Rare adverse reactions to microfocused ultrasound for facial skin tightening / 中华皮肤科杂志

Microfocused ultrasound (MFU) , as a new approach for facial skin tightening and lifting, has been widely applied in recent years. Its action mechanism is that heat can be transmitted to the deep dermis and superficial musculoaponeurotic system through precise and depth-consistent microcoagulation zones, leading to the contraction and remodeling of skin collagen without damage to the epidermis. MFU has high safety with few serious adverse reactions. However, there are still doubts whether it can lead to subcutaneous scar formation, the risk of lipolysis, or nerve, vessel and eye injuries, etc. Appropriate use and selection of patients can minimize the occurrence of these rare adverse reactions as much as possible.

Rare adverse reactions to microfocused ultrasound for facial skin tightening / 中华皮肤科杂志

Microfocused ultrasound (MFU),as a new approach for facial skin tightening and lifting,has been widely applied in recent years.Its action mechanism is that heat can be transmitted to the deep dermis and superficial musculoaponeurotic system through precise and depth-consistent microcoagulation zones,leading to the contraction and remodeling of skin collagen without damage to the epidermis.MFU has high safety with few serious adverse reactions.However,there are still doubts whether it can lead to subcutaneous scar formation,the risk of lipolysis,or nerve,vessel and eye injuries,etc.Appropriate use and selection of patients can minimize the occurrence of these rare adverse reactions as much as possible.

Implicit Dynamic Analysis on Tightening Procedure of Cancellous Lag Screw Placement / 医用生物力学

Objective To simulate the tightening procedure of a cancellous lag screw by using the implicit dynamic analysis method, and to evaluate the stress distributions on the screw-bone interface. Methods Finite element models of a lag screw with the surrounding bone were developed, and the implicit solver was set up for implicit dynamic analysis on the tightening procedure of the lag screw. The mechanical properties of the screw-bone interface were also analyzed according to strain and stress distributions on the screw and the surrounding bone. Results The stress of the lag screw was mainly distributed in the proximal portion of the screw thread rod. The high-stress region of the bone around the screw was located outside the outer edge of the screw, and it was approximately equal to the depth of the thread. The area of high-stress distributions on the bone was the main region that resisted screw stripping. Conclusions The method of implicit dynamic analysis can accurately simulate the mechanical properties of the screw-bone interface during screw tightening. The discovery of high-stress distributions on the surrounding bone can help researchers to further understand and improve the stability of screw insertion.

Digital evaluation of axial displacement by implant-abutment connection type: An in vitro study

PURPOSE: To measure axial displacement of different implant-abutment connection types and materials during screw tightening at the recommended torque by using a contact scanner for two-dimensional (2D) and three-dimensional (3D) analyses. MATERIALS AND METHODS: Twenty models of missing mandibular left second premolars were 3D-printed and implant fixtures were placed at the same position by using a surgical guide. External and internal fixtures were used. Three implant-abutment internal connection (INT) types and one implant-abutment external connection (EXT) type were prepared. Two of the INT types used titanium abutment and zirconia abutment; the other INT type was a customized abutment, fabricated by using a computer-controlled milling machine. The EXT type used titanium abutment. Screws were tightened at 10 N·cm, simulating hand tightening, and then at the manufacturers' recommended torque (30 N·cm) 10 min later. Abutments and adjacent teeth were subsequently scanned with a contact scanner for 2D and 3D analyses using a 3D inspection software. RESULTS: Significant differences were observed in axial displacement according to the type of implant-abutment connection (P < .001). Vertical displacement of abutments was greater than overall displacement, and significant differences in vertical and overall displacement were observed among the four connection types (P < .05). CONCLUSION: Displacement according to connection type and material should be considered in choosing an implant abutment. When adjusting a prosthesis, tightening the screw at the manufacturers' recommended torque is advisable, rather than the level of hand tightening.

