This investigation was undertaken to assess bacterial plaque accumulation adjacent to orthodontic brackets. Experiments were carried out on 11 subjects who were scheduled for orthodontic treatment ...including extraction of two or four premolars. Metal brackets were bonded to the premolars to be extracted using macro‐filled bonding composite. A conventional elastomeric ring was placed around one bracket and a steel ligature wire around the bracket on the contralateral tooth. The subjects were told to continue their normal oral hygiene regimen. Teeth were extracted at 1, 2, or 3 weeks after bracket bonding. Scanning electron microscopic (SEM) examination of brackets, excess composite, and buccal enamel revealed that mature plaque was present on excess composite at 2 and 3 weeks after bonding, whereas plaque on the gingival enamel surface was still at an early stage of development. The results demonstrate that excess composite around the bracket base is the critical site for plaque accumulation due to its rough surface and the presence of a distinct gap at the composite–enamel interface. The method of ligation does not appear to influence the bacterial morphotypes on both composite and enamel surfaces.
Background: Recombinant human bone morphogenetic protein‐2 (rhBMP‐2) has been shown to support the regeneration of alveolar bone and periodontal attachment in surgically created periodontal defects ...and in defects with a history of dental plaque and calculus exposure. Periodontal regeneration has also been shown following guided tissue regeneration using space‐providing expanded polytetrafluoroethylene (ePTFE) devices. The objective of this study was to evaluate the influence of rhBMP‐2 on regeneration of alveolar bone and periodontal attachment used in conjunction with a space‐providing ePTFE device.
Methods: Routine, critical‐size, 5–6 mm, supra‐alveolar, periodontal defects were created around the third and fourth mandibular premolar teeth in four young adult Hound Labrador mongrel dogs. rhBMP‐2 (0.2 mg/ml) in an absorbable collagen sponge (rhBMP‐2/ACS) or buffer/ACS (control) implants were randomly assigned to be placed around the premolar teeth in the left and right jaw quadrants in subsequent animals. Space‐providing ePTFE devices with 300‐μm laser‐drilled pores, 0.8 mm apart, were used to cover the rhBMP‐2 and control implants. The gingival flaps were advanced for primary wound closure. The animals were euthanized at 8 weeks postsurgery for histologic and histometric analyses.
Results: Bone regeneration and ankylosis were significantly increased in jaw quadrants receiving rhBMP‐2/ACS compared to control (bone height 4.8±0.3 versus 2.0±0.2 mm, p=0.001; bone area 10.9±1.3 versus 1.4±0.1 mm2; p=0.009, and ankylosis 2.2±0.2 versus 0.04±0.7 mm; p=0.01). No differences between groups were found for cementum regeneration and root resorption.
Conclusions: rhBMP‐2 significantly enhances regeneration of alveolar bone in conjunction with a space‐providing, macroporous ePTFE device for GTR.
Zusammenfassung
Hintergrund: Es wurde gezeigt, dass das rekombinante menschliche morphogenetische Knochenprotein 2 (rhBMP‐2) die Regeneration von alveolärem Knochen und parodontalem Stützgewebe bei chirurgisch geschaffenen parodontalen Defekten und in Defekten, die dentaler Plaque und Zahnstein ausgesetzt waren, unterstützt. Parodontale Regeneration wurde auch gezeigt in der Folge von gesteuerter Geweberegeneration unter Nutzung eines Platzhalters mit expandierter Polytetrafluorethylen (e‐PTFE) Membranen. Das Ziel dieser Studie war die Überprüfung des Einflusses von rhBMP‐2 auf die Regeneration von alveolärem Knochen und parodontalem Stützgewebe unter Nutzung eines Platzhalters aus e‐PTFE.
Methoden: Routinemäßig wurden supraalveoläre parodontale Defekte mit der kritischen Größe von 5–6 mm um die dritten und vierten mandibulären Prämolaren bei vier jungen erwachsenen Labradormischhunden geschaffen. rhBMP‐2 (0.2 mg/ml) in einem absorbierbaren Kollagenschwamm (rhBMP‐2/ACS) oder Puffer/ACS (Kontrollen) Implantate wurden für die Platzierung um die Prämolaren im rechten und linken Quadranten bei den Tieren zufällig ausgewählt. e‐PTFE Platzhalter mit 300 μm lasergeschaffenen Poren, 0.8 mm auseinander, wurden für die Abdeckung der rhBMP‐2 und Kontrollimplantate genutzt. Die gingivalen Lappen wurden für eine primäre Wundheilung vorgesehen. Die Tiere wurden8 Wochen postoperativ getötet und für histologische und morphometrische Analysen genutzt.
