Physical properties of root cementum: Part 27. Effect of low-level laser therapy on the repair of orthodontically induced inflammatory root resorption: A double-blind, split-mouth, randomized controlled clinical trial.

INTRODUCTION: The purpose of this 2-arm-parallel split-mouth trial was to investigate the effect of low-level laser therapy (LLLT) on the repair of orthodontically induced inflammatory root resorption (OIIRR). METHODS: Twenty patients were included in this study, with 1 side randomly assigned to receive LLLT, and the other side served as a sham. Eligibility criteria included need for bilateral maxillary first premolar extractions as part of fixed appliance treatment. OIIRR was generated by applying 150 g of buccal tipping force on the maxillary first premolars for 4 weeks. After the active force was removed, the teeth were retained for 6 weeks. LLLT commenced with weekly laser applications using a continuous beam 660-nm, 75-mW aluminum-gallium-indium-phosphorus laser with 1/e2 spot size of 0.260 cm2, power density of 0.245 W/cm2, and fluence of 3.6 J/cm2. Contact application was used at 8 points buccally and palatally above the mucosa over each tooth root for 15 seconds with a total treatment time of 2 minutes. After 6 weeks, the maxillary first premolars were extracted and scanned with microcomputed tomography for primary outcome OIIRR calculations. Subgroup analysis included assessment per root surface, per vertical third, and sites of heaviest compressive forces (buccal-cervical and palato-apical). Randomization was generated using www.randomization.com, and allocation was concealed in sequentially numbered, opaque, sealed envelopes. Blinding was used for treatment and outcome assessments. Two-tailed paired t tests were used to determine whether there were any statistically significant differences in total crater volumes of the laser vs the sham treated teeth. RESULTS: Total crater volumes were 0.746 mm3 for the laser treated teeth and 0.779 mm3 for the sham. There was a mean difference of 0.033 ± 0.39 mm3 (95% CI, -0.21 to 0.148 mm3) greater resorption crater volume in the sham group compared with the laser group; this was not statistically significant (P = 0.705). No harm was observed. CONCLUSIONS: No significant difference was found between LLLT and sham control groups in OIIRR repair.

Platelet-rich plasma, low-level laser therapy, or their combination promotes periodontal regeneration in fenestration defects: a preliminary in vivo study.

BACKGROUND: This study histomorphometrically analyzes the influence of platelet-rich plasma (PRP), low-level laser therapy (LLLT), or their combination on the healing of periodontal fenestration defects (PFDs) in rats. METHODS: PFDs were surgically created in the mandibles of 80 rats. The animals were randomly divided into four groups: 1) C (control) and 2) PRP, defects were filled with blood clot or PRP, respectively; 3) LLLT and 4) PRP/LLLT, defects received laser irradiation, were filled with blood clot or PRP, respectively, and then irradiated again. Animals were euthanized at either 10 or 30 days post-surgery. Percentage of new bone (NB), density of newly formed bone (DNB), new cementum (NC), and extension of remaining defect (ERD) were histomorphometrically evaluated. Data were statistically analyzed (analysis of variance; Tukey test, P <0.05). RESULTS: At 10 days, group PRP presented ERD significantly lower than group C. At 30 days, group PRP presented NB and DNB significantly greater than group C. Groups LLLT, PRP, and PRP/LLLT showed significant NC formation at 30 days, with collagen fibers inserted obliquely or perpendicularly to the root surface. NC formation was not observed in any group C specimen. CONCLUSIONS: LLLT, PRP, or their combination all promoted NC formation with a functional periodontal ligament. The combination PRP/LLLT did not show additional positive effects compared to the use of either therapy alone.

Regenerative wound healing in acute degree III mandibular defects in dogs.

