Classification for treatment of adult temporomandibular joint ankylosis and its secondary malformations / 口腔疾病防治

Objective@#To generate a new classification for adult temporomandibular joint ankylosis (TMJA), which could effectively guide treatment strategies for adult TMJA patients with various clinical features. @* Methods@# We developed a new "CD" classification system according to the preservation of the condyle (C) and the severity of dentofacial bone deformity (D). From January 2016 to April 2020, 56 TMJ patients (with 73 ankylosed joints) in our department were classified into 4 subgroups by ‘CD’ classification: condylar head preservation but no dentofacial deformities (C+D-), no condylar head preservation and no dentofacial deformities (C-D-), condylar head preservation and dentofacial deformities (C+ D+), and no condylar head preservation but dentofacial deformities (C-D+). Different strategies were used according to the clinical features of each subgroup. The clinical outcomes of these patients were analyzed. Different treatment strategies of temporomandibular joint reconstruction were adopted for different subclasses of patients and were followed. "C +": lateral arthroplasty (LAP) was used to remove the rigidity and preserve the medial residual condyle. "C-": if the ankylosing bone ball is small and the loss of ascending branch height is not obvious, arthroplasty should be performed to relieve ankylosis; however, if the ankylosing bone ball is large and the ascending branch height decreases significantly, joint reconstruction should be carried out after the ankylosis is relieved. "D +": surgical treatment of secondary dental and maxillofacial malformations at the same time or over stages. "D-": orthodontic treatment after operation to improve occlusal relationship and symptomatic treatment of oral diseases. @*Results@#After treatment, all 73 ankylosed joints were completely released, and the average maximal interincisal opening increased from (3.6±3.2 )to (32.8 ± 5.4) mm (P<0.001), with no recurrence of ankylosis found during the 12-48 month follow-up period.@*Conclusion @#The generation and elaboration of a ‘CD’ classification system is intended to help as a TMJA reconstruction guide for adult TMJA treatment and be widely used in more hospitals.

A novel biomimetic micro/nano hierarchical interface of titanium enhances adhesion, proliferation and osteogenic differentiation of bone marrow mesenchymal cells / 口腔疾病防治

Objective @#To design a novel biomimetic micro/nano hierarchical interface on endosseous titanium implants and investigate its effect on the biological activity of bone marrow mesenchymal cells.@*Methods@#Electrochemical anodization and spark plasma sintering were used to modify smooth titanium (untreated Ti group) with a microporous trabecular bone-like architecture (micro-Ti group) and TiO2 nanotube architecture (nano-TiO2 group). Additionally, electrochemical anodization was employed to prepare TiO2 nanotubes on microporous trabecular bone-like architectures, which formed a novel biomimetic hierarchical interface (micro/nano-TiO2 group). Four groups of titanium samples were characterized by field emission scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle (CA). Bone marrow mesenchymal cells (BMMCs) were seeded on four groups of titanium samples. Scanning electron microscopy (SEM) was employed to observe cell morphology. Cell proliferation was determined by MTT assay. The expression of focal adhesion proteins (F-actin; vinculin; osteocalcin, OCN; osteopontin, OPN) were observed under a confocal laser scanning microscope (CLSM). The mRNA expression levels of osteogenic factors (runt-related transcription factor 2, RUNX2; osteocalcin, OCN; osteopontin, OPN; collagen I, COL I) were assessed by qRT-PCR.@*Results@# The micro/nano- TiO2 group featured a hydrophilic surface (CA=9° ± 2.1°). The results of the MTT assay indicated that the relative cell proliferation rates for the nano- TiO2 and micro/nano-TiO2 samples were significantly increased compared with those for the untreated-Ti and micro-Ti samples (P＜0.001) after 5-9 days. The ALP results indicated that the micro/nano-TiO2 sample gained the highest value at 14 days. After 72 h of incubation, the expression of osteocalcin (OCN) and osteopontin (OPN) on micro/nano-TiO2 was the strongest. After 24 h incubation, the expression of F-actin on micro/nano-TiO2 was the strongest. In comparison with untreated-Ti and micro-Ti samples,the mRNA expression levels of all the osteogenic factors (runt-related transcription factor 2, RUNX2; osteocalcin, OCN; osteopontin, OPN; Collagen I, COL I) were markedly increased on the nano-TiO2 and micro/nano-TiO2 samples, the mRNA expression levels of collagen I (COL I) were significantly different between the nano-TiO2 and micro/nano-TiO2 samples versus the untreated-Ti and micro-Ti samples (P＜0.001). @* Conclusion@#The novel biomimetic micro/nano hierarchical interface has a positive effect on cell attachment, viability and osteogenic differentiation of bone marrow mesenchymal cells.