Ergebnisse: Die Knochenregeneration und die Ankylose waren im Vergleich zu den Kontrollen signifikant vergrößert in den Quadranten, die rhBMP‐2/ACS erhielten (Knochenhöhe 4.8±0.3 vs. 2.0±0.2 mm, p=0.001; Knochenregion 10.9±1.3 vs. 1.4±0.1 mm2; p=0.009, Ankylose 2.2±0.2 vs. 0.04±0.7 mm; p=0.01). Es gab keine Differenzen zwischen den beiden Gruppen hinsichtlich Zementregeneration und Wurzelresorption.
Schlussfolgerungen: rhBMP‐2 erhöht signifikant die Regeneration von alveolärem Knochen in Verbindung mit einem Platzhalter aus makroporösen e‐PTFE Membranen für die GTR.
Résumé
Contexte: Il a été montré que la protéine‐2 morphogénétique osseuse humaine recombinée (rhBMP‐2) soutient la régénération de l'os alvéolaire et du système d'attache parodontal dans des lésions parodontales chirurgicalement créées et dans des lésions ayant un historique d'exposition à la plaque et au tartre. Il a aussi été montré une régénération parodontale consécutive à la régénération tissulaire guidée par utilisation d'un matériel créant de l'espace en polytetrafluoroethylene expansé (ePTFE). L'objectif de cette étude était d'évaluer l'influence de la rhBMP‐2 sur la régénération de l'os alvéolaire et l'attache parodontale en complément d'un matériel créant de l'espace en ePTFE.
Méthodes: Des lésions parodontales supra‐alvéolaires de taille critique, 5–6 mm, furent créées autour des troisièmes et quatrièmes prémolaires chez 4 Labrador adultes. Des implants de rhBMP‐2 (0.2 mg/ml) intégrés dans une éponge de collagène (rhBMP‐2/ACS) ou les éponges contenant seulement une solution tampon (contrôle) furent aléatoirement distribués et placés autour de la prémolaire dans les quadrants gauches et droits des animaux. Le matériel en ePTFE avec des pores de 300‐μm percés par Laser et séparés de 0.8 mm, destinéà créer de l'espace fut utilisé pour couvrir les éponges. Les lambeaux gingivaux furent déplacés pour assurer une fermeture primaire. Les animaux furent sacrifiés 8 semaines après la chirurgie pour des analyses histologiques et histométriques.
Résultats: La régénération osseuse et l'ankylose étaient significativement augmentées dans les quadrants ayant été traités par rhBMP‐2/ACS (hauteur osseuse 4.8±0.3 vs. 2.0±0.2 mm, p=0.001; surface osseuse 10.9±1.3 vs. 1.4±0.1 mm2; p=0.009, et ankylose 2.2±0.2 vs. 0.04±0.7 mm; p=0.01). Aucune différence entre les groupes ne put être observée pour la régénération du cément et la résorption radiculaire.
Conclusions: La rhBMP‐2 augmente significativement la régénération de l'os alvéolaire lorsqu'on l'utilise sous un matériel macro‐poreux en ePTFE permettant de créer de l'espace pour la RTG.
. The objective of this study was to evaluate the effect of recombinant human bone morphogenetic protein‐2 (rhBMP‐2) concentration on regeneration of alveolar bone and cementum, and on associated ...root resorption and ankylosis. Contralateral, critical size, supra‐alveolar, periodontal defects were surgically produced and immediately implanted with rhBMP‐2 in an absorbable collagen sponge (ACS) carrier in 8, young adult, male, beagle dogs. 6 animals received rhBMP‐2/ACS (rhBMP‐2 at 0.05, 0.10, or 0.20 mg/mL; total construct volume/defect ˜4.0 mL) in contralateral defects following an incomplete block design. 2 animals received rhBMP‐2/ACS (rhBMP‐2 at 0 and 0.10 mg/mL) in contralateral defects (controls). The animals were euthanised at 8 weeks post‐surgery and block sections of the defects were collected for histologic and histometric analysis. Supra‐alveolar periodontal defects receiving rhBMP‐2 at 0.05, 0.10, or 0.20 mg/ml exhibited extensive alveolar regeneration comprising 86%, 96%, and 88% of the defect height, respectively. Cementum regeneration encompassed 8%, 6%, and 8% of the defect height, respectively. Root resorption was observed for all rhBMP‐2 concentrations. Ankylosis was observed in almost all teeth receiving rhBMP‐2. Control defects without rhBMP‐2 exhibited limited, if any, evidence of alveolar bone and cementum regeneration, root resorption, or ankylosis. Within the selected rhBMP‐2 concentration and observation interval, there appear to be no meaningful differences in regeneration of alveolar bone and cementum. There also appear to be no significant differences in the incidence and extent of root resorption and ankylosis, though there may be a positive correlation with rhBMP‐2 concentration.