The application of minimally invasive suspension and bury guidance technique in facial rejuvenation / 中华整形外科杂志

Objective@#This paper discusses a surgical method to improve the middle part of face and the temporal surface by using the patented technology of embedding guidance technology.@*Methods@#On the basis of not removing the skin, the application of embedding guidance technology was applied to achieve the effect of facial lifting by placing a 2-0 polyester knitting line under the scalp with a minimally invasive incision(3-5 mm) , paving up to the skull periosteum and down to the hairline edge for compound fixation.@*Results@#Among the 200 patients, 197 were female and 3 were male. Aging from 23-62 years old, all of the patients suffered from mild to moderate problem of saggy skin.Post-operation follow-up was kept from 3 months to 5 years after the treatment, which demonstrated that all of the patients showed different degrees of facial lifting after edema subsided at 3 months, including improvedfacial skin condition, shallower nasolabial groove, lifting of the lateral canthus and tightening of facial skin. The patients were satisfied with the effect.@*Conclusions@#The surgical method is an effective method to solve the problem of facial aging with advantages, such as simple execution, minimized wound, fast recovery, no post-operation bandage requirement and showing great result towards patients suffering from mild and moderate saggy facial skin problem.

Evaluation of electrosurgery and titanium clips for ovarian pedicle haemostasis in video-assisted ovariohysterectomy with two portals in bitches / Eletrocirurgia bipolar e clipes de titânio para hemostasia em pedículos ovarianos durante ovariohisterectomia videoassistida com dois portais em cadelas

ABSTRACT: This study evaluated the use of bipolar electrosurgery and laparoscopic clipping, and their effects on blood loss and the inflammatory response, during a two portal video-assisted ovariohysterectomy technique (two groups with 10 animals each). Surgical time and blood loss volume were significantly lower in the electrosurgery group. There were no significant changes in haematocrit between groups; however, haematocrit did differ between evaluated times, and decreased 10% from the initial measurement to four hours after the procedure. The inflammatory response was significantly higher throughout the post-surgical period, but without any different clinical signs between the two groups. Both techniques had good application for the two portal video-assisted procedure; however, the bipolar electrosurgery allowed for shorter surgical times, reduced blood loss and a minimal learning curve for the surgeon.

RESUMO: Este estudo avaliou a utilização da eletrocirurgia bipolar e do clipador laparoscópico em relação à perda sanguínea e resposta inflamatória durante a ovariohisterectomia videoassistida com dois portais (dois grupos com 10 animais). O tempo cirúrgico, assim como o volume de sangue perdido foram significativamente menores no Grupo Bipolar. Não houve mudanças significativas no hematócrito entre os grupos, mas entre os tempos avaliados houve redução de 10% do valor inicial até quatro horas após o procedimento. A resposta inflamatória foi significativamente maior durante todo o período de avaliação após a cirurgia, mas sem manifestações clínicas diferentes daquelas apresentadas pelo Grupo Clipador. Ambas as técnicas têm boa execução pelo procedimento videoassistido, contudo, o uso da eletrocirurgia bipolar permite tempos cirúrgicos menores, perda de sangue mínima e menor curva de aprendizado para o cirurgião.

Use of Cream Containing Mucus Secreted by Snails Has an Anti-aging Effect on Skin / 대한피부과학회지

BACKGROUND: A cream made from mucus secreted by snails contains 80% mucin, as well as glycosaminoglycan, allantoin for skin rejuvenation, glycolic acid for keratin removal, and collagen and elastin, which are components of dermis. OBJECTIVE: The goal of the present study was to evaluate the efficacy of using cream containing mucus secreted by snails to reduce wrinkles, improve skin elasticity, restore dermal density, and lift the skin. METHODS: Cream containing mucus secreted by snails was applied to the lateral epicanthal areas and the left cheek of 10 subjects for 4 weeks twice per day. Wrinkles, skin elasticity, dermal density, and skin tightening were evaluated at baseline and 2 and 4 weeks. A patient survey was conducted at 4 weeks. RESULTS: There were statistically significant differences between baseline and 4 weeks after applying the cream in terms of wrinkles, skin elasticity, dermal density, and skin tightening (p<0.05). CONCLUSION: Use of cream containing mucus secreted by snails seems to be effective for anti-aging of the skin. Long term follow up studies, such as 3 or 6 months, to confirm the efficacy of the cream should be conducted involving a larger number of patients.

