A comparative study of conventional and Hall techniques of crown placement using finite element stress analysis

Background: Hall technique of crown placement causes the changes in vertical occlusal dimension; the mode of settlement of which needs to be explored. Aim: To assess and compare the changing patterns of stress distribution following placement of stainless steel crowns on primary teeth by Hall and conventional techniques using a finite element model analysis. Materials and Methods: The clinical crown heights of primary molars restored with Hall and conventional techniques and opposing teeth in contact, vertical dimension changes in the primary canine area were measured using intraoral digital scan. T-scan was used to measure the changes in bite force while the finite element analysis was used to assess deformative changes on the 2nd, 5th, 10th, and 15th days. Results: The Hall technique of crown placement caused more stress distribution in the tooth supporting tissues that settled in 2 weeks as compared with conventional technique of crown placement in which settlement occurred in 2 days. Conclusion: The settling of vertical occlusal dimension as well as stress distribution in Hall technique probably takes place by intrusion of crowned tooth and opposing teeth in contact.

Gnathology in implant-supported fixed restoration in edentulous mandible / 华西口腔医学杂志

OBJECTIVE@#This study aims to investigate the occlusal and myoelectric characteristics of implant-supported fixed denture in the mandibular region and provide reference for the design of fixed restoration.@*METHODS@#Sixty edentulous patients with implant-supported fixed denture were selected and divided into three groups: group A, 20 cases with implant-supported fixed restoration in the maxillary region; group B, 20 cases with natural dentition, and group C, 20 cases with removable partial denture. The T-scan 8.0 digital occlusion analysis system was used to evaluate the occlusal characteristics of patients in the three groups at intercuspal, protrusion, and left and right lateral positions. Electromyography was used to analyze the myoelectric amplitude and bilateral asymmetry index of the anterior temporalis and masseter of the three groups in different states such as resting and clenching. The relationship between occlusion and myoelectricity was also investigated.@*RESULTS@#In the occlusion analysis by T-scan, the occlusion time, the balance of left and right bite force, the left and right asymmetry of the occlusion center, the trajectory of central occlusion force, and the disclusion time were higher in group C than in groups A and B (P<0.05). No significant differences were observed in the anterior and posterior asymmetry of the occlusion center and percentage of bite force at anterior region among the three groups. In the analysis of myoelectricity, the myoelectric amplitude at resting state and the asymmetry index of masticatory muscles in group C were higher than those in groups A and B (P<0.05). The myoelectric amplitude during clenching in groups A and B groups was higher than that in group C (P<0.05).@*CONCLUSIONS@#In implant-supported fixed restoration at edentulous mandibular, when maxillary includes the removable partial denture, degree of occlusal instability and left and right asymmetry of occlusion center are greater than those with the natural dentition and implant-supported fixed denture at maxillary. The myoelectricity is closely related to occlusion. The removable partial denture can increase the myoelectric activity and reduce the potential of the masticatory muscle. The asymmetry of bilateral myoelectricity is related to the occlusion imbalance.

Maxillary anterior implant restoration with appropriate anterior guidance using T-Scan in a patient with full fixed prostheses / 대한치과보철학회지

In implant restorations, it is difficult for the patient to percept any symptoms. In addition, they are absent of shock absorbers, which can lead to mechanical failure if stress distribution is not considered. Since maxillary anterior multiple-implant restorations play a significant role in guiding the functional movement of the mandible by distributing lateral force, it is crucial to form appropriate occlusion. The use of the T-scan system is more advantageous in assessing ‘dynamic occlusion’, such as the change of occlusion over time, the amount of tooth contact during functional movement, and assessing the occlusion in the less-visible posterior teeth. The case is reported as it has satisfactory results in harmonious anterior guidance of a maxillary anterior multiple-implant restoration using T-scan analysis.

Evaluation of relationship between cognitive function and occlusal status in elderly individuals using the T-scan III® system / 대한구강보건학회지

OBJECTIVES: The aim of this study was to investigate the relationship between cognitive function and occlusal status in elderly individuals. METHODS: A total of 162 individuals aged 65 years and older, who attended the senior citizen center in Daegu city, were included after consent for participation in the study was obtained. The Korean version of the Mini-Mental State Examination (MMSE-K) was used to evaluate the level of cognitive function. Occlusal status was determined using the T-scan III® system. All collected data were analyzed by χ² test, t-test, one way ANOVA, and linear regression analysis using SPSS version 23.0 for Windows. RESULTS: There was a significant relationship between the cognitive function and the use of dentures. Individuals with posterior occlusal status had higher MMSE-K scores than those with anterior occlusal status. There was a positive correlation between the cognitive function and posterior occlusal force. CONCLUSIONS: These results suggest that occlusal status was associated with cognitive function in the elderly individuals. Active national policies to improve occlusal condition in the elderly population are needed.

