alveolar bone formation. Biomaterial limitations, however, have restricted the biologic potential for onlay indications. The objective of this study was to evaluate regeneration of alveolar bone and periodontal attachment, and biomaterials reaction following surgical implantation of a spaceproviding, bioabsorbable, macroporous, polyglycolic acid-trimethylene carbonate (PGA-TMC) membrane combined with a rhBMP-2 construct in a discriminating onlay defect model. Routine supraalveolar periodontal defects were created at the mandibular premolar teeth in 9 beagle dogs. Contralateral jaw quadrants in subsequent animals were randomly assigned to receive the domeshaped PGA-TMC (100 to 120 μm pores) membrane with rhBMP-2 (0.2 mg/mL) in a bioresorbable hyaluronan (Hy) carrier or the PGA-TMC membrane with Hy alone (control). The gingival flaps were advanced to submerge the membranes and teeth and sutured. Animals were euthanized at 8 and 24 weeks postsurgery for histologic observations. Jaw quadrants receiving the PGA-TMC membrane alone experienced exposures at various time points throughout the study. Jaw quadrants receiving the PGA-TMC/rhBMP-2 combination remained intact, although one site experienced a late minor exposure. Newly formed alveolar bone approached and became incorporated into the macroporous PGA-TMC membrane in sites receiving rhBMP-2. The PGA-TMC biomaterial was occasionally associated with a limited inflammatory reaction. Residual PGA-TMC could not be observed at 24 weeks postsurgery. Residual Hy could not be observed at any time interval. Regeneration of alveolar bone height (means ± SD) was significantly increased in sites receiving the PGA-TMC/rhBMP 2 combination compared to control (3.8 ± 1.3 versus 0.7 ± 0.5 mm at 8 weeks and 4.6 ± 0.8 versus 2.1 ± 0.4 mm at 24 weeks; P <0.05). Limited cementum regeneration was observed for PGA-TMC/rhBMP-2 and PGA-TMC control sites. Ankylosis compromised regeneration in sites receiving PGA-TMC/rhBMP-2. The bioabsorbable, space-providing, macroporous PGA-TMC membrane appears to be compatible biomaterial for bone augmentation procedures. rhBMP-2 significantly enhances alveolar bone augmentation and soft tissue healing when combined with the PGA-TMC membrane. J Periodontol 2003; 74:635-647.

Digital tomosynthesis-experiences with a new imaging device for the dental field.

Based on the principles of classic film tomography, a new digital X-ray device for dental sites was developed and clinically evaluated. The tomosynthesis process produces several slices from a finite number of radiographs taken from different projection angles, obtaining a three-dimensional image of the jaws and teeth. During evaluation of an industrial prototype, a total of 52 tomosynthesis data sets were made covering different anatomic areas. Of those, 32 sets were assessed by ten radiologically experienced dentists. Anatomic regions not shown on conventional intraoral dental films were displayed due to the extraoral sensor. Diagnostic images of high value were mainly achieved within the scope of lateral views and transverse views in the frontal region. Even small structures such as the periodontal ligament could be shown in several planes, resulting in superposition-free representation. The elimination of metal artefacts caused by dental restorations was facilitated. However, improvements can be made in definition and resolution. Views in the sagittal plane and incomplete blurring of the contralateral jaw are difficulties that remain. The tomosynthesis process combined with a planned 3D representation is likely to be well suited for dental radiology. The use of such a device could be much less expensive than computed tomography (CT). Furthermore, it offers higher spatial resolution, exposes patients to less radiation, and could be easily used in daily practice, even chairside.

Effect of surgical implantation of recombinant human bone morphogenetic protein-2 in a bioabsorbable collagen sponge or calcium phosphate putty carrier in intrabony periodontal defects in the baboon.

Recombinant human bone morphogenetic protein-2 (rhBMP-2) in a proper carrier has been shown to induce clinically relevant bone formation for several oral/maxillofacial and periodontal indications and to stimulate regeneration of the periodontal attachment. The objective of this study is to evaluate regeneration of alveolar bone, cementum, periodontal ligament, and associated root resorption and ankylosis following surgical implantation of rhBMP-2 in an absorbable collagen sponge (ACS) or a calcium phosphate putty (alphaBSM) carrier in 3-wall intrabony periodontal defects in the baboon. rhBMP-2/ACS and rhBMP-2/alphaBSM were implanted in surgically produced, maxillary and mandibular, large size, 3-wall intrabony defects in 4 baboons. Contralateral jaw quadrants were implanted with buffer/ACS, buffer/ alphaBSM, or served as sham-operated surgical controls. Treatments were allocated to left and right, maxillary and mandibular, jaw quadrants following a randomization schedule. Four months following implantation, block biopsies of defect sites were obtained, processed, and subjected to histologic and histometric analysis. Defect sites receiving rhBMP-2/ACS and rhBMP-2/alphaBSM demonstrated significantly greater regeneration than controls. No significant differences were observed between defect sites receiving rhBMP-2/ACS or rhBMP-2/alphaBSM regarding epithelial migration and connective tissue attachment and new bone formation. However, rhBMP-2/ACS supported significantly greater new cementum formation. Ankylosis or root resorption were not observed. The results of this study support the use of rhBMP-2 to enhance periodontal regeneration of intrabony periodontal defects. While this novel technology holds promise, refinement in carrier systems may provide the key to enhancement of the regenerative potential.

