Tissue Dimensions Research Articles

Improved co-registration of ex-vivo and in-vivo cardiovascular magnetic resonance images using heart-specific flexible 3D printed acrylic scaffold combined with non-rigid registration

BackgroundEx-vivo cardiovascular magnetic resonance (CMR) imaging has played an important role in the validation of in-vivo CMR characterization of pathological processes. However, comparison between in-vivo and ex-vivo imaging remains challenging due to shape changes occurring between the two states, which may be non-uniform across the diseased heart. A novel two-step process to facilitate registration between ex-vivo and in-vivo CMR was developed and evaluated in a porcine model of chronic myocardial infarction (MI).MethodsSeven weeks after ischemia-reperfusion MI, 12 swine underwent in-vivo CMR imaging with late gadolinium enhancement followed by ex-vivo CMR 1 week later. Five animals comprised the control group, in which ex-vivo imaging was undertaken without any support in the LV cavity, 7 animals comprised the experimental group, in which a two-step registration optimization process was undertaken. The first step involved a heart specific flexible 3D printed scaffold generated from in-vivo CMR, which was used to maintain left ventricular (LV) shape during ex-vivo imaging. In the second step, a non-rigid co-registration algorithm was applied to align in-vivo and ex-vivo data. Tissue dimension changes between in-vivo and ex-vivo imaging were compared between the experimental and control group. In the experimental group, tissue compartment volumes and thickness were compared between in-vivo and ex-vivo data before and after non-rigid registration. The effectiveness of the alignment was assessed quantitatively using the DICE similarity coefficient.ResultsLV cavity volume changed more in the control group (ratio of cavity volume between ex-vivo and in-vivo imaging in control and experimental group 0.14 vs 0.56, p < 0.0001) and there was a significantly greater change in the short axis dimensions in the control group (ratio of short axis dimensions in control and experimental group 0.38 vs 0.79, p < 0.001). In the experimental group, prior to non-rigid co-registration the LV cavity contracted isotropically in the ex-vivo condition by less than 20% in each dimension. There was a significant proportional change in tissue thickness in the healthy myocardium (change = 29 ± 21%), but not in dense scar (change = − 2 ± 2%, p = 0.034). Following the non-rigid co-registration step of the process, the DICE similarity coefficients for the myocardium, LV cavity and scar were 0.93 (±0.02), 0.89 (±0.01) and 0.77 (±0.07) respectively and the myocardial tissue and LV cavity volumes had a ratio of 1.03 and 1.00 respectively.ConclusionsThe pattern of the morphological changes seen between the in-vivo and the ex-vivo LV differs between scar and healthy myocardium. A 3D printed flexible scaffold based on the in-vivo shape of the LV cavity is an effective strategy to minimize morphological changes in the ex-vivo LV. The subsequent non-rigid registration step further improved the co-registration and local comparison between in-vivo and ex-vivo data.

A Novel 450 nm Semiconductor Blue Laser System for Application in Colon Endoscopic Surgery: An Ex Vivo Study of Laser-Tissue Interactions.

Objective: Our study aimed to detect whether 450 nm blue laser can be applied effectively and safely in endosocopic submucosal dissection (ESD) system for surgery in colonic tissue. Background data: Semiconductor blue laser has been applied in surgery due to its excellent cutting property, however, whether blue laser can be applied in colonic surgery has not been reported. Materials and methods: Porcine colon tissues were vaporized by 450 nm blue semiconductor laser at 10-25 W and at working distances from 0.5 to 3 mm, with a three-dimensional scanning system. Moreover, we designed an ESD model and applied blue laser at 10 W on porcine colonic tissues with this system. Dimensions of the vaporized tissues and coagulation zones were assessed under microscopy. Results: Since the thickness of colonic wall is no more than 1 mm, first we determined the cutting property and safety of blue laser on porcine colon tissue and found that blue laser at 10 W made lesions shallower than 1 mm and the depth of vaporization can be controlled effectively within muscularis mucosa and submucosa. Moreover, a large scale of porcine colonic tissue was vaporized precisely by blue laser at power of 10 W with the ESD system ex vivo. Conclusions: Our results indicate that 450 nm blue laser at 10 W can be well controlled for laser-tissue interaction with excellent cutting efficiency and less thermal damage in adjacent tissues especially side of the submucosa. Therefore, 450 nm semiconductor blue laser could be a safe alternative approach for colonic surgery.

