Factors associated with abutment screw loosening in single implant supported crowns: A cross-sectional study.

BACKGROUND: Implant restorations are considered an ideal treatment option for replacement of missing teeth in partially edentulous patients. Abutment screw loosening is one of the frequently observed technical complications of implant-supported prosthesis. This study aimed to determine the prevalence and factors associated with the abutment screw loosening in cement-retained single-implant crowns. METHODS: Enrolment criteria included partially edentulous patients who have been rehabilitated with one or more cement-retained single-implant crowns with minimum postcementation period of 1 year. They were recalled and evaluated for the presence or absence of screw loosening both clinically and radiographically. They were further evaluated for the presence or absence of factors associated with screw loosening such as parafunctional habits, wider occlusal table, steep cuspal inclines, non-axial loading and cantilevering of the pontic. RESULTS: Twenty-six cement-retained single-implant crowns out of 280 showed screw loosening, making the overall prevalence rate of 10.77%. Among the factors evaluated, parafunctional habits were associated with three cases, wider occlusal table in four, steep cuspal inclines in three, non-axial loading in nine and cantilevering of the pontic in three cases. Exact reasons could not be ascertained in four cases. CONCLUSION: Abutment screw loosening seems to be a significant prosthetic complication of cement-retained single-implant crowns. Factors evaluated significantly affect the functional durability of the prosthesis. These factors should be considered while restoring to enhance the longevity of such restorations.

Perfusion maintains functional potential in denervated mimic muscles in early persistent facial paralysis which requires early microsurgical treatment - the histoanatomic basis of the extratemporal facial nerve trunk assessing axonal load in the context of possible nerve transfers.

BACKGROUND AND OBJECTIVES: Early persistent facial paralysis is characterized by intact muscles of facial expression through maintained perfusion but lacking nerve supply. In facial reanimation procedures aiming at restoration of facial tone and dynamics, neurotization through a donor nerve is performed. Critical for reanimating target muscles is axonal capacity of both donor and recipient nerves. In cases of complete paralysis, the proximal stump of the extratemporal facial nerve trunk may be selected as a recipient site for coaptation. To further clarify the histological basis of this facial reanimation procedure we conducted a human cadaver study examining macro and micro anatomical features of the facial nerve trunk including its axonal capacity in human cadavers. Axonal loads, morphology and morbidity of different donor nerves are discussed reviewing literature in context of nerve transfers. METHODS: From 6/2015 to 9/2016 in a group of 53 fresh frozen cadavers a total of 106 facial halves were dissected. Biopsies of the extratemporal facial nerve trunk (FN) were obtained at 1 cm distal to the stylomastoid foramen. After histological processing and digitalization of 99 specimens available, 97 were selected eligible for fascicle counts and 87 fulfilled quality criteria for a semi-automated computer-based axon quantification software using ImageJ/Fiji. RESULTS: An average of 3.82 fascicles (range, 1 to 9) were noted (n = 97). 6684±1884 axons (range, 2655- 12457) were counted for the entire group (n = 87). Right facial halves showed 6364±1904 axons (n = 43). Left facial halves demonstrated 6996±1833 axons (n = 44) with no significant difference (p = 0.73). Female cadavers featured 6247±2230 (n = 22), male showed 6769±1809 axons (n = 40). No statistical difference was seen between genders (p = 0.59). A comparison with different studies in literature is made. The nerve diameter in 82 of our specimens could be measured at 1933±424 µm (range, 975 to 3012). CONCLUSIONS: No donor nerve has been described to match axonal load or fascicle number of the extratemporal facial nerve main trunk. However, the masseteric nerve may be coapted for neurotization of facial muscles with a low complication rate and good clinical outcomes. Nerve transfer is indicated from 6 months after onset of facial paralysis if no recovery of facial nerve function is seen.

The nerve supply of zygomaticus major: Variability and distinguishing zygomatic from buccal facial nerve branches.

