Soft Tissue Position Research Articles

Orbital Soft Tissue Position after Globe-Sparing Maxillectomy and Inferior Orbital Rim Reconstruction: A Pilot Study.

Orbital Soft Tissue Position after Globe-Sparing Maxillectomy and Inferior Orbital Rim Reconstruction: A Pilot Study.

Forensic facial reconstruction: an anthropometric study of the ear

ABSTRACT The recognition of an individual, supported by forensic facial reconstruction (FFR), can be established using several anatomical references, such as soft tissue thickness, position, and size of the eyes, nose, lips, and ears. The inclusion of additional visual inputs to the process, such as the ear, can refine an individual’s appearance. However, to the best of our knowledge, existing methods are scarce and undertested. To improve recognition, this study aimed to verify the size, position, and inclination of the ears, and their possible relationship with the skull. Ninety-nine research participants (55 females and 44 males) aged between 18 and 65 years were evaluated. Direct (on research participants) and indirect (photographs) measurements were performed using imaging software. Eighteen relationships were tested to determine their sizes, inclinations, and positions with respect to other cranial structures. It can be concluded that considering both length and width, the male ear is larger than the female ear, and based on the angle between the superaurale and otobasion inferius line and the Frankfurt plane, the ear inclination is 73º for both sexes. In addition, the upper portion of the ear coincides with the eyebrows. These references can help determine the characteristics of the ear during FFR.

Soft tissue and incisor position changes in class I bimaxillary subjects after retraction using friction and frictionless mechanics

Aim: Bimaxillary protrusion is a common condition observed irrespective of race and ethnicity and is a chief concern for patients who seek orthodontic treatment. The aim of this study was to compare and evaluate changes in soft tissue structures and incisor positions in class I bimaxillary protrusion subjects undergoing orthodontic therapy when friction and frictionless mechanics were used. Methods: Two groups with a total of 40 patients aged 18–30 years diagnosed with class I bimaxillary protrusion treated by extracting first premolars were considered for this study. Patients treated with friction mechanics were included in Group 1 and those treated with frictionless mechanics in Group 2. The digital lateral cephalograms were calibrated and analyzed using Nemoceph software. Selected landmarks were marked on pre- and post-treatment cephalograms and assessed for intra- and inter-group soft tissue and incisor position changes. Student’s t-test was used to analyze the collected data using SPSS 20 software. Result: Intragroup comparison revealed significant changes in both groups. Inter-group comparison of the selected parameters between groups 1 and 2 showed differences but without any statistical significance, except for the inter-incisal angle. Conclusion: Pre- and post-treatment comparison analysis revealed significant soft tissue changes in both groups. However, the comparison between friction and frictionless mechanics showed no statistically significant changes.

Assessment of Soft Tissue, Airway Dimension and Hyoid Bone Position in Class II Patients Treated by PowerScope Class 2 Corrector.

This study aims to assess the changes in the soft tissue, pharyngeal airway dimensions, and hyoid bone position in patients treated with PowerScope Class 2 corrector to correct the skeletal Class II pattern. This study was conducted on a sample of 20 cases diagnosed with Class II malocclusion. The lateral cephalograms were taken before (T1) and after functional appliance therapy (T2) and were traced. The outcomes were compared for the mean changes in soft tissue, airway way dimension, and hyoid bone position. The paired t-test was used for the data comparisons wherein p < 0.05 was kept for statistical significance. The mean values before and after treatment for H angle, mentolabial angle, lower lip E-line, upper lip S-line, lower lip S-line, and lip strain were 19.88 ± 2.77 vs 17.13 ± 1.659, 94.09 ± 12.164 vs 101.75 ± 11.28, -2.47 ± 1.213 vs -1.38 ± 0.976, 3.99 ± 0.19 vs 2.64 ± 0.32, 9.01 ± 0.247 vs 9.43 ± 0.238, 10.24 ± 0.510 vs 10.64 ± 0.52, respectively, which were statistically significant (p < 0.05). All airway spaces (except for lower pharyngeal space) and hyoid bone parameters were significantly improved posttreatment. The facial convexity, upper E-line, Z-angle, nasolabial angle, and lower pharyngeal space did not show statistically significant changes. The rest of the soft tissue parameters, oropharyngeal air spaces, and hyoid positioning measured in the study showed significant improvement after treatment with the PowerScope appliance in Class II patients. Class II malocclusion is the most common dental anomaly with a high degree of prevalence in the population. This study will help the clinician in understanding the improvement of soft tissue, airway dimension, and hyoid bone position changes on treatment with a fixed functional appliance for the correction of Class II cases, thereby ensuring the greater success of orthodontic therapy in the future.