Functional properties of single motor units in inferior head of human lateral pterygoid muscle: task relations and thresholds.

The aim of this study was to clarify the normal function of the inferior head of the human lateral pterygoid muscle (IHLP). The hypothesis was that an important function of the IHLP is in the fine control of horizontal jaw movements. The activities of 99 single motor units (SMUs) were recorded from IHLP (22 recordings from 16 subjects). Most recording sites were identified by computer tomography (CT). All 99 SMUs were active during contralateral jaw movements with the teeth apart, and protrusive jaw movements with the teeth apart, and 81% (48 of 59 units studied during all 3 tasks) were active during submaximal jaw-opening movements. None were active on maximal ipsilateral or retrusive jaw movements with the teeth apart nor on jaw closing/clenching in intercuspal position; nor were they spontaneously active when the jaw was at the clinically determined postural jaw position. Thresholds of SMUs ranged from <0.2 mm of contralateral or protrusive horizontal displacements to 61-89% of the maximum contralateral or protrusive displacement, respectively. For the 35 units continuously active during the contralateral task, 23 (66%) were recruited within 2 mm of contralateral displacement [25 (63% of 40 units) for protrusion]. Recruitment thresholds (mm) of some of the units were rate dependent with thresholds significantly decreasing with increasing rate of horizontal jaw movement in protrusion and contralateral movements. At eight recording sites where up to six SMUs were able to be discriminated, the average thresholds of successively recruited SMUs were within a 1-mm increment of horizontal jaw displacement. After dividing IHLP into four regions, the SMUs recorded in the superior-medial zone exhibited significantly lower mean threshold values than for the SMUs recorded in the other zones (no units were recorded in the inferior-lateral zone). This provides suggestive evidence supporting previously proposed notions of functional heterogeneity within IHLP. Taken together, the data suggest that specific regions of the IHLP are capable of selective activation in a finely controlled manner to allow the application of the appropriate force vector (magnitude and direction) to effect the required condylar movement needed for the generation and control of horizontal jaw movements.

Periodontal repair in dogs: effect of allogenic freeze-dried demineralized bone matrix implants on alveolar bone and cementum regeneration.

The objective of this study was to evaluate alveolar bone and cementum regeneration following surgical placement of an allogenic, freeze-dried, demineralized bone matrix (DBM) cortical strip implant. Critical size, supraalveolar periodontal defects were surgically created around the second, third, and fourth mandibular premolar teeth in eight mongrel dogs. Contralateral jaw quadrants in six animals were randomly assigned to receive the DBM implant, or serve as surgical control. Two additional animals received bilateral DBM implants. Flaps were coronally advanced to submerge teeth and implants, and sutured. Three animals were exited from the study due to extensive early wound failure. Remaining animals were sacrificed at 8 weeks postsurgery. Histometric recordings included defect height, bone regeneration/DBM implant height, cementum regeneration height, root resorption, and ankylosis. Large areas of unresorbed DBM exhibiting fragmentation and empty osteocyte lacunae were observed adjacent to new bone formation, or bone formation was observed adjacent to or within the implant, often exhibiting ankylosis. Cementum regeneration appeared enhanced in shelter of the DBM implant. Histometric recordings (mean+/-SD) for DBM and control defects, respectively, were: defect height, 4.8+/-0.2 mm and 4.4+/-0.2 mm; bone regeneration/DBM implant height, 4.0+/-1.3 mm and 1.2+/-0.6 mm; cementum regeneration height, 1.4+/-0.4 mm and 0.7+/-0.2 mm; root resorption, 0.5+/-0.3 mm and 1.2+/-0.3 mm; and ankylosis, 0.5+/-0.2 mm and 0.1+/-0.1 mm without statistically significant differences between experimental conditions (N=3). Within the limitations of this study, the histologic observations suggest that surgical implantation of allogenic, freeze-dried DBM cortical strip implants may have a potential to support cementum regeneration, possibly by providing conditions for guided tissue regeneration, however, alveolar regeneration appears unpredictable.