Background: Recombinant human bone morphogenetic protein‐2 (rhBMP‐2) in an absorbable sponge (ACS) carrier is currently being evaluated as candidate therapy for periodontal regeneration. The ...objective of this study was to characterize, in some detail, tissue reactions following surgical implantation of rhBMP‐2/ACS into periodontal defects.
Methods: Four young adult, male beagle dogs with surgically induced, bilateral, critical size, supraalveolar, mandibular premolar defects sequentially received rhBMP‐2/ACS (rhBMP‐2 at 0.2 mg/ml) in right and left jaw quadrants. After 4 or 8 weeks of healing, experimental teeth with surrounding tissues were harvested and processed for light and transmission electron microscopy.
Results: Surgical implantation of rhBMP‐2/ACS into large supraalveolar periodontal defects resulted in a variable tissue response without marked difference between 4‐ and 8‐week observations. New bone, exceeding the volume of the normal alveolar process, had formed within 4 weeks. The regenerated bone tissue consisted of finely trabeculated woven bone. Marrow spaces exhibited a continuous lining of osteoblasts, osteoclasts, and resting cells. The marrow spaces contained numerous large, thin‐walled vessels but were almost devoid of collagen fibrils or fibroblasts. Large voids (seromas) encountered in the newly formed bone were free of structured elements except for occasional aggregates of effete erythrocytes. A variety of tissue reactions were observed along the root surface including areas of resorption, areas of hard tissue deposition, and areas without resorptive or appositional activity. Ankylosis was a frequent observation, although areas showing characteristics of a periodontal ligament with a fine layer of acellular fiber cementum and occasional inserting Sharpey's fibers were also observed. Osteoblasts facing the root surface often appeared to be in a highly active state judged by their cuboidal shape, well‐developed endoplasmic reticulum and numerous mitochondria, and the presence of an adjacent layer of preosteoblasts. Conspicuous bundles of wide collagen fibrils near the dentin surface as well as within the marrow spaces were considered to represent remnants of the ACS. These fibrils were associated with areas of mineralization as verified by examination of undecalcified specimens.
Conclusions: rhBMP‐2/ACS elicits a rapid osteoinductive process throughout the implant as well as along and onto the instrumented adjacent root surface. Lamellated trabecular bone was the predominant regenerated tissue. A typical cementum‐periodontal ligament‐alveolar bone relationship was a rare observation. The great variability in histological tissue response along the instrumented root surface indicates that the stimulus to hard tissue formation resided primarily in the rhBMP‐2/ACS implant rather than in the root surface. J Periodontol 2002;73:1020‐1029.
Wound healing in an incisional wound is a highly predictable process which has been studied extensively hour-by-hour and day-by-day. Healing in a periodontal defect following gingival flap surgery ...is, conceptually, a more complex process as one wound margin consists of calcified tissue, including the avascular and rigid root surface. Another complicating factor in this wound healing is the transgingival position of the tooth. Experimental studies, however, have indicated that healing at a dento-gingival interface under optimal conditions occurs at the same rate as in a skin wound. Generally, periodontal healing is characterized by maturation of gingival connective tissue, limited regeneration of alveolar bone and cementum, and the formation of a long junctional epithelium. Such observations have nurtured the hypothesis that the epithelium of the surgical flap needs to be prevented from early access to the root surface during the healing period to achieve connective tissue repair of the root surface-gingival flap interface. Recent experimental findings suggest, however, that connective tissue repair to the root surface following reconstructive periodontal surgery is a function of the establishment and maintenance of a root surface-adhering fibrin clot. Since fibrin adherence to the wound margins is a natural event, it is additionally suggested that apical migration of the gingival epithelium in periodontal surgical wounds may only follow interruption of the adherence of the fibrin clot to the root surface.
Background: Wound closure by suturing is a critical and significant event in general as well as in oral surgery. Information regarding tissue reactions to different suture materials appears ...incomplete and inconsistent, particularly in humans. Thus, the purpose of the present study was to evaluate clinically and histologically tissue reactions to silk and expanded polytetrafluoroethylene (ePTFE) suture materials placed in human oral tissues.
