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.

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.

Clinical comparison of fiber-reinforced composite and stainless steel wire for splinting periodontally treated mobile teeth / Comparação clínica de contenção periodontal com resina composta reforçada por fibra de vidro ou fio de aço inoxidável em dentes com mobilidade

Objective: This clinical study evaluated the success of two different splint materials bonded on periodontally treated mobile teeth. Material and Methods: A total of 14 patients were included in the study. Patients were randomly assigned to the groups to receive either with wire composite splint (WCS) or fiber-reinforced composite splint (FCS). Clinical periodontal parameters were performed and periotest values were recorded at baseline, and after 6 and 12 months. Patients were asked to complete a self-administered questionnaire after the splinting procedures. Failure types for the splints were categorized. Results: Baseline Plaque index (PI) values showed significant decrease at 6 month follow up in the WCS (p = 0.0019) and FCS (p < 0.0001) groups and remained stable after 12 months (WCS; p = 0.36, FCS; p = 0.63). During the course of the study, PD and RD values exhibited no change between and within groups. Clinical parameters including Pocket depth (PD), Gingival recession (GR), PI and Bleeding on probing (BOP) were stable at 6 and 12 months follow-up period. In 6 patients (4 FCS, 2 WCS), reparable failures occurred during the observation period. In four patients (3 FCS, 1 WCS) splints failed completely and were removed. The periotest values of the failing teeth ranged between 47.3 and 50. In 3 patients in the WCS and 1 patientin the FCS group, periotest values were ≥ 40 but no splint failures were observed. Conclusion: FCS tends to show increased mechanical limitations compared to WCS. Teeth with periotest values above 40 may be more prone to splint failures independent of the splint material.

Objetivo: Este estudo clínico avaliou a permanênciade dois materiais diferentes utilizados para contenção de dentes com mobilidade tratados periodontalmente. Material e Métodos: Um total de 14 pacientes foram incluídos no estudo. Os pacientes foram distribuídos aleatoriamente em grupos para receber contenção com fio de aço inoxidável (FA)e resina ou resina reforçada por fibra de vidro (FV). Os parâmetros clínicos periodontais foram realizados e os valores do Periotest foram registrados no início do estudo e após 6 e 12 meses. Os pacientes foram convidados a preencher um questionário após os procedimentos de contenção. Foram classificados os tipos de falhas para as contenções. Resultados: Os valores de índice de placa de base (IP) apresentaram diminuição significativa aos 6 meses de acompanhamento nos grupos FA (p = 0,0019) e FV (p < 0,0001) e manteve-se estável após 12 meses (FA, p = 0,36, FV, p = 0,63). Durante o período do estudo, a profundidade de sondagem (PS), recessão gengival (RG) e nível clínico de inserção (NCI) não apresentaram mudança entre e dentro dos grupos. Os parâmetros clínicos incluindo PS, RG, NCI, IP e sangramento a sondagem ficaram estáveis em 6 e 12 meses de período de acompanhamento. Em 6 pacientes (4 FA, 2 FV), ocorreram falhas reparáveis. Em quatro pacientes (3 FV, 1 FA) a contenção falhou completamente e foram removidos. Os valores Periotest dos dentes que as contenções falharam variaram entre 47,3 e 50. Em 3 pacientes no grupo FA e 1 paciente no grupo FV, os valores Periotest foram ≥ 40, mas não foram observadas falhas na contenção. Conclusão: O grupo FV tendeu a mostrar aumento das limitações mecânicas em relação ao FV. Dentes com Periotest valores acima de 40 podem ser mais propensos a falhas de contenção independentes do material utilizado.

