Evaluation of enamel surface integrity after orthodontic bracket debonding: comparison of three different system.

OBJECTIVE: This study aimed to evaluate enamel surface integrity and time consumed during residual cement removal after bracket debonding using different adhesive removal burs with and without a dental loupe. MATERIAL AND METHODS: Sixty human-extracted premolars were collected, cleaned, mounted, and prepared for orthodontic bracket bonding. Teeth were randomly divided into three main groups (n = 20) based on the adhesive removal method: tungsten carbide system (TC), sof-lex discs system (SD), and diamond system (DB) groups. Then, each group was subdivided into two subgroups (naked eye and magnifying loupe subgroups). The brackets were bonded and then debonded after 24 h, and the Adhesive Remnant Index (ARI) was assessed. The adhesive remnants were removed by different systems, and the final polishing was performed by Silicone OneGloss. The enamel surface roughness was evaluated before bracketing (T0), after residual cement removal (T1), and finally after polishing (T2) using surface Mitutoyo SJ-210 profilometry and Scanning Electron Microscopy (SEM) to determine the Enamel Damage Index (EDI) score. The time consumed for adhesive removal was recorded in seconds. RESULTS: The Kruskal Wallis test showed a statistically significant difference in roughness values at T1 compared to T2 between subgroups (p < 0.001). When comparing EDI at T1 and T2, the Kruskal-Wallis H-test showed statistically significant differences in all subgroups. The pairwise comparisons revealed that EDI scores showed a statistically significant difference at T1 and T2 between DB vs. TC and SD (p = 0.015) but not between TC vs. SD (p = 1.000), indicating the highest roughness value observed in the DB group. The time for cement removal was significantly shorter in the magnifying loupe group than in the naked eye group and was shortest with the TC group, whereas the time was the longest with the DB group (p < 0.05). CONCLUSION: All three systems were clinically satisfactory for residual orthodontic adhesive removal. However, TC system produced the lowest enamel roughness, while the DB system created the greatest. The polishing step created smoother surfaces regardless of the systems used for resin removal.

Evaluation of maxillary sinus changes following molar distalization using clear aligners: A three-dimensional study.

OBJECTIVE: To evaluate the impact of molar distalization with clear aligners (CAs) on maxillary sinus parameters and its proximity to the root apices of maxillary molars using Cone Beam Computed Tomography (CBCT). METHODS: The study involved pre- and post-treatment CBCT images of 27 adult patients. MIMICS 21.0 software was used to measure maxillary sinus volume and surface area, while Invivo Dental 6.0 program was used to measure the sinus diameters and proximity of the maxillary molar root apices to the sinus floor. RESULTS: Post-treatment, there was a marked increase in the average volume and surface area of the maxillary sinus on both sides; however, changes in dimensions were not statistically significant. Sinus proximity to the root apices of the maxillary molars showed statistically significant differences, particularly on the left side for all roots. Gender and age impacted the outcomes, with males and younger individuals showing more pronounced changes. No significant differences were observed between the left and right sinuses in all parameters. CONCLUSION: Molar distalization with CAs increases maxillary sinus parameters, more notably in younger and male patients. All molar teeth roots moved toward the sinus, particularly the mesiobuccal root of the maxillary second molar protruded to the sinus.

CCR7 affects the tumor microenvironment by regulating the activation of naïve CD8+ T cells to promote the proliferation of oral squamous cell carcinoma.

