SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology

0

Objective: To establish a quantitative three-dimensional method based on intraoral scan and apply it to evaluation of the facial soft tissue contour alterations following single immediate implant and immediate provisionalization (IIPP) in central incisor via intraoral scanning. Methods: This study was a prospective clinical study. The trial was conducted at Department of Implantology, Peking University School and Hospital of Stomatology, from January 2016 to September 2017. Twenty-nine eligible consecutive patients (15 women, 14 men) with a mean age of (34.3±12.0) were included and received immediate replacement of the failure maxillary single central incisor. A screw-retained immediate restoration was delivered for each patient. At 6-month follow-up, impression was taken and a screw-retained permanent restoration was performed for each patient. The anterior maxillary region was scanned by an intraoral scanning system at pre-surgery and 1-year follow-up. The Standard Tessellation Language (STL) files were output to a dedicated software and superimposed. Mid-facial recession and gingival zenith symmetry at 1-year follow-up were measured in the digital models. Three-dimensional configurations of the contour change volume were calculated and reconstructed for visual analysis. Furthermore, the following parameters were used to analyze the reconstructed volume: mean contour change in thickness (△d), mesio-distal width (D(W)), coronal-apical height (D(H)), contour change at 0, 1, 2, 3, 4, 5 mm apical to the free gingival margin on the implant site. Results: Twenty-seven out of twenty-nine enrolled patients were finally available for analysis. At 1-year follow-up, the mid-facial mucosa level at implant site was (0.23±0.39) mm apical to the gingival zenith of the contralateral tooth. In general, a contour collapse was found in every patient. △d, D(W) and D(H) of the collapsed volume were (0.62±0.22), (11.03±1.74) and (6.82±1.52) mm, respectively. Contour change at 0, 1, 2, 3, 4, 5 mm apical to the free gingival margin on the implant site were (0.54±0.48), (0.87±0.62), (1.03±0.46), (0.96±0.52), (0.90±0.52), (0.89±0.57) mm. Conclusions: The described quantitative measurement based on intraoral scan can be an effective method for assessment of soft tissue contour changes. At 1 year following single IIPP treatment in maxillary incisor, free gingival margin is stable, with only mild recession. The mean level of the facial soft tissue contour collapse is 0.62 mm.

0

Objective: To investigate the incidence and proportion of salivary gland tumors in order to provide new thinking for clinical diagnosis and treatment. Methods: Collected 3 724 cases salivary gland tumors diagnosed by Pathology Department of Hospital of Stomatology, Jilin University from January 1961 to December 2016. The pathological diagnosis referred to the fourth edition of head and neck-salivary gland tumor histopathological classification standard of WHO. The database was established with Microsoft Excel and analyzed with SPSS 18.0. Made a retrospective analysis and comparison on the numbers of all cases in terms of types, site, gender and age and estimate the trend with the time interval of 8 years, and then make a judgement of the trend of salivary tumors. Results: The benign tumors were more common than the malignant among all periods, the proportion of all tumors was about 2.92∶1; The top three benign tumors were polymorphous adenoma [73.78% (2 046/2 773)], Warthin tumor [15.80% (438/2 773)] and base cell adenoma [8.37% (232/2 773)]. Polymorphous adenoma took up 54.94% (2 046/3 724) of all tumors. The top three malignant tumors were mucous epidermoid carcinoma [31.44% (299/951)], adenoid cystic carcinoma [26.92% (256/951)] and adenocarcinoma [11.88% (113/951)]. As for sex, male female ratio was 0.83∶1. As for site, the pathogenic site of tumors was mainly in parotid gland [63.75% (2 374/3 724)], followed by palatal gland [16.50% (615/3 724)], then submandibular gland [12.67% (472/3 724)]; As for age, the common age was between 51 and 60 years old [23.74% (884/3 724)], followed by 41 to 50 years old [21.56%(803/3 724)]. Conclusions: The incidence of benign and malignant salivary gland tumor increased in the 56 years. Females showed a higher incidence. The majority tumors occurred in parotid gland. The most common salivary gland tumor was pleomorphic adenoma and the most common malignant tumor was mucous epidermoid carcinoma. The most common age was in 51-60 years old period.

