Coronal Level Research Articles

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.

Interfacial adaptation and thickness of bioceramic-based root canal sealers.

This study evaluated and compared the sealer thickness and interfacial adaptation of bioceramic sealers (Sankin Apatite III, MTA Fillapex(®), EndoSequence(®) BC) to root dentin against AH Plus(®) sealer. Sixty extracted single-root premolars were prepared and equally divided into four groups. Sealers were labeled with 0.1% Rhodamine B fluorescent dye. Roots were dissected along the transverse plane at 1 mm (apical), 3 mm (middle), and 6 mm (coronal) levels. Sealer-to-whole canal area ratio was evaluated. Percentage of gap-containing region to canal circumference was calculated using a confocal laser microscope. Sealer thickness was significantly higher at apical and middle levels than at coronal level. EndoSequence BC had the significantly highest thickness compared with MTA Fillapex and AH Plus. The coronal level had significantly less interfacial gaps compared with apical and middle levels. Bioceramic sealers showed more gaps compared with AH Plus, with no significant differences among them.

Assessment Using AutoCAD Software of the Preparation of Dentin Walls in Root Canals Produced by 4 Different Endodontic Instrument Systems.

Objectives. To compare the effectiveness of four instrument systems for preparing oval root canals: manual instrumentation (Step-Back technique), ProTaper Universal, ProTaper Next, and Wave One. Material and Methods. For the purpose of this assessment, 60 teeth extracted for orthodontic or periodontal reasons, specifically canines and premolars with full coronal and root anatomy, were used and 15 samples were assigned to each group. The section of the canals was compared before and after instrumenting and the section of untouched canal wall was measured using AutoCAD software. The data was analysed by means of Shapiro-Wilk, ANOVA, and Kruskal-Wallis tests. Results. In the apical third, 100% of the canals were prepared with all the systems. In the middle third, a p value of 0.5989 in the Kruskal-Wallis test was obtained, which indicates no significant difference between the groups. At the coronal third level, the results obtained revealed that Wave One had a significantly lower mean average than the rest (p < 0.05). Conclusions. There are no differences between the various root canal instrument systems in the apical and middle thirds. At the coronal third level, Wave One system showed performance significantly worse than the rest, among which there were no differences.

Necrosis of the ventral penile skin flap: a complication of hypospadias surgery in children.

Objectives. To review cases of hypospadias that were repaired with TIPU method and consequently resulted in the necrosis of ventral penile skin flaps. Methods. Eighty-three patients with hypospadias underwent TIPU procedure by two surgeons. Neourethra in all patients was covered with dartos flap prepared from the preputium or penile shaft. In cases where ventral skin could not be covered primarily, closure was ensured by using preputial Ombredanne or Byars' flaps to repair ventral defects. Results. The median age of patients was 4 years. Twenty-five (30.12%) patients that underwent hypospadias repair had urethral opening at the coronal level, 33 (39.75%) at the distal penis, 10 (12.04%) at the midpenis, and 15 (18.07%) at the proximal penis. The ventral skin defect could not be primarily covered in 10 patients with penile shaft hypospadias. Consequently, Byars' method was used in 8 of these patients to cover the defect and the Ombredanne method was used in the remaining 2. Ventral skin flap necrosis developed in 5 patients (4 Byars and 1 Ombredanne). It was medically treated in 4 patients. Urethral fistula developed in the other patient whose necrosis was deeper. The mean hospital stay was 7 days for patients without necrosis, and 14 for those with necrosis. Conclusion. We are of the opinion that dartos flaps used in the TIPU method in order to cover neourethra and decrease the incidence of fistula development lead to necrosis in the Ombredanne or Byars' flaps by causing low blood supply to the preputium and thus extend hospital stay.

The effect of budesonide on orthodontic induced root resorption.

Background:The aim of this study was to evaluate the hypothesis that budesonide increases the susceptibility of teeth to root resorption during the course of orthodontic treatment.Materials and Methods:A randomized controlled trial design (animal study) was employed. Budesonide was administered in test group for 14 days during which orthodontic force was applied to upper right molar. Afterwards, root resorption was measured on mesio-cervical and disto-apical parts of the mesial root on transverse histological sections. ANOVA and Bonfferoni tests were used. Statistical significance was considered to be P ≤ 0.05.Results:In general, the subgroups in which the force was applied showed significantly greater root resorption. Where force was applied there was no significant difference, whether budesonide was administered or not. While where there was no force, a group who received budesonide showed significantly greater root resorption than the other, unless at the coronal level where the difference was not significant.Conclusion:Within the limitations of this study, it seems budesonide could increase root resorption, but in the presence of orthodontic force this effect is negligible.

