Mesial Socket Research Articles

Tailoring and characterization of bioactive graft material for alveolar bone preservation and regeneration in fresh extraction sockets of dog model

The objective of this study was to tailor an osteoinductive scaffold for alveolar bone regeneration and around immediately placed implants in extraction sockets of dogs. Tailored amorphous multiporous bioactive glass (TAMP -BG) was prepared and characterized for bioactivity and response of human alveolar bone marrow mesenchymal stem cells (hABMSCs). Extraction sockets of twenty-two male mongrel dogs received TAMP-BG in the right side around implant in the distal socket of the mandibular fourth premolar (P4), while the adjacent empty mesial socket of the same tooth was filled with the same graft. Autologous bone chips were used in the left side. Animals were euthanized at 1, 2, 4, 8 &12 weeks for histological and SEM analyses. SEM/EDX, FTIR and XRD analyses displayed formation of a bioactive hydroxycarbonated apatite layer. TAMP-BG significantly increased proliferation and migration of hABMSCs. Histologically, at the 1st week, advanced bone healing was shown in TAMP-BG group. At four weeks bone density was significantly higher forTAMP-BG (92.71% ± 1.71) versus control (62.92% ± 2.02) (P = 0.0001).At eight weeks, significant increase in width of buccal plate and height of lingual bony plate was observedfor TAMP-BG grafted implant.The socket orifice width significantly decreased for autologous bone from 1 to 12 weeks (P < 0.001), while it significantly increased for TAMP-BG (P = 0.03). We conclude that TAMP-BG can provide a preservative dynamic microenvironment following extraction up to three months which can be attributed to its unique physico-chemical characteristics.

Implant Stability and Histomorphometric Analysis Comparing Two Different Implant Macrogeometries Placed in Fresh Sockets: An Experimental Study in Sheep.

To examine the impact of two implant designs that promote different insertion torque values on implant stability and to histomorphometrically evaluate the bone healing after immediate implant placement in fresh sockets in a sheep model. Twelve female sheep (mean weight: 35.0 ± 5.0 kg) were included in the study. Additionally, 48 conical Morse taper dental implants were included, comprising two groups (n = 24 per group): Group 1, where the implant design can provide high insertion torque values; and Group 2, where the implant design can provide low insertion torque values. Both had the same surface treatment and dimensions (4.0 × 10 mm). The mandibular first and second molars on both sides were extracted carefully. Sequentially, osteotomies were made in the mesial socket of each molar tooth. The final implant position was 2 mm below the buccal bone crest level. On the right side, a Group 1 implant was placed anteriorly, with a Group 2 implant in the posterior position; on the left side, the Group 2 implant was anterior and the Group 1 implant was posterior. A digital torque meter was used to measure the maximum final insertion torque value (f-IT). The initial implant stability quotient (ISQ) was measured immediately after implant insertion (T0) and immediately after the euthanasia and removing the mandibles. The animals were euthanized (n = 6 animals/ time) at 21 days (T1) and 35 days (T2). To compare statistical differences for each analyzed intragroup parameter, t-test was used. Pearson's correlation was used to analyze possible correlations: f-IT and percentage of bone-to-implant contact (%BIC), f-IT and ISQ, and ISQ and %BIC. Group 1 presented higher insertion torque values than Group 2, with a statistically significant difference (P < .0001). The ISQ mean values were higher in the buccolingual direction than those obtained in the mesiodistal direction for both groups. Higher %BIC measurements were seen in Group 2 than Group 1 samples at both times and in both directions. There were statistical differences between groups for new bone, medullary spaces, and collagen matrix at each evaluation time. Using implants with a modified macrogeometry plays a significant role in implant stability and bone tissue healing around the implant. It is important for clinicians to carefully consider implant macrogeometry when planning implant surgery to achieve optimal implant stability and successful osseointegration, mainly in cases of immediate implant placement.

The Synergistic Effect of Leukocyte Platelet-Rich Fibrin and Micrometer/Nanometer Surface Texturing on Bone Healing around Immediately Placed Implants: An Experimental Study in Dogs.