Periodontal Repair in Dogs: Recombinant Human Bone Morphogenetic Protein‐2 Significantly Enhances Periodontal Regeneration

This study evaluated bone and cementum regeneration following periodontal reconstructive surgery using recombinant human bone morphogenetic protein-2 (rhBMP-2) in six beagle dogs. Surgically created mandibular supraalveolar premolar tooth defects in contralateral jaw quadrants were randomly assigned to receive rhBMP-2 or control vehicle. Clinical defect height was prepared to 5 mm. rhBMP-2 was applied with synthetic bioerodable particles and autologous blood using 20 micrograms rhBMP-2 per 100 microliters implant volume. Flaps were advanced to submerge the teeth and sutured. The dogs were sacrificed 8 weeks postsurgery. Histometric recordings included defect height, height and area of alveolar bone regeneration, height of cementum regeneration, root resorption, and ankylosis. Group means, standard deviations, and P values are shown (Student t test; n = 6). Histometric defect height for rhBMP-2 and control defects was 3.7 +/- 0.3 and 3.9 +/- 0.4 mm, respectively (P = 0.446). Height of alveolar bone regeneration amounted to 3.5 +/- 0.6 and 0.8 +/- 0.6 mm for rhBMP-2 and control defects, respectively (P = 0.000). Corresponding values for bone area were 8.4 +/- 4.5 and 0.4 +/- 0.5 mm2, respectively (P = 0.006). Cementum regeneration was observed in all experimental defects (17/17) and in 15 out of 17 controls, averaging 1.6 +/- 0.6 and 0.4 +/- 0.3 mm for rhBMP-2 and control defects, respectively (P = 0.005). Small amounts of root resorption were seen in rhBMP-2 defects, whereas controls exhibited substantial resorption (0.2 +/- 0.1 and 1.1 +/- 0.3 mm, respectively; P = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Ocular protrusion with contralateral jaw movement : Brodsky MC, James CA. Arch Opthalmol 111:1028, 1993

Ocular protrusion with contralateral jaw movement : Brodsky MC, James CA. Arch Opthalmol 111:1028, 1993

Periodontal Repair in Dogs: Space Provision by Reinforced ePTFE Membranes Enhances Bone and Cementum Regeneration in Large Supraalveolar Defects

Regeneration of alveolar bone and cementum following reconstructive therapy with reinforced space providing expanded polytetrafluorethylene (ePTFE) membranes was evaluated in supraalveolar mandibular premolar periodontal defects in five beagle dogs. The surgically-created defects in contralateral jaw quadrants were randomly assigned to receive the dome-shaped membrane or serve as surgical control. Flaps were positioned to completely submerge the teeth and sutured. The dogs were sacrificed 8 weeks after surgery and tissue blocks including teeth and surrounding structures processed for histology. Membrane treated defects in two animals became exposed and infected leaving intact quadrants in three dogs for histometric analysis. Parameters evaluated included defect height, height and area of regenerated alveolar bone, height of regenerated cementum, root resorption, and ankylosis. Mean defect height approximated 4.1 mm. Mean height (+/- s.d.) of regenerated alveolar bone amounted to 2.9 +/- 0.6 and 0.6 +/- 0.2 mm for membrane and control defects, respectively (P = 0.006). Corresponding values for bone area were 1.4 +/- 0.7 and 0.4 +/- 0.4 mm2 (P = 0.02). Cementum regeneration was observed in all teeth averaging (+/- s.d.) 1.6 +/- 0.3 mm for membrane treated and 0.1 +/- 0.1 mm for control defects (P = 0.01). Small amounts of root resorption were seen in all teeth with no significant difference between treatments. Ankylosis was noticed in three membrane treated and two control teeth. The present study provides a biologic rationale for space provision for enhanced bone and cementum regeneration in periodontal defects subject to reconstructive therapy.