OBJECTIVE: To evaluate the healing events in degree III furcation defects in dogs following the application of the combination of an enamel matrix derivative with a biphasic calcium phosphate (Emdogain Plus). METHOD AND MATERIALS: Seventeen degree III furcation defects, 5 mm high and 4 mm wide, were created in 9 dogs. In both groups, the defects were conditioned with EDTA. One defect was treated with Emdogain Plus (n = 9), while the contralateral defect serving as control remained empty (n = 8). The defects in both groups were fully covered by coronally repositioned flaps. After 5 months of healing, histologic and histometric analysis was preformed. RESULTS: A significant amount of new attachment and bone formation was observed in both control and test specimens. However, in a number of control specimens, ankylosis was also observed. In the control and test groups, respectively, the mean new cementum length was 10.8 ± 2.1 mm and 8.6 ± 3.2 mm; the mean periodontal ligament length was 7.6 ± 3.8 mm and 8.1 ± 4.0 mm. The mean new bone height was 4.4 ± 1.3 mm and 4.3 ± 1.6 mm in the control and test groups, respectively. No statistical differences were found between the two groups in terms of amount of cementum, periodontal ligament, and alveolar bone regeneration. CONCLUSION: The present study failed to show higher amounts of newly formed cementum and bone following treatment of acute degree III mandibular furcation defects following use of Emdogain Plus compared with a coronally advanced flap. Emdogain Plus seems to have a protective role against ankylosis in this type of defect.

Healing of acute alveolar bone dehiscence following treatment with porous biphasic calcium phosphate in beagle dogs.

The purpose of the present study was to evaluate histologically in beagle dogs the healing in acute dehiscence type defects following treatment with open flap debridement (OFD) with or without porous biphasic calcium phosphate (PBCP). Alveolar bone dehiscence defects were surgically created bilaterally at the labial aspects of maxillary third incisors in 12 beagle dogs. After root conditioning with ethylenediaminetetraacetate, PBCP was filled in the defects and the contralaterals were cured with OFD. Two fluorochrome labelings were administered at the 7th and 11th weeks, respectively. Four dogs were killed at the 12, 16, and 24 weeks, respectively. Histological observations were processed through microcomputed tomographic imaging, fluorescence microscope, and light microscopy. The formation of new regenerated tissues was assessed histomorphometrically. The results revealed the healing after treatments with PBCP evidenced a new attachment apparatus and that with OFD supported periodontal repair. In PBCP groups, the amount of new bone varied from 1.15 to 3.86 mm (23-77.2% of the original defect size), while only 0.3 to 1.04 mm (6-20.8%) in OFD group. The amount of new cementum in PBCP varied from 1.18 to 4.16 mm (23.6-82.3%), while only 0.67 to 1.15 mm (13.4-23%) in OFD group. The amount of periodontal ligament in PBCP varied from 1.03 to 4.12 mm (20.6-82.4%), while only 0 to 0.93 mm (0-18.6%) in OFD group. There was significantly more regenerated tissue in PBCP groups compared to OFD procedures (p < 0.01). The present results indicate that PBCP may enhance periodontal regeneration in acute-type labial dehiscence defects.

Morphological assessment of dentine and cementum following apicectomy with Zekrya burs and Er:YAG laser associated with direct and indirect Nd:YAG laser irradiation.

OBJECTIVES: This study aimed to assess the apical surface morphology of maxillary central incisors resected 3.0 mm from the tooth apex using Zekrya burs or Er:YAG laser, with or without subsequent direct Nd:YAG laser irradiation (apical and buccal surfaces) and indirect irradiation (palatal surface). STUDY DESIGN: Forty maxillary central incisors were instrumented and obturated. The roots were divided into 4 groups according to the root resection method (Zekrya bur or Er:YAG laser - 1.8 W, 450 mJ, 4 Hz, 113 J/cm(2)) and further surface treatment (none or Nd:YAG laser - 2.0 W, 100 mJ, 20 Hz, 124 J/cm(2)). The teeth were prepared for SEM analysis. Scores ranging from 1 to 4 were attributed to cut quality and morphological changes. The data were analyzed by the Kruskal-Wallis test and by Dunn's test. RESULTS: SEM images showed irregular surfaces on the apical portions resected with Zekrya burs, with smear layer and grooves in the resected dentine and slight gutta-percha displacement and plasticization. On the other hand, apicectomies carried out with Er:YAG laser showed morphological changes compatible with ablated dentine, with rough surfaces and craters. In spite of the presence of plasticized gutta-percha, with the presence of bubbles, an irregular adaptation of the filling material to the root walls was also observed. Direct Nd:YAG laser irradiation of the apical and buccal surfaces of the resected roots resulted in areas of resolidification and fusion in the dentine and cementum, with a vitrified aspect; indirect Nd:YAG laser irradiation of the palatal surfaces yielded a lower number of changes in the cementum, with irregular resolidification areas. CONCLUSIONS: There were no differences in terms of cut quality between the use of burs and Er:YAG laser or between the 2 surfaces (apical and buccal) treated with Nd:YAG laser with direct irradiation. However, morphological changes were significantly less frequent on surfaces submitted to indirect irradiation (palatal) when compared with those directly irradiated.

