Comparison of the registration methods for the three-dimensional facial scans applied to the design of full-arch implant supported restoration / 北京大学学报(医学版)

OBJECTIVE@#To compare the registration accuracy of three-dimensional (3D) facial scans for the design of full-arch implant supported restoration by five methods and to explore the suitable registration method.@*METHODS@#According to the criteria, ten patients with maxillary edentulous jaw or end-stage dentition requiring implant supported restorations were enrolled in this study. A special rim with individual feature marks reflected appropriate occlusal relationship and esthetic characteristics was made for each patient. Both 3D facial scan data of natural laughter and with opener traction to expose the teeth or occlusal rim of each patient were acquired by facial scan and input to the digital analysis software Geomagic Qualify 2012. The dataset was superimposed by five different methods: seven facial anatomical landmark points alignment, facial immobile area alignment (forehead and nasal area), facial anatomical landmark points and immobile area combining alignment, facial feature points alignment, facial and intraoral feature points alignment with the same local coordinate system. The three-dimensional deviation of the same selected area was calculated, the smaller the deviation, the higher the registration accuracy. The 3D deviation was compared among the three registration methods of facial anatomical landmark points, facial immobile area alignment and the combination of the above two methods. Friedman test was performed to analyze the difference among the three methods (α=0.05). The effect of the aid of the facial and intraoral feature points were evaluated. Paired t test were performed to analyze the difference (P<0.05).@*RESULTS@#The average three-dimensional deviation of the selected area after alignment with the facial anatomical landmarks was (1.501 2±0.406 1) mm, significantly larger than that of the facial immobile area best-fit alignment [(0.629 1±0.150 6) mm] and the combination of the two methods[(0.629 1±0.150 6) mm] (P < 0.001). The aid of the facial feature points could significantly reduce the deviation (t=1.001 3, P < 0.001). There was no significant statistical difference in the remaining groups.@*CONCLUSION@#The forehead area of the 3D facial scan can be exposed as much as possible. The establishment of facial characteristic landmark points and the use of the invariant area alignment can improve the accuracy of registration. It should be clinically feasible to apply three-dimensional facial scan to the design of full-arch implant supported restoration with the registration of the immobile area on the face especially the forehead area.

Factores sistémicos asociados con el edentulismo, según edad y género, mediante las radiografías panorámicas y expedientes digitales / Systemic factors associated with edentulism according to age and gender by panoramic radiographs and digital records

Resumen Esta investigación se realizó con el objetivo de determinar los principales factores sistémicos que provocan edentulismo en los pacientes que asisten a la Clínica de Odontología, con el fin de educar y concientizarlos sobre la relación entre la pérdida de piezas dentales y la salud en general, así como las causas y consecuencias del edentulismo. Para el estudio se tomó una muestra de 954 expedientes del último cuatrimestre de 2017. Estos registros se evaluaron para obtener un número de 108 pacientes edéntulos con factores sistémicos, total utilizado para este trabajo.

Abstract This research was carried out with the aim to determine the main systemic factors that cause edentulism in patients attending the Dental Clinic, in order to enhance patient education concerning the relationship between toothloss and with general health, as well as the causes and consequences of edentulism. For this study, a sample of 954 records was acquired from the last four months of the year 2017. These records were evaluated to obtain a number of 108 patients with systemic factors, the overall participants for this study.

Use of a Titanium Mesh "Shelter" Combined with the Soft Tissue Matrix Expansion (Tent Pole) Grafting in the Reconstruction of a Severely Resorbed Edentulous Mandible. Technical Note.

Patients wearing complete dentures for a long time usually exhibit lack of bone and keratinized mucosa in the bearing area due to bone resorption. The patients suffering from this phenomenon usually have unstable and non-retentive complete denture, which result in constant trauma to the mucosa, pain, functional limitations and worsening of facial esthetics. An innovative technique has been described in which a novel surgical approach using osseointegrated dental implants as "tent poles" was applied concomitant with particulate autogenous bone graft. The authors claim that the control and maintenance of the surgically expanded soft tissue volume should prevent graft resorption in the long term. Nevertheless, resorption of the bone graft is usually more significant where the bone mass is poorer, in the mandibular body. This paper describes a case of severely resorbed edentulous mandible in which the "tent pole" technique was applied with some modifications. Use of the titanium mesh "shelters" and two additional implants was effective in "protecting" the bone graft in the posterior portion of the mandibular body increasing bone mass volume in this area. Furthermore, we believe that this kind of graft "protection" on the whole residual alveolar ridge can increase the width of bone mass gain optimizing the "tent pole" technique.

