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Made available in DSpace on 2022-04-29T08:32:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Dental implants are widely used as a long-term treatment solution for missing teeth. A titanium implant is inserted into the jawbone, acting as a replacement for the lost tooth root and can then support a denture, crown or bridge. This allows discreet and high-quality aesthetic and functional improvement, boosting patient confidence. The use of implants also restores normal functions such as speech and mastication. Once an implant is placed, the surrounding bone will fuse to the titanium in a process known as osseointegration. The success of osseointegration is dependent on stress distribution within the surrounding bone and thus implant geometry plays an important role in it. Optimisation analyses are used to identify the geometry which results in the most favourable stress distribution, but the traditional methodology is inefficient, requiring analysis of numerous models and parameter combinations to identify the optimal solution. A proposed improvement to the traditional methodology includes the use of Design of Experiments (DOE) together with Response Surface Methodology (RSM). This would allow for a well-reasoned combination of parameters to be proposed. This study aims to use DOE, RSM and finite element models to develop a simplified optimisation analysis method for dental implant design. Drawing on data and results from previous studies, two-dimensional finite element models of a single Branemark implant, a multi-unit abutment, two prosthetic screws, a prosthetic crown and a region of mandibular bone were built. A small number of combinations of implant diameter and length were set based on the DOE method to analyse the influence of geometry on stress distribution at the bone-implant interface. The results agreed with previous studies and indicated that implant length is the critical parameter in reducing stress on cortical bone. The proposed method represents a more efficient analysis of multiple geometrical combinations with reduced time and computational cost, using fewer than a third of the models required by the traditional methods. Further work should include the application of this methodology to optimisation analyses using three-dimensional finite element models. Centre for Simulation in Bioengineering Biomechanics and Biomaterials (CS3B) Department of Mechanical Engineering Engineering College of Bauru (FEB) São Paulo State University (UNESP) Department of Mathematics Faculty of Science (FC) São Paulo State University, São Paulo State Centre for Simulation in Bioengineering Biomechanics and Biomaterials (CS3B) Department of Mechanical Engineering Engineering College of Bauru (FEB) São Paulo State University (UNESP) Department of Mathematics Faculty of Science (FC) São Paulo State University, São Paulo State

Background: Although nonoperative management of acute Achilles tendon rupture (ATR) is a reasonable option, surgical repair has attracted attention for young and active patients. More reliable Achilles tendon repair techniques are needed to enhance recovery after ATR in this population. Purpose/Hypothesis: To biomechanically analyze the panda rope bridge technique (PRBT) and compare it with other minimally invasive repair techniques over a simulated, progressive rehabilitation program. It was hypothesized that PRBT would result in better biomechanical properties and enhanced recovery after ATR. Study Design: Controlled laboratory study. Methods: An Achilles tendon rupture was created 4 cm from the distal tendon insertion site in 40 bovine lower extremities, and specimens were then randomly allocated to 5 Achilles tendon repair techniques: (1) Achillon, (2) modified Achillon, (3) Percutaneous Achilles Repair System (PARS), (4) modified PARS, and (5) PRBT. Each group was subjected to a cyclic loading protocol that was representative of progressive postoperative rehabilitation for ATR (250 cycles at 1 Hz for each loading stage: 20-100 N, 20-200 N, 20-300 N, and 20-400 N). Results: The PRBT technique demonstrated significantly less elongation (1.62 ± 0.25 mm) than the 4 other repair techniques after the first loading stage of 20 to 100 N ( P < .05). All specimens in the 4 other groups developed a large gap (elongation ≥5 mm) at the 20- to 200-N loading stage. When overall biomechanical performance was examined, the PRBT group exhibited higher strength (20-400 N) and more mean loading cycles (984 ± 10) compared with the 4 other groups ( P < .05). Conclusion: In this bovine model, PRBT biomechanically outperformed the other minimally invasive Achilles tendon repair techniques that were tested and could therefore meet the requirements of accelerated rehabilitation. Clinical Relevance: The reduced tendency for premature rerupture and the overall improved biomechanical properties of PRBT suggest that ATR patients treated with PRBT may more readily complete early and aggressive postoperative rehabilitation protocols. In addition, they may have a lower risk of early irreversible suture failure.