Expression of heat shock proteins, Hsp70 and Hsp25, in the rat gingiva after irradiation with a CO2 laser in coagulation mode.

BACKGROUND AND OBJECTIVE: The therapeutic rationale of low-energy pulsed CO(2) laser coagulation mode has not been clarified yet. We conducted this study to characterize the effect of low-energy pulsed CO(2) laser coagulation mode irradiation of the rat gingiva in terms of the expression of heat shock proteins. MATERIAL AND METHODS: Laser irradiation was achieved with the parameters of 5 W, 600 mus pulse duration, and fluence of 326 J/cm(2). The gingiva dissected at different times after irradiation was processed for immunohistochemical examination of the expression of the heat shock proteins, Hsp70 and Hsp25. RESULTS: One hour after irradiation, the epithelial keratinocytes facing the laser wound exhibited an overexpression of Hsp70 in their nucleus. The connective tissue cells facing the laser wound, which included fibroblasts and capillary endothelial cells, showed de novo expression of Hsp70 at 3 h post-irradiation, the level of which peaked at 1 d and thereafter decreased. An enhanced and/or de novo expression of Hsp25 in the connective tissue cells facing the laser wound became evident at 3 h after irradiation, and after 1 d the Hsp25-expressing cells increased in number and spread over the wound as wound repair progressed. There was a temporospatial difference in the expression pattern between Hsp70 and Hsp25, with only a few cells appearing to co-express both heat shock proteins. CONCLUSION: The CO(2) laser treatment in coagulation mode produced the expression of heat shock proteins, and the findings suggest that while Hsp70 mainly conferred cell protection, Hsp25 was involved in the progress of wound repair as well as cell protection.

Influence of the internal conditioning of indirect restorations of resin composite in relation to microleakage using LEDs and QTH units.

The current study evaluated in-vitro microleakage of indirect composite inlays fixed with flowable composite and resinous cement and cured by LEDs and QTH units, thus modifying the internal conditioning of the inlays. Thirty-two non-carious teeth were selected and 64 cavity preparations were performed in both enamel and cementum. These teeth were divided into four groups: I--Elipar FreeLight appliance and Filtek Flowable composite; II--Ultralux appliance and Filtek Flowable composite; III--Elipar FreeLight appliance and RelyX cement and IV--Ultralux appliance and RelyX cement. The inlays were internally sandblasted with aluminum oxide, etched with 37% phosphoric acid, washed and silanized. The dental etching was carried out with 37% phosphoric acid for 15 seconds in dentin and 30 seconds in enamel. After being washed and dried, Single Bond dentinal adhesive was then applied, and the inlays were fixed with their respective luting agents, cured in close contact with their surfaces for 60 seconds, thermocycled and immersed in 0.5% basic fuchsine solution. The teeth were then washed and sectioned through the center of the restoration in order for the microleakage readings to be performed using the Image Tool Software. Then, ANOVA and Tukey's statistical tests were applied. In enamel, there was no significant difference for both groups with regard to microleakage; in cementum, the significant difference was 5% (p > 0.005). In agreement with the results, the inlays can be fixed with RelyX and Filtek Flowable resins.

Effect of root surface treatment with propolis and fluoride in delayed tooth replantation in rats.

Replantation is an acceptable option for treatment of an avulsed permanent tooth. Nevertheless, an extended extraoral period damages the periodontal ligament and results in external root resorption. The purpose of this study was to assess by histologic and histometric analysis, the influence of propolis 15% (natural resinous substance collected by Apis mellifera bees from various plants) and the fluoride solution used as root surface treatment on the healing process after delayed tooth replantation. Thirty Wistar (Rattus norvegicus albinus) rats were submitted to extraction of their upper right incisor. The teeth were maintained in a dry environment for 60 min. After this, the pulp was extirpated and the papilla, enamel organ and periodontal ligament were removed with scalpel. The teeth were divided into three experimental groups: Group I - teeth immersed in 20 ml of physiologic saline; Group II - teeth immersed in 20 ml of 2% acidulated phosphate sodium fluoride; Group III - teeth immersed in 20 ml of 15% propolis. After 10 min of immersion in the solutions, the root canals were dried and filled with calcium hydroxide paste and the teeth were replanted. The animals were euthanized 60 days after replantation. The results showed that similar external root resorption was seen in the propolis and fluoride groups. Teeth treated with physiologic saline tended to have more inflammatory root resorption compared with those treated with fluoride or propolis. However, the comparative analysis did not reveal statistically significant differences (P > 0.05) between the treatment modalities when used for delayed tooth replantation.