The effects of hard and soft tissue grafting and individualization of healing abutments at immediate implants: an experimental study in dogs.

PurposeTo evaluate the effects of intra-alveolar socket grafting, subepithelial connective tissue grafts, and individualized abutments on peri-implant hard and soft tissue outcomes following immediate implant placement.MethodsThis randomized experimental study employed 5 mongrel dogs, with 4 sites per dog (total of 20 sites). The mesial roots of P3 and P4 were extracted in each hemimandible and immediate dental implants were placed. Each site was randomly assigned to 1 of 4 different treatment groups: standardized healing abutment (control group), alloplastic bone substitute material (BSS) + standardized healing abutment (SA group), BSS + individualized healing abutment (IA group), and BSS + individualized healing abutment + a subepithelial connective tissue graft (IAG group). Clinical, histological, and profilometric analyses were performed. The intergroup differences were calculated using the Bonferroni test, setting statistical significance at P<0.05.ResultsClinically, the control and SA groups demonstrated a coronal shift in the buccal height of the mucosa (0.88±0.48 mm and 0.37±1.1 mm, respectively). The IA and IAG groups exhibited an apical shift of the mucosa (−0.7±1.15 mm and −1.1±0.96 mm, respectively). Histologically, the SA and control groups demonstrated marginal mucosa heights of 4.1±0.28 mm and 4.0±0.53 mm relative to the implant shoulder, respectively. The IA and IAG groups, in contrast, only showed a height of 2.6 mm. In addition, the height of the mucosa in relation to the most coronal buccal bone crest or bone substitute particles was not significantly different among the groups. Volumetrically, the IA group (−0.73±0.46 mm) lost less volume on the buccal side than the control (−0.93±0.44 mm), SA (−0.97±0.73 mm), and IAG (−0.88±0.45 mm) groups.ConclusionsThe control group demonstrated the most favorable change of height of the margo mucosae and the largest dimensions of the peri-implant soft tissues. However, the addition of a bone substitute material and an individualized healing abutment resulted in slightly better preservation of the peri-implant soft tissue contour.

Effect of patient- and surgery-related factors on supracrestal tissue reestablishment after crown lengthening procedure.

The standard application of a mean value of 2.04 mm for the biologic width has been demonstrated to result in inconsistent amounts of tooth extension following a crown lengthening procedure. Biologic width has been replaced by the supracrestal gingival tissue dimension, which includes the biologic width and sulcular depth. The question whether supracrestal gingival tissue dimension established at tissue maturation following a crown lengthening procedure is not significantly different from the presurgical dimension has not been fully answered. The primary objectives of the present prospective clinical study were to compare the preoperative and the 24-week dimensions of supracrestal gingival tissue following a crown lengthening procedure and assess the alterations in gingival margin position. A secondary objective was to assess selected patient- and surgery-related factors on supracrestal gingival tissue reestablishment. Twenty adult systemically healthy patients requiring a crown lengthening procedure were recruited for the study. A crown lengthening procedure was performed at 33 teeth and the patients were followed up to 24 weeks. The following parameters were recorded using customized stents for measurement reproducibility: stent-gingival margin (baseline, immediately after surgery, and at 6, 12, and 24 weeks), stent-bottom of sulcus (baseline and at 6, 12, and 24 weeks), stent-bone crest (baseline, at completion of osseous resection, and at 24 weeks), bone thickness (baseline, postsurgery), buccal gingival thickness (baseline, 24 weeks), and radiographic interproximal bone width (baseline, 24 weeks). Supracrestal gingival tissue, crown extension, and distance between the immediate postoperative position of the gingival margin relative to the contoured bone crest (F) were calculated. There were no statistically significant differences between supracrestal gingival tissue measurements at baseline and at 24 weeks for any of the four tooth sides. Crown extension remained significantly increased at 24 weeks compared to baseline for all sides, with the largest amounts of gingival creeping mesially and distally. A highly significant positive correlation (r = 0.97, P < .001) was demonstrated between flap positioning and stability of the gingival margin during the healing period. The closer was the F measurement to baseline supracrestal gingival tissue dimension, the less change in gingival margin was observed. The preliminary results of this investigation suggest the following: The presurgical supracrestal gingival tissue dimension can be used as a guideline measurement in crown lengthening procedures as it is reestablished with a similar apico-coronal dimension 24 weeks postoperatively; and crown extension is stable when the distance between the sutured gingival margin and the contoured osseous crest is similar to the preoperative supracrestal gingival tissue dimension.

