Effects of Different Implant Design Parameters on Mandibular Tooth Implantation / 医用生物力学

Objective To establish the implant-mandible model with different design parameters, observe stress distributions on the implant and surrounding bone, and analyze the influence of different design parameters on dental implant of the mandible. Methods Eight implant models were designed based on structural characteristic parameters (implant diameter, thread depth, height of abutment through gingiva, thread shape), and assembly of the mandibular model was performed respectively. The models were applied with static 150 N vertical and oblique 45° loads, so as to analyze peak von Mises stress of the implant and bone tissues and explore the structural parameter variables of implant most sensitive to peak von Mises stress. Results The peak stress of the mandible was larger under inclined load than that under vertical load. Implant diameter was the key factor affecting the peak von Mises stress of cortical bone, while thread depth was the key factor affecting the peak von Mises stress of cancellous bone. The peak von Mises stress was also affected by the height of abutment through gingiva, but the effect was not as significant as thread depth and implant diameter. Thread shape had little effect on the peak von Mises stress of the mandible. Conclusions Different implant design parameters can affect the peak stress of different tissues of the mandible, so it is necessary to carefully consider the selection of implant parameters for personalized implants. This study can provide theoretical guidance for structural parameter design of oral implants and provide references for accurate prediction of oral implants.

Short implants in posterior maxilla in elderly patients: A case series

@#<p>Placement of dental implants in reduced bone in the posterior maxilla requires maxillary sinus floor elevation. However, in elderly patients this is to be avoided. A case series on the successful placement of multiple short implants in posterior maxilla and splinted crown restorations in elderly patients was presented. Long term follow up revealed survival of the implants. Short implant is a suitable treatment option for elderly patients</p>

A two-short-implant-supported molar restoration in atrophic posterior maxilla: A finite element analysis

PURPOSE: The aim of this study was to investigate the stress distribution of 2-short implants (2SIs) installed in a severely atrophic maxillary molar site. MATERIALS AND METHODS: Three different diameters of internal connection implants were modeled: narrow platform (NP), regular platform (RP), and wide platform (WP). The maxillary first molars were restored with one implant or two short implants. Three 2SI models (NP-oblique, NP-vertical, and NP-horizontal) and four single implant models (RP and WP in a centered or cantilevered position) were used. Axial and oblique loadings were applied on the occlusal surface of the crown. The von Mises stress values were measured at the bone-implant, peri-implant bone, and implant/abutment complex. RESULTS: The highest stress distribution at the bone-implant interface and the peri-implant bone was noticed in the RP group, and the lowest stress distribution was observed in the 2SI groups. Cantilevered position showed unfavorable stress distribution with axial loading. 2SI types did not affect the stress distribution in oblique loading. The number and installation positions of the implant, rather than the bone level, influenced the stress distribution of 2SIs. The implant/abutment complex of WP presented the highest stress concentration while that of 2SIs showed the lowest stress concentration. CONCLUSION: 2SIs may be useful for achieving stable stress distribution on the surrounding bone and implant-abutment complex in the atrophic posterior maxilla.

Seleção do diâmetro do implante em alvéolos pós-exodontia: uma nova abordagem / Diameter selection of implants placed in extraction sockets: a new approach

A instalação de implantes em alvéolos de extração pode ser considerado um procedimento desafiador, devido ao risco de remodelação óssea e às consequentes alterações gengivais. Objetivo: o presente estudo tem como objetivo propor um protocolo de seleção do diâmetro de implantes osseointegráveis em alvéolos pós-extração na região anterossuperior, baseado na medida vestibulopalatina do alvéolo, permitindo a formação de um espaço entre o implante e a porção externa da parede óssea vestibular, de 3mm, que deverá ser preenchido com biomaterial ou com ósseo autógeno, aumentando a previsibilidade de resultados em longo prazo...