Implant stability evaluation according to the bone condition, fixture diameter and shape in the osseointegration simulated resin model / 대한치과보철학회지

PURPOSE: Resonance frequency analysis, Periotest, and removal torque (RT) test were known as the methods to assess implant stability. The results of these methods are affected by the bone condition, implant diameter and shape. The purpose of this study is to access the meaning and the correlationship of the resonance frequency analysis, Periotest and RT test in osseointegration simulated acrylic resin when the engaged bone thickness and peri-implant bone defect are changed. MATERIALS AND METHODS: To simulate osseointegration, the fixture was fixed to an aluminum mold with a screw. Acrylic resin powder and liquid were poured into the mold for polymerization. The engaged resin thickness with implant was controlled. Simulated cortical bone thicknesses were 1, 3, 5 and 10 mm. Additional 1, 3 and 5 mm peri-implant bone defects were simulated. Three types of implants were used; 4 mm diameter implants of straight shape, 4 mm diameter implants of tapered shape and 5 mm diameter implants of tapered shape. Five fixtures per each type were tested in respective bone condition. Resonance frequency analysis and Periotest were evaluated in all bone conditions. Peak removal torque was measured at simulated cortical bone thicknesses of 1 and 3 mm. The statistical analysis was performed with the Kruskal-Wallis test, Mann-Whitney U test, and Spearman test using a 95% level of confidence. RESULTS: With increasing engaged bone depth, the Implant Stability Quotient (ISQ) values increased and the Periotest values (PTVs) decreased (P<.001, P<.001). With increasing peri-implant bone defect, ISQ values decreased and PTVs increased (P<.001). When the diameter of implant increased, ISQ values increased and Periotest values (PTV) decreased (P<.001). There was a strong correlation between ISQ values and PTVs (r = -0.99, P<.001). Furthermore, the peak removal torque values had weak correlations with both ISQ values and PTVs (r = 0.52, P<.001 ; r = -0.52, P<.001). CONCLUSION: This study confirmed favorable implant stability with increasing engaged bone depth and implant diameter and decreasing peri-implant bone defect. ISQ values and PTVs showed strong correlation with each other and not with the peak removal torque values.

The effect of PostGraft(TM) on implants were installed at the tibia of ovariectomized rats / 대한치과보철학회지

PURPOSE: This study evaluated PostGraft(TM) which enhances implant stability and bone density. MATERIALS AND METHODS: Forty eight implants were installed at the tibia of ovariectomized rats. The group administrated with PostGraft(TM) was the experimental group, and the control group was not administrated. Implant stability was evaluated at the 2nd, 4th and 6th week by Periotest value, bone mineral density, bone-to-implant contact. These values were analyzed statistically with Mann-Whitney U test (P<.05). Histological analysis was evaluated at the 2nd, 4th and 6th week. RESULTS: According to the Periotest(R) measurement, both experimental and control groups showed decrease in values as time elapsed. Greater decrease was observed in the experimental group but there was no significant difference. By examining the radiographic images, both experimental and control groups showed tendency of increase in bone density. Greater increase was seen in the experimental group but there was no significant difference. According to the bone-to-implant contact measurement, both experimental and control groups showed increase in values as time elapsed. Greater increase was seen in the experimental group. At the 2nd and 4th week, there was no significant difference. But at the 6th week, there was significant difference (P<.05). By histological analysis, both experimental and control groups showed increase in bone formation as time elapsed. In addition, greater increase was seen in the experimental group. CONCLUSION: It could be concluded that the PostGraft(TM) medicated group showed better results in the bone density and osseointegration.

Aplicación del método periotest en prostodoncia parcial removible: revisión de la literatura / Application of the method periotest removable partial prosthodontics: a literature review

El método periotest es un parámetro cuantitativo reproducible de la reacción del periodonto a estímulos de percusión, está medida es un parámetro biofísico basado en una escala numérica de -8 a +50. El Periotest por si mismo no es una herramienta de diagnóstico, sin embargo, su empleo en evaluaciones sucesivas genera información precisa y objetiva de la evolución del caso ante la aplicación de tratamientos en diferentes áreas de la odontología

The periotest method is a reproducible quantitative parameter of the reaction of periodonto to percussion stimuli, this measurement is a biophysic parameter based on a representative fraction from -8 to +50. The Periotest to per itself is not a diagnosis tool, nevertheless, its use in successive evaluations generates precise and objective information of the evolution of the case before the application of treatments in different areas from dentistry

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.