Comparison of clinical efficacy between vaginal tightening surgeries of buried lead needle suture and vaginal posterior wall mucosa excision for treatment of vaginal relaxation / 中华医学美学美容杂志

Objective To compare the clinical effects of needle buried suture and the posterior wall of vagina mucosa excision vaginal tightening surgery for the treatment of mild to moderate vaginal relaxation.Methods A total of 71 patients with mild to moderate vaginal relaxation were randomly divided into observation group (39 cases) and control group (32 cases).The patients in the observation group were given buried lead needle suture,and the control group were treated with posterior wall of vagina mucosa resection.Analysis of two groups was conducted in patients with operation time,intraoperative bleeding,vaginal secretion color,postoperative wound healing and complications;sexual satisfaction was evaluated after 6,12 and 24 months in two groups of patients.Results There was no significant difference between two groups in operation time and vaginal secretion color (P＞ 0.05).Intraoperative blood loss was much more in the observation group than those in the control group,with statistically significant differences between the two groups [(6.23±2.43) ml vs (15.79 ± 7.31) ml,P＜0.05)].The follow-up for a number of months showed that sexual satisfaction had significant difference between the two groups (P＜0.05).None of the patients had rectal or urethral injury,no fistula,incision infection or other complications occurred,and the incision healed in stage Ⅰ.Conclusions For patients with mild to moderate vaginal relaxation,buried lead needle suture vaginal tightening surgery does not damage the vaginal mucosa,no scar,and fewer complications,which is a more simple and effective method to improve the quality of life in patients with vaginal relaxation.

Vaginal tightening surgery by strengthening the pelvic floor support / 中华医学美学美容杂志

Objective To explore the related pelvic floor anatomy to the pathological vaginal relaxation and key points of the vaginal tightening surgery.Methods The vaginal tightening surgery was performed in 24 cases of vaginal relaxation.The key points of this operation included levator ani muscle suturation and perineal body reconstruction,and anal sphincter reconstruction as in case of the muscle injury grade Ⅲ.Results The degree of levator ani muscle separation was positively correlated with that of vaginal relaxation in all the 24 cases.18 cases were followed up from 6 months to 2 years,and had no complications of rectovaginal fistula and infections.The average level of perineal body was increased from 2.3 cm to 3.5 cm.Vaginal length of 6 cm from vaginal orifice was proper with good tightness.The patients felt strong anal contraction,enhanced ability of vaginal tightening and improved quality of sex life.There were no more infections of genitourinary tract.Conclusions Through levator ani muscle suturation and perineal body reconstruction,it can get the vaginal tightening effect.

Effect observation of improved senile entropion operation / 国际眼科杂志(Guoji Yanke Zazhi)

AlM: To observe the clinical effect of modified tightening operation of orbicularis combined with lower eyelid retractor muscle aponeurosis suture in the treatment of senile entropion, and to improve reference for clinical treatment planning. METHODS:A retrospective analysis from August 2009 to August 2012, 218 cases of patients with lower eyelid entropion were treated in our hospital, according to the different operation methods for the observation group 128 cases and control group with 90 cases. The observation group was treated with modified tightening operation of orbicularis combined with lower eyelid retractor muscle aponeurosis suture, control group with suture plus margin incision for treatment. Follow-up of two groups were 1a, the clinical curative effect at 1mo and 1a postoperatively was observed. RESULTS:The observation group healed in 124 cases at 1mo after operation, the cure rate was 96. 9%, the control group cured 84 cases, the cure rate was 93. 3%. The differences of cure rate in two groups were not statistically significant (P>0. 05);the observation group healed in 111 cases at 1a after operation, the cure rate was 86. 7%, the control group cured 58 cases, the cure rate was 64. 4%, the recovery rate of observation group was significantly higher than the control group (P CONCLUSlON:The modified senile entropion operation has good curative effect, and the operation is simple, the recurrence rate is low, it is worth popularizing.