Aims. This study evaluated the effects of L-PRF presence and implant surface texture on bone healing around immediately placed implants. Methods. The first mandibular molars of 8 beagle dogs were bilaterally extracted, and implants (Blossom™, Intra-Lock International, Boca Raton, FL) were placed in the mesial or distal extraction sockets in an interpolated fashion per animal. Two implant surfaces were distributed per sockets: (1) dual acid-etched (DAE, micrometer scale textured) and (2) micrometer/nanometer scale textured (Ossean™ surface). L-PRF (Intraspin system, Intra-Lock International) was placed in a split-mouth design to fill the macrogap between implant and socket walls on one side of the mandible. The contralateral side received implants without L-PRF. A mixed-model ANOVA (at α = 0.05) evaluated the effect of implant surface, presence of L-PRF, and socket position (mesial or distal), individually or in combination on bone area fraction occupancy (BAFO). Results. BAFO values were significantly higher for the Ossean relative to the DAE surface on the larger mesial socket. The presence of L-PRF resulted in higher BAFO. The Ossean surface and L-PRF presence resulted in significantly higher BAFO. Conclusion. L-PRF and the micro-/nanometer scale textured surface resulted in increased bone formation around immediately placed implants.

The Effectiveness of a Customized Titanium Mesh for Ridge Preservation with Immediate Implantation in Dogs.

The purpose of this study was to determine the effect of a newly designed titanium mesh (TM) for preserving the buccal bone around an immediately placed implant following tooth extraction in dogs. Immediate implant placements were performed bilaterally in the mesial socket of the fourth premolar in five dogs. In one site, the TM was affixed to the fixture using its own stabilization components (TM group), and the contralateral site was left untreated (control group). All surgical sites were intended to be submerged with primary flap closure. Histologic and histomorphometric analyses were performed 16 weeks postoperatively. All implants were histologically osseointegrated, and buccal bone resorption was evident in both groups with the high rate of TM exposure (4/5). The most coronal level of bone-implant contact and the bone crest were not statistically different between the TM and the control group. A dense connective tissue layer consistently predominated under the TM, where mineralized tissue was not observed, and the vascularity and cellularity were minimal. It can be conjectured that preservation of buccal plate by using the TM in immediate implantation was not predictable due to vulnerability to wound dehiscence and substantial pseudoperiosteum formation beneath the TM.

The effect of overlaying titanium mesh with collagen membrane for ridge preservation.

The aim of this study was to determine the effect of overlaying titanium mesh (TM) with an adjunctive collagen membrane (CM) for preserving the buccal bone when used in association with immediate implant placement in dogs. Immediate implant placements were performed in the mesial sockets of the third premolars of five dogs. At one site the TM was attached to the fixture with the aid of its own stabilizers and then covered by a CM (CM group), while the contralateral site received only TM (TM group). Biopsy specimens were retrieved for histologic and histomorphometric analyses after 16 weeks. All samples exhibited pronounced buccal bone resorption, and a high rate of TM exposure was noted (in three and four cases of the five samples in each of the TM and CM groups, respectively). A dense fibrous tissue with little vascularity or cellularity had infiltrated through the pores of the TM irrespective of the presence of a CM. The distances between the fixture platform and the first bone-implant contact and the bone crest did not differ significantly between the TM and CM groups. Our study suggests that the additional use of a CM over TM does not offer added benefit for mucosal healing and buccal bone preservation.

Effect of nerve growth factor-gelatin sponge composite on peri-implant osseointegration

To observe the peri-implant osseointegration after the application of exogenous nerve growth factor (NGF)-gelatin sponge (GS) composite. Six beagle dogs were used to establish bi-mandible simultaneous implant model after the first and second premolar extraction. Then the dental implants were implanted into the distal socket while the bone defect was made in the mesial socket of each mandible. Then the NGF-GS was implanted into the defects as NGF-GS group, the gelatin sponge alone was implanted as GS control and the control group was left empty. Two dogs were sacrificed each time at 4 weeks, 8 weeks and 12 weeks postoperatively. Specimens were subjected to general observation, radiography, bone histological and histomorphometric analysis for the new bone formation. The data were analyzed with SPSS 11.5 software package. The bone density in the defects around implants at 4 and 8 weeks postoperatively was lower than the normal bone. The bone-implant contact ratio in the NGF-GS group [(57.7 ± 6.4)%] was significantly higher than that in the GS control group and the control group [the ratio were (44.2 ± 3.3)% and (31.2 ± 3.1)%] (P < 0.01) at 4 weeks postoperatively, the bone-implant contact ratio in the GS control group was also significantly higher than that in the control group (P < 0.01) at that time. The bone-implant contact ratio in the NGF-GS group [(94.8 ± 7.7)%] was slightly higher than that in the GS control group and the control group [the ratio were (83.0 ± 4.1)% and (86.4 ± 6.3)%] at 8 weeks postoperatively, but there was no statistical difference (P > 0.05). The bone density in the defects around implants at 12 weeks was almost the same as the normal bone, there was no difference of the bone-implant contact ratio. NGF-GS application could increase new bone formation, accelerate maturation of trabecular bone around the implants and shorten the period of osseointegration.