0

Objective: To investigate the indications and long-term outcomes of endoscopy-assisted removal of parotid gland calculi via a transoral approach. Methods: From August 2005 to December 2016, 158 consecutive patients with parotid gland calculi underwent endoscopy-assisted lithectomy transorally. They included 71 males and 87 females, with an age of 5-84 years. The immediate safety and effectiveness were evaluated. After surgery, the patients were followed up, and gland function was analyzed on the basis of clinical manifestations, sialography, scintigraphy and sialometry. Postoperative sialograms were categorized into 2 types: ①type Ⅰ, the main duct was normal or had ectasia and stenosis, but no persistent contrast was seen on the functional film; ②type Ⅱ, the main duct had ectasia or stenosis, with persistent contrast media on the functional film. Results: Under one endoscopic procedure, the stones (or foreign bodies) were completely removed in 134 cases and almost completely removed in 10 cases, with a success rate of 91.1% (144/158). Of the 144 successful cases, the treatment options included direct basket retrieval or forceps grasping in 77 cases, basket entrapment with direct ostium incision in 36, basket capture with perio-ostium incision in 23 and perio-ostium incision in 8 cases with impacted stones. In two of the initial 14 failure cases, the stones were discharged spontaneously 3 months after operation. During 3-120 months' follow-up (mean 36 months) of the 146 patients, one had recurrent stone, two developed ductal obturation, 16 had mild symptoms, and the remaining 127 cases were asymptomatic. Of the postoperative sialograms in 34 stone-free patients 25 were type Ⅰ, 9 were type Ⅱ. Both scintigraphy and saliva flow rate indicated an improvement of the affected gland function in some degree (P<0.05). Conclusions: Transoral endoscopy-assisted removal of parotid gland calculi is a safe and effective technique. It is mainly indicated for mobile stones in the main duct or impacted stones in the anterior third of the Stensen's duct. Sialography, scintigraphy and sialometry show postoperative improvement of gland function in most of the cases.

0

Objective: To discuss the surgical safeness of the cleft palate children with airway stenosis by means of analyzing characteristics of the shape of the upper airway and comparing clinical data of cleft palate children with airway stenosis and non-airway stenosis. Methods: Tracing back from Apirl 2015 to Apirl 2017, 126 cleft palate children treated in Shanghai Children’s Medical Center, Shanghai Jiao Tong University School of Medicine, were included (46 male and 80 female, age of 7 to 74 months, median age 18 months). According to the spiral CT scan of neck, patients were categorized to airway-stenosis group (65 patients) and non-airway-stenosis group (61 patients). For airway-stenosis group, suspected difficult intubation plan is applied, guiding endotracheal intubation via visible laryngoscope. For non-airway-stenosis group, ordinary plan of endotracheal intubation is applied. Study the statistics of both groups in the measurement of the upper airway, the success rate of tracheal intubation, operation time, hospital day. Results: Based on anatomical location of the airway stenosis, cleft palate children were divided into: nasopharynx, 5 cases; laryngel, 55 cases; initiation part of trachea to arch of aorta, 2 cases; arch of aorta to bronchial bifurcation, 3 cases. Regardless of airway stenosis, the upper airway of cleft palate children in the subglottic area and the cricoid area was elliptical, with the transverse dimension narrow and the anteroposterior dimension wide. Comparing to non-airway-stenosis group, the airway in airway-stenosis group remained narrower in the anteroposterior dimension in the subglottis area [(7.69±1.76) mm]; also remained narrower in the transverse dimension [(5.96±1.27) mm] and the anteroposterior dimension [(8.16±1.31) mm] in the cricoid area (P<0.05). Pre-and post-operative monitor blood oxygen saturation of all patients were normal. Ventilator weaning of all patients was successful. There were no statistical significance in operation time and hospital day between airway-stenosis group and non-airway-stenosis group (P>0.05). Conclusions: The upper airway of the subglottic area and the cricoid area in cleft palate children are elliptical, with the transverse dimension narrow and the anteroposterior dimension wide. Cleft palate children with airway stenosis underwent surgery smoothly by using a portable visible laryngoscope.