Clinical efficacy of improved vaginal tightening surgery on vaginal relaxation / 中华医学美学美容杂志

Objective To explore more effective methods in vaginal tightening surgery for vaginal relaxation treatment. Methods 132 cases of patients who suffered the decline in quality of sex life owing to vaginal relaxation, requiring improved vaginal tightening surgery. The vaginal surgery was performed to repair the muscles and fascia of the anterior and posterior walls effectively, meanwhile the perineal laceration was also repaired. According to the hammock theory of the treatment of urethral disruption, patients with urinary incontinence with tension was treated to strengthen one suture needle on muscle fascia in the middle of urethra, when repairing anterior of vagina. For patients with constipation, the posterior of vagina was repaired to strengthen 3 suture needles on levator ani during repairing the anterior and posterior wall, so that the vaginal mucosa could get maximum protection. Results 118 patients had been followed up for 2-7 years. A questionnaire survey was conducted about four elements targeted on improving sexual satisfaction, tension incontinence, constipation and vaginal discharge. The clinical results were satisfactory. Conclusions The surgical design is professional and highly effective, and the patients are satisfied with the results. It is suitable for experienced specialists to perform the procedures.

Avaliação comparativa da microinfiltração bacteriológica na interface pilar/implante em implantes hexágono externo com 10 e 20Ncm de torque / Comparative evaluation of the bacteriological microleakage in the implant/abutment interface in external hexagon implants with 10 and 20Ncm torque

O objetivo deste estudo foi avaliar a infltração na interface entre implantes hexágono externo (HE) e pilar cônico inseridos com diferentes torques. Uma suspensão bacteriana de Escherichia coli ATCC 35218 foi preparada em caldo nutritivo de Brain Heart Infusion a uma densidade padrão de 0,5 McFarland para inoculação dos implantes. Na primeira fase do experimento foram utilizados nove implantes (HE) e respectivo parafuso e pilar Cônico, divididos aleatoriamente em 3 grupos com diferentes volumes de inoculação da suspensão bacteriana (n=3). V0,5: 0,5 µL; V1,0: 1,0 µL e V1,5: 1,5 µL. Todos os implantes foram apertados com torque recomendado pelo fabricante. Na segunda fase do experimento foram utilizados 18 implantes e componentes semelhantes à fase 1. Estes foram inoculados com 0,5 µL de suspensão bacteriana e divididos em grupos apertados com diferentes torques (n=9). T10: 10 Ncm e T20: 20 Ncm. Os conjuntos foram avaliados pela análise da claridade da solução a cada 24 horas por 14 dias. Ao fnal deste período a viabilidade da bactéria foi verifcada. O teste de Kruskal-Wallis foi realizado para comparação entre os grupos (p<0,05). Na primeira fase V1,0 e V1,5 apresentaram indicativo de contaminação bacteriana em todas as amostras após 24 hs. Na segunda fase duas amostras do T10 e uma do T20 apresentaram resultado positivo para contaminação bacteriana. Os resultados mostraram que a intensidade do torque não infuenciou estaticamente na microinfiltração bacteriana em implantes HE. Após 14 dias a viabilidade bacteriana foi confirmada.