A study to compare the cleaning efficiency of different irrigation systems for macro debris removal in instrumented canals (An in vitro study)

Background: Irrigation of the canal system permits removal of residual tissue in the canal anatomy that cannot be reached by instrumentation of the main canals so the aim of this study was to compare and evaluate the efficiency of conventional irrigation system, endoactivator sonic irrigation system,P5 Newtron Satelec passive ultrasonic irrigation and Endovac irrigation system in removing of dentin debris at three levels of root canals and to compare the percentage of dentin debris among the three levels for each irrigation system. Materials and methods: Forty extracted premolars with approximately straight single root canals were randomly distributed into 4 tested groups of 10 teeth each. All canals were prepared with Protaper Universal hand files to size #F4, and irrigated with 2.5% NaOCI 1 ml between files and 5ml for 60 seconds as a final irrigant by different irrigation devices; group one, by using conventional system; group two, by using Endoactivator sonic irrigation system, group three, by using Satelec Passive Ultrasonic irrigation and group four by using the Endovac system. After the final irrigation, the roots were split longitudinally and photographed with a digital microscope. The roots were magnified to 100X; a percentage of debris was calculated for the apical 0-3, middle 3-6 and coronal 6-9 mm. The debris score was calculated as a percentage of the total area of the canal that contained debris as determined by pixels in Adobe PhotoshopCS5. Data were analyzed statistically by ANOVA and LSD at 5% significant level. Results: when comparing the debris remaining, the Endovac, Endoactivator and Satelec groups showed significantly less debris than the conventional group at all three levels (p < 0.01). The Endovac group showed significantly less debris than the Endoactivator group at middle and coronal levels while no significant difference found between the Endovac system and Endoactivator system at apical level. The apical 0-3 mm showed significantly more debris than both the middle and coronal level for all groups. Conclusion: The EndoVac system showed a higher cleaning capacity of the canal at all levels, followed by the protocols that used Endoactivator sonic irrigation system. The conventional irrigation system with maxi-i-probe needles showed inferior results. The apical three millimeters showed a greater amount of debris than the 3-9 millimetres from the working length, regardless of the irrigation device used.

Comparison of marginal bone loss and patient satisfaction in single and double-implant assisted mandibular overdenture by immediate loading.

PURPOSEThe purpose of this study was to compare the coronal bone level and patient satisfaction in 1-implant and 2-implant assisted mandibular overdentures.MATERIALS AND METHODSTwenty patients who had maladaptive mandibular dentures were treated in this study. Patients were randomly divided into two groups. The first group received 1 implant (Simple line II, Implantium, South Korea) in their mandibular midline and the second group received 2 implants in their B and D regions (according to Misch's category). If the primary stability of each implant was at least 60 ISQ, ball attachment was placed and denture relined with soft liner. After 6 weeks, retentive cap incorporated with hard acrylic resin. In the 6 and 12 months recalls, periapical digital radiograph were made and visual analogue scale questionnaires were used to record patient satisfaction. The Friedman test was done for comparing the presurgical and postsurgical parameters in each group and the U-Mann Whitney test (P<.05) was done for comparison of post-treatment results between the two groups.RESULTSAll implants achieved sufficient primary stability to be immediately loaded. Patient satisfaction was high, and there were no significant differences between two groups (P>.05). In addition, mean marginal bone loss was 0.6 ± 0.67 mm in the first group and 0.6 ± 0.51 mm in the second group, after 12 month. Mean marginal bone loss showed no significant differences between two groups.CONCLUSIONThis preliminary one-year result indicated that mandibular overdentures anchored to a single implant can be a safe and cost-effective method as a starting step for implant-overdenture treatment.

Sequential healing at implants installed immediately into extraction sockets. An experimental study in dogs.