BACKGROUND: Head and neck cancer is the sixth most common malignancy worldwide, and oral squamous cell carcinoma (OSCC) is the most common head and neck cancer, being one of the leading causes of cancer morbidity and mortality worldwide. CC Chemokine receptor 7(CCR7) is a multifunctional G protein-coupled trans-membrane chemokine that affects immune cell chemotaxis, migration, and cancer progression through its interaction with its ligands C-C motif chemokine ligand 19(CCL19) and C-C motif chemokine ligand 21(CCL21). Numerous studies have demonstrated the involvement of CCR7 in the malignant progression of a variety of cancers, reflecting the pro-cancer properties of CCR7. The Cancer Genome Atlas data suggests CCR7 has elevated expression in oral cancer. Specifically, CCR7 expression in tumor microenvironment (TME) may regulate the ability of some immune cells to engage in anti-tumor immune responses. Since CD8+ T cells have become a key immunotherapeutic target, the role of CCR7 in antitumor immune response of naïve CD8+ T cells in TME has not been thoroughly investigated. METHODS: A CCR7 knockout mouse model was constructed, and the mechanism of ccr7 on the regulation of tumor microenvironment by naïve CD8+ T cells was verified under the guidance of single-cell RNA sequencing combined with in vivo animal experiments and in vitro cell experiments. RESULTS: CCR7 is knocked out with impaired tumor growth and altered CD8+ T cell profiles, revealing the importance of this protein in OSCC. CONCLUSIONS: Inhibition of CCR7 enhances CD8+ T cell activation, proliferation, and anti-tumor function, suggesting its potential as a therapeutic target.

Radial and ulnar forearm free flaps: A critical comparison of donor site morbidity and its impact on quality of life.

BACKGROUND: A poor evidence basis exists regarding direct comparing objective and subjective donor site morbidity associated with forearm flap. The authors evaluated the postoperative donor-site complications and quality of life outcomes between radial forearm free flap (RFFF) and ulnar forearm free flap (UFFF). METHODS: All patients undergoing RFFF or UFFF harvest were included. Grip strength, pinch strength, wrist range of movement, and testing skin sensitivity were assessed with the appropriate scales at different time intervals. In addition, cosmetic and quality of life were assessed using the Patient and Observer Scar Assessment Scale (POSAS) and Disability of Arm, Shoulder, and Hand (DASH) score. RESULTS: Eighty patients were enrolled (40 RFFF and 40 UFFF). The results showed a short-term reduction in grip strength, fine motor skills (tip pinch, key pinch, palmar pinch), and range of motion was observed for RFFF and improved over time. None of the patients in either group experienced functional disturbance in grip strength, wrist motion, fine motor skills, or sensation to light touch at 1 year. Nine patients experienced partial skin graft loss (RFFF = 6; UFFF = 3). There was a significantly higher incidence of temporary numbness in the RFFF group (p=0.040). Persistent numbness occurred in 3 cases in RFFF. Cold intolerance was significantly lower in UFFF (2.5 %) than in RFFF (22.5%). Moreover, the mean POSAS and DASH score reduced at 12 months compared to 6 months, significantly superior for UFFF. CONCLUSION: Objective function limitations are reversible short-term effects after forearm flap and do not affect daily routines in the long term. Additionally, UFFF appears to be preferred over RFFF for subjective outcomes, which emphasizes the UFFF should be considered an alternative to RFFF for reconstructing soft-tissue defects.

Reconstruction of large defects of anterior floor of mouth with free flaps using a novel individualized flap design method.

The purpose of this study was to introduce a novel individualized flap design method for large anterior floor of the mouth (AFOM) defect reconstruction, review experience with the use of this flap design method for large AFOM defect reconstruction, and assess its functional results. A retrospective study of patients who received large AFOM defect reconstruction with free flaps was conducted. There was a cohort of patients who were treated using the novel individualized flap design method and a cohort without flap design. Functional outcomes were evaluated with appropriate scales. Outcomes were analyzed, and a p-value <0.05 was considered significant. 22 patients received the individualized flap design, while 21 patients were treated without a special flap design. All flaps survived. All free flaps harvested with the novel individualized flap design method better matched AFOM defects. Relative to patients without flap design, patients in the novel individualized flap design group showed significant improvement in speech intelligibility (p = 0.036) and swallowing function (p = 0.019). Within the limitation of the study it seems that large AFOM defect reconstruction with the novel individualized flap design method can not only cover and close the wound to avoid oral-neck fistulae, but also maintains tongue mobility to achieve better functional outcomes than in patients without flap design.

