Chinese Journal of Dental Research, 04/2020

At present, various antibacterial therapeutic modalities are available in the clinic. However, due to the rampant abuse of antibiotics over the past few decades and the consequent emergence of innumerable drug-resistant strains of bacteria, it is imperative to develop new and effective antibacterial therapeutic strategies. In recent years, the physical stimuli–based approach to antibacterial therapy has aroused much interest as an alternative to antibiotics and has become a major focus of antibacterial research. In this review, the application of different physical stimuli, including electricity, magnetism, light, ultrasound and thermal stimulation, in antibacterial research is critically examined in order to provide new ideas and directions for the further development of antibacterial therapy in clinical dentistry. Keywords: acoustics, electricity, magnetism, photodynamics, physical stimulation, research progress, thermal

Objective: To evaluate the advantages and disadvantages of the transmandibular approach to the posterior area of the maxilla, oropharyngeal region and the hypopharynx in head and neck surgery. Methods: A series of 42 patients who underwent a lip-split mandibulotomy procedure to access malignant tumours affecting deep areas of the head and neck region between 2008 and 2018 in the Department of Oral and Maxillofacial Surgery at the Ramón y Cajal University Hospital (Madrid, Spain) were retrospectively reviewed. The diagnosis and operations data of the patients were collected and analysed. Results: Using the transmandibular approach, 42 patients were operated on to access malignant tumours located in the oropharynx (n = 23, 54.76%) including the posterior third of the tongue, tonsil and soft palate, retromolar trygone (n = 9, 21.43%), floor of the mouth (n = 3, 7.14%), skull base (n = 2, 4.76%), superior maxilla (n = 3, 7.14%) and deep lobe of the parotid gland (n = 2, 4.76%). Primary reconstruction was carried out in all cases. The most used flap reconstruction method was the forearm fasciocutaneous flap in 48.71% of cases, followed by the anterolateral thigh flap in 20.51% of cases. The remaining cases were treated with other methods. The most frequent complication was surgical wound infection. Conclusion: The transmandibular approach is a good alternative to provide access for the removal of complex tumours affecting the oropharyngeal region. This approach facilitates direct visualisation of the lesion and bleeding control, allowing tumour resection with wide margins and making primary reconstruction easier. Although further progress in the transoral robotic approach could be a good option in selected cases, given the current state of knowledge, the transmandibular approach is a good option to access tumours affecting deep areas of the oral cavity and oropharynx. Keywords: block resection, head and neck tumours, mandibulotomy, transmandibular approach

Objective: To evaluate the accuracy of digital models obtained from intraoral scanning of edentulous maxilla and mandible models with and without resin markers. Methods: A pair of standard edentulous models were scanned using a laboratory scanner and saved as reference models. The edentulous models were fixed onto a phantom head and scanned with an intraoral scanner (IOS) five times each. Six resin markers were attached on the maxilla model and two on the mandible model, and another five intraoral scans were taken of each model. The scanning time and number of images were recorded. The digital models obtained using the IOS were superimposed on the reference models using image processing software. The trueness and precision of the models made using the IOS were evaluated, and the scanning time and number of images were also compared. Results: The average trueness and precision of the IOS in the maxilla model with resin markers were 135.50 ± 36.28 μm and 254.55 ± 40.62 μm, respectively, while those in the mandible were 161.40 ± 55.45 μm and 368.75 ± 91.03 μm, respectively. Placing resin markers on the edentulous maxilla and mandible did not improve the trueness of the IOS, but placing resin markers on the edentulous maxilla improved the precision and scanning efficiency. However, placing resin markers on the buccal shelf of the edentulous mandible decreased the precision and increased the scanning time. Conclusion: Resin markers placed on the hard palate of edentulous maxillae could improve the precision of the IOS and improve scanning efficiency. However, they did not affect the trueness of the IOS for edentulous maxillae or mandibles. Keywords: accuracy, edentulous, efficiency, intraoral scan, resin markers