Routine reconstruction of subtotal defects of the mandible and orthopedic rehabilitation supported by dental implants is achieved by means of detailed planning and lasts over a year. This article shows the outcomes of single-stage surgical treatment and immediate orthopedic rehabilitation performed with the help of preoperative virtual computer simulation. 3D investigation of pathological and donor sites, virtual simulation of tumor resection, positioning of the dental implants into fibula, virtual flap bending and transfer, virtual bending of fixing reconstruction plates, and fabrication of navigation templates and bridge prosthesis supported by dental implants were done preoperatively. The surgery included tumor resection, insertion of dental implants into fibula, elevation of fibula osteocutaneous free flap, rigid fixation within recipient site, and immediate loading by bridge orthopedic device. On 10-month follow-up, functional and esthetic results were asses as reasonable. Radiography showed dental implants to be integrated and positioned appropriately. We found that successful rehabilitation of the patients with extensive defects of the jaws could be achieved by ablative tumor resection, dental implants insertion prior to flap elevation guided by navigation templates, further osteotomy, modeling of the flap based on navigation template, flap transfer, and rigid fixation within recipient site by prebended plates, with application of prefabricated prosthesis.

This work aimed to compare the stress distribution and mechanical properties of our bridge combined fixation system and commonly used metal locking plate screw system by finite element analysis and by using the Zwick/Z100 testing machine. In addition, we also investigated the clinical outcome of our bridge combined fixation system for femoral fractures in 59 patients from June 2005 to January 2013. As a result, the stress distribution in the bone plate and screws of metal locking plate screw system during walking and climbing stairs was significantly lower than that of metal locking plate screw system. No significant difference in the displacement was observed between two systems. The equivalent bending stiffness of bridge combined fixation system was significantly lower than that of metal locking plate screw system. There were no significant differences in the bending strength, yield load, and maximum force between two systems. All the cases were followed up for 12–24 months (average 18 months). The X-ray showed bone callus was formed in most patients after 3 months, and the fracture line was faint and disappeared at 6–9 months postoperatively. No serious complications, such as implant breakage and wound infection, occurred postoperatively. According to self-developed standard for bone healing, clinical outcomes were rated as excellent or good in 55 out of 59 patients (success rate: 93.2%). Therefore, our findings suggest that our bridge combined fixation system may be a promising approach for treatment of long-bone fractures.

Objective To assess and develop a monocortical mandibular bone grafting procedure for reconstruction of alveolar cleft. Design Prospective study. Setting Hokkaido University Hospital. Patients Forty-two consecutive Japanese patients who had been treated for a total of 48 clefts according to a strict clinical protocol. Mean age at bone grafting was 6 years 11 months. Interventions Bone grafting was performed by harvesting lateral cortical bone plates from the symphysis and/or body and then placing them on the labial and palatal openings of the alveolar process defect. No particulate bone grafts were packed into the bony cavity. Mean follow-up after bone grafting was 37 months. Main Outcome Measures Status of the grafted area and eruption of cleft-adjacent teeth were assessed prospectively using computed tomography and periapical radiography. Results At 6 months postoperatively, computed tomography showed sufficient bone bridge formation at the cleft site in 85.4% of clefts. Periapical radiography showed ≥75% of the root surfaces of cleft-adjacent teeth were covered with spanning bone in 83.3% of clefts. In 92.6% of clefts in which the cleft-adjacent canine was uncovered with bone during follow-up, the canines erupted spontaneously. Conclusions Monocortical mandibular bone grafting appears extremely effective for sufficient bone bridge formation and facilitation of cleft-adjacent teeth eruption. The procedure is advantageous in that the quantity of bone required per unit volume of cleft defect is relatively reduced, and larger clefts can thus be treated.