Longitudinal measurements of tooth mobility following orthodontic treatment / 대한치과교정학회지

OBJECTIVE: The aim of the present study was to evaluate the changes in tooth mobility following orthodontic treatment and to obtain information regarding the guideline of retainer wear duration during the post-treatment period. METHODS: The sample consisted of twenty patients who had been treated with edgewise appliances. The mobility of the maxillary teeth from the central incisor to the first molar was measured bilaterally by way of the Periotest(R), a non-invasive, electronic device that provides an objective measurement of the reaction of the periodontium to a defined impact load. Tooth mobility was monitored at the time of the removal of the orthodontic appliances and subsequently at three-month intervals during the two years following appliance removal. RESULTS: Tooth mobility decreased rapidly for the first six months and then decreased at a slower rate during the next six months; no statistically significant decrease in mobility was observed during the second year following appliance removal. CONCLUSIONS: The results of the present study suggest that adequate tooth stabilization is critical during the first six months following appliance removal and that continued wearing of retainers is recommended at least until twelve months after the completion of orthodontic treatment.

Comparion of stability in titanium implants with different surface topographies in dogs

STATEMENT OF PROBLEM: A few of studies which compared and continuously measured the stability of various surface treated implants in the same individual had been performed. PURPOSE: We aim to find the clinical significance of surface treatments by observing the differences in the stabilization stages of implant stability. MATERIAL AND METHODS: Eight different surface topographies of dental implants were especially designed for the present study. Machined surface implants were used as a control group. 4 nano-treated surface implants (20 nm TiO2 coating surface, heat-treated 80 nm TiO2 coating surface, CaP coating surface, heat treated CaP coating surface) and 3 micro-treated surface implants [resorbable blast media (RBM) surface, sandblast and acid-etched (SAE) surface, anodized RBM surface] were used as experiment groups. All 24 implants were placed in 3 adult dogs. Periotest(R) & ISQ values measured for 8 weeks and all animals were sacrificed at 8 weeks after surgery. Then the histological analyses were done. RESULTS: In PTV, all implants were stabilized except 1 failed implants. In ISQ values, The lowest stability was observed at different times for each individual. The ISQ values were showed increased tendency after 5 weeks in every groups. After 4 to 5 weeks, the values were stabilized. There was no statistical correlation between the ISQ values and PTV. In the histological findings, the bone formation was observed to be adequate in general and no differences among the 8 surface treated implants. CONCLUSIONS: In this study, the difference in the stability of the implants was determined not by the differences in the surface treatment but by the individual specificity.

Surface characteristics and stability of implants treated with alkali and heat / 대한치과보철학회지

STATEMENT OF PROBLEM: Bioactive materials must have the ability to spontaneously form a bone like apatite layer on their surface and induce direct biochemical bonding to bone. A simple chemical treatment via alkali and heat has been revealed to induce bioactivity in titanium. PURPOSE: The purpose of this study was to evaluate the surface characteristics and stability of alkali and heat treated implants. MATERIAL AND METHODS: Specimens were divided into three groups; group 1 was the control group with machined surface implants, groups 2 and 3 were treated with alkali solutions and heat treated in the atmosphere and vacuum conditions respectively. The surface characteristics were observed with FESEM, XPS, TF-XRD and AFM. Stability was evaluated with the resonance frequency analysis, periotest and removal torque values. One-way ANOVA and Duncan test were used for statistical analysis. RESULTS: 1. Groups treated with alkali and heat showed similar characteristics. Groups 2 and 3 showed high compositions of Na ions on the surface with sub-micron sized pores compared to group 1. Group 2 showed mixed compositions of anatase and rutile with superior contents of rutile. 2. Resonance frequency analysis : The ISQ of group 2 showed significantly higher values than that of groups 1 and 3 at 12 weeks. The ISQ of groups 1 and 2 showed significant increase after 4 weeks, and the ISQ of group 3 increased significantly after 2 and 4 weeks respectively (P < .05). 3. Periotest: The PTV of groups 1 and 2 showed significant decrease after 4 weeks, and the PTV of group 3 showed significant decrease after 2 and 4 weeks respectively (P < .05). 4. Removal torque analysis: The removal torque value of group 2 was significantly higher than those of groups 1 and 3 at 2, 4 and 8 weeks. The removal torque values of groups 1 and 3 showed increase at 4 and 12 weeks, but the removal torque value of group 2 showed increase after 4 weeks (P < .05). CONCLUSION: An oxide layer with appropriate crystal structure and amorphous sodium titanate layer can be obtained on titanium implants through alkali and heat treatment in the atmosphere, and even alkali and heat treatment in vacuum conditions, provided a bioactive surface containing sodium. These surface layers can be considered to be effective for enhancement of osseointegration and reduction of healing period for implant treatment.