Early results of intramedullary nail fixation in distal tibia oblique osteotomy for the reduction of soft tissue complications.

During distal tibial oblique osteotomy, external fixators can increase pin site infection risk, whereas plates can cause wound necrosis, necessitating a compromise between soft-tissue position and length. We provide the first report of the early results of intramedullary nail fixation in these osteotomies for avoiding soft tissue complications. Ten ankles, classed as Takakura-Tanaka stages 3a to 4 and unclassified and treated via distal tibial oblique osteotomy for ankle osteoarthritis between 2017 and 2021, were included. Osteotomy was performed obliquely from the distal medial tibia to the tibiofibular joint. The distal tibial fragment was rotated distally in the coronal plane for realignment. An intramedullary nail fixation was applied for stabilization. The resulting gap was filled with iliac bone graft. Ankles were evaluated on the Japanese Society for Surgery of the Foot ankle-Hindfoot Scale and Self-Administered Foot Evaluation Questionnaire before surgery and at final follow-up. Radiographic assessments were performed. Bone union was achieved within 3 months in all patients. There were no cases of wound necrosis or correction loss postsurgery. Japanese Society scale scores significantly improved from 40.3 ± 15.9 to 87.5 ± 12.6 (P < 0.01). Mean self-evaluation scale scores (pain and pain-related, physical functioning and daily living, social functioning, general health and well-being) improved significantly. shoe-related scores did not change significantly but improved. There was no correction loss after surgery, with an average widening of 24.2 mm and opening angle of 22.6° at the osteotomy site. Our study showed that intramedullary nail for fixation of the osteotomy site in distal tibial oblique osteotomy effectively prevents soft tissues complications even in osteotomy sites with large openings.

Reproducibility of Manual Transfer of the Clinical Natural Head Position: Influence on the Soft Tissue and Hard Tissue Position of 3-Dimensional Virtual Surgical Planning

The purpose of this study was to assess the reproducibility of manually transferring the clinical natural head position (NHP) to the 3-dimensional (3D) virtual surgical planning and its subsequent influence on the soft tissue and maxillary hard tissue position. A retrospective cohort study was set up. The study population consisted of subjects who underwent bimaxillary osteotomies between 2016 and 2020 at the Department of Oral and Maxillofacial Surgery in Radboud University Medical Centre (Nijmegen, the Netherlands). Cone beam computed tomography scans, dentition data, and clinical photographs were acquired 4weeks before surgery. Two attempts (NHP1 and NHP2) were performed by a single examiner to manually transfer the NHP. 3D transformation matrices were used to quantify the transferred NHP in 3 degrees of freedom (pitch, roll, and yaw). Landmarks and surface-based matching were used to quantify the influence on the soft tissue and hard tissue positions in 6 degrees of freedom. The primary outcome variable was the reproducibility of manually aligning the NHP. The secondary and tertiary outcome variables were the effect of the reproducibility of the manually aligned NHP on the soft tissue and hard tissue displacements in the 3D virtual surgical planning. The study population consisted of 109 subjects: 37 males (33.9%) and 72 females (66.1%) with a mean age of 29.1±10.3years (range, 17.0 to 59.0). The manual transfer of pitch alignment (2.24±1.64⁰; 95% confidence interval [CI], 1.93 to 2.55) was significantly less reproducible than the roll (0.56±0.44⁰; 95% CI, 0.48 to 0.64; P<.001) and yaw (0.67±0.92⁰; 95% CI, 0.50 to 0.85; P<.001). Subsequently, this alignment error influenced the position of the maxilla (incisal point) and soft tissue menton by 0.85±0.86mm and 1.01±1.00mm vertically and 0.78±1.10mm and 0.80±1.18mm sagittally. The present study demonstrated that the manual transfer of the NHP from the clinical situation to the virtual environment influenced the soft tissue and hard tissue position and that a more reproducible method of transferring the clinical NHP is recommended.