Registro interoclusal digital en rehabilitación oral: «Sistema T-Scan® III¼: Revisión bibliográfica / Digital interocclusal registration in oral rehabilitation using the "T-Scan® III System": A literature review

El objetivo de esta revisión bibliográfica es describir y comprender cómo funciona la medición y el registro digital de las fuerzas oclusales a través del transductor intraoral del sistema T-Scan® III. Analizar la exactitud, confiabilidad del dispositivo y resultados de estudios recientes que utilizan este sistema digital de registro oclusal, sus indicaciones y aplicación clínica en el análisis de las relaciones dentarias en oclusión antes y después de tratamientos de rehabilitación oral, donde el balance de las fuerzas oclusales es fundamental para el éxito en el largo plazo. El método utilizado consistió en una revisión no sistemática en la base de datos PubMed. Se encontraron 10 artículos que cumplían los criterios de inclusión. Luego de revisar la literatura se puede concluir que el método de análisis oclusal con T-Scan® III es apropiado como dispositivo de diagnóstico oclusal y medición de fuerzas oclusales relativas, tanto en posiciones estáticas como en dinámica mandibular. Existe solo un estudio que indica que es más exacto que los registros existentes de papel marcador. Sin embargo, faltan más estudios tipo ensayos clínicos y/o experimentales para tener mayor certeza de su incorporación a la práctica clínica habitual en rehabilitación oral.

The aim of this review is to describe and understand how the occlusal forces are measured and recorded using an intraoral transducer system, T-Scan® III. An analysis was made of the accuracy and reliability of the device, using the results of recent studies found in the PubMed database using the digital method of recording occlusal indications and clinical application in the analysis of the relationships of the teeth in occlusions before and after oral rehabilitation treatments, where the balance of occlusal forces is essential for long-term success. The method used consisted of a non-systematic review in PubMed. Ten articles were found that met the inclusion criteria. After reviewing the literature, it can be concluded that the method of occlusal analysis with T-Scan® III is suitable as a diagnostic device for measuring relative occlusal forces in both static and dynamic jaw positions. There is only one study that indicates that it is more accurate than paper recordings. However, more clinical and/or experimental studied are required for greater certainty of its incorporation into routine clinical practice in oral rehabilitation.

Association between psychological distress and occlusion among temporomandibular disorder patients – a clinical study.

Background: TMD is a multifactorial disorder significant research efforts have been invested in finding its etiologies and management to improve their quality of life. Objectives: To evaluate and compare digital occlusal parameters, depression, anxiety and serum cortisol level between temporomandibular disorder patients and control group. Material and methods: A sample size of 24 TMD patients and 24 apparently healthy age and sex matched controls were recruited in the study. The patients occlusion time and disclusion time was recorded using T-Scan III, the level of anxiety and depression was evaluated by using Hospital Anxiety and Depression scale questtionaire and serum cortisol was evaluated by collecting fasting blood sample, under aseptic conditions. Results: The incidence of premature contacts (occlusal interferences), clusion time and disclusion time was significantly longer in TMD group than in control subjects. The anxiety and depression scores were statistically significant in TMD group compared to control group, but no statistically significant difference was observed in serum cortisol levels. Conclusion: The present study demonstrated increase in the premature contacts i.e occlusal interferences were high with increase in clusion time, disclusion time, anxiety and depression scores in TMD group, where as no significant increase in serum cortisol levels was seen among TMD group even though their anxiety and depression levels were high. Hence, patients with temporomandibular disorders should always be evaluated for stress and anxiety along with the T- Scan evaluation of occlusal prematurities and correction of the same.

