Survival rate and stability of surface-treated and non-surface-treated orthodontic mini-implants: a randomized clinical trial

ABSTRACT Objectives: This clinical trial was conducted to evaluate the stability and failure rate of surface-treated orthodontic mini-implants and determine whether they differ from those of non-surface-treated orthodontic mini-implants. Trial Design: Randomized clinical trial with a split-mouth study design. Setting: Department of Orthodontics, SRM Dental College, Chennai. Participants: Patients who required orthodontic mini-implants for anterior retraction in both arches. Methods: Self-drilling, tapered, titanium orthodontic mini-implants with and without surface treatment were placed in each patient following a split-mouth design. The maximum insertion and removal torques were measured for each implant using a digital torque driver. The failure rates were calculated for each type of mini-implant. Results: The mean maximum insertion torque was 17.9 ± 5.6 Ncm for surface-treated mini-implants and 16.4 ± 9.0 Ncm for non-surface-treated mini-implants. The mean maximum removal torque was 8.1 ± 2.9 Ncm for surface-treated mini-implants and 3.3 ± 1.9 Ncm for non-surface-treated mini-implants. Among the failed implants, 71.4% were non-surface-treated mini-implants and 28.6% were surface-treated mini-implants. Conclusion: The insertion torque and failure rate did not differ significantly between the groups, whereas the removal torque was significantly higher in the surface-treated group. Thus, surface treatment using sandblasting and acid etching may improve the secondary stability of self-drilling orthodontic mini-implants. Trial registration: The trial was registered in the Clinical Trials Registry, India (ICMR NIMS). Registration number: CTRI/2019/10/021718

RESUMO Objetivos: Este ensaio clínico foi conduzido para avaliar a estabilidade e a taxa de falha de mini-implantes ortodônticos com superfície tratada, e determinar se elas diferem das dos mini-implantes ortodônticos sem superfície tratada. Desenho do estudo: Ensaio clínico randomizado com desenho de boca dividida. Instituição: Department of Orthodontics, SRM Dental College, Chennai/India. Participantes: Pacientes que necessitavam de mini-implantes ortodônticos para retração anterior em ambas as arcadas. Métodos: Mini-implantes ortodônticos autoperfurantes, cônicos, de titânio com ou sem tratamento de superfície, foram colocados em cada paciente, seguindo um desenho de boca dividida. Os torques máximos de inserção e de remoção foram medidos para cada mini-implante, usando um torquímetro digital. As taxas de falha foram calculadas para cada tipo de mini-implante. Resultados: O valor médio do torque máximo de inserção foi de 17,9 ± 5,6 Ncm para mini-implantes com superfície tratada e 16,4 ± 9,0 Ncm para mini-implantes sem superfície tratada. O valor médio do torque máximo de remoção foi de 8,1 ± 2,9 Ncm para mini-implantes com superfície tratada e 3,3 ± 1,9 Ncm para mini-implantes sem superfície tratada. Entre os implantes que falharam, 71,4% eram mini-implantes sem superfície tratada e 28,6% eram mini-implantes com superfície tratada. Conclusão: O torque de inserção e a taxa de falha não diferiram significativamente entre os grupos; porém, o torque de remoção foi significativamente maior no grupo com superfície tratada. Assim, o tratamento de superfície com jateamento e condicionamento ácido pode melhorar a estabilidade secundária dos mini-implantes ortodônticos autoperfurantes. Registro do estudo: Esse estudo foi registrado no Clinical Trials Registry, Índia (ICMR NIMS). Número de registro: CTRI/2019/10/021718

Calculation Model for Insertion Torque of Medical Bone Screws Based on ASTM F543-17 / 医用生物力学

Objective To study numerical model for calculating the insertion torque of bone screw. Methods The three stages of screw insertion process for the self-tapping screw were analyzed, so as to make mechanical modeling and simulation calculation on torque and torque angle at screw forming stage. Meanwhile, the insertion experiments of screws with specification of φ2.9×12 from three manufactures on polyurethane test blocks with different grades were performed according to ASTM F543-17(YY/T 1506-2016), and the experimental results were compared with the calculated ones. Results The deviations between the predicted insertion torque by the model and the measured torque in the experiments were 5 mN·m and 12 mN·m within the acceptable error range, which were 10% smaller than the average measured torque in the experiments. Conclusions The developed mechanical calculation model can be used to simulate and predict the insertion torque of medical bone screws in research and development or clinical use, and its combination with in vitro mechanical experiments provides an effective way of developing and designing bone screws.