Generally, it is relatively easy to obtain a high joint strength with most modern bonding systems if these are cured under ideal factory conditions. However, civil engineering construction joints are cured on site and are required to last the lifetime of the structural member in harsh environmental conditions. This implies that site joints might not be constructed and cured as well as those fabricated in the factory. The paper compares two possible methods for bonding an FRP composite patch/plate to a steel adherend suitable for construction sites. The first method utilises the accepted technique of bonding two dissimilar materials using a two-part cold cure adhesive. The second method employs a pre-impregnated FRP composite plate in conjunction with a compatible film adhesive; these comparisons are undertaken by examining the results of double-strap butt joint tests. A possible site technique using the pre-impregnated FRP composite to upgrade a steel beam whilst it is under a low frequency vibration load is investigated; this represents the repair of a steel bridge constantly under traversing traffic. The butt joint test results show that on average, the pre-impregnated composite in conjunction with the film adhesive leads to a failure load which is 15% higher than that of the cold setting adhesive technique. The results of the rehabilitated beam tests show that the bonded joint between the pre-impregnated CFRP composite and the steel adherend did not suffer any significant damage from the low frequency vibrations imposed upon the steel beam during the cure period.

Objective To examine the prognostic significance of the skeletal morphology around the nasal cavity and the alveolar cleft in secondary bone grafting (SBG). Design and Setting Fifty-one alveolar clefts in 41 patients (10 bilateral and 31 unilateral cleft lips and palates) registered in the Tokushima University Dental Hospital were examined in this study. Method Evaluation of the bony bridge after SBG using dental radiographs at 1 year after surgery. The clefts were divided into two groups: group I (54.9%) in which the upper border of the bony bridge was preferably maintained on or above the horizontal reference line (RL) constructed at the level of the root apex of the upper central incisor adjacent to the cleft, and group II (45.1%) in which the bone level was lower than the RL. Presurgical cleft width was determined by the dental radiographs. The cleft/nasal cavity ratio; the value of the cleft width divided by the nasal cavity width on the cleft side, which was analyzed by frontal cephalograms before the SBG; and the cleft/apertura piriformis ratio, the value analyzed by computed tomography, were used. Results and Conclusion The age, sex, and eruptive stage of the canine teeth at the time of the SBG showed no significant difference between groups. The presurgical cleft width also showed no significant difference between group I (6.6 ± 3.1 mm) and group II (7.9 ± 3.3 mm). The cleft/nasal cavity ratio showed a significant difference between groups I and II (0.42 ± 0.14, 0.75 ± 0.25; p < .05). Furthermore, the cleft/apertura piriformis ratio also showed a significant difference between groups I and II (0.32 ± 0.12, 0.65 ± 0.26; p < .05). These results suggested that measurements of the skeletal morphology around the nasal cavity and alveolar cleft might aid in predicting the stability of the bony bridge after SBG.

Category: Midfoot/Forefoot, Sports, Trauma Introduction/Purpose: Open reduction and internal fixation (ORIF) with transarticular screws or bridge plating is the standard of care for unstable Lisfranc injuries. There are no studies comparing the clinical outcomes of fixation with transarticular screws or bridge plates in young, athletic patients who sustained low-energy injuries. Methods: All low-energy Lisfranc injuries that underwent ORIF between 2010 and 2015 were reviewed. Injuries were classified as low-energy if the occurred during athletic activity, ground level twisting, or a fall from less than three feet (typically stairs or curbs). Tarsometatarsal (TMT) joint fixation with transarticular screws or bridge plating was documented. Transarticular screws were typically removed between four and six months postoperatively. Injury characteristics, complication rates, pain scores, and Foot and Ankle Ability Measure (FAAM) scores were compared. All continuous variables were compared with a two-tailed Student t-test. All categorical variables were compared using the Chi Squared test. Results: Of the fifteen patients identified, nine were fixed with transarticular screws and six with bridge plates. Average patient age was 27 years old. 12 of 15 were primarily ligamentous injuries. Implant removal was performed in the entire transarticular screw group and three out of six in the bridge plate group (p=0.018). Secondary arthrodesis for arthritis was recommended in two of the transarticular screw group and none of the bridge plate group (p=0.21). Mean FAAM scores were significantly higher in all subscales (ADL 96.2 v 76.7 p=.035, ADL SANE 92.5 v 72.6 p=.055, Sport 89.5 v 62.5 p=.027, Sport SANE 90 v 58.7 p=.024) in the bridge plate group at an average of 43 months follow up. Conclusion: In this study, ORIF with bridge plate fixation of the TMT joints had a lower rate of HWR and higher medium term FAAM scores than fixation with transarticular screws. A statistically significant difference in rates of secondary arthritis could not be established in this small cohort. Prospective studies are necessary to confirm these findings.