The influence of abutment screw tightening timing and DLC coating of conical connection implant system / 대한치과보철학회지

STATEMENT OF PROBLEM: It is difficult about assessing the loosening tendency of conical connection type implant after cyclic loading with diamond like carbon coating one-piece abutments, and also about the retightening effect. PURPOSE: This study was performed to investigate the influence of one-piece abutment screw retightening after 5.0X10(4) cyclic loading and Diamond like coating MATERIAL AND METHODS: Thirty two ITI implant were divided to 4 groups. Group 1,3-titanium abutment, group 2,4 - diamond like carbon coated abutment. Group 1,2 - 20.0X10(4) cyclic loading after 5.0X10(4) cyclic loading, Group 3,4- after 20.0X10(4) Cyclic loading. After cyclic loading, periotest values were taken and removal torque values of abutments were measured with a digital torque gauge. RESULTS: 1. The removal torque of group 2 after 5.0X10(4) cyclic loading is slightly greater than the other groups but not significantly higher than others (P>0.05). 2. The final removal torque values after 20.0X10(4) cyclic loading of group 1 is bigger than group 3, and group 2 is bigger than group 4, but not significantly higher (P>0.05). 3. The final removal torque values after 20.0X10(4) cyclic loading of all groups are not significantly different (P>0.05).

The effect of the recipient site depth and diameter on the implant primary stability in pig's ribs

The influencing factors of periotest. value and implant stability quotient / 대한치과보철학회지

STATEMENT OF PROBLEM: Periotest. and OsstellTM were known as the most objective and quantitative mobility tests available for evaluating stability of implant in vivo. Although a correlation between PTV widely used and ISQ recently introduced exist, a PTV was corresponded to various ISQ. A correct evaluation of implant stability could be obtained only after one has a thorough understanding of the limitations of devices and factors that affect measurements. PURPOSE: The purpose of this study was to investigate the causes of variables in the values obtained with these two tests. MATERIAL AND METHOD: A total of 333 implants: 134 Bra.nemark, 5 Silhouette and 194 ITI implants were investigated. Result: 1. There was a correlation between PTV and ISQ (Spearman correlation =0.39, p<0.0001) 2. The factors that affected ISQ were diameter of implant fixture, location of implant and implant system (submerged type vs non-submerged type). 3. The factors that affected PTV were diameter of implant fixture, location of implant, and elapsed time after implant placement. 4. There was no significant difference between different surface treatments of RBM, smooth surface and ti-unite on PTV and ISQ. 5. In radiographic finding, no saucerization or bone resorption has been detected in implants with ISQ values that were above the average level of each PTV. These higher values had higher bone densities around the implant fixture. Saucerization was observed in the most impants with ISQ values that were below the average level of each PTV. CONCLUSION: There was a correlation between ISQ and PTV. However, each measuring methods had factors influencing the measured values. PTV were less sensitive to marginal bone resorption and influenced with the striking point on an implant to the level of bone. With ISQ, the height of implant from bone level to transducer should be considered.