Pacientes portadores de próteses totais por um longo período geralmente apresentam perda significativa de osso do processo alveolar e de mucosa ceratinizada na área chapeável devido ao processo de reabsorção óssea associada com a perda de função. Estes pacientes geralmente possuem próteses totais sem retenção e estabilidade, o que resulta em trauma crônico à mucosa, limitações funcionais e piora da estética facial. Uma técnica cirúrgica inovadora foi descrita na qual implantes osseointegráveis são posicionados em forma de "pilares" conjuntamente com enxerto ósseo autógeno particulado. Os autores afirmam que o controle e manutenção do volume tecidual obtido cirurgicamente diminui a perda em volume do enxerto ósseo utilizado. Entretanto esta reabsorção geralmente ocorre com maior intensidade onde a massa óssea é mais pobre, ou seja, em corpo mandibular. Este artigo descreve um caso onde uma mandíbula severamente reabsorvida foi reconstruída utilizando-se a técnica de "tent pole" com algumas modificações propostas pelos autores. O uso da malha de titânio em forma de "cabana" e dois implantes dentários osseointegráveis adicionais contribuíram para "proteger" o enxerto ósseo autógeno na região posterior do corpo mandibular aumentando o volume ósseo na região. Adicionalmente, nós acreditamos que o uso deste tipo de proteção em todo rebordo alveolar residual pode melhorar o ganho de massa óssea otimizando, portanto, a técnica original de "tent pole".

Incidence of mandibular nutrient canals in hypertensive patients: a radiographic study.

Hypertension, also called a 'silent killer,' is one of the most common medical problems seen in our profession. A prospective study was conducted in the Department of Oral Medicine and Radiology to determine the incidence of the appearance of nutrient canals in the periapical radiographs of the mandibular anterior region of patients with high blood pressure. A total of 100 patients, between 10-80 years, were examined. After taking a proper history, systemic and oral examinations were done and the findings were recorded under two categories, hypertensive patients and normotensive patients. They were further subdivided according to their periodontal status. Intraoral periapical radiographs of the lower anterior region were then taken. Radiographs were interpreted with a good X-ray viewer and the use of a magnifying glass. Findings were recorded on a prepared format.

Evaluation of radiographic predictors to assess the rate of mandibular residual ridge resorption.

Sixty healthy clinical edentulous patients (thirty male and thirty female) were chosen for the study. Panoramic and lateral cephalometric radiographs were taken of each patient. The amount of bone loss was estimated from the panoramic radiographs as per the formula proposed by Wical and Scoop. The rate of mandibular residual resorbed ridge (RRR) expressed as percentage of bone loss per year was then computed. The correlation between the mandibular RRR and gonial cortical thickness and the percentage of cortical bone at the symphysis was tested. These parameters were also compared between the male and female patients. The rate of mandibular RRR, expressed as percentage of bone loss per year, was found to be indirectly correlated with the cortical thickness at gonion as measured from the panaromic and the lateral cephalometric radiographs. The values of students 't' test for mean differences between the female and the male patients with respect to the rate of mandibular RRR and the cortical thickness at the gonion were found to be statistically significant.

Maxillary sinus floor in edentulous and dentate patients.

To compare the depth of the maxillary sinus floor on panoramic radiographs between the edentulous and dentate patients. Thirty panoramic radiographs of edentulous female patients and 47 panoramic radiographs of female dentate patients were used for the sample. To measure the depth of the maxillary sinus floor, the outline of the maxillary sinus on the panoramic radiograph was traced on transparent paper. An apparent difference in depth of the maxillary sinus floor was recognized only in comparing the left sides of the edentulous and dentate jaws(P < 0.05). However, there was no statistical difference in the depth of the maxillary sinus floor between the right and left sides in the edentulous and dentate jaws. In this study there seems to be no difference in the depth of maxillary sinus floor between the right and left sides of either the edentulous or dentate jaws. It is not clear as to why, on the other hand, there is a statistical difference in between only the left maxillary sinus floor of the edentulous and dentate jaws, this apparent contradiction might be further investigated statistically.