Non-submerged Healing Research Articles

Early and late implant failure of submerged versus non-submerged implant healing: A systematic review, meta-analysis and trial sequential analysis.

The aim of this systematic review was to analyse current evidence regarding differences in early and late implant failure as well as in marginal bone level (MBL) changes between submerged and non-submerged healed dental implants. PUBMED, SCOPUS, EMBASE and Web of Science databases were searched for prospective randomized and non-randomized controlled studies addressing direct comparison between submerged and non-submerged implant healing, without performing immediate loading. Early and late implant failure (before or after 6months from implant placement, respectively) together with MBL were the investigated outcomes. Risk of bias assessment was performed using the Cochrane Collaboration Tool for Randomized clinical trials. Meta-analysis was performed and the power of the meta-analytic findings determined by trial sequential analysis (TSA). Eleven studies met the inclusion criteria and were included in the review. Results of this systematic review revealed a small higher rate (2%) of early implant failure when a non-submerged healing approach is performed. Late implant failure appears not to be different in submerged or non-submerged healing, but the power of evidence, as determined by TSA, is not high. If we consider MBL changes at 1year from implant load, it seems that non-submerged healing may better preserve marginal bone, although with a small effect size (0.13mm). Implants placed with a non-submerged technique have a higher risk (2%) of early failure. The power of the evidence about the effects on MBL is low, but present results seem to favour non-submerged healing, although with a very small effect size.

Clinical and aesthetic outcomes of immediately placed single-tooth implants with immediate vs. delayed restoration in the anterior maxilla: A retrospective cohort study.

To evaluate the impact of the timing of restoration on clinical and aesthetic outcomes following immediate implant placement in the maxillary aesthetic zone. Forty patients (16 males, 24 females) with a mean age of 50.55±12.79years (range 19-74) who had a single maxillary anterior tooth replaced by an immediate implant were included in this study. Twenty patients had their implant restored immediately with a provisional restoration (Group A), while the other 20 patients had a delayed restoration placed after 3-4months of non-submerged healing (Group B). Clinical parameters and hard-tissue changes were evaluated after a mean follow-up period of 3years. Aesthetic evaluation was carried out using the Pink Esthetic Score (PES) and the White Esthetic Score (WES). No significant differences were observed in the bone level changes between the two groups: 0.05±0.65mm mesially and 0.06±0.52mm distally for the immediate group and 0.30±0.54mm mesially and 0.21±0.60mm distally for the delayed group, respectively. The median PES scores were 11.5 for Group A and 10 for Group B. Mean PES and WES scores did not differ significantly between Groups A and B: PES (11.1 vs. 10.3; p=.16) and WES (8.4 vs. 7.8; p=.16). In terms of individual PES variables, the distal papillae were significantly better in Group A as compared to Group B (p=.006). Within the limits of this study, timing of restoration seemed to positively affect the aesthetic outcomes of immediately placed implants as evidenced by higher median PES values for the immediate restoration group when compared to the delayed restoration group. Restoration timing had no impact on the individual PES variables, except for the distal papillary height which was superior in the immediate restoration group.

Vancomycin and tobramycin impregnated mineralized allograft for the surgical regenerative treatment of peri-implantitis: a 1-year follow-up case series.

To assess the clinical and radiographic outcomes of the regenerative treatment of peri-implantitis using a vancomycin and tobramycin impregnated allograft (VTA) after a 12-month period. Thirteen consecutive patients who required a regenerative treatment of peri-implantitis were recruited. For the 17 implant sites, a flap was raised, and after mechanical and chemical implant decontamination, a vancomycin and tobramycin impregnated allograft was placed in the defect and then covered with a collagen membrane. Soft tissues were sutured allowing a non-submerged healing. Clinical and radiographic variables were evaluated at baseline and at 12months after treatment. No signs of continuous bone loss were observed and no implant was lost, yielding a 100% survival rate. All patient's clinical examination at 12months revealed peri-implant health showing absence of suppuration and a statistically significant reduction in terms of bleeding on probing scores (70.6%, P = 0.001). Initial probing pocket depth (7.88 ± 1.22mm) was significantly reduced at 12months healing, a mean reduction of 4.23 ± 1.47mm (P = 0.001) was achieved. The mean radiological infrabony defect at baseline reached 4.33 ± 1.62mm, and was significantly reduced up to 0.56 ± 0.88mm, which represents an 86.99 ± 18.2% bone fill from the original infrabony defect. Within the limits of the study, the application of VTA with a collagen membrane yielded positive outcomes in terms of radiographic bone fill, pocket depth reduction, and attachment gain after a 12-month period. Thus, VTA plus a collagen membrane seem to be suitable for the regenerative treatment of peri-implantitis. The use of locally delivered antibiotic together with the bone graft may reduce the undesirable effects related to the systemic administration and the risk of resistances. In the light of the results obtained, these grafting materials might offer new treatment strategies in the surgical regenerative treatment of peri-implantitis.