Research on the precision of virtual surgical planning in two⁃jaw orthognathic surgery / 口腔疾病防治

Objective@#To provide a clinical reference by evaluating the precision of virtual surgical planning in two⁃ jaw orthognathic surgery.@*Methods @#Thirty consecutive patients who required two⁃jaw orthognathic surgery were includ⁃ ed. A composite skull model was reconstructed using data from spiral computed tomography scan and surface scanning of the dental arch. LeFort I osteotomy of the maxilla and bilateral sagittal split ramus osteotomy of the mandible were simulated using Dolphin Imaging 11.7 Premium. Genioplasty was performed if indicated. Virtual plan was then trans⁃ ferred to operation room using 3D⁃printed surgical templates. Frankfort horizontal plane (FHP), midfacial plane (perpen⁃ dicular to the FHP through the nasion), and coronal plane (perpendicular to the FHP through the sella point) were the selected three symmetry planes.Midpoint of the contact of the maxillary and mandibular central incisors (UI, LI), and the mesio⁃buccal cusp of the first maxillary and mandibular molars (U6⁃R,U6⁃L, L6⁃R, L6⁃L) were the six chosen volu⁃metric landmarks. To calculate the linear difference and overall mean linear difference (mean difference of the distance between UI, LI, U6⁃R, U6⁃L, L6⁃R, L6⁃L to FHP, midfacial and coronal plane) between simulated and postoperative models, the distance between selected landmarks and symmetry planes was measured. To calculate the angular differ⁃ ence and overall mean angular difference, values of the angles constructed by the occlusal, palatal, and mandibular plane to FHP and midfacial plane respectively were determined on simulated and postoperative models@* Results@#The virtual surgical planning was successfully transferred to actual surgery with the help of 3D⁃printed surgical templates. All patients were satisfied with the postoperative facial profile and occlusion. The overall mean linear difference was 0.81 mm (0.71 mm for maxilla and 0.91 mm for mandible); and the overall mean angular difference was 0.95° (the mean angular difference relative to FHP was 1.10°, and that relative to midfacial plane was 0.83°)@* Conclusion@#Virtual sur⁃ gical planning facilitated the diagnosis, treatment planning, and precise bony segments repositioning in two⁃jaw orthog⁃ nathic surgery.

Application of digital technology in diagnosis and treatment of dentofacial deformities / 口腔疾病防治

@#Dento-maxillofacial deformity refers to an abnormal relationship of the volume or shape of the upper and lower jaw bones with the other bones of the craniofacial area. Its correction mainly involves hard tissues, such as the jaws and teeth. In recent years, digital techniques based on virtual surgery, real-time navigation, and 3D printing have developed rapidly in the area of craniomaxillofacial surgery. Digital technology has advantages for preoperative diagnosis, surgical plan formulation, surgical simulation, intraoperative navigation, effect prediction, doctor-patient communication, and young physician training. The Department of Orthognathic and TMJ Surgery of West China Hospital of Stomatology, Sichuan University, has conducted digitized diagnosis and treatment of dento-facial deformities since 2008 and has established a digital center for the treatment of dentofacial deformities based on equipment such as spiral CT, dental arch laser scanners, facial 3D cameras, virtual surgery software, 3D printers, and sleep-breathing monitoring. The result is a diagnostic and treatment protocol for dentofacial deformity specific to the characteristics of the population of West China. This article combines the latest domestic and foreign literature and comprehensively introduces the application of digital technology for the diagnosis and treatment of dental and maxillofacial deformities.