Objective: To investigate the influence of CYP1A1 rs1048943 on short- and long-term outcomes of nonsurgical periodontal therapy (NSPT) for generalised aggressive periodon- titis (GAgP). Methods: The CYP1A1 rs1048943 polymorphisms of 224 GAgP patients were genotyped by time-of-flight mass spectrometry. A total of 125 patients received NSPT and subsequent followup for 3 months. Of the 125 patients, 81 were followed for at least 3 years. Clinical periodontal parameters were collected at baseline and at the follow-up visits. Negative binomial regression was used to analyse the association between the number of teeth lost during the 3-year observation period and CYP1A1 rs1048943 genotypes. Results: The mean probing depth (PD) and percentage of sites with Bleeding Index (BI) ≥ 3 were all significantly greater in CYP1A1 rs1048943 G allele carriers than non-carriers at 3 months and 3 years after treatment (P < 0.05). In the PD ≥ 7 mm subgroup, the mean PD was significantly higher in G allele carriers than non-carriers at the 3-year follow-up (P < 0.05). The other clinical parameters did not show a similar trend (P > 0.05). Furthermore, the changes of percentage of sites with BI ≥ 3 were significantly smaller in G allele carriers than non-carriers at 3 months and 3 years after treatment (P < 0.05). GAgP patients with the GG genotype had lost more over the 3-year follow-up period compared with patients with the AA genotype (P < 0.05). Conclusion: These data indicated that the CYP1A1 rs1048943 AG/GG genotypes may influence the short- and long-term outcomes of NSPT in GAgP patients. Keywords: generalised aggressive periodontitis, rs1048943, tooth loss, treatment outcome

Objective: To investigate the role of the application of role-play in endodontic study in improving the communication skills of Chinese dental undergraduates prior to their direct interactions with patients at the Fourth Military Medical University’s School of Stomatology, China. Methods: Students were recruited from the 5-year bachelor’s programme (n = 36) and randomly divided into six groups, and from the 8-year DDS programme (n = 10) and randomly divided into two groups to participate in the role-play training. Cases selected randomly from the case pool were distributed to the groups. The teacher gave an outline of the roles in the simulation. Each member of each group randomly selected their own role for the role-play. Four types of surveys were distributed to students and faculty members at different points after the role-plays had taken place, to evaluate their attitude towards the use of role-plays in endodontic study. Frequency analysis and a one sample t test were used to describe and analyse students’ acceptance of role-play as a teaching technique. The level of statistical significance was set at P < 0.05. Results: Students’ performance and satisfaction as well as the supporting faculty responses were very favourable towards role-playing. In total, 93.5% of students responded favourably to the role-play, answering ‘strongly agree’ or ‘agree’ to the positive statements about their role-play performance. A total of 95.1% of students stated that they had benefited psychologically and technically from the role-play (‘strongly agree’ or ‘agree’) after their 1-year rotating internship. Conclusion: The application of role-play in endodontic study is an effective way of educating Chinese dental undergraduates and can be beneficial for their transition from students to dentists. Keywords: communication skills, dental education, endodontic study, role-play, teaching technique

Objective: To evaluate and analyse granulomatous reaction caused by intradermal injections with hyaluronic acid (HA) fillers in the orofacial region. Methods: A retrospective review of 11 cases of foreign body granulomas caused by HA fillers was performed. Demographic data, clinical symptoms, imaging features, treatments, pathology results, history of facial cosmetic procedures and prognosis were reviewed. Results: Most of the cases appeared as painless palpable nodules with no significant growth, located in the cheeks, chin, lips or temples. The nodules were excised, and pathological examination revealed amorphous basophilic material surrounded by foreign body giant cells and macrophages. No patient’s clinical and pathological diagnosis was linked to HA during the first appointment. During follow-up, all patients admitted that they had received dermal filler injections from 3 to 10 years previously. Most of the patients had a favourable prognosis; one patient complained of facial asymmetry and another reported mild pain in the upper lip after surgery. Conclusion: The increase in the number of cases showing delayed complications caused by HA fillers merits closer clinical attention. A thorough understanding of the patient’s medical history and biopsy specimen are necessary to make a definite diagnosis and offer appropriate treatment. Keywords: complications, delayed foreign body granulomas, hyaluronic acid, orofacial region

Ideally, orthognathic surgery is indicated to treat skeletal Class III malocclusion with severe open bite in adults. In this borderline case, however, camouflage treatment without any skeletal anchorage was chosen. This report describes the orthodontic treatment of a 23-year-old man who presented with multiple orthodontic problems including severe open bite of the anterior and posterior teeth up to the first molars, bilateral posterior crossbite, bilateral Class III molar relationship, severe crowding, increased vertical dimension, and dental and facial midline deviation. The treatment included the extraction of four wisdom teeth, uprighting and distalisation of the mandibular arch with molar intrusion using curved NiTi wires with intermaxillary elastics. After 36 months of treatment, satisfactory improvements in the vertical overlap, horizontal overlap and sagittal malocclusion were achieved. The design of the mechanical system used in this case confirmed stable results at the 4-year follow-up. Keywords: anchorage, molar distalisation, open bite, skeletal class III malocclusion