Multicenter retrospective study of immediate two different RBM surfaced implant systems after extraction

Distortion of tooth axes on panoramic radiographs taken at various head positions / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to evaluate the effect of head position changes on the root parallelism between adjacent teeth on panoramic radiographs. METHODS: A model with normal occlusion was constructed in the SolidWorks program, then RP (rapid protyping) model was fabricated. The model was repeatedly imaged and repositioned five times at each of the following nine positions: ideal head position, 5degrees C up, 10degrees C up, 5degrees C down, 10degrees C down, 5degrees C right, 10degrees C right up, and 5degrees C right rotation, 10degrees C right rotation. Panoramic radiographs were taken by Planmeca ProMax and the angle between the long axes of adjacent teeth was directly measured in the monitor. RESULTS: Axes of adjacent teeth tended to converge toward the occlusal plane when the head tilted up and converged in the opposite direction to the occlusal plane when the head tilted down. Anterior teeth showed the most notable differences. When one side of the head tilted up 5degrees C and 10degrees C along the anteroposterior axis (Y axis), tooth axes of the same side tended to converge toward the occlusal plane and tooth axes of the opposite side tended to converge in the opposite direction to the occlusal plane. When the head rotated to one side along the vertical axis (Z axis), the canine and lateral incisor of the same side converged in the opposite direction to the occlusal plane and the canine and lateral incisor of the other side converged toward the occlusal plane. CONCLUSIONS: When assessing the root parallelism on panoramic radiographs, the occlusal plane cant (anteroposterior or lateral) or asymmetry of the dental arch should be considered because these can cause distortion of tooth axes on panoramic radiographs.

A retrospective multicenter clinical study of installed US II / SS II implants after maxillary sinus floor elevation

PURPOSE: The purpose of this study was to evaluate the Osstem(R) implants (US II/SS II implants) through the retrospective study for the clinical success rate during the installation of the Osstem(R) implants (US II/SS II implants) by using of the procedures of maxillary sinus floor elevation. MATERIALS AND METHODS: The current study was researched in the 6 medical institutions: Chonnam National University, Chosun University, Pusan DaeDong Hospital, Bundang Seoul National University Hospital, Ap-Seon Clinic, and All Clinic. Based on the total number of 116 patients whose treatment was the installation of the US II/SS II implants with the procedures of the maxillary sinus floor elevation, they were conferred on the dental records of the patients under the joint consultation of the 6 medical institutions. On the dental recording charts, there were included in as the following; the name of the institutions, gender, age, with or without smoking or drinking, with or without the generalized diseases, the height of the alveolar bone on the operational sites, elapsed edentulous state period, the state of the opposed or adjacent teeth, the methods of the maxillary sinus floor elevation, secondary time period for surgery, the lengths, types, and diameters of implants, with or without bone transplantation or the types of bone, postoperative current bone height, current adjacent soft tissue state of the implants, with or without the success of the installations of the implants. We have done our survey with the clinical and radiolographical examinations and dental questionaries. The success and survival rate of the implants was evaluated. RESULTS : 1. Total number of the patients with the installation of the US II implants were 62. The 252 numbers of US II implants were installed on the 89 maxillary sinuses. The patient's mean age was 54.1 years old and there were 36 men and 27 women. 2. Total number of patients with the installation of SS II implant were 57. The 165 numbers of SS II implants were planted on the 80 maxillary sinuses. Their mean age was 48.7 years old and there were 37 men and 20 women. 3. The follow-up period was 30.7 months(21-49 mon) on average. The vertical bone loss of installed implants after the procedures of the maxillary sinus elevation was 1.1 mm on average in SS II and 1.3 mm on average in US II. There existed no statistical significance on each group. The mean enlarged bone height after the maxillary sinus floor elevation was 8.2 mm. 4. For the procedures of the maxillary sinus elevation, the Lateral approach technique occupied 87.1%, which was the most used one. In addition, the most frequently used transplanted bone was autogenous bone only which was 72.7% during the maxillary sinus floor elevation. 5. The complication of maxillary sinus floor elevation were perforation of sinus membrane, disesthesia on doner site, exposure of cover screw and exposure of maxillar bone. 6. The survival rate of US II and SS II after maxillary sinus floor elevation was 99.2% and 95.8%, respectively. And the success rate of US II and SS II after maxillary sinus floor elevation was 97.6% and 89.7%, respectively. CONCLUSION : On the evaluation of the analysis of our study, both US II and SS II implants showed the excellent clinical results by use of the procedures of maxillary sinus floor elevation.