The significance and parameter standards of the implant primary stability / 口腔疾病防治

@#The nature, significance, parameters, influencing factors and testing of implant primary stability were studied by a literature review. Primary stability is a kind of anchorage force at the interface between the implant and bone, and it is merely mechanical. The significance of primary stability is to keep the implant unmovable so that the new bone can grow undisturbed on the surface of the implant without interference from fibrous tissue. The implant is finally bound to the bone by osseointegration. The most common assessments of primary stability are insertion torque (IT), the implant stability quotient (ISQ) of the resonance frequency analysis (RFA) and Periotest. IT is more commonly used to directly imply initial stability. At present, no consensus has been reached regarding the concrete parameters of primary stability to predict osseointegration. Implant osseointegration could be developed through all phases of primary stability. However, the excessive primary stability would cause mini-bone fractures, followed by bone necrosis at the interface and the final failure of implantation. Primary stability is influenced by three factors: implant design, bone condition of alveolar bone, and surgical technique. Under the condition of a lack of primary stability and immediate implantation, there may be the possibility of successful osseointegration. Therefore, it is necessary to re-examine the accuracy of the current elaboration on the primary stability. It is related directly to whether the clinic can choose the appropriate implant treatment path.

Estabilidad primaria en implantes inmediatos versus implantes colocados en hueso maduro: un estudio clínico retrospectivo / Primary stability in immediate implants versus implants placed in mature bone: a retrospective clinical study

La estabilidad primaria es un requisito importante para la supervivencia y éxito de los implantes durante la osteointegración. En los últimos años, los implantes inmediatos postextracción han demostrado ser una opción de tratamiento exitosa y predecible para la reposición de dientes con mal pronóstico, pero surge la duda de si dichos implantes alcanzan valores de estabilidad primaria comparables a aquellos colocados en hueso maduro. Comparar la estabilidad primaria de implantes inmediatos colocados en alveolos postextracción con la de implantes colocados en hueso maduro. Se llevó a cabo un estudio clínico retrospectivo, con los datos recogidos sobre 175 implantes, colocados en 175 pacientes. Todos los implantes colocados pertenecían al modelo Essential Cone (Klockner Implant System) y se dividieron en dos grupos: implantes inmediatos (Grupo A, n=31) e implantes colocados en hueso maduro (Grupo B, n=144). La estabilidad primaria de todos los implantes se midió mediante torque de inserción y análisis de frecuencia de resonancia con Osstell ISQ. No se encontraron diferencias estadísticamente significativas respecto a la estabilidad medida a través del torque de inserción (26,29+10,07 Vs 25,76+9,72 N/cm) pero sí que se encontraron diferencias significativas en la medida de la estabilidad primaria mediante AFR, siendo inferiores los valores correspondientes a los implantes colocados en los alveolos post exodoncia (60,74 ± 6,17 en sentido VL y 62,19 ± 7.64 en sentido MD frente a 68,34 ± 6.26 en sentido VL y 69,29 ± 7.98 en sentido MD obtenidos en los implantes colocados en hueso maduro). El torque de inserción de los implantes inmediatos es similar al de los implantes colocados en hueso maduro, pero sus valores ISQ son significativamente inferiores, lo que demuestra un mayor grado de micromovimiento, y por consiguiente, un mayor riesgo de fracaso durante el período de osteointegración.

Primary stability is an important requirement for the survival and success of implants during osseointegration. In recent years, immediate post-extraction implants have proven to be a successful and predictable treatment option for the replacement of teeth with a poor prognosis, but the question arises as to whether these implants reach primary stability values comparable to those placed in mature bone. The objective of the study was to compare the primary stability of immediate implants placed in post-extraction alveoli with that of implants placed in mature bone. A retrospective clinical study was carried out, with data collected on 175 implants, placed in 175 patients. All implants placed belonged to the Essential Cone model (Klockner Implant System) and were divided into two groups: immediate implants (Group A, n = 31) and implants placed in mature bone (Group B, n = 144). The primary stability of all implants was measured by insertion torque and resonance frequency analysis with Osstell ISQ. No statistically significant differences were found regarding the stability measured through the insertion torque (26.29 + 10.07 Vs 25.76 + 9.72 N / cm) but significant differences were found in the measurement of primary stability by means of AFR, the values corresponding to implants placed in the post-exodontic alveoli being lower (60.74 ± 6.17 in the VL direction and 62.19 ± 7.64 in the MD direction versus 68.34 ± 6.26 in the VL direction and 69.29 ± 7.98 in the MD direction obtained in implants placed in mature bone). The insertion torque of immediate implants is similar to that of implants placed in mature bone, but their ISQ values are significantly lower, which demonstrates a higher degree of micromotion, and therefore, a greater risk of failure during the period of osseointegration.