The aim of this study was to evaluate the infiltration at the interface between implant external hexagon (HE) and conical pillar inserted with different torques. A bacterial suspension of Escherichia coli ATCC 35 218 was prepared in nutrient broth of Brain Heart Infusion at a density of 0.5 McFarland standard for inoculation in the implants. In the first phase of the experiment, nine implants (HE) and its tapered abutment screw were randomly divided into three groups with diferent volumes of inoculation of bacterial suspension (n = 3). V0, 5: 0.5 mL, V1, 0: 1.0 mL and V1, 5: 1.5 mL. All implants were tightened with a recommended torque by the manufacturer. In the second phase of the experiment 18 implants and components were used similar to Phase 1. These were inoculated with 0.5 mL of bacterial suspension and divided into groups with diferent torques tight (n = 9). T10: 10 Ncm and T20: 20 Ncm. The sets were evaluated by the clarity of the solution every 24 hours for 14 days. Thereafter the viability of bacteria was found. The Kruskal-Wallis test was performed for comparison between groups (p < 0.05). In the first stage V1, and V 1, 5 presented indications of bacterial contamination in all samples after 24 hours. In the second phase of the two samples of T10 and T20 were positive for bacterial contamination. The results showed that the intensity of torque did not influence the microleakage statically bacterial HE implants. After 14 days the bacterial viability was confirmed.

Removal torque of zirconia abutment screws under dry and wet conditions

The aim of this study was to verify whether screw abutment lubrication can generate higher preload values compared to non-lubricated screws, a titanium abutment was screwed onto an implant analog and scanned with the Procera System to generate 20 zirconia abutments. MKIII Brånemark implants were clamped to a precision torque device, and the abutments were distributed in dry and wet groups with 10 specimens each. In the wet groups, the inner threads of the implants were filled with artificial saliva. All abutments were fastened with a Torqtite screw under 32 Ncm. Ten detorque measurements were performed per group pushing the reverse button of the Torque controller soon after screw tightening with values registered. The mean detorque values were calculated and compared by a Student's t test (?=0.05). The wet condition presented significantly higher mean detorque than the dry condition (31.5 ± 1.2 versus 27.5 ± 1.5 Ncm, respectively; p=0.0000024). In conclusion, there was always a loss in the initial torque values when the removal torque was measured under both conditions. The wet condition presented higher mean torque than the dry condition. Better preload values were established in the wet group, suggesting that the abutment screw must be lubricated in saliva to avoid further loosening.

A fim de verificar se a lubrificação do parafuso do pilar pode gerar valores maiores de pré-carga do que nos parafusos não lubrificados, um pilar de titânio foi parafusado no análogo do implante e escaneado pelo Sistema Procera para gerar 20 pilares de zircônia. Depois, os implantes MKIII Brånemark foram presos num dispositivo de torque. Os pilares foram distribuídos em grupos seco e úmido com 10 amostras cada. No grupo úmido, as roscas internas dos implantes foram preenchidas com saliva artificial. Então, todos os pilares foram apertados com parafuso Torqtite a 32 Ncm. Dez medidas de destorque foram realizadas por grupo apertando-se o botão reverso do Torque Controller logo depois do parafusamento, e os valores foram registrados. As medias de destorque foram calculadas e comparadas pelo teste t de Student (?=0,05). Os valores médios obtidos nas condições seca e úmida foram 27,5 ± 1,5 Ncm e 31,7 ± 1,2 Ncm, respectivamente. Diferenças estatisticamente significantes foram observadas (p=0,0000024). Observou-se sempre existir uma perda do torque inicial quando o torque de remoção é mensurado em ambas as condições. A condição úmida demonstrou um valor médio maior de torque do que a condição seca. Valores melhores de pré-carga podem ser estabelecidos no grupo úmido, sugerindo que o parafuso do pilar deve ser lubrificado em saliva para evitar seu afrouxamento.