Secondary implant stability outcome of immediate versus late placed variable-thread implants in the maxilla. A retrospective cohort study.

BackgroundThe healing of xenograft augmentated intra-alveolar gaps following immediate implant placement (IMIP) after tooth extraction is likely to differ in time and density compared to the native bone part that directly contacts the implant.Material and MethodsSecondary implant stability (SIS) data recorded 2-3 months following a late implant placement protocol (LIP) (n= 43) and 6-8 months following an immediate implant placement protocol (IMIP) (n=33) of variable-thread implants (Nobel Active™) in the maxilla were retrospectively collected from files of 63 patients (42 females, 21 males). Statistical analysis was performed using a generalized estimating equation model (GEE). Data split-up according to implant diameter (RP, Ø= 4.3mm) , narrow platform (NP, Ø= 3.5mm) was adopted.ResultsFor NP implants, the mean ISQ (±SD) values were 70.84 (±4.86) in LIP group and 72.41 (±3.89) in the IMIP group. For RP implants, mean ISQ (±SD) values were 73.45 (±8.77) in the LIP group and 75.93 (±5.73) in the IMIP group. Significant effect of treatment modus in favour of the IMIP and gender in favour of males and implant position was noted (p<0.05).ConclusionsSIS following a IMIP protocol after 6-8 months is comparable to LIP protocol after 2-3 months. A minor ISQ outcome difference in favour of the IMIP protocol can be attributed to a difference in hard tissue alteration during healing of the xenograft part. Key words:Secondary implant stability, RFA, Osstell Mentor, variable thread implants, Nobel Active, Bio-Oss, immediate implant placement, late implant placement, non-submerged healing, gap.

Healing at implants placed in bone of different morphology: an experimental study in dogs.

To study osseointegration at implants installed using a standard bed preparation in sites of different bone morphology. In six Labrador dogs, all mandibular premolars and first molars were extracted. After 4months of healing, flaps were elevated, and two recipient sites were prepared in each side of the mandible, one in the second premolar and the other in the molar regions. Bone morphology and final insertion torque were evaluated. Healing abutments were applied, and the flaps were sutured to allow a non-submerged healing. After 4months, the animals were sacrificed and ground sections were obtained for histomorphometric analyses. At the premolar sites, bone morphology Class 2 and at the molar regions Class 3 or 4 were identified. The final insertion torque was 50-55Ncm at the premolar and 30-35Ncm at the molar sites. Mean osseointegration in percentage reached 61.5±11.5% and 63.3±10.1% at the premolar and molar sites, respectively. Mineralized bone density evaluated from the implant surface up to a distance of about 0.6mm lateral to the implant surface was 63.0±7.4% and 65.4±17.7% at the premolar and molar sites, respectively. Similar implant bed preparations performed at premolar and molar sites with different bone morphology, yielding insertion torque values of about 30-35 and 50-55Ncm, respectively, did not affect osseointegration after 4months at non-submerged implants.

Marginal healing using Polyetheretherketone as healing abutments: an experimental study indogs.

To evaluate the marginal soft and hard tissue healing at titanium and Polyetheretherketone (PEEK) healing implant abutments over a 4-month period. In six Labrador dogs, all mandibular premolars and first molars were extracted. After 4months of healing, flaps were elevated, and two implants were installed at each side of the mandible, one in the premolar and the other in the molar regions. Four different types of healing abutments were positioned on the top of each implant: (i) titanium (Ti); (ii) PEEK material bonded to a base made of titanium (Ti-P), randomly positioned in the premolar region; (iii) PEEK, pristine (P); and (iv) PEEK, roughened (P-R), randomly positioned in the molar region. The flaps were sutured to allow a non-submerged healing, and after 4months, the animals were sacrificed and ground sections obtained for histological evaluation. A higher resorption of the buccal bone crest was observed at the PEEK bonded to a base made of titanium abutments (1.0±0.3mm) compared to those made of titanium (0.3±0.4mm). However, similar dimensions of the peri-implant mucosa and similar locations of the soft tissues in relation to the implant shoulder were observed. No statistically significant differences were seen in the outcomes when the pristine PEEK was compared with the roughened PEEK abutments. The mean apical extension of the junctional epithelium did not exceed the implant shoulder at any of the abutment types used. The coronal level of the hard and soft tissues allows the conclusion that the use of PEEK as healing abutments may be indicated.