Change in tooth length and angulation on panoramic radiographs taken at different labiolingual and buccolingual inclinations / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to examine how the mesio-distal angulation and the length of each tooth changes on panoramic radiograph at different bucco-lingual inclinations. METHODS: After constructing an acrylic model based on the mean arch of 30 adults with normal occlusion, the wire was placed in the center of the teeth on the acrylic model. First, the wire was implanted in normal angulation and inclination and a panoramic radiograph taken. After changing the inclination from I-15 degrees to I+15 degrees by 5 degrees a panoramic radiograph was taken again and the mesio-distal angle and wire length on the panoramic radiograph were assessed. RESULTS: When the wire was implanted at the normal angulation and inclination, the length measured in the panoramic radiograph was magnified 111 ~ 117% from the original length in the anterior region and 121 ~ 125% in the posterior region. Only the central and lateral incisors showed significant length differences when the inclination was changed from I-15 degrees to I+15 degrees at fixed angulation. When the inclination was changed from I-15 degrees to I+15 degrees, the angulation of most teeth on panoramic radiograph appeared to be more disto-angulated than in reality, and the lateral incisor and canine showed the largest difference. Only I-15 degrees, I+15 degrees groups of premolars and I+15 degrees group of molars showed more mesio-angulation than in reality. As the labio(bucco)lingual inclination of all teeth were decreased, tooth angulation in the panoramic radiograph appeared to be more disto-angulated. CONCLUSION: The labio-liugual inclination of teeth should be considered because it affects panoramic image of teeth, such as length of incisors and angulation of other teeth.

Comparison of analysis of the lateral cephalogram and analysis of lateral facial photograph / 대한치과교정학회지

Analysis of lateral cephalometric radiograph (cephalogram) has been used routinely to evaluate skeletal and dental relationships, but analysis of the lateral facial photograph has not been used frequently for evaluation of skeletal relationships. As concerns about harm of X-ray irradiation increases, this study was planned to evaluate the possibility of substituting analysis of the lateral cephalogram with analysis of the lateral facial photograph by comparing these two analyses. According to the ANB values from cephalometric analysis, subjects were divided into three groups: Class I malocclusion group (n = 32). Class II malocclusion group (n = 32), and Class III malocclusion group (n = 31). After measurements of angles indicating horizontal and vertical relationships of the maxilla and mandible on the lateral cephalograms and photographs, differences between Class I, II and III groups were evaluated. To evaluate the similarity between two similar values in the cephalograms and photographs, t-test using standardized variable Z and correlation analysis were performed in the Class I malocclusion group. The results showed that 1) SnN'Pg' on the photograph can be used to evaluate the antero-posterior relationship of the maxilla and mandible (ANB), 2) N'-Sn/Sn-Pg' on the photograph can be used to evaluate facial convexity (NA/APg), 3) Sn-Tra-Me' on the photograph can be used as a measurement similar to FMA. In conclusion, partly substituting lateral cephalogram analysis with lateral facial photograph analysis was possible in the evaluation of the maxilla and mandible.

Survey of the preferred vertical lip-chin ratio / 대한치과교정학회지

The purpose of this study was to investigate the preference of Vertical Lip-Chin Ratio (= Sn-Stm /Stm-Me', hereafter VLCR) in Koreans. The assessors consisted of 44 dentists (male 22, female 22) and 430 lay persons (male 303, female 127). The survey was performed using a questionnaire asking the order of preference. The profiles presented in the questionnaire were based on the profiles of two males and two females, each morphed according to the VLCRs of 1/1.8, 1/1.9, 1/2.0, 1/2.1, 1/2.2. The results were as follows: The difference between males and females, and the difference between dentists and lay persons in the preference of VLCR were not statistically apparent. The most preferred VLCR was 1/1.9, and the least preferred VLCR was 1/2.2. These results indicate that the preferred VLCR is smaller than the previously reported VLCR ratios based on the cephalometric evaluation of samples with favorable facial esthetics.