To compare the sequential healing at implants installed in a healed alveolar bony ridge or immediately after tooth extraction without functional load. In the mandible of 12 dogs, the mesial roots of the first molars were endodontically treated, the tooth hemisected, and the distal roots extracted. After 3months, the mesial roots of the fourth premolars were endodontically treated, the tooth hemisected, and the distal roots extracted in one side of the mandible. Implants were placed immediately into extraction sockets (IPIES) of the fourth premolar and in the healed sites in the molar regions. Healing abutments were placed, and the flaps were sutured to allow a non-submerged healing. The time of surgery and of sacrifices were planned in such a way to obtain biopsies representing the healing after 1 and 2weeks and 1 and 3months, respectively. Ground sections were prepared for histological evaluation of tissues components on the implant surface and the coronal termination level of osseointegration (M-B). New bone apposition on the implant surface was slightly higher at the healed compared to the IPIES sites, being 7.4% and 4.1% after 1week, and 67.3% and 65.3% after 3months, respectively. Old bone was progressively resorbed, from 27.0% and 21.9% after 1week, to 2.5% and 2.0% after 3months, at healed and IPIES sites, respectively. M-B was 1.4mm and 2.6mm after 1week, 1.2mm and 1.2mm after 3months, at healed and IPIES sites, respectively. Similar patterns of sequential osseointegration were found at implants installed in healed alveolar bone or in alveolar sockets immediately after tooth extraction. The coronal termination level of osseointegration, that was different after 1week, was found similar at the 3-month observation.

Comparison the Accuracy of the Cone-Beam Computed Tomography With Digital Direct Intraoral Radiography, in Assessment of Periodontal Osseous Lesions

La Ciotat-France) was taken, and then CBCT (Newtom 3G, Verona. Italy) was carried out. Periodontal flap surgery was done to achieve the gold standard. The distance between cementoenamel junction (CEJ) and the bottom of the vertical pattern of bone loss or the most coronal level of bone in horizontal pattern was measured. These measurements were analyzed by paired t test. The intraclass correlation coefficient (ICC) was used to evaluate the degree of agreement between observers. Results: Accuracy is higher with CBCT in evaluating vertical dimension of periodontal bony defects (0.53 ± 0.59 to 0.56 ± 0.45) (P < 0.001). ICC shows high level of agreement between observers in two image modality. Conclusions: We conclude that CBCT and digital images can be used in periodontal bone assessments; each modality should be chosen based on defect type and patient's specific characteristics.

Morphological Characterization of the Anterior Palatine Region Using Cone Beam Computed Tomography.

Surgery of the anterior maxillary zone has a strong impact upon dental and facial aesthetics and function. To determine the anatomical characteristics and dimensions of the nasopalatine canal and alveolar bone using cone beam computed tomography (CBCT). A retrospective, cross-sectional study was made of the nasopalatine canal in 122 randomly selected CBCT scans corresponding to 66 males (44.3%) and 56 females (55.6%). The following measurements were made: maximum length and diameters of the nasal and oral openings of the nasopalatine canal; distance from the crestal margin to the buccal wall (at apical, middle, and coronal level); and angulation of the nasopalatine canal. The anatomical variants were morphologically classified as follows: A (single canal), B (double canal), or C (Y-shaped canal). The anatomy of the nasopalatine canal showed important variability in terms of morphology and dimensions. Type A was observed in 48 patients (39.34%), type B in 10 (8.19%), and type C in 64 (52.45%). The mean diameter of the nasal opening or orifice was 3.02 ± 1.0 mm versus 3.29 ± 1.0 mm in the case of the oral opening. The mean length of the canal was 11.02 ± 2.4 mm. Significant differences were found between males and females, with greater canal dimensions and alveolar bone thickness values anterior to the nasal canal zone among males (p < .05). Our study shows gender to exert a significant influence upon the anatomical dimensions of the anterior maxilla and incisor canal. Given the anatomical variability characterizing the nasopalatine canal, we recommend CBCT evaluation prior to any type of surgery of the anterior maxillary zone.

Sub-crestal positioning of implants results in higher bony crest resorption: an experimental study in dogs.