Healing of BoneCeramic™ at buccal dehiscence defects at implants installed immediately into extraction sockets. An experimental study in dogs

To assess the healing outcomes at buccal dehiscence defects after 4months following implant placement immediately into extraction sockets (IPIES) and filled with a mixture of synthetic hydroxyl apatite (HA) 60% and β-tri-calcium phosphate (β-TCP) 40% in comparison with leaving a blood clot. Eight Labrador dogs were used, and an implant was placed immediately following tooth extraction into the distal alveolus of the third premolars, bilaterally. Standardized buccal defects, 8mm in depth and 4mm in width at the coronal and 2mm in width at the apical outlines were created. A mixture of synthetic HA 60% and β-TCP 40% was used to fill the defects at the test sites, while the control sites were left unfilled. Collagen membranes were used to cover the defects at both sides, and a non-submerged healing was allowed. After 4months of healing, biopsies were obtained and processed for morphometric analysis. A vertical gain in the extent of the bony crest and of osseointegration levels of 4.2±2.4 and 3.3±2.1mm at the test sites and of 5.0±0.8 and 4.6±1.0mm at the control sites, respectively, were observed. BIC% within the buccal defects reached similar levels (37-42%) both at test and control sites. None of the means of the variables differed significantly between the two groups. New bone formation within the defects was higher, and the percentage of the connective tissue was lower at the control (65.7±11.7% and 2.5±3.3%, respectively) compared to the test sites (16.8±11.3% and 48.9±29.5%, respectively). These differences were statistically significant. The use of a mixture of synthetic HA 60% and β-TCP 40% to fill surgically created buccal dehiscence defects at IPIES sites covered with a collagen membrane did not improve osseointegration in the defect area.

A Three-Dimensional Finite Element Study on the Biomechanical Simulation of Various Structured Dental Implants and Their Surrounding Bone Tissues.

Background/Purpose. This three-dimensional finite element study observed the stress distribution characteristics of 12 types of dental implants and their surrounding bone tissues with various structured abutments, implant threads, and healing methods under different amounts of concentrated loading. Materials and Methods. A three-dimensional geometrical model of a dental implant and its surrounding bone tissue was created; the model simulated a screw applied with a preload of 200 N or a torque of 0.2 N·m and a prosthetic crown applied with a vertical or an inclined force of 100 N. The Von Mises stress was evaluated on the 12 types of dental implants and their surrounding bone tissues. Results. Under the same loading force, the stress influence on the implant threads was not significant; however, the stress influence on the cancellous bone was obvious. The stress applied to the abutment, cortical bone, and cancellous bone by the inclined force applied to the crown was larger than the stress applied by the vertical force to the crown, and the abutment stress of the nonsubmerged healing implant system was higher than that of the submerged healing implant system. Conclusion. A dental implant system characterised by a straight abutment, rectangle tooth, and nonsubmerged healing may provide minimum value for the implant-bone interface.

Peri‐implant tissues morphometry at SLActive surfaces. An experimental study in the dog

The objective was to study tissue components around implants with highly hydrophilic surfaces during early healing. In 12 Labrador dogs, the second and third mandibular premolars were extracted bilaterally. After 3months of healing, full-thickness flaps were elevated in the edentulous region of one side of the mandible. An implant was installed, and the flaps were sutured to allow a non-submerged healing. The timing of the implant installations in the other side of the mandible until sacrifices were performed in such a way to collect biopsies representing healing after 4, 7, 15, and 60days. An n=6 was achieved for each healing period. Paraffin sections were obtained for morphometric analyses. Provisional matrix with a percentage of 32.9±16.7% was found already after 4days. This percentage became 37.3±8.5%, 24.3±9.1%, and 1.6±1.7 after 7, 15, and 60days, respectively. New bone was found after 7days of healing, at a percentage of 26.2±3.2%. This proportion increased to 36.0±9.6% and 50.4±8.3% after 15 and 60days, respectively. Marrow spaces free from a blood clot, inflammatory cells, and provisional matrix represented a low proportion of the tissues after 4days (1.6±2.4%). This proportion increased over time to 9.2±6.4%, 20.3±12.9%, and 37.9±9.6%, respectively. The percentage of old bone was noted in a similar percentage (~8%) up to 15days. The percentage decreased to ~5% at 60-day of observation. The tissue changes observed during the healing were similar to those from historic controls studying healing in a chamber adjacent to implants. Hence, the characteristics of the implant surfaces may not be reflected in the tissue composition adjacent to the implant but rather affect the adhesion of tissue onto the implant surfaces.