Occlusal plane rotation and orthodontic decompensation: influence on the outcome of surgical correction of classIII malocclusion.

The aim of this retrospective multicenter study is to evaluate the influence of surgical manipulation of the upper occlusal plane (UOP) and orthodontic decompensation on the outcome of classIII orthognathic surgery. Incisor inclinations, occlusal plane inclination as well as skeletal and soft tissue changes were assessed in lateral cephalograms of 85classIII patients who had previously undergone orthognathic surgery. Fourteen linear and eight angular measurements were performed on each radiograph at the beginning of treatment (T0), before surgery (T1) and at the end of treatment (T2) using imaging software. After measurement of variables, Mann-Whitney U‑test, repeated-measures analysis of variance (ANOVA) with Bonferroni multiple comparison test, and Spearman's correlation analysis were performed. Astatistically significant improvement was observed in both sagittal skeletal and soft tissue measurements (p < 0.05). Surgical change in UOP was significantly correlated with changes in overbite, upper lip strain and soft tissue B‑point change in the sagittal direction (p < 0.05). Overjet change was significantly correlated with changes in the soft tissue and all sagittal skeletal parameters except for SNA. Changes in the incisor inclinations was significantly correlated with changes in the sagittal skeletal parameters and lower facial height. Significant differences were also observed between the groups with induced clockwise or counterclockwise rotation of the mandible in terms of IMPA (long axis of LI to mandibular plane), overbite, upper lip strain and position of soft tissue B‑point (p < 0.05). Sufficient dental decompensation is crucial for controlling the sagittal as well as the vertical relationship during surgery. Counterclockwise rotation provides an increase in sagittal projection of the mandibular body at the soft tissue B‑point.

Simulation of soft tissue stimulation–Indication of a skull bone vibration mechanism in bone conduction hearing

Soft tissue conduction has been proposed as an alternative to bone conduction (BC) for hearing vibrations applied at soft tissue positions at the human head. Arguments for soft tissue conduction originate primarily from experimental studies with stimulation applied to different positions such as the neck, the eye, and directly to the dura. To investigate the mechanism for hearing when stimulations are at soft tissue positions, experimental studies were replicated using the finite element model for BC research, the LiUHead. The vibrations at the cochlear promontory and the sound pressure in the cerebrospinal fluid (CSF) close to the inner ear were extracted from simulations in the LiUHead. The LiUHead simulations were able to replicate data in the literature of cochlear promontory vibration levels and CSF sound pressures with stimulation applied at the soft tissue positions and at the skin covered mastoid. It was shown that the mechanical point impedance of the soft tissue positions affected the output of the BC transducer at frequencies below 1 kHz. The LiUHead simulated cochlear promontory velocities predicted the soft tissue position's hearing thresholds reported in the literature within the inter-study range. This indicates that the hearing mechanism for stimulation at soft tissue positions equals the hearing mechanism for conventional BC hearing, and that soft tissue conduction is not an alternative hearing mechanism. Moreover, the simulations indicated that the CSF sound pressure is not an important pathway for BC hearing and that the CSF pressure is generated by the local skull bone vibrations.

Custom-Made Zirconium Dioxide Implants for Craniofacial Bone Reconstruction.

Reconstruction of the facial skeleton is challenging for surgeons because of difficulties in proper shape restoration and maintenance of the proper long-term effect. ZrO2 implant application can be a solution with many advantages (e.g., osseointegration, stability, and radio-opaqueness) and lacks the disadvantages of other biomaterials (e.g., metalosis, radiotransparency, and no osseointegration) or autologous bone (e.g., morbidity, resorption, and low accuracy). We aimed to evaluate the possibility of using ZrO2 implants as a new application of this material for craniofacial bone defect reconstruction. First, osteoblast (skeleton-related cell) cytotoxicity and genotoxicity were determined in vitro by comparing ZrO2 implants and alumina particle air-abraded ZrO2 implants to the following: 1. a titanium alloy (standard material); 2. ultrahigh-molecular-weight polyethylene (a modern material used in orbital surgery); 3. a negative control (minimally cytotoxic or genotoxic agent action); 4. a positive control (maximally cytotoxic or genotoxic agent action). Next, 14 custom in vivo clinical ZrO2 implants were manufactured for post-traumatologic periorbital region reconstruction. The soft tissue position improvement in photogrammetry was recorded, and clinical follow-up was conducted at least 6 years postoperatively. All the investigated materials revealed no cytotoxicity. Alumina particle air-abraded ZrO2 implants showed genotoxicity compared to those without subjection to air abrasion ZrO2, which were not genotoxic. The 6-month and 6- to 8-year clinical results were aesthetic and stable. Skeleton reconstructions using osseointegrated, radio-opaque, personalized implants comprising ZrO2 material are the next option for craniofacial surgery.