To compare peri-implant soft- and hard-tissue integration at implants installed juxta- or sub-crestally. Furthermore, differences in the hard and soft peri-implant tissue dimensions at sites prepared with drills or sonic instruments were to be evaluated. Three months after tooth extraction in six dogs, recipient sites were prepared in both sides of the mandible using conventional drills or a sonic device (Sonosurgery(®)). Two implants with a 1.7-mm high-polished neck were installed, one with the rough/smooth surface interface placed at the level of the buccal bony crest (control) and the second placed 1.3 mm deeper (test). After 8 weeks of non-submerged healing, biopsies were harvested and ground sections prepared for histological evaluation. The buccal distances between the abutment/fixture junction (AF) and the most coronal level of osseointegration (B) were 1.6 ± 0.6 and 2.4 ± 0.4 mm; between AF and the top of the bony crest (C), they were 1.4 ± 0.4 and 2.2 ± 0.2 mm at the test and control sites, respectively. The top of the peri-implant mucosa (PM) was located more coronally at the test (1.2 ± 0.6 mm) compared to the control sites (0.6 ± 0.5 mm). However, when the original position of the bony crest was taken into account, a higher bone loss and a more apical position of the peri-implant mucosa resulted at the test sites. The placement of implants into a sub-crestal location resulted in a higher vertical buccal bone resorption and a more apical position of the peri-implant mucosa in relation to the level of the bony crest at implant installation. Moreover, peri-implant hard-tissue dimensions were similar at sites prepared with either drills or Sonosurgery(®).

Bone recontouring in fresh sockets with buccal bone loss: a cone beam computed tomography study.

The aim of this study was to assess buccal bone plate recontouring in maxillary fresh extraction sockets with buccal bone loss using cone beam computed tomography (CBCT). Healthy patients who required the extraction of one tooth with buccal bone loss in the maxilla were included in this study. CBCT examinations were made before extractions and after 3 months. The alveolar bone levels were assessed from the most coronal, buccal, and palatal bone in which the crest was identified. Buccolingual width at the apical and coronal level was also measured. Fifty healthy patients underwent 50 extractions. Mean bone levels for both single-rooted and multiple-rooted teeth, from a buccopalatal perspective, showed no statistically significant difference between preextraction status and 3 months later. However, in both groups, mean bone levels of the buccal bone plate showed statistically significant differences between extraction and 3 months later. In single-rooted teeth, a mean bone gain of 5.36 ± 2.65 mm was seen after 3 months, and for multiple-rooted teeth, a mean bone gain of 5.89 ± 2.88 mm was seen. Growth in buccolingual width was seen; nevertheless, volume dimensional changes were reported after tooth extraction. In the first months after extraction, it is possible to observe the formation of buccal bone in sockets with previous buccal bone loss.

Penile strangulation by hair.

To know the causes and results of treatment of complications from a penile strangulation by hair in seven boys. From April 2000 to December 2012, seven boys presenting serious penile complications by hair strangulation have been operated in two centers. All seven boys had transection of the urethra at the coronal level. And none of our patients were at the stage of necrosis or amputation of the glans. The age of the patients at surgery ranged from 34 to 134 months (mean 96 months). Four children presented urethrocutaneous fistulas (57% of cases), and the innervation and vascularization of the glans remained poor after repair in three patients. The penile strangulation by hair was due to a simple accident. However, several predisposing factors were discovered in our patients: lack of cleanliness; a moist environment with nocturnal enuresis; the presence of pubic hair in young children reported in the four children, and a coronal sulcus not covered by the foreskin in circumcised children.

Microcomputed Tomography and Histologic Analysis of a Maxillary Implant Retrieved 19 Months After Placement and Indirect Sinus Augmentation With Biphasic Calcium Phosphate: A Case Report

Introduction: Implant osseointegration in regenerated bone and the resorptive outcome of graft materials are major clinical concerns.Case Presentation: A 40‐year‐old female patient underwent an indirect maxillary sinus augmentation with biphasic calcium phosphate (BCP) in conjunction with implant placement. Because of implant fracture, the implant and adjacent tissues were excised with a trephine bur 19 months after placement. The biopsy with the implant in place was analyzed by microcomputed tomography (micro‐CT) and histology. Marginal bone loss of the implant was evident, particularly on the fractured side. The graft particles were predominantly integrated in bone. Resorption lacunae were observed in the marginal bone area, but were not observed on the surface of the graft particles. Graft particles without contact to bone were observed coronal to the most coronal level of bone‐to‐implant contact, presumably exfoliated after marginal bone resorption. Of the total peri‐implant volume, 20.5% was residual graft material and 62.5% was bone according to the micro‐CT analysis. The histomorphometry demonstrated 30.4% residual graft material and 46.8% bone of the total peri‐implant area. The percentage of bone‐to‐implant contact was 60.3% when counting the total vertical implant perimeter.Conclusions: The BCP particles were mostly embedded in new bone, and the implant was clinically and histologically osseointegrated. This case report suggests that BCP graft material may not resorb during inflammation, resulting in exfoliation from the grafted compartment.