Dynamic and static analyses of glass-like properties of three-dimensional tissues.

The mechanical properties of tissues are influenced by those of constituent cells in various ways. For instance, it has been theoretically demonstrated that two-dimensional confluent tissues comprising mechanically uniform cells can undergo density-independent rigidity transitions, and analysis of the dynamical behavior of tissues near the critical point revealed that the transitions are geometrically controlled by the so-called cell shape parameter. To investigate whether three-dimensional tissues behave similarly to two-dimensional ones, we herein extend the previously developed model to three dimensions both dynamically and statically, demonstrating that two mechanical states similar to those of glassy materials exist in the three-dimensional case. Scaling analysis is applied to the static model focused from the rearrangement viewpoint. The obtained results suggest that the upper critical dimension of tissues equals two and is therefore the same as that of the jamming transition.

Effect of Provisional Restorations with Ovate Pontics on Preservation of the Ridge after Tooth Extraction: Case Series.

To evaluate the effect of provisional restorations using ovate pontics on the hard and soft tissues of the alveolar ridge after tooth extraction. Patients with intact buccal bone after extraction of a maxillary incisor underwent a series of treatments. The protocol included tooth extraction and provisional restoration using ovate pontics. The outcomes were assessed 1, 3 and 6 months after the procedure, regarding changes in bone volume and soft tissue dimension. A total of 11 patients (6 female and 5 male) were treated using an ovate pontic provisional restoration after tooth extraction. After 6 months, bone loss at level 1, 3 and 5 mm below the most coronal section of the bone crest was 2.28 ± 0.53 mm, 1.51 ± 0.30 mm and 1.46 ± 0.41 mm, respectively. Changes in bone volume of these three levels were significantly lower (P < 0.01) than changes previously reported in the literature. The mesial and distal papillae recessed 0.47 ± 0.24 mm and 0.88 ± 0.57 mm, respectively, whereas the midfacial shrinkage was 0.86 ± 0.44 mm. The dimension of the ridge contour around the socket reduced mostly at 3 and 5 mm below the coronal section and the gingival mucosa, with values of 1.68 ± 0.48 mm and 1.61 ± 0.48 mm, respectively. Using a provisional restoration with ovate pontics after tooth extraction may preserve the alveolar ridge by sustaining the soft tissue, in particular the gingival papilla.

Immediate implant of immediate load in esthetic zone: Technique Socket Shield

Numerous publications have proved the dimensional changes alveolar ridges suffer after a tooth extraction. These changes lead, in most of the cases, to a width’s reduction close to 50%. Trying to minimize this physiological process which occurs after the extraction, different complementary techniques have been implemented in relation to dental implants placing. Many studies have tested how the dental root’s permanency in the alveolar bone attains to conserve the tissue dimensions to achieve esthetic restorations. Socket Shield technique, based on these criteria, is applied to avoid structural changes on the buccal bone plate, conserving a dental root portion which remains intact (the vestibular-buccal third), alongside with its periodontium. The dental implant is placed simultaneously to the dental extraction, behind the root remain.The stability and maintenance results of the alveolar bone volume are optimal, being this technique the only one which can achieve that. These results can be translated not only at the gingival margins, but also in the papilla architecture, a very important factor in the fixed prosthesis contours.