Effect of early intra-articular injection of alendronate in reducing subchondral bone loss in rat mandibular condyle after ovariectomy / 口腔疾病防治

Objective @#To investigate the effects of intra-articular injection of alendronate on the mandibular condyle in ovariectomized rats.@*Methods @#Sixty female rats were randomly divided into five groups: ovariectomy with vehicle treatment alone, early alendronate treatment at ovariectomy, late alendronate treatment at 4 weeks after ovariectomy, shamoperation with vehicle treatment, and the normal control rats. The changes in subchondral bone were evaluated by micro-computed tomography (Micro-CT), tartrate-resistant acid phosphatase (TRAP) staining and real-time quantitative polymerase chain reaction (RT-PCR). @*Results @# Compared with late alendronate treatment, early alendronate treatment improved microstructural properties of the subchondral bone, with higher bone volume ratio (46.4 + 2.5 vs 37.5 + 2.1; P= 0.038), increased trabecular thickness (47.3 + 1.7 vs 34.6 + 1.4; P = 0.029), elevated trabecular number (8.5 + 0.6 vs 6.2 + 0.3; P = 0.041) and lower trabecular separation (30.2 + 1.6 vs 37.7 + 2.6; P = 0.034). Fewer TRAP-positive cells (4.2 + 0.2 vs 6.8 + 0.4; P = 0.019) and a higher OPG/RANKL ratio (0.38 + 0.01 vs 0.25 + 0.03; P = 0.043) in the subchondral bone were observed in the animals with early treatment group compared to late treatment or ovariectomy/vehicle treatment group. @*Conclusion @#Our results suggest the therapeutic potential of intra-articular alendronate injection in the treatment of osteoporosis-associated temporomandibular disorders.

Expression of Notch signaling pathway in temporomandibular osteoarthritis / 口腔疾病防治

Objective@# To investigate the expression of Notch signaling molecules in temporomandibular joint arthritis (TMJOA), and to explore the role and mechanism of Notch signaling pathway in the development and progression of TMJOA. @*Methods @#72 Kunming mice were randomly divided into experimental group, sham-surgery group and normal group. In experimental group, discs on the right TMJ were subjected to total discectomy, sham-operation group underwent the same procedure without disc removal, while normal group serve as blank control. All the left temporomandibular joint discs were not treated. 8 mice in each group were sacrificed respectively at 1 week, 2 week, 4 week after surgery. Histological examinations were performed to assess success of TMJOA model, according to the pathological standard of osteoarthritis diagnosis. Immunochemistry techniques were performed in the successful TMJOA cartilages to evaluate the expression levels of Notch1 (NICD1), Jagged1, Hes1 and Hes5. The scores were evaluated by semi-quantitative method. @*Results @#Notch1 (NICD1), Jagged1 and Hes5 were activated in the experimental group with the expression levels increased dramatically over time. While Hes1 expression was suppressed at the beginning of osteoarthritis but was up-regulated afterwards.@*Conclusion @# Notch pathway-related molecular expression changed greatly in TMJOA model, indicating that the pathway in the occurrence and development of TMJOA plays an important role.

Surgical treatment of mandibular hypoplasia using inverted-L osteotomy of ramus and iliac creat bone grafting / 口腔疾病防治

Objective@# The present study was designed to evaluate the use of inverted-L osteotomy of ramus combined with iliac bone graft for the treatment of mandibular hypoplasia inadult patients.@*Methods@#Intraoral or extraoralinverted-L osteotomy of ramus and iliac crest bone grafting were used for the treatment of mandibular hypoplasia in 11 adult patients (aged 19 to 29 years) from 2010 to 2016. Data were collected from the patients’ records, photographs andradiographs.@*Results @#The height and width of the mandibular ramus were significantly augmented by inverted-L osteotomy and iliac crest bone grafting with minimal complications in all patients, resulting in remarkable improvements both in facial appearance and occlusion.@*Conclusions @#Our preliminary results showed that the inverted-L osteotomy of ramus and iliac crest bone grafting is safe and effective, and should be considered as a good alternative for the patients with mandibular hypoplasia.