The effect of screw tightening techniques on the detorque value in internal connection implant superstructure / 대한치과보철학회지

PURPOSE: This study evaluated the effect of different screw tightening sequences and methods on detorque values in a well-fitting implant superstructure. MATERIAL AND METHODS: A fully edentulous mandibular master model and a metal framework directly connected to four parallel implants (Astra Tech) with a passive fit to each other were fabricated. Six stone casts were made with a splinted impression technique to represent a 'well-fitting' situation with the metal framework. Detorque values were measured twice after screw tightening using 20 Ncm. Detorque values and minimum detorque values for three screw tightening sequences (1-2-3-4, 2-4-3-1, and 2-3-1-4) and for two tightening methods (two-step and one-step) were analyzed using multi-way analysis of variance and two-way analysis of variance, respectively, at a .05 level of significance. RESULTS: The mean detorque values for screw tightening sequences ranged from 12.8 Ncm (2-4-3-1) to 13.1 Ncm (2-3-1-4), and for screw tightening methods were 13.1 Ncm (two-step) and 11.8 Ncm (one-step). The mean of mimimum detorque values for screw tightening sequences were 11.1 Ncm (1-2-3-4) and 11.2 Ncm (2-4-3-1 and 2-3-1-4), and for screw tightening methods were 11.2 Ncm (two-step) and 9.9 Ncm (one-step). No statistically significant differences among three screw tightening sequences were found for detorque values and for mimimum detorque values. But, statistically significant differences between two screw tightening methods were found for two values. Two-step screw tightening method showed higher detorque value (P = .0003) and higher minimum detorque value (P = .0035) than one-step method. CONCLUSION: Within the limitations of this study, the screw tightening sequence was not a critical factor for the detorque values in a well-fitting implant superstructure by the splinted impression technique. But, two-step screw tightening method showed greater detorque values than one-step method.

Effect of Tightening Torque on Abutment-Fixture Joint Stability using 3-Dimensional Finite Element Analysis / 대한치과보철학회지

STATEMENT OF PROBLEM: Loosening or fracture of the abutment screw is one of the common problems related to the dental implant. Generally, in order to make the screw joint stable, the preload generated by tightening torque needs to be increased within the elastic limit of the screw. However, additional tensile forces can produce the plastic deformation of abutment screw when functional loads are superimposed on preload stresses, and they can elicit loosening or fracture of the abutment screw. Therefore, it is necessary to find the optimum tightening torque that maximizes a fatigue life and simultaneously offer a reasonable degree of protection against loosening. PURPOSE: The purpose of this study was to present the influence of tightening torque on the implant-abutment screw joint stability with the 3 dimensional finite element analysis. MATERIAL AND METHODS: In this study, the finite element model of the implant system with external butt joint connection was designed and verified by comparison with additional theoretical and experimental results. Four different amount of tightening torques (10, 20, 30 and 40 Ncm) and the external loading (250 N, 30degrees C) were applied to the model, and the equivalent stress distributions and the gap distances were calculated according to each tightening torque and the result was analyzed. RESULTS: Within the limitation of this study, the following results were drawn; 1) There was the proportional relation between the tightening torque and the preload. 2) In case of applying only the tightening torque, the maximum stress was found at the screw neck. 3) The maximum stress was also shown at the screw neck under the external loading condition. However in case of applying 10 Ncm tightening torque, it was found at the undersurface of the screw head. 4) The joint opening was observed under the external loading in case of applying 10 Ncm and 20 Ncm of tightening torque. 5) When the tightening torque was applied at 40 Ncm, under the external loading the maximum stress exceeded the allowable stress value of the titanium alloy. CONCLUSION: Implant abutment screw must have a proper tightening torque that will be able to maintain joint stability of fixture and abutment.