Flow Chart for Reconstructive Head and Neck Surgery in Composite Soft and Hard Tissue Defects.

Virtual planning of reconstructive surgical procedures in patients with osseous and composite defects in the head and neck region is becoming increasingly a state of the art modality. However, computational algorithms lack the capability of planning the involved soft tissue and vascular pedicle position. The authors present a flow-chart to solve this problem in the reconstruction of defects of the upper and lower jaw. Clinical records from 2013 to 2018 from a tertiary care center were screened for patients undergoing osseous reconstruction in the head and neck region. A flow-chart considering soft tissue positioning and the anatomical course of the vascular pedicle was assessed in consideration of the defect and donor-site. A total of 81 osseous and composite microvascular reconstructive procedures have been conducted. Defects of the lower jaw were the most common (n = 61). The free fibula flap was the most common reconstructive measure and showed a wide versatility of surgical options to reconstruct these defects. The flow charts were assessed accordingly in these procedures. Soft tissue and vascular pedicle positioning can be planned pre-operatively by the use of virtual planning and should be considered as an enhancement tool to the already existing computational algorithms of planning hard tissue reconstruction.

Correlations between objective measurements and subjective evaluations of facial profile after orthodontic treatment.

ObjectiveTo investigate the correlations between objective measurements and subjective evaluations of post-treatment facial attractiveness.MethodsTen orthodontists rated the subjective visual analog scale (VAS) scores of the facial profiles of 95 patients who had undergone orthodontic treatment. Post-treatment cephalograms and photographs were used. Eleven soft tissue measurements and eight maxillary incisor measurements were constructed and analyzed. Correlations between objective measurements and subjective VAS scores were evaluated using Pearson correlation and quadratic regression analysis.ResultsThe VAS scores of different facial proportions were all correlated with the total VAS score. Among soft tissue measurements, the distances from the upper and lower lips to the E line, H angle, forehead inclination, distance from lower lip to the H line, and pogonion-menton angle were negatively correlated with the VAS scores. The Z angle, with a parabolic distribution, was also correlated with the VAS scores. Among maxillary incisor measurements, the distance from the maxillary incisors to the forehead’s anterior limit line and the angulation of the maxillary incisors to the APo line were negatively correlated with the VAS scores.ConclusionsSeveral soft tissue and maxillary incisor position measurements were correlated with facial profile evaluation and therefore might be used to evaluate facial attractiveness.

Esthetic, clinical, and radiographic outcomes of two surgical approaches for single implant in the esthetic area: 1-year results of a randomized controlled trial with parallel design.

The objectives of this study were to compare (a) esthetic, (b) clinical, (c) radiographic, and (d) patient-centered outcomes following immediate (Type 1) and early implant placement (Type 2). Forty-six subjects needing a single extraction (premolar to premolar) were randomly allocated to Type 1 or Type 2 implant placement. One year following permanent restoration, evaluation of (a) Esthetics using soft tissue positions, and the pink and white esthetic scores (PES/WES), (b) Clinical performance using probing depth, modified plaque index, and sulcus bleeding index (c) Radiographic bone level, and (d) Patient satisfaction by means of visual analogue scales (VAS) was recorded. Thirty-five patients completed the one-year examination (Type 1, n=20; Type 2, n=15). Type 1 implants lost 1.03±0.24mm (mean±SE) of mid-facial soft tissue height while Type 2 implants lost 1.37±0.28mm (p=0.17). The papillae height on the mesial and distal was reduced about 1mm following both procedures. Frequency of clinical acceptability as defined by PES≥6 (Type 1: 55% vs. Type 2 40%), WES≥6 (Type 1: 45% vs. Type 2 27%) was not significantly different between groups (p>0.05). Clinical and radiographic were indicative of peri-implant health. Patient-centered outcomes failed to demonstrate significant differences between the two cohorts. One year after final restoration, there were no significant differences in esthetic, clinical, radiographic, and patient-centered outcomes following Type 1 and Type 2 implant placement. At one year, patient satisfaction may be achieved irrespective of the two placement protocols.