Sequential Healing at Implants with Different Configuration and Modified Surfaces: An Experimental Study in the Dog.

To evaluate the peri-implant soft and hard tissue adaptation at implants with different modified surfaces and configurations. Six Beagle dogs were used. Mandibular premolars and first molars were extracted bilaterally. After 3 months, full-thickness flaps were elevated, and two different types of trans-mucosal implants (ICX-Gold®, Medentis Medical GmbH, Dernau, Germany and SLActive®, Institute Straumann, Bern, Switzerland) and two different surfaces were randomly installed in the distal regions of one side of the mandible. Abutments were applied, and a nonsubmerged healing was allowed. After 1 month, the procedures were performed in the other side of the mandible, and after a further month, the animals were sacrificed, biopsies were collected, and ground sections prepared for histological examination. Similar results in marginal bone and soft tissues dimensions were observed after 1 month of healing at the two implant systems used, and no major changes could be observed after 2 months of healing. After 1 month, the percentage of new bone was 69.0% and 68.8% at ICX-Gold and SLActive surfaces, respectively. After 2 months, the percentage of new bone was 67.8% and 71.9% at ICX-Gold Medentis and SLActive surfaces, respectively. No statistically significant differences in osseointegration were found. The two implant systems used resulted in similar osseointegration after 1 and 2 months of healing.

Bone Ceramic® at Implants Installed Immediately into Extraction Sockets in the Molar Region: An Experimental Study in Dogs.

The aim of this paper was to study the healing of 1-1.4 mm wide buccal defects at implants placed immediately into extraction sockets (IPIES) filled with a mixture of synthetic hydroxyapatite (HA) 60% and beta-tricalciumphosphate (TCP) 40% or left with the clot alone and both covered with collagen membranes. Eight Labrador dogs were used and implants were placed immediately into the extraction sockets of the first molar bilaterally. A mixture of synthetic HA 60% and beta-TCP 40% at the test or the clot alone at the control sites were used to fill the defects. All surgical sites were subsequently covered by a resorbable collagen membrane and a non-submerged healing was allowed. After 4 months, the animals were euthanized, biopsies harvested and processed for histomorphometric analysis. At the time of installation, residual buccal defects occurred that were 1.1 mm and 1.4 mm wide and 3 mm and 4 mm deep at the control and test sites, respectively. After 4 months of healing, the top of the bony crest and the coronal level of osseointegration were located respectively at 0.1 ± 1.8 mm and 1.5 ± 1.8 mm at the test, and 0.6 ± 1.6 mm and 1.2 ± 0.7 mm at the control sites apically to the implant shoulder. Bone-to-implant contact at the buccal aspect was 34.9 ± 25.9% and 36.4 ± 17.3% at the test and control sites, respectively. No statistically significant differences were found between test and control sites for any of the variables analyzed at the buccal aspects. The use of a mixture of synthetic HA 60% and beta-TCP 40% to fill residual buccal defects 1-1.4 mm wide at IPIES did not improve significantly the results of healing.

The effect of piezoelectric surgery implant osteotomy on radiological and molecular parameters of peri-implant crestal bone loss: a randomized, controlled, split-mouth trial.

To evaluate the effect of piezoelectric surgery (PS) implant osteotomy on biochemical and radiological parameters of crestal bone (CB) loss. In this randomized, controlled, clinical study, 38 osteotomies were prepared with PS and drilling in the posterior maxilla in a split-mouth design. Implants were placed and left for non-submerged healing. Osteotomy time, insertion torque, pain perception, probing depth, and modified gingival and plaque indices were recorded. Peri-implant sulcular fluid (PISF) was collected from four sites of each implant at 2, 4, 8, 12, and 24 weeks. PISF samples were analyzed by ELISA for receptor activator of nuclear factor kappa-B-ligand (RANKL) and osteoprotegerin. CB loss was assessed on periapical radiographs at the 12th and on cone beam computed tomography (CBCT) at the 24th weeks. The influence of time and osteotomy method on biochemical and radiological parameters of CB loss employed statistical method of Brunner-Langer. Osteotomy time for PS group was significantly longer than the drill group (P < 0.05). Pain perception that was lower in the PS than in the drill group depended on osteotomy method (P < 0.05). PS group had lower RANKL total amount than the drill group (P < 0.05). Mean CB loss on periapical radiographs at the 12th week for PS and drill groups were 0.11 and 0.18 mm, respectively (P > 0.05). At the 24th week, PS and drill groups showed 0.11 and 0.12 mm CB losses on CBCT, respectively (P > 0.05). However, CB loss values did not depend on osteotomy modality (P > 0.05). PS may modify and reduce bone-destructive inflammatory response during implant osseointegration. Therefore, on the molecular level, it might be a less traumatic osteotomy modality than drilling although this was not reflected by CB loss values in the present study.