Application of inorganic nanomaterials in bone tissue engineering and regenerative medicine

Recently, tissue engineering and regenerative medicine, especially bone tissue engineering and regenerative medicine have developed rapidly. Bone tissue engineering is a complicated and dynamic bone remodeling process that starts with recruitment and migration of osteoblasts and then regulates their proliferation, differentiation, and mineralization. Scaffold is typically biodegradable material that plays a crucial role as one of the three elements of bone tissue engineering and regenerative medicine. Bone scaffold provides the mechanical support during reformation and repair of damaged or diseased bone. For more than a decade, a large amount of research work has been carried out on the designing of scaffolds, processing techniques, performance assessment, and medical application. Significant progress has been made toward scaffold materials for structural support for desired osteogenesis and angiogenesis abilities. To date, depending on the advanced technologies, the bioresorbable scaffolds possess controlled porosity and high mechanical properties are possible used as bone scaffold. Natural bone has delicate architectural structure that spans nanoscale to macroscopic dimensions, which determine the unique mechanical properties of bone. The hierarchical structure of natural bone can be defined as a nanocomposite consisting of inorganic nanocrystalline hydroxyapatite (HA), organic components (mostly are collagens) and water. The outside proteins assemble together to form an extracellular matrix (ECM) with nanostructured which influences the adhesion, proliferation, differentiation, and mineralization of several cell types, such as bone lining cell, mesenchymal stem cells, osteoblasts, osteocytes, and osteoclasts. To better mimic the nanostructure in natural ECM, many research groups over the past decade developed nano-based scaffolds (nanotubes, nanofibers, nanoparticles, and hydrogel) to resemble the ECM for promising candidates in replacing defective tissues. The high biomimetic properties and excellent mechanical features of nano-based scaffolds plays a vital role in stimulating cell adhesion and proliferation, as well as directing bone tissue formation through mimetic the nanometer dimension of natural bone tissue. Besides, mechanical properties are key factors for bone regeneration and bone local function. Nowadays, a large number of research groups have tried to manipulate the mechanical properties of scaffolds through designing the different nanosturctures, including nanofiber, nanoparticle, polymer matrices to mimic the nanocomposite structure of natural bone. These materials have highly stiffness, strength, and toughness properties that are promising in bone tissue engineering. Nanobiomaterials, especially inorganic nanobiomaterials, have excellent mechanical properties and biocompatibility, and are ideal for the preparation of scaffold materials for bone tissue engineering and regenerative medicine, showing a broad application prospect. In this article, we systematically review the application of inorganic nanomaterials, including hydroxyapatite, silicon-based nanomaterials, carbon-containing nanomaterials and several metal nanomaterials in bone tissue engineering and regenerative medicine. Although nanotechnology represents a major frontier with potential to significantly advance the field of bone tissue engineering, the application in the clinical regenerative engineering has limited. Currently, there are several limitations in regenerative strategies, including low efficient cellular proliferation, differentiation and mineralization, insufficient mechanical strength of scaffolds, and limited production of growth factors necessary for efficient osteogenesis. Therefore, there are still some issues on the nano-based scaffold should be cleared: (1) The interaction of nano-based scaffold and bioactive molecules, growth factors, and genetic material, (2) the biocomptibility, cytotoxicity, and biodegradation of nano-based scaffold, and (3) nano-based scaffold mechanical stability, cellular survival, and molecular mechanism of inducing bone formation. As the development of nanotechnology, ultimate translation to the clinical application may allow for improved therapeutic outcomes in patients with large bone deficits and osteodegenerative diseases.