The influencing factors of periotest. value and implant stability quotient / 대한치과보철학회지

STATEMENT OF PROBLEM: Periotest. and OsstellTM were known as the most objective and quantitative mobility tests available for evaluating stability of implant in vivo. Although a correlation between PTV widely used and ISQ recently introduced exist, a PTV was corresponded to various ISQ. A correct evaluation of implant stability could be obtained only after one has a thorough understanding of the limitations of devices and factors that affect measurements. PURPOSE: The purpose of this study was to investigate the causes of variables in the values obtained with these two tests. MATERIAL AND METHOD: A total of 333 implants: 134 Bra.nemark, 5 Silhouette and 194 ITI implants were investigated. Result: 1. There was a correlation between PTV and ISQ (Spearman correlation =0.39, p<0.0001) 2. The factors that affected ISQ were diameter of implant fixture, location of implant and implant system (submerged type vs non-submerged type). 3. The factors that affected PTV were diameter of implant fixture, location of implant, and elapsed time after implant placement. 4. There was no significant difference between different surface treatments of RBM, smooth surface and ti-unite on PTV and ISQ. 5. In radiographic finding, no saucerization or bone resorption has been detected in implants with ISQ values that were above the average level of each PTV. These higher values had higher bone densities around the implant fixture. Saucerization was observed in the most impants with ISQ values that were below the average level of each PTV. CONCLUSION: There was a correlation between ISQ and PTV. However, each measuring methods had factors influencing the measured values. PTV were less sensitive to marginal bone resorption and influenced with the striking point on an implant to the level of bone. With ISQ, the height of implant from bone level to transducer should be considered.

On the surface characteristics and stability of implant treated with anodizing oxidation / 대한치과보철학회지

PURPOSE: This experiment examined the effects of anodization on commercially pure titanium implant fixtures. MATERIAL AND METHODS: The implant fixtures were anodized at three different voltage levels, producing three different levels of oxidation on the surface of the fixure. Implant were divided into four groups according to the level of oxidation. Group 1 consist of the control group of machined surface implants, Group 2 implants were treated by anodizing to 100 voltage, Group 3 implants were treated by anodizing oxidation to 200 voltage Group 4 implants were treated by anodizing oxidation to 350 voltage. Surface morphology was observed by Scanning Electron Microscope(SEM) and the surface roughness was measured using NanoScan E-1000(R). Implantation of the fixtures were performed using New Zealand white rabbits. Periotest(R) value(PTV), resonance frequency analysis(RFA), and removal torque were measured in 0, 2, 4, 8, 12 weeks after implantation. RESULTS: The results of the study were as follows: 1. Values for the measured surface roughness indicate statistically significant differences in Ra, Rq, and Rt values among group 1, 2, 3, and 4 at the top portion of the thread,(p<0.05) while values at the base of the threads indicated no significant difference in these values. 2. A direct correlation between the forming voltage, and surface roughness and irregularities were observed using scanning electron microscope. 3. No statistically significant differences were found between test groups regarding Periotest(R) values. 4. Analysis of the data produced by RFA, significant differences were found between group 1 and group 4 at 12 weeks after implantation.(p<0.05) CONCLUSIONS: In conclusion, no significant differences could be found among test groups up to a certain level of forming voltage threshold, beyond this forming voltage threshold, statistically significant differences occurred as the surface area of the oxide layer increased with the increase in surface porosity, resulting in enhanced bone response and osseointegration.

The effect of different surface treatment on the osseointegration and stability of implants / 대한치과보철학회지