The effect of occlusal loading on the microleakage of class V restorations.

OBJECTIVE: This in vitro study evaluated the microleakage of Class V cavities restored with a resin composite and different adhesive systems after occlusal loading. METHODS & MATERIALS: Standardized box-shaped Class V cavities were prepared on the buccal side of 135 non-carious human premolars. The teeth were randomly divided into three groups of 45 premolars each and restored as follows: Group 1-two-step total-etch adhesive (Single Bond, 3M) + resin composite (Supreme, 3M ESPE); Group 2-two-step self-etch adhesive (Clearfil SE, Kuraray) + resin composite and Group 3-one-step self-etch adhesive (Xeno III, Dentsply) + resin composite. The restorations were finished with aluminum oxide discs (Sof-Lex, 3M). Fifteen teeth in each group received 10,000 x 100 N and 250 N occlusal loads, respectively, and the remaining 15 teeth served as the control. The premolars were immersed in 2% methylene blue for 24 hours. The dye penetration was examined under a stereomicroscope, and the results were statistically analyzed by Kruskal Wallis, Mann-Whitney U and Wilcoxon Signed Rank tests to determine differences between the groups. RESULTS: Gingival margins showed more dye penetration than occlusal margins in all the tested groups (p<0.05). In all the tested adhesive systems, 100 N occlusal loading did not change dye penetration; however, Groups 1 and 2 exhibited better marginal sealing than Group 3 at the enamel margins under 250 N occlusal loading. CONCLUSION: Within the limitations of this in vitro study, it may be concluded that enamel margins provided better marginal sealing than dentin/cementum margins and the two-step self-etch adhesive exhibited better marginal sealing than an all-in-one adhesive at the enamel margins under 250 N occlusal loading.

Periapical tissue healing after post space preparation with or without use of a protection plug and root canal exposure to the oral environment. Study in dogs.

The purpose of this study was to evaluate the influence of coronal leakage on the healing of dogs' periapical tissues after root canal filling, post space preparation and protection or not with a temporary sealer plug. Forty root canals of dogs' teeth were instrumented and filled by the lateral condensation technique with gutta-percha points and Endomethasone or CRCS sealers. After post space preparation, the remaining filling material was protected or not with a plug of temporary Coltosol sealer and exposed to the oral environment for 90 days. Thereafter, the animals were sacrificed and the specimens were removed and prepared for histomorphological and histobacteriological analysis. The findings revealed 35% of microbial leakage in the groups without plugs and 15% of leakage in the groups with plugs. Statistical analysis showed that the use of a Coltosol plug improved significantly the histomorphological results regardless of the type of root canal sealer (p=0.05) and that CRCS and Endomethasone sealers showed similar results (p>0.05).

Periapical tissue healing after post space preparation with or without use of a protection plug and root canal exposure to the oral environment: study in dogs

The purpose of this study was to evaluate the influence of coronal leakage on the healing of dogs' periapical tissues after root canal filling, post space preparation and protection or not with a temporary sealer plug. Forty root canals of dogs' teeth were instrumented and filled by the lateral condensation technique with gutta-percha points and Endomethasone or CRCS sealers. After post space preparation, the remaining filling material was protected or not with a plug of temporary Coltosol sealer and exposed to the oral environment for 90 days. Thereafter, the animals were sacrificed and the specimens were removed and prepared for histomorphological and histobacteriological analysis. The findings revealed 35 percent of microbial leakage in the groups without plugs and 15 percent of leakage in the groups with plugs. Statistical analysis showed that the use of a Coltosol plug improved significantly the histomorphological results regardless of the type of root canal sealer (p=0.05) and that CRCS and Endomethasone sealers showed similar results (p>0.05).