Differences in percussion-type measurements of implant stability according to height of healing abutments and measurement angle / 대한치과보철학회지

PURPOSE: The purpose of this study was to evaluate the effect of healing abutment height and measurement angle on implant stability when using Periotest and AnyCheck. MATERIALS AND METHODS: 60 implants were placed into artificial bone blocks. After implant insertion, 2, 3, 4 and 5 mm healing abutments were installed on 15 specimens, respectively. Insertion torque value, implant stability test, Periotest value were measured. Insertion torque value was controlled between 45 – 55 Ncm. AnyCheck was used for measuring implant stability test and Periotest M was used for measuring Periotest value. Implant stability test and Periotest value were measured at the angles of 0 and 30 degrees to the horizontal plane. Measured values were analyzed statistically. RESULTS: Insertion torque value had no significant difference among groups. When healing abutment height was higher, implant stability test and Periotest value showed lower stability. Also when measurement angle was decreased, implant stability test and Periotest value showed lower stability. CONCLUSION: When measuring stability of implants with percussion type devices, measured values should be evaluated considering height of healing abutments and measurement angle.

Effect of Laser Pre-Drilling on Insertion Torque of Orthodontic Miniscrews: A Preliminary Study

PURPOSE: To evaluate the effect of different-sized drill tips and laser irradiation times on the initial stability of orthodontic miniscrews placed in Er,Cr:YSGG-laser pre-drilled holes in an animal model. MATERIALS AND METHODS: Laser pre-drilled holes were made in dog mandibular bone with an Er,Cr:YSGG laser using irradiation times of 5, 7, 9, 11, and 13 seconds, and tip diameters of 0.4 and 0.6 mm. The maximum diameter and depth of the pre-drilled holes was measured with micro computed tomography. The maximum insertion torque was measured during placement the miniscrew. RESULT: Laser pre-drilled holes were conical shaped. The maximum diameter of pre-drilled holes increased with longer laser irradiation times (P>0.05) and larger tip diameters (P < 0.05). The depth of pre-drilled holes increased with longer laser irradiation times and larger tip diameters (P < 0.05). When the 0.4 mm tip, but not the 0.6 mm tip, was used, the insertion torque decreased significantly with longer laser irradiation times (P < 0.05). CONCLUSION: Tip diameter impacted insertion torque more than irradiation time. It takes at least 9 seconds using a 0.6 mm tip to create a 0.8 mm diameter and 1.0 mm depth hole in thick cortical bone.

Estabilidade em implantes dentários: análise da frequência de ressonância e torque de inserção / Stability in dental implants: analysis of resonance frequency and insertion torque

As pesquisas clínicas na área da implantodontia apresentam uma grande dificuldade em relação à avaliação da osseointegração e estabilidade dos implantes. Dessa forma, a análise de frequência de ressonância (AFR) têm se tornado uma das principais ferramentas utilizadas, já que oferece, de forma simples e não invasiva, a possibilidade de se monitorar a estabilidade durante todo o período desejado. Outra medida também bastante usada na prática clínica é o torque de inserção dos implantes. No entanto, essa medida é limitada ao trans-cirúrgico e nos fornece unicamente a estabilidade primária dos implantes, o que a torna mais indicada para avaliação da possibilidade de se submeter à carga imediata. Este estudo apresenta como objetivos avaliar, por meio de um estudo transversal, se os valores do coeficiente de estabilidade do implante (ISQ) são similares em diferentes alturas do componente protético e diretamente na plataforma, quando mensurados por meio da AFR e avaliar por meio de uma revisão sistemática e meta-análise a relação entre o torque de inserção e a AFR, investigando se estes dois instrumentos fornecem avaliações similares da estabilidade primária de em um mesmo implante. Para tal, foi realizado um estudo transversal em 31 implantes osseointegrados com plataforma de hexágono externo, com 4.1 mm de diâmetro e comprimento maior ou igual a 10mm e uma revisão sistemática com ensaios clínicos que reportassem valores de ISQ e torque de inserção. Assim, nossos estudos recomendam que explorar e desenvolver a AFR como método de avaliação da estabilidade implantar deve ser uma busca ainda necessária das pesquisas científicas para melhor compreensão do comportamento dos implantes dentários, nos seus diversos momentos e situações na cavidade oral, bem como determinar um bom nível de estabilidade que consequentemente determinaria uma maior longevidade e funcionalidade dos implantes dentários

Clinical research in the implantology presents a great difficulty regarding the evaluation of the osseointegration and stability of the implants. Thus, resonance frequency analysis (RFA) has become one of the main tools used, since it offers, in a simple and non-invasive way, the possibility of monitoring the stabiblity during the desired period. Another measure also widely used in clinical practice is the insertion torque of the implants. However, this measureis limited to the transsurgical and provides only the primary stability of the implants, which makes it more suitable for evaluation the possibility of undergoing immediate loading. This study aims to evaluate, through a cross-sectional study, whether implant stability coefficient (ISQ) values are similar at different heights...