Computerized occlusal analysis: correlation with occlusal indexes to assess the outcome of orthodontic treatment or the severity of malocculusion / 대한치과교정학회지

OBJECTIVE: The aims of our study were to verify the validity of the T-Scan III system (Tekscan) as an objective occlusal evaluation tool, and to assess the differences between two occlusal indexes-the peer assessment rating (PAR) index and the American Board of Orthodontics objective grading system (OGS)-by comparing the scores derived from the T-Scan III system with the two occlusal indexes and analyzing the correlations between them. METHODS: The final study sample included 48 adult volunteers (39 men and 9 women, mean age 24.14 +/- 3.16 years), after excluding 29 volunteers whose occlusion could not be evaluated by the T-Scan III system due to severe skeletal or occlusal problems. PAR index and OGS scores were assessed using dental study models, and measurements of centric occlusion, protrusive movement, and lateral excursion movement were obtained via the T-Scan III system. The results were analyzed to determine correlations. RESULTS: Occlusal analysis by the T-Scan III system was clinically reliable (p < 0.05), and the PAR index and OGS scores were significantly correlated with several measurements obtained with the T-Scan III system (p < 0.05). CONCLUSIONS: The T-Scan III system is a quantitative and reliable method for occlusal evaluation, and represents a potential substitute for occlusal indexes. Compared to the PAR index, the OGS scores of more variables were significantly correlated with the T-Scan measurements.

Re-restoration of temporomandibular joint disorder acquired after implant prosthetic restoration using T-Scan: A case report / 대한치과보철학회지

In cases of extensive prosthetic restoration, correction of occlusal contact is often needed, as it is the essential component for a successful restoration. If occlusal contact is given incorrectly, various symptoms of occlusal trauma can occur of which temporomandibular joint disorder (TMD) is one of them. As one of the common symptoms of TMD, patients may suffer with masticatory muscle disorder and temporomandibular joint pain. This case presents satisfactory results for the improvement of masticatory muscles and temporomandibular joint pain of a TMD patient, caused by incorrect occlusal contact of the restoration, by replacing the prosthesis after occlusion correction.

An occlusal contact analysis of lateral mandibular movement using T-Scan system / 대한치과보철학회지

PURPOSE: Most of the former studies about the occlusal contact patterns during the mandibular movement focused on foreigner. The purpose of this study is analyzing the occlusal contacts of young Koreans by using T-Scan system. MATERIALS AND METHODS: The sample size was 87 and the occlusal contacts of each right and left lateral movements were measured from the maximum intercuspation to the 3mm excursive position for three times respectively. All of the occlusal contacts were double checked through the thin metal foil. The results were categorized as two; 1) considering occlusal contact patterns on working side only, 2) considering occlusal contact patterns on working and nonworking sides. RESULTS: The results showed that the nonworking side occlusal contacts play major roles in the lateral mandibular movement. In both cases of considering with and without the nonworking side occlusal contacts, the group function was the most prevalent. In the working side, the contacts were the most frequent in canine and the frequency of contacts was decreased as the distance was increased from canine to molar. In the nonworking side, the contacts were the most frequent in second molar. And the gender factor was statistically significant (alpha=.05), as females have more nonworking side occlusal contacts in this study. CONCLUSION: Among the three factors of anterior guidance, the group function was the most dominant factor. The analysis of 87 samples showed that canine contact was the most frequent in the working side and second molar contact was the most common in the nonworking side.

Computerized analysis of occlusal contacts in bruxism patients treated with occlusal splint therapy

PURPOSE: Occlusal splints are commonly used to prevent tooth wear caused by bruxism. However, the effects of splints on occlusion are still unclear. Although it is rarely alluded in literature, splints can provoke severe occlusal alterations and other complications. This study was aimed to identify differences in the responses of individuals with bruxism and healthy individuals to a full-arch maxillary stabilization splint in terms of occlusal changes. MATERIALS AND METHODS: Occlusal contacts in 20 (5 male, 15 female) bruxism patients and 20 (5 male, 15 female) controls with normal occlusion were evaluated before and after occlusal splint therapy. T-Scan III, a computerized occlusal analysis system, was used to simultaneously measure occlusion and disclusion times as well as left-right and anterior-posterior contact distributions before splint therapy and 3 months after therapy. Wilcoxon and Mann-Whitney U tests were used for statistical analyses (alpha=.05). RESULTS: No differences were found in the posterior contact of bruxism patients before and after stabilization splint treatment. However, differences in posterior contact were observed between bruxists and normal individuals prior to treatment, and this difference disappeared following treatment. CONCLUSION: The results of this study showed the use of a stabilization splint may not have an effect on occlusion. However, the area of posterior occlusal contact among bruxists was found to be greater than that of normal individuals. According to this study, the clinical use of splints may be harmless.