O propósito deste trabalho foi avaliar a influência da infiltração coronária no reparo dos tecidos periapicais após obturação dos canais radiculares, preparo para pino e proteção ou não de um "plug" de cimento temporário. Quarenta canais de dentes de cães foram instrumentados e obturados pela técnica da condensação lateral ativa com cones de guta-percha e os cimentos Endomethasone e CRCS. Após preparo para pino os remanescentes do material obturador foram protegidos ou não com um "plug" do cimento temporário Coltosol e expostos ao meio oral por 90 dias. Decorrido este período, os animais foram mortos e os espécimes foram removidos e preparados para análises histomorfológica e histobacteriológica. Foi observado 35 por cento de casos de infiltração bacteriana nos grupos sem "plug" e 15 por cento nos grupos com "plug". Concluiu-se estatisticamente que o "plug" de Coltosol foi eficiente no controle da infiltração coronária de microorganismos (p=0,05), e que os cimentos CRCS e Endomethasone apresentaram resultados semelhantes (p>0,05).

Effect of an oily calcium hydroxide suspension (Osteoinductal) on healing of intrabony periodontal defects. A pilot study in dogs.

The aim of the present study was to evaluate histologically in dogs the effect of treating intrabony defects with an oily calcium hydroxide suspension (OCHS). Intrabony defects were surgically created bilaterally at the distal aspects of the maxillary first premolars and at the mesial aspects of the third premolars in two mongrel dogs. Subsequently, the defects were randomly treated with (a) access flap surgery followed by the application of an OCHS or (b) access flap surgery alone. After 8 weeks of healing, the animals were killed. Dissected blocks containing the experimental specimens were fixed in formalin, decalcified in EDTA, and embedded in paraffin. The formation of new cementum and bone was assessed histomorphometrically. In the control group, healing was predominantly characterized by the formation of a long junctional epithelium along the root surface and limited periodontal regeneration at the most apical part of the defect. The OCHS-treated defects consistently revealed periodontal regeneration (i.e., new periodontal ligament, new cementum with inserting collagen fibers, and new bone). Within the limits of the present study, it can be concluded that OCHS may favor periodontal regeneration in acute-type intrabony periodontal defects.

A histopathologic investigation on the effects of electrical stimulation on periodontal tissue regeneration in experimental bony defects in dogs.

BACKGROUND: One endpoint of periodontal therapy is to regenerate the structure lost due to periodontal disease. In the periodontium, gingival epithelium is regenerated by oral epithelium. Underlying connective tissue, periodontal ligament, bone, and cementum are derived from connective tissue. Primitive connective tissue cells may develop into osteoblasts and cementoblasts, which form bone and cementum. Several procedural advances may support these regenerations; however, the regeneration of alveolar bone does not always occur. Therefore, bone stimulating factors are a main topic for periodontal reconstructive research. The present study was designed to examine histopathologically whether the application of an electrical field could demonstrate enhanced alveolar and cementum regeneration and modify tissue factors. METHODS: Seven beagle dogs were used for this experiment. Mandibular left and right sides served as control and experimental sides, respectively, and 4-walled intrabony defects were created bilaterally between the third and fourth premolars. The experimental side was treated with a capacitively coupled electrical field (CCEF) (sinusoidal wave, 60 kHz, and 5 V peak-to-peak), applied for 14 hours per day. The following measurements were performed on the microphotographs: 1) the distance from the cemento-enamel junction to the apical notch (CEJ-AN) and from the crest of newly formed bone (alveolar ridge) to the apical notch (AR-AN); 2) the thickness of new cementum in the apical notch region; and 3) the length of junctional epithelium. The following histopathologic parameters were assessed by a semiquantitative subjective method: 1) inflammatory cell infiltration (ICI); 2) cellular activity of the periodontal ligament; 3) number and morphology of osteoclasts; 4) resorption lacunae; and 5) osteoblastic activity. RESULTS: The results showed that the quantity of new bone fill and the mean value of the thickness of the cementum were significantly higher for the experimental side (P < 0.01). The location of the base of the pocket was positioned more coronally with respect to the apical point of the coronal notch in the experimental side (statistically significant P < 0.01). The length of the junctional epithelium and the number of osteoclasts were higher in the stimulated side than the coronal side; these findings were also statistically significant (P < 0.01). The comparison of the electrically stimulated versus non-stimulated mandibles with the semiquantitative subjective method demonstrated statistically significant differences in defined histopathologic parameters, except for osteoclast morphologies (P > 0.05). CONCLUSIONS: This study demonstrated that the CCEF method has the potential to produce reconstructive effects and bone deposits. Further investigations with respect to the theoretical determination of local field parameters of the periodontal tissue complex, such as permittivity, conductivity, strength of the field electrical stimulation applied to the periodontal field current density, wavelength, and signal frequency appropriate for this field, should be undertaken. Using different electromotive forces alone or in combination with bone graft materials, guided tissue regeneration techniques, and dental implants may achieve a new dimension in periodontal therapy in the near future.