Implant placement in extraction sockets is a challenging procedure, since it offers risks of bone remodeling and, as a consequent, gingival alterations. Objective: This study aims at proposing a protocol for selecting the diameter of osseointegrated implants placed in extraction sockets in the anterosuperior region. This protocol is based on the buccal palatal dimension of the socket and allows a 3-mm gap to form between the implant and the outer surface of the buccal bone wall.Such gap must be filled with biomaterial or autograft so as to increase the predictability of long-term results...

Assessment of demographic and clinical data related to dental implants in a group of Turkish patients treated at a university clinic

PURPOSE: This retrospective study analyzed the distribution of the dental implants with regards to age and gender of the patients and type of indication for the implant therapy, as well as the location, dimension and type of the implants. MATERIALS AND METHODS: The data of demographics (age and gender), type of indication for implant therapy, anatomical location, dimensions (length and diameter) and type (bone and tissue level) of 1616 implants were recorded from patient charts between January 2000 and January 2010. Descriptive statistics were analyzed using a chi-squared test for demographic parameters, type of indication, tooth position, anatomical location, implant dimensions and type (alpha=.05). RESULTS: The patient pool comprised of 350 women and 266 men, with a mean age of 52.12 +/- 13.79 years. The difference in n% of the implants of the age groups was statistically significant between the types of indications. The difference in the position of the implants was statistically significant between the n% of the implants of all age groups. Gender did not significantly vary, except that the diameter of the implants was significantly higher for the standard diameter implants in males. The difference between the implant positions was statistically significant when considered according to indication. The relationship between implant length and anatomical location was statistically significant. CONCLUSION: The indication for dental implant use is age dependent and the type and size of the implant seems to be strongly related to the location of the implant.

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.

Influence of implant diameter on the osseointegration of implants; an experimental study in rabbits / 대한치과보철학회지

STATEMENT OF PROBLEM: The survival rate of wide diameter implants was lower than of 3.75-mm implants in some clinical researches. PURPOSE: The purpose of this study was to investigate the influence of implant diameter on the osseointegration of implants in the rabbit femoral condyle and tibial metaphyses by means of removal torque measurements and histomorphometric analysis. MATERIAL AND METHOD: Ten adult New Zealand White rabbits were used in this study. Two 3.75-mm diameter implants were inserted through one cortical layer in the tibial metaphyses and one 3.75-mm diameter implant was inserted in the femoral condyle. 5.0-mm diameter implants were inserted in the other leg in the same manner. A total of 60 implants (3.75-mm diameter implants:30 ; 5.0-mm diameter implants:30) were installed. After a healing time of 4 and 12 weeks, the peak removal torque values required to shear off the implants were recorded. From the removal torque values (Ncm) obtained, the mean shear stress (N/mm2) was calculated. And the percentage of direct bone-to-implant contact and the percentage of bone area inside the thread were measured by Kappa Image Base-metreo. The Student's t-test was undertaken for statistical analysis (p0.05). The percentage direct bone-to-implant contact had no statistical difference between two groups (p>0.05). The percentage of bone area inside the thread had no statistical difference between two groups (p>0.05). CONCLUSION: It is concluded that the quality of osseointegration is not influenced by increasing implant diameter.

An analysis of ITI implants placed in korean patients / 대한치주과학회지

The aim of this study was to analyze various data of 120 non-submerged ITI implants placed in 64 korean adults. The data were retrieved from patients' charts and registered in the computer and coded for a statistical analysis. The results revealed that the most common type of edentulism was a distal extension case, and the largest number of implants were placed in the mandibular first molar position. Implants were placed more frequently in mandibular, posterior position than maxillary, anterior position, respectively. With respect to the implant diameter and length, an implant with 4.1mm in diameter and more than 10mm in length was the most common. Since a molar position was the most prevalent position for implant placement in korean patients, clinicians should be careful about implant diameter which can resist a strong occlusal force expected in the molar position. In addition, the distance to the mandibular canal and the floor of maxillary sinus should be considered to avoid possible damages, such as nerve injury and sinus perforation in selecting a proper implant length.