Category: Midfoot/Forefoot Introduction/Purpose: A prospective, randomized, non-inferiority clinical trial demonstrated that first metatarsophalangeal joint (MTPJ1) hemiarthroplasty with a synthetic polyvinyl alcohol hydrogel implant (Cartiva®) had equivalent pain relief and functional outcomes to MTPJ1 arthrodesis at 2 years. Despite 91% success, there was a 9.2% rate of implant removal and conversion to fusion. Other implants with more bone resection have demonstrated poorer outcomes after conversion to fusion than if a primary arthrodesis was performed. Since bone loss with synthetic cartilage implant hemiarthroplasty is minimal, we hypothesized that outcomes following implant removal and conversion to fusion would be similar to those following primary arthrodesis. We determined the outcomes of revision of synthetic implant hemiarthroplasty of the great toe to MTPJ1 arthrodesis and compared these outcomes to the primary arthrodesis cohort. Methods: In the original pivotal trial, 152 patients >/=18 years diagnosed with hallux rigidus grade 2, 3, or 4 underwent synthetic cartilage implant MTPJ1 hemiarthroplasty, as previously described (Baumhauer et al., Foot Ankle Int. 2016;37(5):457-69). Outcome measures including the Foot and Ankle Ability Measure (FAAM), pain visual analogue scale (VAS), and Short Form-36 Physical Functioning (SF-36 PF) score were obtained preoperatively, and at 2 weeks, 6 weeks, and 3, 6, 12 and 24 months postoperatively. Revision surgery of the MTPJ1 was performed using the original surgical incision. The medial and lateral capsule was released, the metatarsal head was exposed to permit implant removal, and the void was filled with cancellous autograft or bone graft substitute. Joint compression was achieved using two crossed screws or a compression plate. Patients were non-weightbearing for six weeks. Union was confirmed on radiographs. Patients were followed post-conversion and assessed for pain and functional outcomes. Results: Fourteen patients (9.2%) underwent implant removal and conversion to MTPJ1 arthrodesis. Mean time to revision surgery was 12.8 (range: 1.8-24.2) months. The removed implants demonstrated no signs of wear, fragmentation, fracture or other defects; the cause for failure was patient-reported pain. Eleven revision patients were followed up for mean 11.6 (range 3.1- 22.9) months. Pain VAS decreased by mean 65.2 (range: 19.5-96.0) mm from baseline (i.e., prior to implant hemiarthroplasty). The FAAM ADL and Sports scores increased by mean 39.0 (range: 2.4-73.8) points and 49.2 (range: 5.8-90.6) points, respectively (Figure 1), compared to baseline, with minimal clinically important differences (MCIDs) of 8 and 9 points, respectively. The SF-36 PF subscore improved by mean 37.8 (range: 10-65) points from baseline, with MCID of 3.3 points. Conclusion: Patients who underwent implant removal and conversion to MTPJ1 arthrodesis exhibited outcome measure scores statistically similar (p>0.05 for all scores) to those of the MTPJ1 fusion cohort at 24 months in the original pivotal trial (Figure 1). These results indicate that removal of the synthetic cartilage implant does not “burn a bridge” to having excellent pain relief and a successful functional outcome with a subsequent fusion procedure, if needed. The amount of bone loss with synthetic implant hemiarthroplasty is minimal, as the original joint surface length is maintained.