A novel flap design technique for subtotal tongue reconstruction with an "Individualized and Convenient Tongue Model".

BACKGROUND: To achieve improved functional outcomes in subtotal tongue reconstruction, a flap design with sufficient volume and appropriate shape is necessary. In this study, we introduce an "Individualized and Convenient Tongue Model" (ICTM) for flap design in subtotal tongue reconstruction. METHODS: By studying the anatomical morphology of the tongue, we found a similar geometry within the dorsum and body of the tongue as well as the mouth floor. This can be used to create an ICTM through folding and splicing. We can simulate tongue defects in the ICTM and transform defect shapes into guide plates for flap design. In this study, fifty-eight patients requiring subtotal tongue reconstruction were randomly divided into two groups: an ICTM group (35 patients) and a conventional group (31 patients). In the ICTM group, we individually designed profunda artery perforator flaps (PAPFs) or anterolateral thigh flaps (ALTFs) using the ICTM method. In the conventional group, the flap was designed according to the surgeon's clinical experience. Patient demographics, operative and follow-up data were recorded. Swallowing, speech intelligibility, and cosmetic results were assessed using appropriate scales. RESULTS: All flaps survived, although there were no significant differences in tumor size, operation time, flap size, and complication rate compared to the conventional group. Patients in the ICTM group had significantly improved speech intelligibility (p = 0.019), cosmetic appearance (p = 0.009), and swallowing ability (p = 0.003). CONCLUSIONS: The ICTM technique is an effective and convenient solution for subtotal tongue reconstruction that provides an individualized flap design and improves functional outcomes compared to the conventional design.

Donor-site morbidity of free fibula flap in pediatric patients: A systematic review and meta-analysis.

The morbidity of free fibula flap (FFF) in pediatric patients has gained attention. Thus, we aimed to evaluate donor-site morbidity after FFF harvesting in pediatric patients and its relationship with age. A systematic literature search of databases for cross-sectional studies related to pediatric donor-site morbidity after FFF harvesting was performed. Two independent reviewers evaluated relevant article titles and abstracts to extract data regarding donor-site morbidity from each article. Fifteen studies were included in the meta-analysis that evaluated the rate of complications. Individual cases of ankle instability were divided into the 0-13- and 13-17-year-old groups. The Chi-square test was used to compare ankle instability between both groups. A logistic regression model was created to analyze the relationships between age and ankle instability/claw toe. Sixteen English articles published between 2007 and 2021 were included in the systematic review. Information on morbidities of 294 cases in which FFF was used was collected. The mean incidence rate of complications, instability, claw toe, and nerve injury were 19.3%, 12.9%, 5.9%, and 5.1%, respectively. Bivariate analysis showed that age was significantly correlated with the incidence of ankle instability but not with the incidence of claw toe. The Chi-square test showed that the incidence rate of ankle instability between the age groups was significantly different. Therefore, we recommend 14 years of age as a new predictive factor for ankle instability. Nevertheless, there is limited evidence in this field, and more pediatric research is needed to clarify these findings.

An early microvascular training program of dental intern students and junior residents: a comparative prospective study.