Pre-vascularized dermis model for fast and functional anastomosis with host vasculature

Skin engineering for clinical applications has gained numerous advances, however, most of the available dermis substitutes are exogenous matrices acting for a limited time. Indeed, after implantation these matrices need to be colonized by host cells such as fibroblast and endothelial cells which respectively produce their own extracellular matrix and set a vascular network within the construct. These steps are essential to guarantee implant efficacy, but they may require a long time depending on tissue dimension and lesion severity. Here we show the pre-vascularization process of a dermis equivalent featured by an endogenous matrix produced by human dermal fibroblasts. In this environment, endothelial cells were able to develop mature capillary-like-structures (CLS) as demonstrated by both the inner lumen and the positivity for alpha-SMA, laminin and collagen. The pre-vascularized dermis model (PVD) so obtained had a human matrix populated by fibroblasts as well as a complex capillary network making the construct ready to be implanted. These features make the graft very easy to handle during the surgery. In vivo results showed that 7 days after implantation CLS effectively anastomosed with host vessels. Therefore we argue that the proposed PVD may represent a new class of dermis substitute of strong clinical interest.

Mandibular advancement device therapy for obstructive sleep apnea: a prospective study on predictors of treatment success

ObjectiveTo survey potential predictors of success of mandibular advancement device (MAD) therapy in patients with obstructive sleep apnea (OSA), and in particular, to examine anatomical narrowings and sleep-related collapse levels in the upper airway. MethodsThis was a prospective study of 62 OSA patients (median apnea–hypopnea index [AHI] of 34), who were treated with a custom-made, monobloc MAD. The upper airway was examined by inspection, nasopharyngoscopy, overnight acoustic reflectometry recording collapses, and cephalometry of soft tissue dimensions (in addition to skeletal parameters). MAD treatment was controlled by polysomnograpy before and after at least five weeks from the beginning of treatment. Independent predictors of actual reduction in AHI and treatment success (reduction in AHI ≥ 50% with residual AHI < 10) were determined, using multivariable linear and logistic regression. ResultsPositional OSA (POSA) and nonsupine AHI (adjusted for upper airway narrowness and collapses, together with gender, age, body mass index, neck circumference, and baseline AHI) were the only independent predictors: POSA indicative for success, and nonsupine AHI inversely related to success. Cephalometry was not predictive. Two predictive models were proposed, one based on POSA having a specificity of 70% and sensitivity of 69%, and the other based on nonsupine AHI, generating a receiver operating characteristic (ROC) curve (area under ROC = 0.78). Using the ROC model, specificity could be increased to 80% without lowering sensitivity. ConclusionsOnly variables related to sleep position proved to be independent predictors of success with MAD therapy. The results could be explained by the MAD counteracting the mandible from moving backwards when sleeping supine.

The Influence of Initial Hard and Soft Tissue Dimensions on Initial Crestal Bone Loss of Immediately Loaded Dental Implants.

The aim of this case-control study was to evaluate the influence of soft tissue thickness at implant placement (thin [< 3 mm] vs thick [≥ 3 mm]) and bone volume (abundant vs limited) on initial crestal bone remodeling of immediate postextraction and delayed (healed site) implants in immediate loading situations. A total of 67 patients with 133 implants could be evaluated, of which 77 were placed immediately after extraction and 56 in healed ridges. If sufficient bone volume is present and primary stability is achieved, immediate loading of the implant yields good clinical and radiographic outcomes, yet implants placed in healed ridges with thin soft tissues are more prone to initial crestal bone loss.

Discs large 1 controls daughter-cell polarity after cytokinesis in vertebrate morphogenesis

Vertebrate embryogenesis and organogenesis are driven by cell biological processes, ranging from mitosis and migration to changes in cell size and polarity, but their control and causal relationships are not fully defined. Here, we use the developing limb skeleton to better define the relationships between mitosis and cell polarity. We combine protein-tagging and -perturbation reagents with advanced in vivo imaging to assess the role of Discs large 1 (Dlg1), a membrane-associated scaffolding protein, in mediating the spatiotemporal relationship between cytokinesis and cell polarity. Our results reveal that Dlg1 is enriched at the midbody during cytokinesis and that its multimerization is essential for the normal polarity of daughter cells. Defects in this process alter tissue dimensions without impacting other cellular processes. Our results extend the conventional view that division orientation is established at metaphase and anaphase and suggest that multiple mechanisms act at distinct phases of the cell cycle to transmit cell polarity. The approach employed can be used in other systems, as it offers a robust means to follow and to eliminate protein function and extends the Phasor approach for studying in vivo protein interactions by frequency-domain fluorescence lifetime imaging microscopy of Förster resonance energy transfer (FLIM-FRET) to organotypic explant culture.