Radiofreqüência e infravermelho: [revisão] / Radiofrequecy and infrared: [review]

Com o avanço da tecnologia há demanda cada vez maior por procedimentos minimamente invasivos de rejuvenescimento, como a radiofreqüência (RF) e a luz infravermelha (IR), que oferecem uma opção não cirúrgica para o tratamento da flacidez cutânea. A RF se baseia no aquecimento volumétrico controlado da derme profunda, enquanto a epiderme é preservada através de sistemas de resfriamento, levando a contração imediata do colágeno e neocolagênese tardia. A luz infravermelha é uma fonte de energia alternativa utilizada para promover a retração da pele. A água atua como cromóforo-alvo, permitindo um aquecimento uniforme da derme. A seleção adequada do paciente e o manejo cuidadoso da sua expectativa são fundamentais, uma vez que os resultados clínicos obtidos com RF e IR ainda apresentam baixa previsibilidade e reprodutibilidade e não são equivalentes aos de uma cirurgia plástica. Porém, são técnicas não invasivas e podem oferecer alternativas para o tratamento não cirúrgico da flacidez cutânea.

Influence of Tightening Torque on Implant-Abutment Screw Joint Stability / 대한치과보철학회지

STATEMENT OF PROBLEM: Within the elastic limit of the screw, the greater the preload, the tighter and more secure the screw joint. However, additional tensile forces can incur plastic deformation of the abutment screw when functional loads are superimposed on preload stresses, and they can elicit the loosening or fracture of the abutment screw. Therefore, it is necessary to find the optimum preload that will maximize fatigue life and simultaneously offer a reasonable degree of protection against loosening. Another critical factor in addition to the applied torque which can affect the amount of preload is the joint connection type between implant and abutment. PURPOSE: The purpose of this study was to evaluate the influence of tightening torque on the implant-abutment screw joint stability. MATERIAL AND METHODS: Respectively, three different amount of tightening torque (20, 30, and 40 Ncm) were applied to implant systems with three different joint connections, one external butt joint and two internal cones. The initial removal torque value and the postload (cyclic loading up to 100,000 cycles) removal torque value of the abutment screw were measured with digital torque gauge. Then rate of the initial and the postload removal torque loss were calculated for the comparison of the effect of tightening torques and joint connection types between implant and abutment on the joint stability. Results and CONCLUSION: 1. Increase in tightening torque value resulted in significant increase in initial and postload removal torque value in all implant systems (P .05), however GS II and US II systems exhibited significantly lower loss rates with 40 Ncm torque value than with 20 Ncm (P .05).

The effect of screw tightening sequence and tightening method on the detorque value in implant-supported superstructure / 대한치과보철학회지

STATEMENT OF PROBLEM: The screw detorque value is a measure of the preload remaining in the screw just before detorquing. PURPOSE: This study evaluated the effect of different screw tightening sequences and tightening methods on detorque values for a well-fitting implant superstructure. MATERIAL AND METHOD: An implant superstructure that connected directly to four implants (Astra Tech) was fabricated on a fully edentulous mandibular acrylic resin model. Six wellfitting dental stone casts were made with a pickup impression of the superstructure from the acrylic resin model. To evaluate the effect of three screw tightening sequences (1-2-3-4, 2-4-3-1, and 2-3-1-4) and two tightening methods (2-step and 1-step) on the stability of screw joint, the detorque values for a well-fitting implant superstructure were measured twice after screw tightening using 20 Ncm. Detorque values were analyzed using multi-way analysis of variance and two-way analysis of variance at a .05 level of significance. RESULTS: 1. The mean detorque values for three screw tightening sequences were 12.3 Ncm, 12.6 Ncm, and 12.0 Ncm, respectively. 2. The mean detorque values for two screw tightening methods were 12.0 Ncm, and 12.2 Ncm, respectively. 3. The mean of mimimum detorque values for three screw tightening sequences and for two tightening methods were 10.6 Ncm, 11.1 Ncm, 10.5 Ncm, and 9.8 Ncm, respectively. 4. No statistically significant differences among the variables of screw tightening sequence and tightening method were found (p>.05) for detorque values and for mimimum detorque values. CONCLUSION: Within the limitations of this study, the screw tightening sequence and tightening method did not have a significant effect on the detorque values for a well-fitting implant superstructure.