Microcomputed Tomographic Analysis of the Alveolar Ridge Alteration around Extraction Sites with and without Immediate Implants Placement: In Vivo Study

The aim was to assess the alveolar ridge alteration around extraction sites with and without immediate implants according to extraction socket classification (ESC) using microcomputed tomography (micro-CT). Ten beagle dogs (mean age and weight: 24 ± 0.83 months and 13.8 ± 0.49 kg, respectively) were randomly divided into three groups according to the ESC. In Group 1 (ESC-I), bilateral first and third premolars were extracted and replaced with immediate implants. In Group 2 (ESC-II), two adjacent premolars were extracted with one immediate implant placement in the mesial socket in the maxilla and in the distal socket in the mandible. In Group 3 (ESC-III), three adjacent teeth were extracted and an immediate implant was placed in the central socket. Primary closure was achieved using resorbable sutures. Buccal sites with dehiscence defects were excluded. After 4 months, subjects were sacrificed and alveolar ridge widths were measured at 1 mm interval in axial and sagittal views, using micro-CT in sites with and without immediate implants. In sites without immediate implant placement, alveolar ridge width was significantly higher in Group 1(6.1 ± 1.35mm) than Group 3 (4.14 ± 1.53 mm) (p <.05). In sites with immediate implant placement, the alveolar ridge width was higher among sites in Group 1 (6.4 ± 3.8 mm) than Group 2 (4.8 ± 0.46 mm) (p < .05) and Group 3 (5.02 ± 0.84 mm) (p <.05). Overall, between each corresponding group in both sites with and without immediate implant placement at 1 mm thickness, there was no significant difference in the alveolar ridge widths. With the exception of Group 1 (ESC-I), immediate implant placement did not prevent or minimize bone remodeling in extraction sites according to ESC.

Bone modelling at fresh extraction sockets: immediate implant placement versus spontaneous healing. An experimental study in the beagle dog

The purpose of this investigation is to describe histologically the undisturbed healing of fresh extraction sockets when compared to immediate implant placement. In eight beagle dogs, after extraction of the 3P3 and 4P4, implants were inserted into the distal sockets of the premolars, while the mesial sockets were left to heal spontaneously. Each animal provided four socket sites (control) and four implant sites (test). After 6weeks, animals were sacrificed and tissue blocks were dissected, prepared for ground sectioning. The relative vertical buccal bone resorption in relation to the lingual bone was similar in both test and control groups. At immediate implant sites, however, the absolute buccal bone loss observed was 2.32 (SD 0.36) mm, what may indicate that while an apical shift of both the buccal and lingual bone crest occurred at the implant sites, this may not happen in naturally healing sockets. The results from this investigation showed that after tooth extraction the buccal socket wall underwent bone resorption at both test and control sites. This resorption appeared to be more pronounced at the implant sites, although the limitations of the histological evaluation method utilized preclude a definite conclusion.

Vertical and horizontal ridge alterations after tooth extraction in the dog: flap vs. flapless surgery

To compare ridge alterations after flap and flapless tooth extraction in the vertical and horizontal dimension in the dog model. This study was carried out on five Beagle dogs. Four extractions were performed in the lower jaw of each dog (two per side. Pm3, Pm4). At the time of tooth extraction, flap surgery was performed on one side (control group). On the contra-lateral side, a flapless extraction was performed (test group). Mesial sockets were left untreated on both sides. After 3 months of healing, the dogs were sacrificed and prepared for histological analysis. Ten samples were evaluated on each group. The vertical difference in height between the buccal and lingual crest was 1.48 mm for the flap, and 1.22 mm for the flapless group. The horizontal dimension of the ridge was 4.41 mm (at 1 mm from the crest), 5.72 mm (at 3 mm from the crest) and 6.67 mm (at 5 mm form the crest) in the flap group. In the flapless group, the measurements were 4.5, 5.58 mm and 6.44 at 1, 3 and 5 mm from the crest, respectively. Evaluating ridge alterations in the vertical and horizontal dimension after 3 months of healing following tooth extraction, results for the flap and the flapless group were very similar.