Automated 3D–2D registration of X-ray microcomputed tomography with histological sections for dental implants in bone using chamfer matching and simulated annealing

We propose a novel 3D–2D registration approach for micro-computed tomography (μCT) and histology (HI), constructed for dental implant biopsies, that finds the position and normal vector of the oblique slice from μCT that corresponds to HI. During image pre-processing, the implants and the bone tissue are segmented using a combination of thresholding, morphological filters and component labeling. After this, chamfer matching is employed to register the implant edges and fine registration of the bone tissues is achieved using simulated annealing.The method was tested on n=10 biopsies, obtained at 20 weeks after non-submerged healing in the canine mandible. The specimens were scanned with μCT 100 and processed for hard tissue sectioning. After registration, we assessed the agreement of bone to implant contact (BIC) using automated and manual measurements. Statistical analysis was conducted to test the agreement of the BIC measurements in the registered samples.Registration was successful for all specimens and agreement of the respective binary images was high (median: 0.90, 1.–3. Qu.: 0.89–0.91). Direct comparison of BIC yielded that automated (median 0.82, 1.–3. Qu.: 0.75–0.85) and manual (median 0.61, 1.–3. Qu.: 0.52–0.67) measures from μCT were significant positively correlated with HI (median 0.65, 1.–3. Qu.: 0.59–0.72) between μCT and HI groups (manual: R2=0.87, automated: R2=0.75, p<0.001).The results show that this method yields promising results and that μCT may become a valid alternative to assess osseointegration in three dimensions.

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.

Marginal masticatory mucosa dimensional changes in immediate post-extractive implants: a 2year prospective cohort study.

The present two-year prospective cohort study was undertaken to evaluate marginal masticatory mucosa dimensional changes around immediate post-extractive implants positioned transgingivally with a non-submerged healing screw. Twenty-one immediate post-extractive implants from 21 patients were enrolled, peri-implant gap was filled with bovine bone mineral, and soft tissue was allowed to heal around a non-submerged healing screw. Post-extractive socket dimension was recorded. Intraoperative (T0) vertical distances: bone margin level (BML) from the bone margin to the implant platform and mucosal margin height (MMH) from marginal mucosa to implant platform were taken; MMH measurement was repeated 4months later (T4). Horizontal mucosal level (HML): from customized stent to marginal mucosa at 0, 4, 12, and 24months postoperatively (T0, T4, T12, T24) and vertical mucosal level (VML): from the stent to marginal mucosa at T4, T12, T24 were registered. One implant failed at 3weeks; in the remaining 20 cases the MMH, coronally positioned with respect to the BML ≅2mm at T0, showed a statistically significant vertical contraction of the mucosa at T4. Other vertical mucosal measurements (VML) did not show further changes over time. HML measures showed a, statistically significant, shrinkage of the mucosa on the transverse plane between T0/T12 and T0/T24 and between T4/T12 and T4/T24. Immediate post-extractive implant inserted transgingivally with a non-submerged healing screw and internal peri-implant gap filled with bovine bone mineral may favor an early and stable peri-implant soft tissue healing over 2years.

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(®).

Healing of Bio-Oss® grafted marginal gaps at implants placed into fresh extraction sockets of incisor teeth in dogs: a study on the effect of submerged vs. non-submerged healing.