Comparative study of enamel matrix derivative with or without GTR in the treatment of class II furcation lesions in dogs.

Chronic Class II furcation lesions were created in four dogs. After 21 days, group I remained as a control, group 2 was treated with membranes and enamel matrix derivative (EMD), and group 3 received EMD alone. Healing in group 1 was characterized by a long junctional epithelium and discrete bone formation; group 2 showed reduced bone formation; and group 3 showed significant bone regeneration (area of new bone = 67.36%+/-3.93%; distance from furcation roof to bone crest = 0.57+/-0.15 mm). The EMD led to significant regeneration of the furcation lesions, and the association with membranes was detrimental.

Root resorption and its association with alterations in physical properties, mineral contents and resorption craters in human premolars following application of light and heavy controlled orthodontic forces.

OBJECTIVES: To study the effect of different orthodontic force levels on cementum, investigating from the point of view of its physical properties, alterations in the mineral components, type and location of the resorption craters and the exploration in 3D of space. DESIGN: In vivo human premolars subjected to heavy and light forces were employed for this study. After a period of movement they were analyzed for hardness and elasticity. Also, the mineral composition measuring Ca, P and F of the cementum root surface was investigated. A new method for volumetric analysis of resorption craters was developed. RESULTS: There were no significant differences for hardness and elastic modulus between the light and heavy force groups and no significant effects for different tooth positions. Significant inter-individual variation in the Ca, P and F concentrations was noted. Force-related data showed that mean volume of the resorption crater in light-force group was 3.49-fold greater than the control group, and the heavy-force group 11.59-fold more than control group. The heavy force group had 3.31-fold greater total resorption volume then light force group. Buccal cervical and lingual apical regions demonstrated significantly more resorption craters than the other regions. The 2D measurements were strongly correlated to 3D measurements. CONCLUSION: The application of light and heavy forces did not show any statistically significant differences in hardness and elastic modulus when compared with untreated teeth. The inconsistent increase or decrease of Ca, P and F contents between control and experimental teeth at sites of compression and tension were difficult to explain. There was more resorption by volume in the heavy force group as compared with the light group and controls. Our data also suggested that the high-pressure zones might be more susceptible to resorption after 28 days of force application.

Healing of human intrabony defects following regenerative periodontal therapy with a bovine-derived xenograft and guided tissue regeneration.

The purpose of the present study was to histologically evaluate the healing of human intrabony defects following treatment with either a bovine-derived xenograft (BDX) and guided tissue regeneration (GTR) [BDX + GTR] or a bovine-derived xenograft mixed with collagen (BDX Coll) and GTR [BDX Coll + GTR]. Eight patients with chronic periodontitis and each with one very deep intrabony defect around a tooth scheduled for extraction were treated with either a combination of BDX + GTR (five patients) or with BDX Coll + GTR (three patients). The postoperative healing was uneventful in all eight cases. After a healing period of 6 months, the teeth or roots were extracted together with some of their surrounding soft and hard tissues and subsequently fixed in 10% buffered formalin. Following decalcification in EDTA, the specimens were embedded in paraffin and 8-microm histological sections were cut in the mesio-distal direction, parallel to the long axes of the teeth. The sections were alternatively stained with hematoxylin and eosin, van Giesson's connective tissue stain or with the Ladevig's connective tissue staining method and examined under the light microscope. Generally, formation of new cementum with inserting collagen fibers was found in seven out of the eight treated cases, whereas in the remaining case (treated with BDX + GTR) the healing was characterized by formation of a long junctional epithelium along the debrided root surface and no formation of cementum or bone. In the specimens demonstrating periodontal regeneration the new cementum was always of a cellular type. In most cases, the graft particles were surrounded by bone. In some areas, the bone tissue around the graft particles was connected by perpendicularly inserting collagen fibers to the newly formed cementum on the root surface. The epithelium downgrowth stopped always at the most coronal part of the newly formed cementum. No remnants of the membrane material were observed in any of the biopsies. Connective tissue encapsulation of the graft particles was rarely observed and was limited to the most coronal part of the defects. The findings of the present study provide evidence that treatment of intrabony defects with both BDX + GTR and BDX Coll + GTR may enhance periodontal regeneration in humans.