0

Objective: To evaluate and compare the clinical effects of three surgical procedures for the periodontal treatment of root surface exposure after resection of epulis. Methods: Thirty patients with epulis were selected in this study and the exposed root surfaces of the patients' teeth were covered with laterally transposition flap, laterally pedicled transposition flap or coronally advanced flap combined with a connective tissue graft in the treatments of epulis. At the time of follow-up during the operation, 3 months after operation and 6 months after operation, respectively, the color, shape and quality of the gum in the operation area and the coordination of the diaphragm and diaphragm were observed, and the root surface exposure (recession depth, RD) and angle were recorded. Keratinized tissue height (KTH), root coverage rate (RC) and patients' satisfaction with the surgery were also recorded. Results: The flap widths in groups of laterally pedicled transposition flap and coronally advanced flap combined with a connective tissue graft were significantly wider than that in the group of laterally transposition flap at three-month and six-month follow-ups after the surgery. The width of keratoderma [(2.70±1.16) mm] in the group of laterally transposition flap was significantly lower at 6 months postoperatively than that in the other two groups [(4.80±1.14) and (4.90±1.66) mm, respectively] (P<0.01). At the 6th month after surgery, the root flap coverage was at the lowest level [(24±43)%] in the group of laterally transposition flap, and it was significantly lower than that in the other two groups [(80±23)% and (86±24)%, respectively] (P<0.01). There was no significant difference of the root flap coverage between groups of laterally pedicled transposition flap and coronally advanced flap combined with a connective tissue graft. At the time of follow-up, patients were satisfied with the aesthetic effects of the three surgical procedures. Conclusions: After the resection of the gingival tumor, the defect of the gingiva is caused. The laterally pedicled flap and pedicled flap combined with connective tissue transplantations for soft tissue repairing can achieve satisfactory aesthetic effects which are superior to the effect of simple flap technique.

0

Objective: To analyze the stress distribution of different types of bone tissue around porous titanium implant in different mechanical loads and to further evaluate the biomechanical properties of porous titanium implant. Methods: Finite element (FE) models of implant restorations for the maxillary first premolar was established, and the diameter of implants in the models was 4.1 mm. Five models was constructed according to diameter of implant central pillar and the thickness of outer porosity: solid group (group A), central pillar 1.5 and 3.1 mm and outer porosity 30% (group B and C), central pillar 1.5 and 3.1 mm and outer porosity 40% (group D and E). Different loads (150 N vertical force, 50 N lateral force) were applied to the occlusal surface of implant restorations in type Ⅲ bone and maximal von Mises stress was evaluated. Meanwhile, a couple of simplified maxillary part models varied in four types of bone were constructed with the implants bearing load of simulation ultimate force to evaluate the stress distribution of different types of bone. Results: With different mechanical loading, the stress value of bone tissue around porous implant (group B-E) was greater than that in the solid structure (group A). Under the load of simulation ultimate force, the maximum stress of the bone rised with the increase of porosity and thickness of the porous implant. And the maximum stress value of the surrounding bone tissue changed with the change of bone. Under vertical loading, the maximal von Mises stress of the bone around solid implants of group A was 17.56 MPa, which was a little lower than that of group B and C. And the maximal equivalent von Mises stress of group D and E was 69.24 MPa. The results of lateral force and simulation ultimate force loading were similar. The stress of the bone tissue around implant increased with the decrease of bone quality. The maximum stress value of group D implant was 134.95 MPa. Conclusions: Porous structure of the implant is conducive to transmit stress to surrounding bone tissue and increases the mechanical stimulation of bone. However, if the value and direction of load are inappropriate or quality of bone is poor, pathological stress may be produced.