Influência do torque de inserção na deformação da superfície de implantes osseointegráveis / Influence of insertion torque on dental implant surface deformation

Objetivo: avaliar as alterações na morfologia da superfície de implantes osseointegráveis submetidos a diferentes torques de inserção e analisar as possíveis interferências no processo de osseointegração. Material e métodos: foram utilizados implantes com superfícies tratadas com ácidos e inseridos em costelas bovinas com torques entre 32 Ncm e 171 Ncm. Após a inserção, os implantes foram removidos sem torção, com corte das costelas para não alterar a superfície e analisados no microscópio eletrônico de varredura (MEV). Resultados: as análises mostraram deformações plásticas heterogêneas das superfícies dos implantes inseridos com torques acima de 72 Ncm. O implante que recebeu maior torque de inserção apresentou deformações nos vértices e flancos dos filetes de roscas, com a presença de microtrincas na camada de óxido de titânio. Conclusão: as deformações alteram as microcavidades da superfície, criadas pelo ataque ácido, e podem prejudicar na adesão das células e proteínas.

Objective: the purpose of the present study was to evaluate the alterations on the surface of dental implants submitted to different insertion torques. Material and methods: acid-etched dental implants were used and placed into bovine ribs with insertion torques between 32 Ncm and 171 Ncm. After that, the bovine ribs were cut for implant removal without torque. Scanning electron microscopy were used for implant surface analyses. Results: surface plastic deformations were seen after insertion torque higher than 72 Ncm. The implant surface plastic deformation increased with insertion torque value. The highest insertion torque values induced plastic deformation and microcracks in the titanium oxide film. Conclusion: the deformations seen can alter the microcavities and infl uence in the interactions among cells and proteins with the implant surface.

The effect of the thread depth on the mechanical properties of the dental implant

PURPOSE: This study aimed to evaluate the effect of implant thread depth on primary stability in low density bone. MATERIALS AND METHODS: The insertion torque was measured by inserting Ti implants with different thread depths into solid rigid polyurethane blocks (Sawbones) with three different bone densities (0.16 g/cm3, 0.24 g/cm3, and 0.32 g/cm3). The insertion torque value was evaluated with a surgical engine. The static compressive strength was measured with a universal testing machine (UTM) and the Ti implants were aligned at 30degrees against the loading direction of the UTM. After the static compressive strength test, the Ti implants were analyzed with a Measurescope. RESULTS: The Ti implants with deeper thread depth showed statistically higher mean insertion torque values (P.05). After the static compressive strength, the thread shape of the Ti implants with deeper thread depth did not show any breakage but did show deformation of the implant body and abutment. CONCLUSION: The implants with deeper thread depth had higher mean insertion torque values but not lower compressive strength. The deep threads had a mechanical stability. Implants with deeper thread depth may increase the primary stability in areas of poor quality bone without decreasing mechanical strength.

The effect of the thread depth on the mechanical properties of the dental implant

PURPOSE: This study aimed to evaluate the effect of implant thread depth on primary stability in low density bone. MATERIALS AND METHODS: The insertion torque was measured by inserting Ti implants with different thread depths into solid rigid polyurethane blocks (Sawbones) with three different bone densities (0.16 g/cm3, 0.24 g/cm3, and 0.32 g/cm3). The insertion torque value was evaluated with a surgical engine. The static compressive strength was measured with a universal testing machine (UTM) and the Ti implants were aligned at 30degrees against the loading direction of the UTM. After the static compressive strength test, the Ti implants were analyzed with a Measurescope. RESULTS: The Ti implants with deeper thread depth showed statistically higher mean insertion torque values (P.05). After the static compressive strength, the thread shape of the Ti implants with deeper thread depth did not show any breakage but did show deformation of the implant body and abutment. CONCLUSION: The implants with deeper thread depth had higher mean insertion torque values but not lower compressive strength. The deep threads had a mechanical stability. Implants with deeper thread depth may increase the primary stability in areas of poor quality bone without decreasing mechanical strength.