Influence of Implant Neck Design on Peri-Implant Tissue Dimensions: A Comparative Study in Dogs.

This in vivo study assessed (hard and soft) peri-implant tissue remodeling around implants with micro-ring and open-thread neck designs placed in a dog model. Twenty histological sections corresponding to four different implant designs that were placed in America Foxhound dogs were obtained from previous studies. All the implants had been placed under identical conditions and were divided into four groups: Group A, micro-rings on implant neck plus 0.5 mm refined surface; Group B, micro-rings on implant neck; Group C, open-thread neck; and, Group D, double-spiral neck. Eight weeks after surgery, the integrated implants were removed and processed for histological examination. Crestal bone loss and bone-to-implant contact was greater for micro-ring necks than open-thread necks. Soft tissues showed significant differences on both buccal and lingual aspects, so that the distance from peri-implant mucosa to the apical portion of the barrier epithelium was smaller in the micro-ring groups. So, in spite of generating greater bone-to-implant contact, implants with micro rings produced more bone loss than open-thread implants. Moreover, the outcomes that were obtained IPX implants smooth neck design produced less bone loss in the cervical area, following by Facility implants when compared with the other open thread and microthreaded implant designs. Implant thread design can influence on bone remodeling in the cervical area, related to bundle bone preservation.

Marginal soft tissue stability around conical abutments inserted with the one abutment-one time protocol after 5 years of prosthetic loading.

Soft tissue stability is crucial to obtain and maintain optimal esthetic results. This study aimed to investigate, over 5 years, the soft tissue response using a conical abutment together with the "one-abutment one-time" (OA-OT) protocol in the restoration of implants inserted in the anterior esthetic area. From January 2011 to January 2012, all consecutive patients requiring an implant n the maxillary area between canines were enrolled. After submerged healing and osseointegration, a definitive abutment with a provisional crown was inserted. After 1 month, the definitive crown was delivered (Tdef). Analog impressions were taken before tooth extraction (T0), at implant insertion Timpl, and Tdef, and at 12 months (T1) and 60 months (T5). Casts were scanned and superimposed using a dedicated software. Differences in vertical height of soft tissue margins between the digitized model casts were calculated and paired sample t test was conducted to compare results. To detect the potential role of biotype, groups (thick vs. thin) were compared by analysis of variance with general linear model. Twenty-five patients were enrolled. Three patients dropped out. At the 60-month, 22 patients (12 men and 10 women with mean age of 68.3 ± 11 years) concluded the study follow-up. Horizontal changes demonstrated gain of 1.06 mm at Timpl, 0.94 mm at Tdef, 0.92 mm at T1 and 0.97 mm at T5 compared to T0. Vertical changes demonstrated gain of 0.84 mm at Timpl, 0.11 mm at Tdef, 0.29 mm at T1 and 0.59 mm at T5 compared to T0. The analysis of variance showed a significant better performance of thick biotype in soft tissue horizontal width (P = .022). No statistical differences were noticed for vertical width (P = .111). The use of a conical abutment together with the OA-OT approach allowed longitudinal stable soft tissue dimensions.

A simplified soft tissue management for peri-implant bone augmentation.