The influence of abutment screw length and repeated tightening on screw loosening in dental implant / 대한치과보철학회지

Statement of problem: One of common problems associated with dental implant is the loosening of abutment screws that retain the implants. Purpose: This study was performed to investigate the influence of abutment screw length and repeated tightening on screw loosening in dental implant. Material and method: Forty nine Hexplants (13mm length, 4.3mm diameter, Ti grade IV, Warantec. Co. Ltd. Seongnam, Korea) and cementation type abutments(straight abutment) and abutment screws (0.4mm/pitch) were divided into 7 groups, depending on abutment screw length. Each implant and abutment was tightened to 30Ncm by torque controller(MGT50, MARK-10 Inc., USA) and the removal torque values were measured during 10 consecutive closure/opening trials Results and Conclusion: The results of comparing the removal torque value are as follows: 1. There is no significant difference in the removal torque value between groups in 10 consecutive closure/opening trials(p=0.97). 2. If the fractured abutment screw is engaged in longer than 2.425 thread length, there is no significant difference in the preload between the fractured abutment screw and the new abutment screw when both are equally tightened to 30 Ncm 3. The removal torque value in the 1st trial(24.510 Ncm) was lower than that in the 2nd,3rd,4th,5th,6th,7th trials and the removal torque value in the 2nd trials(25.551 Ncm) was maximum and was decreased in following trials. The removal torque value in the 1st trial was significantly lower than that in the 2nd,3rd,4th trials and was significantly higher than that in the 8th,9th,10th trials(p<0.05). 4. In the 2nd,3rd,4th,5th,6th,7th trials, the abutment screw was mainly influenced by settling effect and the higher preload was obtained. In the 8th,9th,10th trials, the abutment screw was mainly influenced by adhesive wear and the progressively lower preload was obtained.

Comparative accuracy of the splinted and unsplinted impression methods for internal connection / 대한치과보철학회지

STATEMENT OF PROBLEM: Accurate impression is essential to success of implant prostheses. But there have been few studies about the accuracy of fixture-level impression techniques in internal connection implant systems. PURPOSE: The purpose of this study was to compare the accuracy of two fixture-level impression techniques in two conditions (parallel and divergent) and to assess the effect of tightening sequences and forces on stresses generated on superstructures in internal connection implant system (Astra Tech). MATERIAL AND METHODS: Two metal master frameworks made from two abutments (Cast-to Abutment ST) each and a corresponding, passively fitting, dental stone master cast with four fixture replicas (Fixture Replica ST) were fabricated. Ten dental stone casts for each impression techniques (direct unsplinted and splinted technique) were made with vinyl polysiloxane impressions from the master cast. Strain gauges for each framework were fixed midway between abutments to measure the degree of framework deformation on each stone cast. Pairs of strain gauges placed opposite each other constituted one channel (half Wheatstone bridge) to read deformation in four directions (superior, inferior, anterior, and posterior). Deformation data were analyzed using one-way ANOVA and the Tukey test at the .01 level of significance. And the effect of tightening sequences (right-to-left and left-to-right) and forces (10 Ncm and 20 Ncm) were assessed with ten stone casts made from parallel condition by the splinted technique. Deformation data were analyzed using paired t-test at the .01 level of significance. CONCLUSIONS: Within the limitations of this study, the following conclusions could be drawn. 1. Frameworks bent toward the inferior side on all casts made by both direct unsplinted and splinted impression techniques in both parallel and divergent conditions. 2. There was no statistically significant difference of accuracy between the direct unsplinted and splinted impression techniques in both parallel and divergent conditions (P>.01). 3. There was no statistically significant difference of stress according to screw tightening sequences in casts made by the splinted impression technique in parallel condition (P>.01). 4. Greater tightening force resulted in greater stress in casts made by the splinted impression technique in parallel condition (P<.01).