Insertion Torque of Mini Dental Implants and their Failure Risk after Immediate Loading / Torque de Inserción de Mini Implantes Dentales y su Riesgo de Fracaso cuando son Cargados Inmediatamente

A minimum insertion torque has been suggested for immediate function of regular diameter implants. Even when there is a growing tendency to use Mini Dental Implants (MDIs) for immediate function of dentures, there is no clinical data concerning MDIs insertion torque, nor its influence on implant failure. The aim of this prospective study was to assess the insertion torque of immediate loaded MDIs in edentulous patients and its association with risk failure. Ninety MDIs were placed in the anterior mandible of 45 edentulous patients, two per patient. The insertion torque was recorded with an electronic device and failures were documented during two years follow-up. All implants were immediately loaded with overdentures, using ball (44/90) or bar (46/90) attachments. A Kaplan­Meier survival probability estimator and a fitted multiple Cox regression model were performed to establish the influence of insertion torque and other clinical parameters on implant risk failure. The average insertion torque of 90 MDIs was 12.5±7.8 Ncm. A cumulative survival rate of 94.2% (5/90) was found by means of the Kaplan-Meier estimation. The Cox proportional-hazards regression model showed no association between insertion torque and MDIs failure. MDIs have much lower insertion torque than average conventional implants. The insertion torque of MDIs immediately loaded with mandibular dentures, seems not to be a risk factor associated to failure, at two years follow-up.

Un mínimo torque de inserción ha sido sugerido para realizar carga inmediata de implantes de diámetro regular. Aún cuando existe una tendencia creciente a utilizar Mini Implantes Dentales (MID) para la función inmediata de las prótesis totales, no hay datos clínicos relativos a los valores de torque de inserción de estos, ni tampoco de su influencia en el fracaso del implante. El objetivo de este estudio prospectivo fue evaluar el torque de inserción de mini implantes dentales con carga inmediata en pacientes desdentados y su asociación con el riesgo de fracaso. Noventa MIDs fueron colocados en la mandíbula anterior de 45 pacientes desdentados, dos por paciente. El torque de inserción fue obtenido con un dispositivo electrónico y los fracasos fueron documentadas a dos años de seguimiento. Todos los implantes fueron cargados inmediatamente con sobredentaduras, usando un sistema de retención de bola (44/90) o barra (46/90). Se utilizó el estimador de probabilidad de sobrevida de Kaplan-Meier y el modelo riesgos proporcionales de Cox ajustado para establecer la influencia de torque de inserción y otros parámetros clínicos sobre el riesgo de fracaso del implante. El promedio de torque de inserción de 90 MIDs fue 12,5±7,8 Ncm . Los MIDs mostraron a través de la estimación de Kaplan-Meier, una tasa de supervivencia acumulada de 94,2% (5/90). El modelo de riesgos proporcionales de Cox reveló que no existe asociación entre el valor de torque de inserción y el fracaso MIDs. MIDs tienen un valor de torque de inserción mucho más bajo que los implantes convencionales. El torque de inserción de MIDs cargados inmediatamente con prótesis mandibulares, no parece ser un factor de riesgo asociado al fracaso, a dos años de seguimiento.

Geometrical design characteristics of orthodontic mini-implants predicting maximum insertion torque / 대한치과교정학회지

OBJECTIVE: To determine the unique contribution of geometrical design characteristics of orthodontic mini-implants on maximum insertion torque while controlling for the influence of cortical bone thickness. METHODS: Total number of 100 cylindrical orthodontic mini-implants was used. Geometrical design characteristics of ten specimens of ten types of cylindrical self-drilling orthodontic mini-implants (Ortho Easy(R), Aarhus, and Dual Top(TM)) with diameters ranging from 1.4 to 2.0 mm and lengths of 6 and 8 mm were measured. Maximum insertion torque was recorded during manual insertion of mini-implants into bone samples. Cortical bone thickness was measured. Retrieved data were analyzed in a multiple regression model. RESULTS: Significant predictors for higher maximum insertion torque included larger outer diameter of implant, higher lead angle of thread, and thicker cortical bone, and their unique contribution to maximum insertion torque was 12.3%, 10.7%, and 24.7%, respectively. CONCLUSIONS: The maximum insertion torque values are best controlled by choosing an implant diameter and lead angle according to the assessed thickness of cortical bone.

Influence of insertion torque on primary stability of dental implants in beagle / 实用医学杂志

Objective To investigate the correlation between the insertion torque values and primary stability of dental implants using different insertion torque values ,and search for the best insertion torque values that can acquire good primary stability. Methods Six male pure beagles were selected, and the first molars and four premolars of bilateral mandibulars were extracted. Three months later, a total of 48 XIVE dental implants were inserted. All implants were divided into group A, group B, group C, and group D based on the insertion torque value (ITV): group A, 0 0.05). Conclusion With the limitations of the study, it was concluded the primary stability does not simply depend on the insertion torque;When the insertion torque value was no less than 20Ncm, the dental implant can acquire good primary stability.