This case series illustrates a simplified soft tissue management, namely, the subperiosteal peri-implant augmented layer (SPAL), to increase hard and soft tissue dimensions at the most coronal portion of an implant. Twenty-seven implants in 16 patients presenting either a buccal bone dehiscence or a thin (< 1 mm) buccal cortical bone plate (BCBP) were consecutively treated. Briefly, a split-thickness flap (namely, the mucosal layer) was raised on the buccal aspect. Then, the periosteal layer was elevated from the bone crest. A full-thickness flap was elevated on the oral aspect. After implant site preparation, a xenograft was used to fill the space between the periosteal layer and the BCBP and/or exposed implant surface and, if present, to completely correct the bone dehiscence. The periosteal layer was sutured to the oral flap. The mucosal layer was coronally advanced and sutured to submerge both the graft and the implants. At 3 to 6 months, a re-entry procedure for implant exposure was performed. Healing was uneventful, with no signs of infection in all cases. A wound dehiscence was observed in three implants in two patients at 2 weeks postsurgery. Out of 15 implants showing an initial bone dehiscence, 12 implants (80%) showed a complete resolution, with a subperiosteal tissue thickness (SPTT) at the time of re-entry of 3.1 ± 1.0 mm. Three implants presented a residual dehiscence of 1 mm (two implants) or 2 mm (one implant), with a SPTT of at least 2 mm. Out of 12 implants showing a thin BCBP at implant placement, 10 implants (90%) revealed a SPTT ≥ 2 at the time of re-entry. Two implants revealed a SPTT of 1 mm. The SPAL technique represents a valuable simplified surgical approach associated with a low rate of complications in the treatment of peri-implant bone dehiscence and in the horizontal augmentation of peri-implant tissue thickness.

Peri‐implant soft and hard tissue response to hybrid implant + a 6 month follow up

Background The health of the periimplant tissues play an important in the long term outcome of dental implants. Bone and soft tissue remodeling can be influenced by dental implant materials, designs and surface modifications. Several studies on implants with the same design but with different surfaces such as hybrid implants are lacking at the present time. Aim/Hypothesis The purpose of this prospective study was to investigate the influence of soft and hard tissue response to a hybrid dental implant with a platform switch inserted at 6 months after implantation in the posterior mandible. Material and Methods From August 2016 to January 2017, 16 consecutive patients were enrolled (8 men and 8 women, mean age 51.2 years with 32 implants, needing two implant-supported restoration in the posterior mandible. An impression was taken 6 weeks later, and a final restoration was positioned. Follow-up examinations, clinical parameters, photographs, and intraoral digital radiographs were made at baseline and six month after definitive restorations to evaluate the marginal bone level changes. Cast analysis were performed to detect soft tissue vertical and horizontal changes. Implant stability was measured with an (Osstell®) ISQ implant stability meter. Results Postoperative healing was uneventful. All implants were clinically osseointegrated. Changes of marginal bone level and soft tissue dimensions were recorded at implant installation and at 6 months. No bone defect around implants and there were no signs of inflammation. Soft tissue levels significantly improved between baseline and 6 month follow up. Periodontal parameters never exceeded the physiological levels. The ISQ readings obtained the high stability at 6 month follow up. Conclusions and Clinical Implications Within the limitations of this prospective study, the analyzed hybrid implants obtained favorable results in the posterior mandible. Long term randomized controlled clinical trials on hybrid implants are necessary to confirm these results.

Lateral Cephalometric Standards for Mongolian 6-15 Year Old Children with Normal Occlusion

Objectives: The aim of this study was to establish the age and gender-specific lateral cephalometric standards for Mongolian children with normal occlusion. Methods: A total of 541 children between 6 and 15 years of age were selected based on the normal occlusion criteria. Lateral cephalograms of each subject were scanned and analyzed with the use of WinCeph version 11.0 software package. Descriptive statistics (mean and standard deviation) were calculated for all measured variables. Independent t-tests were performed to assess the intergender differences. Results: Cephalometric angular measurements remain largely constant, whereas most cephalometric linear measurements change with advancing age, such as anterior facial height (N-Ans, Ans-Me), hard palatal length (Ans-Pns) mandibular ramus height (Cd-Go), mandibular body length (Cd-Gn) were increasing significantly by dental age in both gender. Gender differences were not statistically significant for any of the angular measurement at ages studied, but linear measurements of male subjects had larger average values than female subjects. Conclusion: Our results showed that linear cephalometric dimension of the hard tissue was gender-dependent. Therefore, gender-specific differences of craniofacial distances should be taken into account during diagnosis and treatment planning. The results from this study can be used as reference values for 6-15 years old children of Mongolia.