The zygomaticus major (ZM) is important for the human smile. There are conflicting data about whether the zygomatic or buccal branches of the facial nerve are responsible for its motor innervation. The literature provides no precise distinction of the transition zone between these two branch systems. In this study, a definition to distinguish the facial nerve branches at the level of the body of the zygoma is proposed. In the light of this definition, we conducted an anatomical study to determine how the source of innervation of the ZM was distributed. A total of 96 fresh-frozen cadaveric facial halves were dissected under loupe magnification. A hemiparotidectomy was followed by antegrade microsurgical dissection. Any branch topographically lying superficial to the zygoma or touching it was classed as zygomatic, and any neighboring inferior branch was considered buccal. The arborization of the facial nerve was diffuse in all cases. In 64 out of 96 specimens (67%, 95% CI: 56% to 76%), zygomatic branches innervated the ZM. Buccal branches innervated ZM in the other 32 facial halves (33%, 95% CI: 24% to 44%). There were no differences in respect of sex or facial side. All facial halves displayed additional branches, which crossed the muscle on its inner surface without supplying it. In 31 specimens, a nerve branch ran superficial to ZM in its cranial third. According to our classification, the zygomaticus major is innervated by zygomatic branches in 67% of cases and by buccal branches in 33%. Clin. Anat. 31:560-565, 2018. © 2018 Wiley Periodicals, Inc.

Prefabrication and free transfer of a tissue engineered composite flap - An experimental model in the rat.

BACKGROUND: The technique of flap-prefabrication has been successfully established in tissue engineering: missing intrinsic vascularisation of engineered tissue can be generated in vivo by microsurgical vesselloop construction. It is possible to move engineered tissue into a defect with microsurgery. In the literature, the combination of engineered tissue covered with skin is not widely reported. OBJECTIVE: Aim of this study was to establish a model to investigate scaffold prefabrication with full thickness skin graft coverage with subsequent free tissue transfer. METHODS: 8 Wistar rats were operated in 2 separate steps: 1) after creating an arteriovenous loop with the femoral vessels, a porous scaffold was placed on the loop and covered with an inguinally based skin flap. A control was implanted without loop into the contralateral groin. 2) 6 weeks later the prefabricated composite flaps were microsurgically transferred to the cervical region. Skin-island monitoring was performed with Laser Doppler-scanner after the transfer. RESULTS: Continuous loss of the skin islands was observed within 72 hours. Complications included wound-dehiscence, thrombosis and death from anaesthesia; in spite of consistent loop viability. CONCLUSION: Evaluation showed that modifications are necessary to maintain the skin-island cove.

Comparative evaluation of surgical modalities for coverage of gingival recession: An Armed Forces Medical College perspective.

BACKGROUND: Esthetics represents an inseparable part of today's oral therapy, and several procedures have been proposed to preserve or enhance it. Gingival recessions may cause hypersensitivity, impaired esthetics and root caries. Keeping in mind patient's desire for improved esthetics and other related problems, every effort should be made to achieve complete root coverage. METHODS: Different types of modalities have been introduced to treat gingival recession including displaced flaps, free gingival graft, connective tissue graft, different type of barrier membranes and combination of different techniques. The aim of this study was to compare the commonly used techniques for gingival recession coverage and evaluate the results obtained. 73 subjects were selected for the present study who were randomly divided into four groups and were followed at baseline and 180 days where following parameters were recorded: (a) Assessment of gingival recession depth (RD); (b) Assessment of pocket depth (PD); (c) Assessment of clinical attachment level (CAL) and (d) Assessment of width of attached gingiva (WAG). RESULTS: Results of this study showed statistically significant reduction of gingival recession, with concomitant attachment gain, following treatment with all tested surgical techniques. However, SCTG with CAF technique showed the highest percentage gain in coverage of recession depth as well as gain in keratinized gingiva. Similar results were obtained with CAF alone. The use of GTR and other techniques showed less predictable coverage and gain in keratinized gingiva. CONCLUSION: Connective tissue grafts were statistically significantly superior to guided tissue regeneration for improvement in gingival recession reduction.

[Neovascularisation and free microsurgical transfer of cartilage-engineered constructs]. / Neovaskularisation und freier mikrochirurgischer Transfer von in vitro gezüchteten Knorpelkonstrukten.