Correlação entre torque final de inserção e frequência de ressonância em três modelos de implantes dentários: estudo experimental in vitro / Correlation between final insertion torque and resonance frequency in three dental implant models: an experimental in vitro study

A estabilidade primária dos implantes dentários está relacionada principalmente a fatores como técnica cirúrgica, qualidade e quantidade óssea. A experiência do operador aliada à técnica cirúrgica adequada, e a mensuração da estabilidade primária por meio da frequência de ressonância (FR) e torque de inserção, podem ajudar o profissional a documentar e traçar o prognóstico do caso clínico. Objetivos: analisar a estabilidade primária entre três modelos de implantes dentários, com desenhos diferentes entre si, da empresa Conexão Sistema de Próteses (Arujá/SP, Brasil), por meio do torque final de inserção e FR. Material e métodos: o torque de inserção dos implantes foi mensurado com torquímetros digitais e, quando necessário, manual; a mensuração da FR foi realizada logo após a instalação, usando o equipamento Osstell ISQ em duas direções (paralelo e perpendicular ao osso), na escala ISQ. Resultados: os resultados indicaram que a maior média de torque de inserção foi do implante Flash (Grupo 3 – 68 Ncm); seguida do EasyGrip (Grupo 2 – 63,5 Ncm), e com média mais baixa no modelo Master (Grupo 1 – 50 Ncm). O teste Anova não mostrou diferenças significativas para o torque (p > 0,05), porém, quando aplicado à FR, apresentou um nível de significância elevado (p < 0,05). Conclusão: existe uma correlação positiva e significativa entre torque final de inserção e a FR nos Grupos 2 e 3

The primary stability of dental implants is mainly related to factors such as surgical technique, bone quality, and quantity. The operator’s experience combined with adequate surgical technique and the measurement of primary stability by the resonance frequency (RF) and insertion torque can help professionals to document and trace the prognosis of each clinical case. Objectives: to evaluate the primary stability between three implant models (Conexão Sistemas de Prótese (Arujá/SP, Brazil) with different designs through final insertion torque and RF. Material and methods: the insertion torque was measured with digital and manual devices when necessary, and RF measurement performed shortly after installation using the Osstell in two directions (parallel and perpendicular to the bone) by ISQ values. Results: group 3 (Flash) presented the highest mean torque (68 Ncm), followed by Easy Grip (Group 2 – 63.5 Ncm), and Master (Group 1 – 50 Ncm). The Anova test demonstrated no differences among torque values (p >0.05), but a high level of significance was found for RF (p <0.05). Conclusion: a positive and significant correlation was found between the final insertion torque and RF in the Groups 2 and 3.

The influence of implant diameter, length and design changes on implant stability quotient (ISQ) value in artificial bone / 대한치과보철학회지

PURPOSE: The purpose of this study is to ascertain the stability of the implant by comparing the effects of the change of implant diameter, length and design on implant stability quotient. MATERIALS AND METHODS: To remove the variable due to the difference of bone quality, the uniform density (0.48 g/cm3) Polyuretane foam blocks (Sawbones(R), Pacific Research Laboratories Inc, Vashon, Washington) were used. Implants (Implantium(R), Dentium, Seoul, Korea) were placed with varying diameters (phi3.8, phi4.3 and phi4.8) and length (8 mm, 10 mm and 12 mm), to assess the effect on implant stability index (ISQ). Also the influence of the design of the submerged and the non-submerged (SimplelineII(R), Dentium, Seoul, Korea) on ISQ was evaluated. To exclude the influence of insertion torque, a total of 60 implants (n = 10) were placed with same torque to 35 N. Using Osstell(TM) mentor (Integration Diagnostic AB, Sweden) ISQ values were recorded after measuring the resonant frequency, one-way ANOVA and Tukey HSD test results were analyzed. (alpha=0.05). RESULTS: 1. The change of the diameter of the implant did not affect the ISQ (P>.05), but the increase of implant length increased the ISQ(P<.001). 2. The change in implant design were correlated with the ISQ, and the ISQ of submerged design was significantly higher than that of the non-submerged design(P<.05). CONCLUSION: In order to increase implant stability, the longer implant is better to be selected, and on the same length of implant, submerged design is thought to be able to get a higher ISQ than the non-submerged.

Analysis of thermal changes in bone by various insertion torques with different implant designs / 대한치과보철학회지