Influence of different implant operative procedures on morphologic changes in peri-implant alveolar bone and soft tissue: a one-year prospective clinical study

PurposeTo prospectively evaluate morphological changes in the horizontal and vertical dimensions of peri-implant tissue at 1-year post-prosthesis implantation. MethodsThirty-four patients who had received implants with conical connections in the aesthetic region were included in the follow-up study. Patients had received either traditional delayed implant placement or tissue augmentation with or without immediate implant placement. The horizontal and vertical dimensions of the buccal alveolar bone of the implant and its surrounding soft tissues were then evaluated using cone beam computed tomography. ResultsImplants placed alongside tissue augmentation, with or without immediate placement, were as successful as those placed into sites with traditional delayed implant placement. Statistically significant negative correlations were observed between initial horizontal bone thickness and changes in vertical bone height (r=0.585, p<0.05) and vertical soft tissue height (r=0.378, p<0.05), and between initial horizontal soft tissue thickness and the change in vertical soft tissue height (r=0.627, p<0.05). ConclusionsRegardless of the bone and soft tissue augmentation approach, implants with conical connections may effectively preserve peri-implant tissues. However, the thickness of the peri-implant soft tissue is essential, because a change in soft tissue margin level tends to be affected by the thickness of the peri-implant soft tissue rather than the bone width.

Sub-periosteal peri-implant augmented layer technique for horizontal bone augmentation at implant placement.

In the present study, a novel surgical technique, namely the sub-periosteal peri-implant augmented layer (SPAL), to increase hard and soft tissue dimensions at the most coronal portion of an implant will be thoroughly described. The surgical buccal access at the time of implant placement first consisted of a split-thickness flap to raise the most superficial mucosal layer, followed by the elevation of the periosteal layer which was detached from the buccal cortical bone plate (BCBP). A full-thickness flap was elevated on the oral aspect. A xenograft was used to fill the space between the periosteal layer and the BCBP, and the periosteal layer was sutured to the oral flap. The mucosal layer was coronally advanced and sutured to submerge both the graft and the implants. At implant uncovering at 4 months, an increase in the thickness (>2 mm) of the buccal peri-implant tissues was observed. A free gingival graft was used to enhance the dimensions of buccal keratinized mucosa. The SPAL technique may represent a surgical option for the horizontal augmentation of peri-implant tissue thickness.

Influence of the Buccal Bone Crest Width on Peri-Implant Hard and Soft Tissues Dimensions: A Histomorphometric Study in Humans.

To histologically evaluate hard and soft tissues adaptation at screw-shaped devices installed at recipient sites in the distal segments of the alveolar edentulous ridge prepared with a buccal bone width of 1 or 2 mm. Sixteen volunteers received 2 nonsubmerged titanium implants each; after 3 months, biopsies were obtained and processed for histology. The distances between implant shoulder (IS), top of the bony crest (C), coronal level of osseointegration (B), peri-implant mucosa (PM), and apical extension of the junctional epithelium (aJE) were measured. There were no significant statistically differences between test and control sites regarding IS-C, IS-B, PM-IS, PM-B, PM-aJE, aJE-B measurements. The horizontal bone resorption 1 mm below IS was 0.3 ± 0.3 and 1.0 ± 0.7 mm at the test and control sites, respectively. This difference was statistically significant. Similar hard and soft tissues dimensions were observed in both groups. However, a higher horizontal bone resorption was seen at the control sites. Nonsubmerged implant installation should be performed when a 1 mm buccal bony crest width is present so as to limit the horizontal bone resorption.