Periodontal Repair in Dogs: Expanded Polytetrafluoroethylene Barrier Membranes Support Wound Stabilization and Enhance Bone Regeneration

A wound stabilizing effect of expanded polytetrafluoroethylene (ePTFE) membranes was evaluated in supra-alveolar periodontal defects in 5 beagle dogs. The defects, 5 to 6 mm in height, were surgically created around the 2nd, 3rd, and 4th mandibular premolar teeth in contralateral jaw quadrants. The root surfaces were conditioned with heparin, which, in this model, has been demonstrated to compromise periodontal healing and result in formation of a long junctional epithelium. Wound closure included application of ePTFE membranes around each premolar tooth in one jaw quadrant in each dog and flap positioning coronal to the cemento-enamel junction in both jaw quadrants. Healing progressed uneventfully except for 3 teeth in 2 dogs, which experienced membrane exposure. The dogs were sacrificed after a 4-week healing period and tissue blocks were prepared for histometric analysis. Connective tissue repair in heparin+membrane-treated teeth averaged 98% of the defect height compared to 84% in control heparin-treated teeth (P < or = 0.05). Junctional epithelium formation was smaller in membrane-treated teeth than in control teeth (P < or = 0.05) and was usually terminated coronal to the membrane. Bone regeneration was enhanced in membrane-treated teeth compared to controls (P < or = 0.01) and was strongly correlated to the area under the membrane in teeth without membrane exposure (r2 = 0.993; P = 0.002). This correlation was reduced when teeth with membrane exposure were included in the analysis (P < or = 0.05). Cementum regeneration was minimal under both treatment conditions. Root resorption was increased in membrane-treated compared to control teeth (P < or = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Periodontal repair in dogs: effect of a composite graft protocol on healing in supraalveolar periodontal defects.

This study evaluated the effect of a composite graft as an adjunct to gingival flap surgery in induced chronic supraalveolar periodontal defects in the mandibular premolar region in beagle dogs. The vertical dimension of the defects, measured from the cemento-enamel junction to the alveolar bone, approximated 5 mm. Root surface treatment in quadrants receiving the graft protocol included conditioning with both critic acid and tetracycline. The composite graft (including: hydroxyapatite, freeze-dried decalcified bone, tetracycline, and fibronectin) was then fitted to the defects. Flaps were placed and sutured to cover most of the crowns of the teeth but the tips of the cusps. The root surfaces in contralateral jaw quadrants were conditioned with critic acid and the flaps similarly placed and sutured. Dogs were sacrificed 6 weeks after surgery and tissue blocks including teeth and surrounding structures processed for histometric analysis. Connective tissue repair to the root surface in teeth treated with the graft protocol approximated 60% of the defect height. Connective tissue repair in teeth treated with citric acid only was significantly greater and averaged 98% of the defect height (P less than or equal to 0.01). Cementum formation was limited following both treatments (approximately 6% of the defect height). Bone regeneration was significantly smaller in grafted sites than in sites treated with citric acid only (approximately 2% and 10% of the defect height, respectively; P less than or equal to 0.05). Root resorption was observed in almost all teeth. Ankylosis was present in two citric acid-treated specimens, both from the same dog.(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship between lateral border movements of the mandible and the determinants of occlusion

Border movements of the mandible were measured with a jaw movement analyzer in nine subjects. This instrument records movement with 6 degrees of freedom and has the ability to accurately and linearly record the full range of jaw movement. The result of this study showed a relationship between the presence of balancing side molar contacts and restricted contralateral jaw border movements. This restriction is probably due to aberrant external pterygoid muscle activity.

Restoration of mandibular jaw defects in the rabbit by subperiosteally implanted Teflon® mantle leaf

The present investigation was undertaken to study the healing pattern of mandibular jaw defects where one or two lateral bone walls were missing. The bone regeneration between contralateral defects was compared; in one jaw the defects were covered with perforated mantle leaf of Teflon®, in the contralateral jaw the defects were left uncovered. Eighteen adult white rabbits were used for the study. Experimental standardized defects with respectively one and two lateral bone walls missing were made in the mandibular base area. On one side the defects were covered with subperiosteally implanted perforated mantle leaf before suturing the soft tissue. The bone healing was followed during 52 weeks and three different fluorochromes were administered at 2, 4, 6, 12, 26 and 52 weeks in order to estimate the activity and source of the bone regeneration during different time periods. Specimens were obtained both for paraffin sections and ground sections. Light microscopic and fluorescence microscopic examinations were made of the sections. Healing of defects covered with subperiosteally implanted Teflon mantle leaf showed almost complete bone regeneration of both two-wall defects and three-wall defects, whereas in the contralateral jaws the uncovered two-wall bone defects showed incomplete healing of the defects with a central part of fibrous connective tissue. The three-wall defects without mantle-leaf cover, on the contrary, healed with almost complete bone regeneration; only a small concavity in the normal outline of the bone could be seen. It seems as if subperiosteally implanted mantle-leaf cover prevents formation of a fibrous scar tissue and allows the bone regeneration to proceed and fill up the two-wall defects completely.