PURPOSE: This study aims at investigating the influence of various insertion torques on thermal changes of bone. A proper insertion torque is derived based on the thermal analysis with two different implant designs. MATERIALS AND METHODS: For implant materials, bovine scapula bone of 15 - 20 mm thickness was cut into 35 mm by 40 - 50 mm pieces. Of these, the pieces having 2 - 3 mm thickness cortical bone were used as samples. Then, the half of the sample was immersed in a bath of 36.5degrees C and the other half was exposed to ambient temperature of 25degrees C, so that the inner and surface temperatures reached 36.5degrees C and 28degrees C, respectively. Two types of implants (4.5 x 10 mm Branemark type, 4.8 x 10 mm Microthread type) were inserted into bovine scapula bone and the temperature was measured by a thermocouple at 0.2 mm from the measuring point. Finite element method (FEM) was used to analyze the thermal changes at contacting surface assuming that the sample is a cube of 4 cm x 4 cm x 2 cm and a layer up to 2 mm from the top is cortical bone and below is a cancellous bone. Boundary conditions were set on the basis of the shape of cavity after implants. SolidWorks was used as a CAD program with the help of Abaqus 6.9-1. RESULTS: In the in-vitro experiment, the Microhead type implant gives a higher maximum temperature than that of the Branemark type, which is attributed to high frictional heat that is associated with the implant shape. In both types, an Eriksson threshold was observed at torques of 50 Ncm (Branemark type) and 35 Ncm (Microthread type), respectively. Based on these findings, the Microthread type implant is more affected by insertion torques. CONCLUSION: This study demonstrate that a proper choice of insertion torque is important when using a specific type of implant. In particular, for the Microthread type implant, possible bone damage may be expected as a result of frictional heat, which compensates for initial high success rate of fixation. Therefore, the insertion torque should be adjusted for each implant design. Furthermore, the operation skills should be carefully chosen for each implant type and insertion torque.

The validation of Periotest values for the evaluation of orthodontic mini-implants' stability / 대한치과교정학회지

OBJECTIVE: The aim of this study was to validate the Periotest values for the prediction of orthodontic mini-implants' stability. METHODS: Sixty orthodontic mini-implants (7.0 mm x O1.45 mm; ACR, Biomaterials Korea, Seoul, Korea) were inserted into the buccal alveolar bone of 5 twelve month-old beagle dogs. Insertion torque (IT) and Periotest values (PTV) were measured at the installation procedure, and removal torque (RT) and PTV were recorded after 12 weeks of orthodontic loading. To correlate PTV with variables, the cortical bone thickness (mm) and bone mineral density (BMD) within the cortical bone and total bone area were calculated with the help of CT scanning. RESULTS: The BMD and cortical bone thickness in mandibular alveolus were significantly higher than those of the maxilla (p< 0.05). The PTV values ranged from -3.2 to 4.8 for 12 weeks of loading showing clinically stable mini-implants. PTV at insertion was significantly correlated with IT (-0.51), bone density (-0.48), cortical bone thickness (-0.42) (p< 0.05) in the mandible, but showed no correlation in the maxilla. PTV before removal was significantly correlated with RT (-0.66) (p< 0.01) in the mandible. CONCLUSIONS: These results show that the periotest is a useful method for the evaluation of mini-implant stability, but it can only be applied to limited areas with thick cortical and high density bone such as the mandible.

A comparison of bone bed preparation with laser and conventional drill on the relationship between implant stability quotient (ISQ) values and implant insertion variables

PURPOSE: The aim of this study was to investigate a comparison of implant bone bed preparation with Er,Cr:YSGG laser and conventional drills on the relationship between implant stability quotient (ISQ) values and implant insertion variables. MATERIALS AND METHODS: Forty implants were inserted into two different types of pig rib bone. One group was prepared with conventional drills and a total of 20 implants were inserted into type I and type II bone. The other group was prepared with a Er,Cr:YSGG laser and a total of 20 implants were inserted into type I and type II bone. ISQ, maximum insertion torque, angular momentum, and insertion torque energy values were measured. RESULTS: The mean values for variables were significantly higher in type I bone than in type II bone (P or = .05). The ISQ values were correlated with maximum insertion torque (P < .01, r = .731), total energy (P < .01, r = .696), and angular momentum (P < .01, r = .696). CONCLUSION: Within the limitations of this study, the effects of bone bed preparation with Er,Cr:YSGG laser on the relationship between implant stability quotient (ISQ) values and implant insertion variables were comparable to those of drilling.

Influence of high insertion torque on implant placement: an anisotropic bone stress analysis

The aim of this study was to evaluate the influence of the high values of insertion torques on the stress and strain distribution in cortical and cancellous bones. Based on tomography imaging, a representative mathematical model of a partial maxilla was built using Mimics 11.11 and Solid Works 2010 softwares. Six models were built and each of them received an implant with one of the following insertion torques: 30, 40, 50, 60, 70 or 80 Ncm on the external hexagon. The cortical and cancellous bones were considered anisotropic. The bone/implant interface was considered perfectly bonded. The numerical analysis was carried out using Ansys Workbench 10.0. The convergence of analysis (6 percent) drove the mesh refinement. Maximum principal stress (σmax) and maximum principal strain (εmax) were obtained for cortical and cancellous bones around to implant. Pearson's correlation test was used to determine the correlation between insertion torque and stress concentration in the periimplant bone tissue, considering the significance level at 5 percent. The increase in the insertion torque generated an increase in the σmax and εmax values for cortical and cancellous bone. The σmax was smaller for the cancellous bone, with greater stress variation among the insertion torques. The εmax was higher in the cancellous bone in comparison to the cortical bone. According to the methodology used and the limits of this study, it can be concluded that higher insertion torques increased tensile and compressive stress concentrations in the periimplant bone tissue.