Fifty-six cleft sites were reviewed prior to alveolar bone grafting and subsequently evaluated for graft success using study models, periapical and occlusal radiographs from the Lancaster Cleft Palate Clinic. All patients in this sample had presurgical orthodontics to expand and align the maxillary arch prior to alveolar bone grafting. Ninety-five percent of the grafts were done using iliac crest, the remaining 5% were cranial grafts. The alveolar bone grafting technique used was as described by Boyne and Sands (1972, 1976). Cleft width was measured on a radiograph taken no more than 1 month preoperatively, following the completion of all orthodontic expansion. Cleft width was determined by inspection at its narrowest point. A distortion correction was attempted by determining the ratio of the radiographic width of the maxillary central incisor adjacent to the cleft compared with the actual width of this tooth measured on study models. The radiographic cleft width was then multiplied by this factor to approximate true cleft width. Alveolar contour was measured at least 6 months postoperatively using ratios of actual bone heights measured at the mesial, middle, and distal margin of the previous cleft compared with root length of adjacent teeth. This was to eliminate the radiographic distortion factors of foreshortening and elongation. Regression analysis was carried out to see if there was a correlation between preoperative cleft width and eventual success of the graft as measured on postsurgical radiographs. The success rate for achieving a bony bridge across the cleft was 91%. Mean alveolar crest height achieved was 93% of the anatomic root length of the tooth in the proximal segment and 96% of the anatomic root length of the tooth in the distal segment. There was significant, but low, negative correlation between presurgical cleft width and alveolar bone attachment of teeth adjacent to the grafted cleft site, after a mean radiographic follow-up of 3.1 years. Notching of the alveolar ridge in the region of the bone graft had a statistically significant low positive correlation with differing cleft widths.

An examination of the relation between the number of teeth used as the abutment of a fixed prosthesis and the increase of the functional loading capacity of the upper jaw was conducted in four male patients with unilateral cleft lip and palate (age range, 19 to 21 years). This was measured at the maximum biting force at each two teeth adjacent to the cleft under various splint extension conditions and compared with that in the nonsplint condition. In all subjects, the maximum biting force under every splinted condition was significantly increased compared with the nonsplint condition. The increase was proportional to the number of teeth included in the splinting. Results indicated that two teeth should be used in each segment in the abutment of the splint across the cleft in order to increase the functional loading capability of the upper jaw comparable to that of the lower jaw. The results also indicated that inclusion of more than two teeth has no further advantageous effect on the functional loading capability.

Defects of the laryngeal framework after trauma, cancer, and thyroplasty have been reconstructed with mini-reconstruction plates. Six patients had miniplates used to repair the thyroid cartilage defect after type I thyroplasty to prevent lateralization of the Silastic implant; three patients had miniplates used after hemilaryngectomy to bridge the thyroid cartilage remnants, resulting in better deglutition after hemilaryngectomy; and three patients had miniplates used to repair laryngeal fractures. The plates were tolerated well by the patients; there were no major complications. Rigid fixation using miniplates for laryngeal reconstruction has unique advantages over the use of wires. It offers the advantages of rigid and immediate stabilization with the ability to bridge large defects. It can be an alternative to existing techniques of laryngeal reconstruction.

A 21-year-old man had proximal radioulnar synostosis 10 months after fracture of the proximal radius and the ulna. The bony bridge was excised and a direct posterior interosseous island flap was interposed as a biological barrier. One year after surgery, the range of forearm rotation was 65°. There was no radiographic evidence of recurrence.

Three dogs each received a three-unit fixed-fixed porcelain-veneer bridge for the replacement of traumatically-lost upper first or second incisor teeth. The bridges remained in place for a period ranging from 6–36 months, before becoming dislodged as a result of external trauma. It was concluded that this type of bridgework is technically feasible and may be justifiable.

The dimensional accuracy of porcelain fused to metal crown and bridge castings was determined on truncated cone-shaped steel dies. Ni-Cr castings produced in manufacturers' laboratories were consistently undersize, while precious metal castings were consistently oversize. Ni-Cr castings, produced in NBS laboratories using a modified investing technique, were routinely oversize.

A gold-nickel master alloy was prepared by arc melting in an inert atmosphere and from it, mechanical test specimens and dental prostheses were made by centrifugal casting. The cast alloy had a yield strength of about 7,400 kg/cm2, with an elongation of 12%. The alloy was clinically tested in the form of partial dentures and crown and bridge materials. For the 32-month period these protheses have been in use, no tissue reaction, tarnish, or corrosion had been observed.