Dynamic simulation on the area shrinkage of lower leg for the top part of men’s socks using finite element method

Socks are one of the most important clothes in people’s daily life. This study aimed at the problems existing in the wearing of socks, took the top part of men’s socks as research object, and the contact between human body and socks as elastic contact. The position and shape of skin, soft tissue, and bones in lower leg cross section were acquired through non-contact three-dimensional human scanning and CT scan. Based on these, finite element model of the lower leg cross-section and top part of socks were established for the first time, respectively. Because wearing socks is a continuous process, consequently, we defined the maximum time putting on the sample socks as 12 h in this research work, and then divided the periods of dressing time into six stages, which were instantaneous, 1 h, 2 h, 4 h, 8 h, and 12 h, respectively. After simulating the distribution of pressure and displacement of the top part of socks in dressing using ANSYS software, we divided the lower leg cross section into 12 equal regions according to angle considering the displacement distribution, and then obtained the area shrinkage of each region in six periods of times by calculation. According to the tendency of area shrinkage distribution, the top part of men’s sock could be designed with a different degree of elasticity in diverse regions combined with subjective pressure comfort during the course of sock design. All these solutions are of great significance to the optimization design of socks and can provide theoretical basis for the structural improvement of functional socks and the prediction of clothing pressure.

Orthognathic Surgery and Facial Changes - A Review

Overlying facial soft tissue is influenced by both surgical movement of bony segment and orthodontic movement of the teeth. That is why supportive evidence about calculation of surgical movement and changes in soft tissue positions should be considered before making any treatment plan to predict soft tissue changes that can occur with dental and skeletal tissue alteration after surgery. Thus, soft tissue consideration is an important factor for any orthognathic surgical treatment planning for excellent, acceptable and satisfactory results. This review article is focused on soft tissue changes associated with various orthognathic surgeries.

2017

Extensor mechanism complications involving the patella frequently result in total knee arthroplasty (TKA) failure. Postoperative patellar dislocation may be caused by soft tissue imbalance, improper sizing, and position of the prosthesis. This report describes a case of revision TKA requiring several rounds of soft tissue releases in an effort to treat the patient's chronic patellar dislocation. In the process, a novel surgical approach was developed for the surgical management of refractory chronic patellar dislocations. Postoperative follow-up at 1, 2, 6, 12, and 24 months indicated no complaints of patellar subluxation or dislocation. Plain films also demonstrated no effusion, fracture, or patellar dislocation on sunrise, anteroposterior, and lateral views. This novel anatomic repositioning of the vastus lateralis around the quadriceps tendon converted a pathologic lateralizing force into a medial stabilizer. On follow-up evaluations, successful patellar tracking without dislocation has been demonstrated. (Journal of Surgical Orthopaedic Advances.

Eye Size and Set in Small-Bodied Fossil Primates: A Three-Dimensional Method.

We introduce a new method to geometrically reconstruct eye volume and placement in small-bodied primates based on the three-dimensional contour of the intraorbital surface. We validate it using seven species of living primates, with dry skulls and wet dissections, and test its application on seven species of Paleogene fossils of interest. The method performs well even when the orbit is damaged and incomplete, lacking the postorbital bar and represented only by the orbital floor. Eye volume is an important quantity for anatomic and metabolic reasons, which due to differences in eye set, or position within (or outside) the bony orbit, can be underestimated in living and fossil forms when calculated from aperture diameter. Our Ectopic Index quantifies how much the globe's volume protrudes anteriorly from the aperture. Lemur, Notharctus and Rooneyia resemble anthropoids, with deeply recessed eyes protruding 11%-13%. Galago and Tarsius are the other extreme, at 47%-56%. We argue that a laterally oriented aperture has little to do with line-of-sight in euprimates, as large ectopic eyes can position the cornea to enable a directly forward viewing axis, and soft tissue positions the eyes facing forward in megachiropteran bats, which have unenclosed, open eye sockets. The size and set of virtual eyes reconstructed from 3D cranial models confirm that eyes were large to hypertrophic in Hemiacodon, Necrolemur, Microchoerus, Pseudoloris and Shoshonius, but eye size in Rooneyia may have been underestimated by measuring the aperture, as in Aotus. Anat Rec, 299:1671-1689, 2016. © 2016 Wiley Periodicals, Inc.