BACKGROUND: Clinical instructional strategies and the climate in which teaching and learning take place have a significant impact on the quality of dental education. Therefore, this study aimed to evaluate the impact of early microsurgery training on the skills of dental intern students who are planning to join an oral and maxillofacial surgical field (DIS) as compared with junior residents within an oral and maxillofacial surgery department who had no microsurgery experience (JR). METHODS: A total of 100 trainees, 70 were DIS, while the other 30 were JR. The average age was 23.87 ± 2.05 years for DIS group and 31.05 ± 3.06 for JR group. All trainees attended a microsurgical course (theoretical and practical parts) for seven days within a Microvascular Laboratory for Research and Education of a university-affiliated tertiary hospital. Two blinded examiners had assessed the performance of trainees independently using a specific scoring system. The independent sample t-test was used to compare the effect of microsurgery training between DIS and JR groups. The significance level was set at 0.05. RESULTS: The DIS group had showed higher attendance rate than JR group (p < 0.01), with a lower absence score in DIS than JR groups (0.33 ± 0.58 vs. 2.47 ± 1.36). The total score of the theoretical test was significantly different between both groups (p < 0.01). In this context, the DIS group had revealed higher total score than JR group (15.06 ± 1.92 vs. 12.73 ± 2.49). In term of tissue preservation, there was a significant difference between both groups, with the DIS had better performance score than JR (1.49 ± 0.51 vs. 0.93 ± 0.59). Further, the practical exam score was significantly higher in DIS group than JR group (p < 0.01). CONCLUSION: Overall, the performance of dental intern students was favourably compared with junior residents in most aspects. Therefore, it is promising and essential for dental colleges to add a microsurgery course to the curriculum of dental intern students who plan to specialize in oral and maxillofacial surgery.

Alveolar bone changes following bi-maxillary vertical molars' movements using clear aligners.

OBJECTIVE: This study aimed to assess the alveolar bone changes following maxillary and mandibular molars' intrusion and extrusion movements using Clear Aligners using Cone-Beam Computed Tomography (CBCT). MATERIALS AND METHODS: This is a retrospective clinical study in which 24 adult patients with pre-designed selection criteria and a mean age of 31.1 + 9.9 years were enrolled. The alveolar bone changes around one hundred thirty-three maxillary and mandibular molars intruded or extruded by Clear Aligners therapy were analyzed from CBCT using Invivo 6.0 software. Intra- and inter-examiner reliability analysis was performed using the intra-class correlation coefficient (ICC) and Cronbach's Alpha statistics. The paired t-test was used to analyze significant differences before and after treatment (T0-T1). The significance level was considered at P < 0.05. RESULT: The patients were divided into two groups: extrusion (48.9%, n = 65 molars' root) and intrusion (51.1%, n = 68 molars' root) group. There was a significant decrease in the alveolar bone changes in the buccal surface of the mandibular right and left 1st molars in the extrusion group (-1.05 ± 0.97, -0.76 ± 1.12 mm, respectively) and the maxillary left 2nd molars in intrusion group (-0.42 ± 0.77 mm), and the lingual surface of intrusion of the mandibular left 1st molar (-0.64 ± 0.76 mm). Comparing the mean maxillary and mandibular changes (T0-T1) of both studied groups showed that the buccal alveolar bone changes for the left 1st and right 2nd molars showed a significant difference in extrusion and intrusion groups, respectively. CONCLUSIONS: The buccal alveolar bone changes is considered the most affected surface following maxillary and mandibular molars' intrusion and extrusion movements using clear aligners, with mandibular molars being more affected than the maxillary ones.

Lower lip reconstruction using McGregor fan technique with or without depressor anguli oris chimeric flap. Is there a difference in function and aesthetic outcomes?

BACKGROUND: Lower lip reconstruction aims to maintain facial subunit function and aesthetics. We present a minor modification of the McGregor flap technique, in which depressor anguli oris (DAO) muscle is separately elevated as a chimeric flap together to investigate the outcomes for reconstructing lower lip defects using various functional parameters. METHODS: The study included patients who underwent surgical repair of lower lip defects using a McGregor fan flap with or without DAO muscle chimeric flap between January 2018 and May 2021. The patients were divided into our modified technique with DAO chimeric flap (study group) and conventional McGregor (control group). The primary outcomes were functional evaluation of oral competency, speech intelligibility, and tactile sensation of reconstructed lip outcomes. The functional satisfaction and Patient and Observer Scar Assessment Scale (POSAS) were analyzed. RESULTS: A total of 20 patients were enrolled (10 patients for each group). Excellent oral competence was present in 12 patients, favorably significant in patients with DAO chimeric flap (n = 8/10, p = 0.018). All patients had intelligible speech with insignificant differences between the two groups. No patients demonstrated differences to light touch from baseline sensation at 1 year. Patients in the study group reported more lip function satisfaction (p = 0.049). The POSAS score indicates satisfaction with the appearance of all patients. CONCLUSION: McGregor fan technique combined with DAO muscle chimeric flap offers a good choice by maintaining sensory and motor functions. Our minor modification can ensure the integrity of the oral sphincter, leading to improved lower lip function.