0

Objective: To compare the biomechanical characteristics of four-implants mandibular overdentures supported by Locator attachment or bar-clip attachment under different mechanical loads using three-dimensional finite element analysis method. Methods: Two different models of four-implants supported mandibular overdentures using Locator attachment and bar-clip attachment (hereinafter called Locator model and bar-clip model) were established. Each model was subjected to five different mechanical loading conditions: 100 N vertical loading in central incisor (vertical load of incisor), 100 N vertical loading or oblique loading in canine (vertical or oblique loads of canines), 100 N vertical or oblique loading in mandibular first molar (vertical or oblique loads of mandibular first molar). The stress distributions in implants, peri-implant bone and mucosa were recorded under the above five conditions to evaluate the effects of different attachments on the biomechanical properties of implant-supported mandibular overdentures. Results: Regardless of loading conditions and types of attachments, the stress concentration in implants were located at the neck of implants, and the stress concentration in peri-implant bone was located in the cortical bone. The stress values in mucosa were always much smaller than those in implants and cortical bone. Regardless of loading positions (on canine or on mandibular first molar), the maximum stress at the bone interface around the implant under lateral loading was much higher than that under vertical loading. Under various loading conditions, the stress in implants and cortical bone of the Locator model (the highest von Mise stress value was respectively 79.5 and 22.3 MPa) were lower than that of bar-clip model (the highest von Mise stress value was 110.3 and 28.7 MPa respectively) while the maximum compressive stress in mucosa (0.198 MPa) in Locator model was slightly higher than that in the bar-clip model (0.137 MPa). Conclusions: In clinical practice, the lateral force applied to the implant-retained overdenture should be minimized to avoid complications caused by pathological loads. Under the same loading condition, the stress distributions in overdenture using Locator attachment are more dispersed, which is more conducive to long-term stability of implants.

0

Objective: To explore the osteogenic activity of Zn/Ca/P-containing coatings on titanium implant surface modified by plasma electrolytic oxidation (PEO). Methods: Three groups implants including Zn/Ca/P-containing surface treated by PEO in experimental groups and Ca/P-containing and TiO(2) sandblasted surface in control group were randomly inserted in the bilateral mandibular of rabbits. Mechanical testing and implant-bone interface observation were performed at 4, 6, 8, 10 and 12 weeks after implantion. Results: Zn/Ca/P-containing coating presented a microporous structure. The push-out value indicated the statistical differences among the three groups at each observed time point (P<0.05), and implant-bone bonding power reached a maximum value at 12 weeks, those in the Zn/Ca/P-containing group [(1.57±0.26) MPa] was higher than those in the group with sandblasted surface [(0.83±0.24) MPa] (P<0.05). Histological examination and implant-bone interface observation using field scaning electron microscope (FSEM) showed that the new bone of implant-bone interface increased with healing time and the result from Zn/Ca/P-containing group was superior to that from the control groups at each observed time point. Conclusions: Zn/Ca/P-containing coatings by PEO can accelerate bone formation and remodeling, and enhance bone-implant bonding force.

0

In the 19th century, modern stomatology education were introduced into China with the impact of the west medicine and education. The apprenticeship of modern stomatology education were carried out by missionaries firstly, and then changed to dental schools established by the missionaries or foreigners, which was replaced partly by local Chinese dentists later and improved the development of modern Chinese stomatology education preliminarily.

0

In recent years, robot-assisted surgery (RAS) has developed rapidly and become one of the hot topics in clinical research. Compared with traditional surgery, RAS has advantages in terms of minimal invasiveness, aesthetics, and functional preservation, and has been gradually applied in clinical practice such as neurosurgery, urology, and head and neck surgery. In the treatment of head and neck tumors, RAS can effectively minimize the surgical injury and accelerate postoperative recovery. This article reviews the application of RAS in the resection of primary lesions of head and neck tumors, neck dissection, and reconstruction of tissue defects.