BACKGROUND: Clinical imperatives for new cartilage to replace or restore the function of traumatized or missing tissue as a consequence of trauma, inherent malformations or disease has led to the need for therapies or procedures to generate cartilage for clinical applications. To ensure shape, function, and survival, in vitro cartilage-engineered constructs need to be revascularized. This study presents a viable method for neovascularization and free microsurgical transfer of these in vitro constructs. MATERIAL AND METHODS: Twelve female Chinchilla Bastard rabbits were operated. Cartilage-engineered constructs were created by isolating chondrocytes from auricular biopsies, amplifying in monolayer culture, and then seeding them onto polycaprolactone scaffolds. In each prefabricated skin flap, three in vitro cartilage-engineered constructs measuring 2×2×0.5 cm and one construct without cells, which served as the control, were implanted beneath an 8×15-cm random-pattern skin flap, neovascularized by implantation of an arteriovenous vascular pedicle with maximal blood flow. After 6 weeks, the neovascularized flaps with embedded cartilage-engineered constructs were completely removed based on the newly implanted vascular pedicle, and then freely retransferred into position using microsurgery. Macroscopic observation, histology, selective microangiography, and immunohistochemistry were performed to determine the construct vitality, neovascularization, and new cartilage formation. RESULTS: All neovascularized skin flaps with embedded tissue-engineered cartilage constructs were effectively free-transferred as free flaps. The implanted constructs were protected and well integrated within the flap. All constructs were well neovascularized and showed histologically stability in both form and size. Immunohistology showed the existence of cartilage-like tissue with extracellular matrix neosynthesis. CONCLUSION: Our experimental study revealed the reliable ability of neovascularization and free microsurgical transplantation of cartilage-engineered constructs using prefabricated flaps. With respect to effective clinical application, engineered cartilage composed of a patient's own cells can become a feasible option for the reconstruction of large cartilage defects or auricular reconstruction using this method. The procedure also represents a promising alternative for clinical practice due to minimal donor site morbidity and favorable aesthetic outcomes.

Evaluation of Aerosol and Water Contamination and Control of Cross Infection in Dental Clinics.

BACKGROUND: The oral cavity is an unique environment which provides an ideal medium for bacterial growth. As a result of repeated exposure to the microorganisms present in blood and saliva, the dental health professionals and the patients are at a higher risk for developing many infectious diseases. A pilot study was carried out in the Dept of Dental Surgery, Armed Forces Medical College to assess the risk of cross infection in dental clinics. METHODS: Samples were collected from different dental surgeries of the Dept of Dental Surgery, Armed Forces Medical College and sent for microbiological culture and identification to the Dept of Microbiology, Armed Forces Medical College. The sampling was carried out in two stages, before and after implementing a set protocol. RESULT: All dental unit waterlines were coated with a well established biofilm made up of filamentous and bacillus-like microorganisms in first stage of study. There was marked reduction in the number of colonies from the samples collected during second stage. Same findings were observed in the samples of aerosol produced by ultrasonic scalers. CONCLUSION: The present study concluded that the new set protocol followed is significantly effective in reducing the microbial load in the water tubing, container and aerosol production. It is an effective measure for reducing the chances of cross infection in the dental surgery.

Optimization of platelet isolation and extraction of autogenous TGF-beta in cartilage tissue engineering.

Platelets are enriched with Transforming Growth Factor-beta (TGF-beta). However, information is limited concerning TGF-beta's effects at the molecular level. Nevertheless, it has been demonstrated that TGF-beta activates cell proliferation and its positive influence on cartilage formation has been proven within the field of Tissue Engineering (TE). As Platelet Rich Plasma (PRP) contains TGF-beta, it was the purpose of this study to optimize PRP-isolation for further TGF-beta extraction. Red blood cell count (RBC) was separated from whole blood by centrifugation. From the supernatant PRP and platelet poor plasma (PPP) layer, the latter supernatant was re-centrifuged to extract PRP. Various experimental series were run to investigate influences concerning anticoagulating alternatives, different amounts of buffer, various centrifugal forces, or substituting centrifugation for sedimentation. TGF-beta levels were determined using ELISA. The technique of platelet-/ TGF-beta-extraction described here proves to be more effective than other methods, is easily repeatable and not time-consuming, which predisposes it for TE requirements.