O objetivo deste estudo foi avaliar a influência dos altos valores de torque de inserção na distribuição de tensões e deformações no osso cortical e medular. Com base em imagens de tomografia computadorizada, um modelo matemático representativo de um segmento da maxila foi construído utilizando os programas Mimics 11.11 e Solid Works 2010. Seis modelos foram construídos e cada um recebeu um implante com os seguintes torques de inserção no hexágono externo: 30, 40, 50, 60, 70 ou 80 Ncm. O osso cortical e medular foi considerado anisotrópico. A interface osso/implante foi considerada perfeitamente unida. A análise numérica foi realizada através do Ansys Workbench 10.0. A convergência de análise (6 por cento) determinou o refinamento da malha. A tensão máxima principal (σmax) e a deformação máxima principal (εmax) foram obtidos para o osso cortical e medular ao redor do implante. O teste de correlação de Pearson foi utilizado para determinar a correlação entre torque de inserção e de concentração de tensões e deformações no tecido ósseo peri-implantar, considerando o nível de significância de 5 por cento. O aumento no torque de inserção gerou um aumento nos valores σmax e εmax para o osso cortical e medular. O σmax foi menor para o osso medular, com maior variação de tensão entre os torques de inserção. O εmax foi maior no osso medular em relação ao osso cortical. De acordo com a metodologia utilizada e com os limites do estudo, pode-se concluir que torques alto de inserção aumentou as concentrações de tensões de tração e compressão no tecido ósseo peri-implantar.

Carga inmediata sobre implante único: estudio clínico prospectivo / Immediate load in single-tooth restorations: a clinical prospective study

Introducción: la carga inmediata se ha convertido en una alternativa viable de tratamiento que ofrece múltiplesbeneficios a los pacientes como función y estética inmediata, reducción del trauma quirúrgico y disminución del tiempo total de tratamiento. Se hizo un estudio prospectivo controlado para la colocación de implantes en casos clínicos de restauración de dienteúnico que recogiese el consenso propuesto en la literatura para evaluar el éxito clínico bajo el protocolo de carga inmediata: implantes de conexión interna, cónicos, de superficie texturizada y un mínimo de 32 Ncm de torque inicial. Métodos: se colocaron21 implantes Renova® (Lifecore Biomedical Inc., Chaska, MN) en 17 pacientes adultos (6 hombres y 11 mujeres) rango de edad entre 18 y 74 años, sistémicamente sanos con necesidad de reemplazo de diente único en sectores anterior y premolar de ambos maxilares. Resultados: la tasa de éxito acumulativa a 18 meses fue de 95,2%. Se obtuvieron valores de éxito similares a los reportados con el protocolo de carga convencional y se encontró correlación directa entre la distancia desde el hueso al punto decontacto y el porcentaje de presencia de papila en el espacio interproximal. Conclusión: los resultados indican que el protocolo de carga inmediata para el tratamiento de restauraciones de diente único en la zona anterior mediante implantes temporalizadosinmediatamente, sin función oclusal, es una alternativa viable con tasas de éxitos mayores al 95%, comparables a las logradas con el protocolo de carga convencional.

Introduction: immediate loading of implants has become a viable treatment alternative that offers multiple benefitsfor patients such as providing immediate function and esthetics, reduction of surgical trauma and less treatment time. A controlled prospective clinical trial was conducted to evaluate the success of immediately loaded implants for single-tooth restoration following consensus protocols in recent literature. Methods: twenty-one 3.75 x 13mm RBM-treated surface internal connection implants (Renova®, Lifecore Biomedical Inc., Chaska Mn.) were placed in 17 systemically healthy patients (6 males, 11 females), ages between 18 and 74 years who required single-tooth replacement in the anterior and premolar regions of both jaws. Results: the 18-month cumulative success rate for this study was 95.2%. According to the statistical analysis in this study, immediate loading of implants for single-tooth restoration compares favorably to the two-stage protocol and a direct correlation between the distancefrom bone to contact point and papilla filling was found. Conclusions: results from the present study indicate that the single-tooth restoration in the anterior area with immediately loaded surface-treated threaded titanium implants and no occlusal function is a viable treatment alternative with a success rate greater than 95%, comparable to the conventional loading protocol.