PURPOSE: This experiment examined the effect of different surface treatment on the osseointegration and stability of implants. MATERIAL AND METHODS: In this study, 40 each of machined, SLA and RBM implants, which are the most commonly used implants, were implanted into the tibia of 20 normal rabbits using OsseoCareTM. The rabbits were sacrificed after 1 week, 4 weeks, 8 weeks and 12 weeks for implant stability analysis, removal torque analysis, histologic and histomorphometric analysis. RESULT: ISQ showed significant difference between Machined and RBM at first week and at 4 weeks. There was significant difference between Machined and both SLA and RBM(p<0.05) but after 8 weeks there were no significant difference between each group. In the removal torque, RBM showd significantly higher values than SLA and Machined surface at 1st week. At 4th and 12th week, there was significant difference between Machined and SLA, RBM(p<0.05). In the bone to implant contact variable, there was no significant difference between each surface treatment method. In the Machined surface group, there was no significant difference between each time interval, but in SLA group, there were significant differences between the 1st week and 12th week. and in RBM group, there were significant differences between the 1st week and 8th, 12th week and between 4th and 12th week(p<0.05). The bone area showed significantly higher values in SLA and RBM compared to Machined surface 1st and 8th week and significantly higher values in SLA than Machined surface at the 4th week(p<0.05). CONCLUSION: The roughened surface of implants showed positive effect in the early stages of implantation and assisted in bone formation. After the bone formation stage, there was no statistical difference between Machined and roughened surface groups. In dental implantation, where initial stability is critical to the success of implants, the use of roughened surface implants should assist in reducing the healing period after implantation.

AN EVALUATION OF PRECISION FIT OF IMPLANT-SUPPORTED PROSTHESIS USING THE PERIOTEST / 대한치과보철학회지

In this study, the Periotest value was measured with Periotest to evaluate precision fit of the 2-unit and 3-unit implant-supported prosthesis by modifying the size and location of ill-fitted conditions. The 2-unit prosthesis was fabricated with the right implant fitted incorrectly and the 3-unit prosthesis with the right and center implant fitted incorrectly. To evaluate the effects of the ill-fitted sizes, 4 groups were divided.:The control group being the accurately fabricated sample group fitted properly. Group 1 was constructed with 40micrometer ill-fitted conditions, group 2 with 70micrometer and group 3 with 100micrometer ill-fitted conditions. The Periotest value was measured at each implant site after tightening 10Ncm. The result was follows: 1. The PTV on the ill-fitted area in the 2-unit implant-supported prosthesis increased as the ill-fitted conditions increased. There was a statistically significant difference among groups(p<0.05). In the same ill-fitted sample, the PTV depending on the measured location demonstrated a statistically significant difference (p<0.05). 2. The PTV on the ill-fitted area of the 3-unit implant-supported with an ill-fitted condition in the right implant increased as the ill-fitted conditions increased. There was a significant difference among groups (p<0.05). In the same ill-fitted sample, the PTV depending on the measured location demonstrated a statistically significant difference (p<0.05). 3. In the 3-unit implant-supported prosthesis with ill fitting conditions in the center implant, the PTV on the ill-fitted area demonstrated a statistically significant difference between the control group, group 1 and group 2 (p<0.05). In the same ill-fitted sample, the PTV depending on the measured location demonstrated significant difference between the gap side and the adjacent side with over 70micrometer ill-fitted conditions (p<0.05). The results suggest that Periotest is a valuable objective method for evaluating the precision fit of an implant superstructure.

The change of tooth mobility following orthodontic tooth movement ; A short-term study / 대한치과교정학회지

The purpose of the present study was to evaluate the change of tooth mobility following orthodontic tooth movement. Six orthodontic patients which had been treated with edgewise appliance were used. Tooth mobility was measured with Periostest at the time of the removal of orthodontic appliance and 1, 2, 3, 4, 6, 8, 10, 12, 16, 20, 24 weeks after appliance removal. Following results were obtained. 1. Tooth mobility upon the removal of orthodontic appliance showed individual variation while incisor showed greater mobility than the other teeth. 2. Tooth mobility showed continued decrease pattern until 24 weeks after appliance removal. 3. While maxillary incisors showed continued decrease pattern during the study period, the other teeth showed steep decline pattern during the first 12 weeks and gentle slope during the second 12 weeks. 4. The tooth mobility of the maxillary second premolar showed the most typical change in terms of the consistency of the decline. 5. There were no significant differences of tooth mobility between heavy and light-contacted anterior teeth during experimental period. The results of the present study suggested that periodontal reorganization is not completed even in 24 weeks following orthodontic tooth movement.