Evaluation of calcium hydroxide removal using EndoActivator system: An in vitro study

Aim: The aim of this study was to compare the calcium hydroxide (Ca(OH) 2 ) removal efficacy of the EndoActivator system with that of conventional irrigation with a syringe and hand file manipulation. Materials and Methods: A total of 44 extracted human single-rooted mandibular premolars were used. The root canal systems of all teeth were cleaned and shaped, then filled with Ca(OH) 2 paste. The teeth were divided into two groups: Ca(OH) 2 was removed using ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) with hand filing and irrigation (Group 1) or the EndoActivator system (Group 2). Each tooth was split into two halves and examined under a scanning electron microscope. Results: Ca(OH) 2 particles were completely removed at the coronal level in both experimental groups. More Ca(OH) 2 particles were present in the apical third than in the middle-third in both groups. No significant interaction was observed between the two experimental groups or among the three examined levels (P > 0.05). Conclusion: Agitation with NaOCl and EDTA improved Ca(OH) 2 removal only in the coronal third of the root canal. Use of the EndoActivator system did not improve the efficacy of Ca(OH) 2 removal in the middle and apical thirds.

Comparative Evaluation of Push-out bond Strength of Three Endodontic Sealers with and without Amoxicillin-An Invitro Study

The purpose of this study was to evaluate the sealing ability of three different root canal sealers with and without amoxicillin, using a push-out bond strength test. Sixty single-rooted extracted human teeth were used for this study. Each tooth was instrumented and irrigated with 5.25% Sodium hypochlorite (NaOCl) and 17% EDTA. The teeth were then divided into six test groups: Gutta percha (GP)/AH Plus (Dentsply, Germany), GP/AH Plus with 10% amoxicillin (TEVA Pharmaceuticals Sellersville, PA), GP/Pulp Canal Sealer EWT (Extended Working Time, SybronEndo Orange, CA), GP/Pulp Canal Sealer EWT with amoxicillin, GP/Apexit Plus, GP/Apexit Plus (Vivadent, Tulsa, US) with amoxicillin. After the sealer was set, the entire root was sectioned into 1 mm thick slices. A push-out bond strength test was performed by using a universal testing machine. The Student's t-test was used to compare the sealer bond strength within the specific sealer test groups and within each sealer at apical, middle and coronal root levels. There was no significant difference between the groups within each sealer (p>0.05) with or without amoxicillin at the same root level. This study demonstrated that the addition of 10% by weight of amoxicillin does not significantly (p> 0.05) change the overall push-out bond strength of three endodontic sealers when compared at the apical, middle, and coronal tooth level.

Influence on alveolar resorption of the buccal bony plate width in the edentulous ridge expansion (E.R.E.) – an experimental study in the dog

To compare the hard tissue changes at implants installed applying edentulous ridge expansion (E.R.E.) at sites with a buccal bony wall thickness of 1 or 2 mm. In six Labrador dogs, the first and second maxillary incisors were extracted, and the buccal alveolar bony plates and septa were removed. After 3 months of healing, partial-thickness flaps were dissected, and the E.R.E. was applied bilaterally. Hence, an expansion of the buccal bony crest was obtained in both sides of the maxilla with a displacement of either a 1- or a 2-mm-wide buccal bony plate at the test and control sites, respectively. After 3 months of healing, biopsies were obtained for histological analyses. A buccal vertical resorption of the alveolar crest of 2.3 ± 0.8 and 2.1 ± 1.1 mm, and a coronal level of osseointegration at the buccal aspect of 2.7 ± 0.5 and 2.9 ± 0.9 mm were found at the test (1 mm) and control (2 mm) sites, respectively. The differences did not reach statistical significance. The mean values of the mineralized bone-to-implant contact (MBIC%) ranged from 62% to 73% at the buccal and lingual sites. No statistically significant differences were found. Horizontal volume gains of 1.8 and 1.1 mm were observed at the test and control sites, respectively, and the difference being statistically significant. Implants installed using the E.R.E. technique yielded a high degree of osseointegration. It is suggested that the displacement of buccal bony plates of 1 mm thickness is preferable compared with that of wider dimensions.