The effect of enamel matrix proteins on periodontal regeneration as determined by histological analyses.

BACKGROUND: Therapeutic approaches to periodontal regeneration in the past have utilized bone replacement grafts, growth factors, barrier membranes, or combinations of these approaches. More recently, enamel extracellular matrix proteins have been introduced to stimulate periodontal regeneration. One factor thought to have an impact on the outcome of the regenerative process is the initial size of the periodontal defect. This is particularly the case when using proteins to stimulate regeneration, because the concepts of guided tissue regeneration emphasize the need for space maintenance to allow for selected cell repopulation. The goal of this study was to evaluate periodontal regeneration in intrabony defects of various sizes treated with enamel matrix proteins. METHODS: Periodontal defects ranging in size from 1 to 6 mm were created bilaterally around 3 teeth in the mandibles of baboons. Plaque was allowed to accumulate around ligatures placed into the defects. After 2 months, the ligatures were removed, the teeth were scaled and root planed, and a notch was placed at the base of the defect. On one side of the mandible, neutral ethylene diamine tetracetic acid and enamel matrix proteins were used to treat the defects. The other side served as a control, with neutral ethylene diamine tetracetic acid treatment alone after scaling and root planing. Flaps were sutured and the animals were allowed to heal without oral hygiene procedures. After 5 months, the animals were sacrificed and the teeth were processed for histological evaluation. RESULTS: Periodontal regeneration occurred in all sizes of the periodontal defects. Qualitatively, new cementum, periodontal ligament with Sharpey's fibers, and new bone tissue were observed. In general, enamel matrix protein treatment resulted in greater tissue formation than controls. In many instances, dramatic tissue formation occurred far coronal to the base of the defects. In addition, horizontal bone fill occurred in defects that were initially 4 or 6 mm wide. The resultant width of the periodontal ligament was similar in all defects regardless of the original defect width. The cementum width was slightly greater in the wider (4 and 6 mm) defects compared to the more narrow (1 and 2 mm) defects. When evaluating the combined 1 and 2 mm defects, the height of new cementum with enamel matrix protein treatment was 45% greater than the control, with 31% greater new bone height versus the control. In the combined wider defects (4 and 6 mm), new tissue height was more similar between enamel matrix protein-treated defects and control defects. The results from the wider defects must be interpreted cautiously, because the interproximal bone heights were resorbed more adjacent to the wider defects during the plaque accumulation period and likely limited the potential for regeneration. CONCLUSIONS: The treatment of various sized periodontal defects with enamel matrix proteins stimulated substantial periodontal regeneration. In many cases, dramatic amounts of new cementum, Sharpey's fibers, periodontal ligament, and bone tissue were formed far coronal to the notch at the base of the defect, especially considering the width of the original defects. This periodontal regeneration occurred in the absence of exogenous growth factors, bone replacement grafts, barrier membranes, or their combination.

Immunohistochemical evaluation of matrix molecules associated with wound healing following treatment with an enamel matrix protein derivative in humans.