To evaluate the effect of submerged vs. non-submerged (NS) protocols in healing outcomes of grafted marginal defects of immediate implants. The second maxillary incisors were extracted bilaterally in six greyhound dogs. Bone level reduced diameter implants were installed into the extraction sockets leaving orofacial gaps of 2 mm wide. Defects were filled with Bio-Oss(®) and covered with Bio-Gide(®). On the one side, the flap was advanced to fully submerge the implant, and on the other, the flap was sutured to allow NS healing. After 3 months of healing, the dogs were sacrificed and block biopsies were obtained to perform histological and morphometric analysis. All implants were clinically healthy and well integrated into bone. In the majority of the specimens, the original bone in the coronal 2-3 mm of the buccal crest had completely resorbed and was replaced by a regenerated bone wall consisting of Bio-Oss(®) particles surrounded by newly formed bone. Horizontal and vertical resorption of the buccal bone resulted in ≥1 mm exposure of the implant surface in one-third of implants. Minor differences existed in some aspects of hard tissue healing between submerged and NS. There was very little difference in healing outcomes as well as modelling of the facial bone wall between the submerged and NS protocols in relation to immediate implant placement in this dog model.

Evaluation of contiguous implants with cement-retained implant-abutment connections. A minipig study

Aim The presence of a microgap at the implant-abutment interface may permit bacterial contamination and lead to bone resorption, interfering with papillae formation. The present study evaluated adjacent implants with cement-retained abutments as an option to control such deleterious effects. Materials and methods Seven minipigs had their bilateral mandibular premolars previously extracted. After 8 weeks, four implants were installed in each hemi-mandible of each animal. The adjacent implants were randomly inserted on one side at the crestal bone level and on the other, 1.5 mm subcrestally. Immediately, a non-submerged healing and functional loading were provided with the abutments cementation and prostheses installation. Clinical examination and histomorphometry served to analyze the implant success. Results A total of 52 implants were evaluated at the end of the study. The subcrestal group achieved statistical better results when compared to the crestal group, clinically in papillae formation (1.97 x 1.57 mm) and histomorphometrically in crestal bone remodeling (1.17 x 1.63 mm), bone density (52.39 x 45.22%) and bone-implant contact (54.13 x 42.46%). Conclusion The subcrestal placement of cement-retained abutment implants showed better indexes of osseointegration and also improved papillae formation and crestal bone remodeling at the interimplant area after immediate loading, making them a promising option for the treatment of esthetic regions.

Healing at implant sites prepared conventionally or by means of Sonosurgery®. An experimental study in dogs

To compare peri-implant tissue healing at implants installed in sites prepared with conventional drills or a sonic device. In six Beagle dogs, the mandibular premolars and first molars were extracted bilaterally. After 3 months, full-thickness muco-periosteal flaps were elevated and recipient sites were prepared in both sides of the mandible. In the right side (control), the osteotomies were prepared using conventional drills, while, at the left side (test), a sonic device (Sonosurgery(®)) was used. Two implants were installed in each side of the mandible. After 8 weeks of non-submerged healing, biopsies were harvested and ground sections prepared for histological evaluation. The time consumed for the osteotomies at the test was more than double compared to the conventional control sites. No statistically significant differences were found for any of the histological variables evaluated for hard and soft tissue dimensions. Although not statistically significant, slightly higher mineralized bone-to-implant contact was found at the test (65.4%) compared to the control (58.1) sites. Similar healing characteristics in osseointegration and marginal hard tissue remodeling resulted at implants installed into osteotomies prepared with conventional drills or with the sonic instrument (Sonosurgery(®)).

A digital evaluation of alveolar ridge preservation at implants placed immediately into extraction sockets: an experimental study in the dog

To compare with pristine sites bone resorption and soft tissue adaptation at implants placed immediately into extraction sockets (IPIES) in conjunction with deproteinized bovine bone mineral (DBBM) particles and a collagen membrane. The mesial root of the third premolar in the left side of the mandible was endodontically treated (Test). Flaps were elevated, the tooth hemi-sectioned, and the distal root removed to allow the immediate installation of an implant into the extraction socket in a lingual position. DBBM particles were placed into the defect and on the outer contour of the buccal bony ridge, concomitantly with the placement of a collagen membrane. A non-submerged healing was allowed. The premolar on the right side of the mandible was left in situ (control). Ground sections from the center of the implant as well as from the center of the distal root of the third premolar of the opposite side of the mandible were obtained. The histological image from the implant site was superimposed to that of the contralateral pristine distal alveolus, and dimensional variation evaluated for the hard tissue and the alveolar ridge. After 3 months of healing, both histological and photographic evaluation revealed a reduction of hard and soft tissue dimensions. The contour augmentation performed with DBBM particles and a collagen membrane at the buccal aspects of implants placed IPIES was not able to maintain the tissue volume.