Non-aggressive central giant cell granuloma in Mandible- A case report.

Central giant cell granuloma is an uncommon benign proliferative lesion accounting for less than 7% of all benign jaw lesions of unknown etiology, and known to occur in anterior mandible in the first three decades of life with female predilection. Clinical, radiological and histopathological parameters describes Aggressive and Non aggressive lesion with features of high recurrence in the aggressive forms which are found in younger age group. This case report presents a 16 year old female with classical features of non aggressive central giant cell granuloma crossing mid line in the mandible which is extending posteriorly.

Changes of bite force and occlusal contacts after stabilization splint therapy / 대한치과교정학회지

This study was done to identify the changes of bite force and occlusal contact between before and after stabilization splint therapy. 16 female patients, accepted for orthodontic treatment at the Department of Orthodontics, College of Dentistry, Chosun University, were selected as the sample of this investigation. For comparisons, the samples of 16 were divided into just before stabilization splint, 1 month after stabilization splint, 2months after stabilization splint, and 3 months after stabilization splint and used the T-scan system to identify the bite force and occlusal contact changes for each group. Statistical analysis of the data was carried out ANOVA tests, and Turkey test using SPSS/PC(+). The results were as follows : 1. Bite force change from just before treatment to 1 month after stabilization splint therapy was statistical significantly decreased (P0.05). 3. The changes of anterior occlusal contacts showed no statistical significance regardless of the wearing periods of stabilization splint (p>0.05). 4. The changes of posterior occlusal contacts from just before treatment to 1 month after stabilization splint therapy was statistical significantly decreased (p>0.05). 5. The changes of posterior occlusal contacts during 1 to 3 months after stabilization splint therapy showed no statistical significance (p>0.05). 6. Posterior teeth rather than anterior teeth were more influenced by the changes of the number of occlusal contacts. To sum up above results, we may respect to capturing and stabilizing centric relation position just 1 month after stabilization splint therapy.

A study on the bite force and the electromyographic activity of masticatory muscle in deepbite / 대한치과교정학회지

This study was undertaken to investigate the correlations bite force and the electromyographic activities of masticatory muscle in deepbite, using the Tr Scan system and electromyograph. The subjects of this study consisted of two groups; one of 20 individuals with normal occlusion, the other group of 30 with deepbite. The deepbite was composed of Class I deepbite(male 9, female 7) and Clas II div. 1 deepbite(rnale 8, female 6). The obtained results of this study were as follows: 1. The maximum bite force was 155.93 N in normal occlusion, 165.11 N in Class I deepbite group, 111.55 N in Class II div. 1 deepbite group. 2. The greater the number of tooth contacts, the more the bite force increased in all groups. 3. During maximum clenching, masseter and ant. temporalis muscle activity of normal and Class I deepbite group were significantly higher than that of Class II div. 1 deepbite group, and the activity of masseter muscle was higher than that of ant. temporalis muscle in all groups. 4. The greater the maximum bite force, tile more the muscle activities increased in all groups.

A study on the changes of tooth contacts following orthodontic treatment by use of the T-Scan system / 대한치과교정학회지

This study was undertaken to investigate the changes of tooth contacts following orthodontic treatment, using T-Scan system. Occlusal contacts in maximum intercuspation were examined in 26 patients at the end of the active phase of orthodontic treatment and again 3 months into the retention phase to assess the initial posttreatment occlusal changes. The obtained results of this study were as follows: 1. The mean total number of contacts increased from 11.27 at the end of orthodontic treatment to 13.15 at the follow up visit, which was found to be statistically significant (P0.05). 6. The number of post. teeth in contact significantly increased, which was statistically significant (P<0.05). 7. A statistically significant relationship was found between the total number of contacts at the end of treatment and the change in the contacts over time. The fewer the number of tooth contact was at the end of orthodontic treatment, the greater number of tooth contact increased over time(r=-0.38, P<0.05).