Methods: Twelve patients undergoing periodontal treatment, who had bilateral periodontal defects in the maxillary premolar and molar region scheduled for resective surgery, were included. In each patient, one single interrupted ePTFE suture (CV–5) and one single interrupted silk suture (4‐0) were inserted in gingival tissues in contralateral jaw quadrants 10 days prior to scheduled surgery and a second set of sutures was inserted at 7 days prior to surgery. After placement, the length of the suture embedded in the tissue as well as the slack of the suture loop were measured and tabulated. The measurements were repeated on the day of surgery. At this time biopsy specimens, including the suture loop and surrounding tissue, were harvested and processed for histologic analysis. The inflammatory response was evaluated by measuring the thickness of the perisutural epithelium and the diameter of the connective tissue infiltrate, by estimating the proportion of inflammatory cells to epithelial cells, and by recording the presence or absence of bacterial plaque along the suture track.
Results: At 7 days, silk sutures showed a significantly higher degree of slack of the suture loop than did ePTFE sutures (P = 0.02), while the difference was not significant at 10 days (P = 0.21). The mean change of “tissue bite” was greater for silk compared to ePTFE at 7 as well as at 10 days. However, none of the differences were statistically significant (P = 0.43). The thickness of the perisutural epithelium increased significantly from 7 to 10 days for both suture materials, while the difference in proportion of inflammatory cells to epithelial cells was not significant (P = 0.43). An overall significantly greater diameter of connective tissue infiltrate was present around the silk sutures. Bacterial plaque was detected in 10 of 11 silk and four of 11 ePTFE suture channels at 7 days, and eight of 10 and four of 11 suture channels at 10 days.
Conclusions: The results revealed that placement of sutures in gingival tissues elicits an inflammatory reaction and that the magnitude of this reaction may vary with the suture material used. Braided silk sutures apparently cause a more extensive inflammatory tissue reaction in an environment characterized by moisture and infectious potential. J Periodontol 2005;76:34‐42.
Sixteen intrabony defects in 12 patients were treated by gingival flap surgery including root surface debridement and placement of an expanded polytetrafluoroethylene (ePTFE) membrane. The membranes ...were removed after 4 to 6 weeks and examined by scanning electron microscopy (SEM) for bacterial contamination and adherent connective tissue elements. Twelve months postsurgery, the defect sites were reexamined for changes in probing attachment level and probing bone level. Comparison of ultrastructural findings and clinical observations revealed that extent of bacterial contamination of the membrane correlated inversely with clinical assessment of attachment gain. The results indicate that the extent of oral exposure and bacterial contamination of the ePTFE membrane at the time of removal may be an indicator of the long-term success or failure of the regenerative procedure.
Background: In the oral cavity, sutures are placed within tissues of high vascularity in a moist environment with infectious potential. The objective of this study was to evaluate tissue reactions at ...silk and expanded polytetrafluoroethylene (ePTFE) sutures in the presence and absence of anti‐infective therapy (AT).
Methods: Thirty‐six sutures were placed within the mandibular keratinized gingiva in six Beagle dogs. Each animal received one braided silk (4‐0) and one ePTFE (CV‐5) suture in contra‐lateral jaw quadrants at 14, 7, and 3 days prior to biopsy. Three animals received daily AT including topical 2% chlorhexidine solution and a systemic broad‐spectrum antibiotic. Biopsy specimens allowed histometric analysis of tissue reactions along the central part of the suture loop including the area of perisutural epithelium, ratio inflammatory cells (ICs)/epithelial cells and IC/fibroblasts, and presence/absence of bacterial plaque in the suture track.
Results: A perisutural epithelial sheath was forming within 3 days. The cross‐sectional area of the epithelium increased with time for both suture materials (p=0.003) but was particularly pronounced for the silk sutures in the absence of AT. Clusters of IC were present in the perisutural connective tissue and epithelium. Over time, a more prominent increase in IC/fibroblasts was evident for the silk sutures in the absence of AT. The pooled material revealed a significantly higher IC/fibroblast ratio for silk compared with ePTFE sutures (p=0.017). Bacterial plaque influx was detected in 6/9 silk and 0/9 ePTFE suture channels in the presence, and 6/6 and 3/6 suture channels, respectively, in the absence of AT.
Conclusions: AT may reduce biofilm formation and inflammation along the suture track. Braided silk, however, elicits more severe tissue reactions than ePTFE regardless of infection control.
PDF