Effect of bismuth subgallate (a hemostatic agent) on bone repair; a histologic, radiographic and histomorphometric study in rats

Bismuth subgallate (BS) is a hemostatic agent used for soft tissue surgery in otorhinolaryngology and dermatology. Its effect on bone repair has not been studied. The present study undertook a quantitative and qualitative evaluation of post-extraction bone healing in the presence of BS. Under intraperitoneal anesthesia, forty male Wistar rats, 80+/-5g body weight, underwent the extraction of both lower first molars. BS was placed in the right post-extraction socket (group E) and the contralateral socket served as control (group C). The animals were killed in groups immediately, 7, 14 and 30 days post-extraction. The mandibles were resected, radiographed and processed for embedding in paraffin. The mesial socket was sectioned along the bucco-lingual axis and stained with hematoxylin-eosin. Total tissue volume and trabecular bone volume of the apical third of the sockets were determined histomorphometrically. At 14 and 30 days post-extraction, group E exhibited bone tissue that resembled that of group C. Histomorphometric analyses showed no statistically significant differences between groups C and E. Bismuth subgallate did not interfere with post-extraction bone healing. Further studies will analyze the effect of this hemostatic agent on bone repair in aniticoagulated rats.

Injectable bone substitute to preserve alveolar ridge resorption after tooth extraction: a study in dog.

The aim of the present study was to assess the efficacy of a ready-to-use injectable bone substitute on the prevention of alveolar ridge resorption after tooth extraction. Maxillary and mandibular premolars were extracted from 3 Beagle dogs with preservation of alveolar bone. Thereafter, distal sockets were filled with an injectable bone substitute (IBS), obtained by combining a polymer solution and granules of a biphasic calcium phosphate (BCP) ceramic. As a control, the mesial sockets were left unfilled. After a 3 months healing period, specimens were removed and prepared for histomorphometric evaluation with image analysis. Histomorphometric study allowed to measure the mean and the maximal heights of alveolar crest modifications. Results always showed an alveolar bone resorption in unfilled sockets. Resorption in filled maxillary sites was significantly lower than in control sites. Interestingly, an alveolar ridge augmentation was measured in mandibular filled sockets including 30% of newly-formed bone. It was concluded that an injectable bone substitute composed of a polymeric carrier and calcium phosphate can significantly increase alveolar ridge preservation after tooth extraction.

Effect of diphosphonate on the prevention of X-radiation-induced inhibition of bone formation in rats.

A histologic and histometric study of the effect of EHDP (ethane-1-hydroxy-1,1-diphosphonate) on the alveolar wound healing of irradiated animals is presented. This drug was selected based on its osteosclerotic effect when applied at low doses. The three left mandibular molars of 80 male Wistar rats were extracted. The rats were grouped into 4 sets of 20 rats each. Group I received no further treatment; Group II received daily intraperitoneal injections of EHDP (7.5 mg/Kg of body weight during 10 days); Group III: 15 Gy of X-radiation were applied to the head; and Group IV were irradiated and injected with EHDP as were animals of Groups III and II. Half of the animals were killed after 14 days and the other half 30 days post-extraction. Sections were made at the level of the mesial socket of the first molar in a bucco-lingual orientation, on which histometric determinations of bone activity were made. The results showed the attenuation of the inhibitory effect of radiation on bone formation when the animals were treated with EHDP.

Dental implant fixation by electrically mediated process. I. Interfacial strength.

In order to determine the effect of electrical stimulation on canine alveolar bone, porous PMMA dental implants with a solid core (on which a Pt-13% Rh electrode was wound) were implanted in the mesial socket of the canine mandibular fourth premolars bilaterally. The positive electrode was implanted into the distal socket. The power pack was placed over the masseteric fossa. The implants, wires and power packs were all implanted subcutaneously. Each animal had an experimental and control implant. Mechanical push-out samples were prepared by sectioning a 2mm thick section of the mandible with the implant in the middle. The samples were tested immediately and the load-deflection curves were obtained.