Influence of immediate loading on healing of implants installed with different insertion torques – an experimental study in dogs

To evaluate the influence of different insertion torques on healing of implants loaded immediately or left unloaded. In six Labrador dogs, all mandibular premolars and molars were extracted. After 4 months of healing, flaps were elevated, and two implant sites were prepared at each side of the mandible. The distal sites were prepared conventionally while the mesial sites were underprepared by 0.3 mm. As a consequence, different final insertion torques of about 30 Ncm at the distal and >70 Ncm at the mesial sites were recorded. Healing abutments were applied to the left and transmucosal abutments to the right side. Flaps were sutured, crown preparation of the upper right second and third premolars was performed, and impressions were taken. Within 24 h, crowns were cemented both to implants and teeth in the right side of the mouth. After 4 months, the animals were sacrificed and ground sections obtained for histological evaluation. A higher buccal bony crestal resorption and a more apical position of the coronal level of osseointegration were found at the loaded compared with the unloaded sites. MBIC% and percentages of peri-implant mineralized tissue (MB%) were higher at the loaded compared with the unloaded sites. Moreover, a higher MBIC% was found at the lower compared with the higher final insertion torque. Immediate loading does not seem to have a negative effect on osseointegration. High torque values for the immediate loading procedures were not necessary. Probably, low torque values, were sufficient to obtain primary stability and hence may provide better osseointegration than high torque value.

The edentulous ridge expansion (ERE) technique an experimental study in the dog

To compare the healing and bony crest resorption at implants installed conventionally or applying an edentulous ridge expansion (ERE) technique in the maxilla. In six Labrador dogs, the first and second maxillary incisors were extracted bilaterally. In the left side of the maxilla (Test), the flaps were elevated and the buccal plate of the alveoli and septa was removed. After 3 months of healing, partial-thickness (split) flaps were dissected and the residual alveolar bone was exposed. In the right side of the maxilla, an implant was installed conventionally (Type IV; Control) while, in the left side, the ERE technique was adopted. Hence, an expansion of the buccal bony crest was obtained, and the implant was subsequently installed (Test). After 3 months of healing, biopsies were obtained and ground sections were prepared for histological analyses. A buccal vertical resorption of the bony crest of 2.2 ± 1.2 mm and 1.6 ± 0.7 mm was found at the test and control sites, respectively. The difference, however, did not reach statistical significance. The coronal level of osseointegration at the buccal aspect was located at 3.1 ± 1.0 mm and 2.2 ± 0.7 mm from the implant shoulder at the test and control sites, respectively, the difference being statistically significant. The mean values of the mineralized bone-to-implant contact (MBIC%) ranged from 43% to 48% at the buccal and lingual sites. No differences reached statistical significance. Implants installed by applying an ERE technique may osseointegrate similarly to conventional implant installation. However, vertical and horizontal resorption of the displaced buccal bony wall occurred as well.

The platform switching concept revisited. An experimental study in dogs

To evaluate the influence of the configuration of the marginal aspect of implants placed immediately into extraction sockets on peri-implant hard tissue adaptation. In 6 Labrador dogs, endodontic treatments of the mesial roots of 1 M1 were performed and the distal roots were removed. 2 P2 was extracted as well. Implants were immediately placed in the center of the distal alveoli. Cylindrical straight implants were installed in the right side of the mandible (Control), while, in the left side, implants with a reduced diameter in the coronal portion, yielding an indentation in the surface continuity (Test), were installed. Cover screws were affixed, and the flaps were sutured to allow non-submerged healing. After 4 months of healing, histological slides were obtained for assessments. A buccal resorption of 1.58 ± 1.28 and 1.90 ± 1.93 mm at the control and of 0.26 ± 0.90 and 0.14 ± 0.66 mm at the test sites was observed at the premolar and molar regions, respectively. The buccal coronal level of osseointegration was located apically to the margin of the smooth/rough surface border by 2.40 ± 0.90 and 3.70 ± 0.87 mm at the control sites and 1.19 ± 0.45 and 2.16 ± 0.96 mm at the test sites at the premolar and molar sites, respectively. All differences yielded statistical significance. The use of implants with a reduced diameter in their coronal aspect may contribute to preservation of the buccal bony crest in a more coronal level compared with conventional implants. Thus, the study confirmed the efficacy of the "platform switching" concept.