Immediate implant placement and provisionalization in the aesthetic zone using a flapless or a flap-involving approach: a randomized controlled trial.

We conducted a randomized controlled trial to compare the effect of flapless (FLS) or flap-involving (F) immediate placement and provisionalization of single-tooth implants in the aesthetic zone. Thirty-nine patients were randomized following extraction of a non-restorable tooth to a FLS or F group. All implants were immediately placed and provisionalized. We monitored prospectively changes in the peri-implant mucosal margin, the interproximal bone and buccal horizontal ridge at 3, 6 and 12months. At 3months post-surgery, the mean±SD [median (interquartile range)] mesiobuccal peri-implant gingival margin recession from the pre-surgical soft tissue position amounted to 0.11±0.32mm [0 (0, 0.5)] in the FLS treatment arm versus 0.43±37mm [0.5 (0, 0.5)] in the F treatment arm (p=0.02); corresponding values at the distobuccal surface were 0.11±32mm [0 (0, 0)] in the FLS arm versus 0.48±0.44mm [0.5 (0, 1)] in the F arm (p=0.01). No other significant differences in soft or hard tissue remodelling between the treatment arms were observed at 3, 6 or 12months. Flapless and a flap-involving immediate implant placement and provisionalization in the aesthetic zone resulted in comparable remodelling of the peri-implant mucosa, interproximal bone and buccal ridge at 6 and 12months.

Total hip arthroplasty for post-traumatic hip fusion ankylosis secondary to operation in acetabular combined with femoral head fracture

Objective To investigate the technique and clinical results of total hip arthroplasty in treating post-traumatic hip fusion ankylosis secondary to operation in acetabular combined with femoral head fracture. Methods From October 2009 to January 2015, 7 patients (7 hips) with post-traumatic hip fusion ankylosis underwent total hip arthroplasty. There were 6 males and 1 female with an average age of 38 years (range, 25-51 years). There were 4 hips on the left side, 3 hips on the right side. Open reduction and internal fixation were performed on all patients. One patient had a postoperative deep infection and 6 patients under-went implant removal. The hip bony fusion ankylosis was developed secondary to post-traumatic arthritis after the surgery of ipsilateral acetabular combined with femoral head facture. The interval between internal fixation and total hip arthroplasty was 37.6 months on average (range, 21-67 months). The hip bony fusion ankylosis was relieved by wedge shape osteotomy at femoral neck level. The cementless prostheses were implanted in suitable places based on the accuracy position of acetabular center. One infection case was treated via surgical debridement, removal of all the screws, and antibiotic-loaded cement spacer implantation in the first stage. The cementless prostheses were implanted in the second stage. Results The average operation time and blood loss was 108 min (90-150 min) and 320 ml (280-450 ml) respectively. The internal fixation devices were explanted completely, including plate and screw in 5 cases, only screw in 1 case, intramedullary nail and screw in 1 case. The mean fallow-up period was 32.5 months (range, 15-48 months). The average Harris hip score improved from 48.8±6.5 points preoperatively to 92.6±5.1 points post-operatively (t=22.82, P=0.001). Osseointegration was developed in all of the acetabular and femoral components at 3 months post-operatively. Radiograph analysis showed satisfied position of acetabular cup and no evidence of implant migration or center of rotation change. Stem subsidence (<1.0 mm) occurred in 2 cases and heterotopic ossification in 2 cases (Brooker typeⅠ and typeⅡin 1 case, respectively) at one year postoperatively. No complication occurred, such as damages of vessels and nerve, dislocation, component loosening or infection. Conclusion The wedge shape osteotomy of femoral neck is a safe and reliable method in treating hip fusion ankylosis. Total hip arthroplasty can be achieved by reconstruction of acetabular center, suitable components implanted in anatomical position and ideal reconstruction of soft tissue around hip. Key words: Acetabulum; Femur head; Fractures, bone; Ankylosis; Arthroplasty, replacement, hip

Long-term stability of peri-implant tissues after bone or soft tissue augmentation. Effect of zirconia or titanium abutments on peri-implant soft tissues. Summary and consensus statements. The 4th EAO Consensus Conference 2015.