Brain Computerized Tomographic Findings in Various Epilepic Children

Epilepsy is, in some occassions, manifested as one of the symptoms complex of central nervous system diseases, as well as systemic diseases such as metabolic disorders. In 1976, Bachman reported that 33% of epileptic patients manifested abnormal lesions in their computerized tomographic findings. 1005 epileptic children with various types of seizures have been investigated to detect the possible causes of epilepsies. 32% of the patients had abnormal brain C-T findings, of these patients, infantile spasm was the most frequently manifested abnormal C-T finding, rating 52.9%; simple partial seizure, 37.7%; complex partial seizure, 36.1% and generalized seizure, 27.1%, in order of frequency. Curable lesions, such as tumor, granuloma and arachnoid cyst were detected by brain C-T scan, and a brain tumor was detected in 2% of the patients. The brain C-T scan is one of the most effective diagnostic tools to evaluate the underlying lesions of the central nervous system of epileptic children.

A Case of Thoracic Spinal Canal Stenosis

A compression of spinal cord or nerve roots is commonly seen sequale of acquired or congenital stenosis of the cervical of lumbar portions of the spine. The authors have treated a case of thoracic myelopathy associated with thoracic canal stenosis, which was diagnosed with thoracic myelography and thoracic C-T scan. The pathological findings was thickened ligament flavum, hypertrophied articular processes, narrow spinal canal and compression of spinal cord. It is suggested that the syndrome should be considered in any patient who has a thoracic myelopathy.

The Pre-operative Assesment for Shunt Surgery in Normal Pressure Hydrocephalus

Normal pressure hydrocephalus(NPH) is defined as a combination of dementia, gait disturbance and/or urinary incontinence, hydrocephalus on C-T scan, with a normal intracranial pressure. The clinical effect of CSF shunting in patients with this syndrome is sometimes striking but generally only 50-60% of the shunted patients benefit from the treatment. So many pre-operative investigations are performed including clinical examination, computed tomography, R-I cistrnography, T1/2 calculated from ventricular volume pressure curve and lumbar drainage. Among the pre-operative investigations, the effect of preoperative lumbar drainage was the most reliable indicator of NPH. The possible mechanisms of improved case are proposed. The differential diagnosis of primary brain atrophy and NPH can be made by the effect of pre-operative lumbar drainage.

Clinical Analysis of Surgical Treatment of Postmeningitic Hydrocephalus

To evaluate the surgical results, the author made a clinical analysis on 70 patients of postmeningitic hydrocephalus who had been treated surgically. And the results were summarized as follows. 1) The tuberculous meningitis was the most common type causing the postmeningitic hydrocephalus(72.9%). 2) Among 70 patients, 51 were male and 19 were female. About 40% of cases were under 5 years old. 3) The most common clinical symptom was vomiting(67%). Headache, fever and generalized seizure were symptoms in order of frequency. Neurological sings represented neck stiffness, cranial nerve palsy and motor weakness. 4) The most common clinical condition on admission was stage 3 (advanced cases with unconciousness and severe neurological deficits). 5) The spinal fluid analysis showed more abnormal findings comparing to the ventricular fluid. But ventricular pressure was higher than spinal fluid pressure. 6) Plain skull x-rays, carotid angiograms were useful diagnostic methods but CT brain scan was though to be the most accurate, noninvasive method which showed size of ventricle and effectiveness of shunting procedures with Evans'ratio. In enhanced CT brain scans, the basal cistern enhancement was the most common finding beside ventricular enlargement (64.1%). 7) Ventriculoperitoneal shunting was the most common procedure in this series. 8) The initial revision rate was 12/70(19%) and the most of the revision was performed within 6 months after the initial shunting. 9) The revision rate in relation to shunting system and cerebrospinal fluid finding was not statistically significant. 10) The most common cause of the shunt malfuntion was obstruction of the ventricular catheter. 11) Forty one patients(58.6%) showed favorable outcome. The motality rate was 14/70(20%) and they were all belong to the stage 3. About half of the patients in stage 2 and stage 3 showed dramatic improvement after early shunting procedures. So the timing of operation was the most important factor influencing their outcome.

Intracranial Cysticercosis: A Report of 6 Cases

Cysticercosis infestation is a cosmopolitan disease. Recently we experienced six cases of intracranial cysticercosis in childhood, three of them were male and their age distributed from 2 to 15 years. Their main clinical manifestations were symptoms of increased intracranial pressure signs and other neurological sings as well, In diagnostic procedures, brain C-T scan was performed in all cases and Conray ventriculography was very helpful in cases of intra-ventricular location of cysticerci. By surgical exploration, single cysticerci were removed from 4 th ventricle in five cases, and cysticercus racemosus was found in subdural space in one cases. Five cases were successfully cured and one case was died of persistent brain swelling after surgical manipulation.