Application of enamel matrix protein derivative (EMD) onto a debrided and conditioned root surface has been shown to promote periodontal regeneration in animals and humans. However, until now there is virtually no information from humans describing the expression of different matrix molecules in the newly formed periodontal tissues following treatment with EMD. This study investigated immunohistochemically in humans the expression of matrix molecules associated with periodontal tissues reformed after treatment with EMD. Eight patients with intrabony defects were treated with EMD. Six months after surgery teeth together with some of their surrounding soft and hard tissues were removed, fixed in buffered formalin, decalcified in EDTA, and embedded in paraffin. Serial sections of 6 micro m were cut in mesiodistal direction. Sections were evaluated immunohistochemically by means of polyclonal antibodies against osteopontin, collagen I and collagen III. The original (non-treated) parts of the periodontium served as controls. In all specimens the healing resulted to a varying extent in formation of cementum, periodontal ligament and alveolar bone. In all specimens the expression of the investigated matrix molecules was stronger at the reformed than at the original sites. Osteopontin expression was most intense at the border near the newly formed cementum and bone. In the regenerated periodontal ligament, collagen I and III were localized throughout the entire periodontal ligament connective tissue. Within the newly formed PDL connective tissue the immunohistochemical staining appeared stronger for collagen III than for collagen I. The present findings suggest that (a) treatment of human intrabony defects with EMD creates an environment favourable for periodontal regeneration and, (b) in humans the healing and/or remodelling process of the reformed tissues may be followed immunohistochemically for a period of 6 months.

Wound healing of degree III furcation involvements following guided tissue regeneration and/or Emdogain. A histologic study.

BACKGROUND: The use of enamel matrix proteins (EMD) has been recently introduced as a new treatment alternative for periodontal regeneration. However, no histological studies are available investigating the effect of EMD in the treatment of degree III furcation involvements. OBJECTIVES: The aim of this study was to evaluate the healing of mandibular degree III furcation involvements histologically following treatment with guided tissue regeneration (GTR), EMD and a combination of EMD and GTR. MATERIAL AND METHODS: Degree III furcation involvements were surgically created at the teeth 36, 37, 46, 47 in three monkeys (Macaca fascicularis). Spontaneous healing of the defects was prevented by placing impression material into the defects. After 6 weeks, full-thickness flaps were elevated at the buccal and lingual aspect of the experimental teeth. Following removal of all granulation tissue from the furcation defects, scaling/root planing and conditioning of the root surfaces with 24% EDTA gel, the defects were treated with one of the following treatment modalities: (i) EMD, (ii) GTR or (iii) a combination of EMD and GTR. The defects serving as control did not receive any treatment, except from complete coverage with coronally displaced flaps. After 5 months of healing, the animals were killed and perfused with 10% buffered formalin for fixation. The experimental teeth with surrounding tissues were dissected free, decalcified in EDTA, dehydrated and embedded in paraffin. 8 microm thick histological sections were cut and stained and subsequently examined under the light microscope. RESULTS: The histological analysis revealed that with GTR or combined EMD and GTR treatment, new attachment formation (new cementum with inserting collagen fibers) had occurred on almost the entire circumference of the furcation and new bone was almost filling the defect in the situations where the membrane was not exposed. The sites treated only with EMD exhibited new attachment and new bone formation to a varying extent, while the control sites presented only limited new attachment and bone formation. CONCLUSION: The results provided histological evidence suggesting that both GTR and EMD may result in true periodontal regeneration, and suggest that this type of healing might be favored by such treatments in comparison with flap surgery.

Effect of a collagen membrane enriched with fibronectin on guided tissue regeneration in dogs.

The present study was planned to assess the capacity of a resorbable collagen membrane enriched with fibronectin to prevent the apical migration of epithelium and to facilitate new attachment and new bone. Experimental osseous dehiscence defects were produced on the bilateral labial aspect of mandibular 2nd, 3rd and 4th premolar teeth in six mongrel dogs. Guided tissue regeneration therapy using collagen membranes, which were rehydrated with fibronectin solution, was performed on one quadrant (group A). In the contralateral quadrant, the same collagen membranes, but rehydrated only with saline (group B), were placed over the bony defects. The third premolar teeth, which were treated by open-flap debridement, served as control (group C). Flaps were positioned slightly coronally and sutured; sutures were removed 10 days later. The dogs were killed 30 days after reconstructive therapy. Tissue blocks containing the experimental and control teeth were excised, demineralized in EDTA, and embedded in paraffin. Histological and histometric evaluation revealed that all groups demonstrated similar effects on preventing the down-growth of epithelium and formation of new cementum and new bone. Collagen membranes were tolerated well within the tissues, and membrane remnants were identified at 30 days. In summary, this study indicated that in this dog model similar healing results could be achieved with a bovine type I collagen membrane with or without fibronectin solution and open-flap debridement.