Several surgical techniques and prosthetic devices have been developed in the last decades, aiming to improve aesthetic, hygienic and functional outcomes that may affect the peri-implant tissues, such as procedures of bone and soft tissue augmentation and the use of custom-made abutments of titanium and zirconium. Three systematic reviews, based on randomized clinical trials and prospective studies covering the above reported topics were analysed, and the detected evidence was exposed to interactive experts' discussion during the group's and general assembly's meetings of the 4th EAO Consensus Conference. The results are reported using the following abbreviations: S-T: short-term evidence, M-T: medium-term evidence; L-T: long-term evidence; LE: limited evidence. Soft tissue augmentation procedures may be indicated for the increase of soft tissue thickness and keratinized tissue, the reduction of interproximal peri-implant bone loss, and the coverage of shallow peri-implant soft tissue recessions (S-T, LE), L-T is lacking. Guided bone regeneration approaches (GBR) showed efficacy when used for ridge reconstruction after the complete healing of the soft tissues (S-T & L-T), and the stability of the augmented bone may play a role in the maintenance of the soft tissue position and dimensions (LE). No significant differences were observed between titanium and zirconia abutments when evaluating probing pocket depth, bleeding on probing, marginal bone levels and mucosal recessions. Zirconia abutments were associated with more biological complications but demonstrated superiority in terms of achieving natural soft tissue colour (S-T).

SU‐E‐J‐231: Comparison of Delineation Variability of Soft Tissue Volume and Position in Head‐And‐Neck Between Two T1‐Weighted Pulse Sequences Using An MR‐Simulator with Immobilization

Purpose:There is growing interests in applying MR‐simulator(MR‐sim) in radiotherapy but MR images subject to hardware, patient and pulse sequence dependent geometric distortion that may potentially influence target definition. This study aimed to evaluate the influence on head‐and‐neck tissue delineation, in terms of positional and volumetric variability, of two T1‐weighted(T1w) MR sequences on a 1.5T MR‐simMethods:Four healthy volunteers were scanned (4 scans for each on different days) using both spin‐echo (3DCUBE, TR/TE=500/14ms, TA=183s) and gradient‐echo sequences (3DFSPGR, TE/TR=7/4ms, TA=173s) with identical coverage, voxel‐size(0.8×0.8×1.0mm3), receiver‐bandwidth(62.5kHz/pix) and geometric correction on a 1.5T MR‐sim immobilized with personalized thermoplastic cast and head‐rest. Under this setting, similar T1w contrast and signal‐to‐noise ratio were obtained, and factors other than sequence that might bias image distortion and tissue delineation were minimized. VOIs of parotid gland(PGR, PGL), pituitary gland(PIT) and eyeballs(EyeL, EyeR) were carefully drawn, and inter‐scan coefficient‐of‐variation(CV) of VOI centroid position and volume were calculated for each subject. Mean and standard deviation(SD) of the CVs for four subjects were compared between sequences using Wilcoxon ranksum test.Results:The mean positional(&lt;4%) and volumetric(&lt;7%) CVs varied between tissues, majorly dependent on tissue inherent properties like volume, location, mobility and deformability. Smaller mean volumetric CV was found in 3DCUBE, probably due to its less proneness to tissue susceptibility, but only PGL showed significant difference(P&lt;0.05). Positional CVs had no significant differences for all VOIs(P&gt;0.05) between sequences, suggesting volumetric variation might be more sensitive to sequence‐dependent delineation difference.Conclusion:Although 3DCUBE is considered less prone to tissue susceptibility‐induced artifact and distortion, our preliminary data showed that both sequences had insignificant differences on positional and volumetric CV in most head‐and‐neck tissues except for PGL. This study is majorly limited in its small sample size. Influences of image contrasts(T1w v.s. T2w) and inter‐observer difference have to be further investigated.