Influence of inflammation on bleeding and wound healing following surgical extraction of impacted lower third molars.

OBJECTIVE: This study aimed to investigate the effect of inflammatory states following impacted lower third molar (ILTM) surgery regarding postoperative bleeding and wound healing. METHODS: The study included patients who underwent extraction of ILTMs associated with or without inflammatory conditions. Post-extraction bleeding and wound healing were assessed. In addition, mean grey values (MGVs) of alveolar bone and bone height using an orthopantomography radiograph were analyzed. RESULTS: A total of 376 patients were enrolled; 171 pericoronitis, 51 pulpitis, 44 chronic periapical periodontitis, 36 chronic periodontitis, and 74 control. The bleeding score in the control group was significantly lower than in the periapical periodontitis and periodontitis groups. Excellent wound healing for control, pericoronitis, pulpitis, periapical periodontitis, and periodontitis groups was (78.38%, 35.67%, 70.59%, 70.45%, and 33.33%, respectively). Patients with pericoronitis and periodontitis had significantly poorer wound healing (P < 0.01). The MGV in periapical periodontitis and periodontitis was considerably lower than in the control group. CONCLUSIONS: The inflammatory conditions associated with ILTMs increase the risk of bleeding. So suturing with the placement of local hemostatic agents over a pressure pack alone is recommended. The poorest wound healing was in localized gingival inflammation. Furthermore, MGV was affected by age and was lower with periapical periodontitis.

CC chemokine receptor 7 promotes macrophage recruitment and induces M2-polarization through CC chemokine ligand 19&21 in oral squamous cell carcinoma.

PURPOSE: This study aimed to investigate the impact of CC chemokine receptor 7 (CCR7) on the recruitment and polarization of tumor-associated macrophages (TAMs) in oral squamous cell carcinoma (OSCC). METHODS: We analyzed CCR7 expression pattern, clinicopathological significance, and its association with M2 macrophage infiltration in OSCC by bioinformatic methods. Small interfering RNA (siRNA) was utilized to silence CCR7 in OSCC cells. Conditioned media (CM) was harvested from transfected OSCC cells to establish a co-culture model of THP-1 derived macrophages and OSCC cells. Transwell assay and cell adhesion assay were performed to examine the effect of CCR7 on macrophages recruitment and adhesion. Cytoskeleton was labelled by phalloidin to observe macrophage morphological changes. Moreover, phenotypic alteration of macrophages was measured using quantitative real-time PCR (qRT-PCR), flow cytometry, and immunofluorescence (IF) staining. Ultimately, recombinant human CCL19 and CCL21 were added into the medium of THP-1 derived macrophages to explore their effects on polarization in vitro. RESULTS: In OSCC patients, the overexpression of CCR7 positively correlated with lymph node metastasis and M2 macrophage infiltration. Macrophage not only exhibited enhanced migration, invasion and adhesion abilities, but also appeared more spindle and branched in vitro when treated with CM from OSCC cells. However, these phenomena were abrogated with knockdown of CCR7. We also discovered that inhibition of CCR7 in OSCC cells suppressed TAMs polarization to an M2 phenotype. In addition, recombinant human CCL19 and CCL21 promoted macrophage M2-polarization in vitro. CONCLUSION: CCR7 in OSCC cells promoted recruitment and M2-polarization of THP-1 derived macrophages in vitro by regulating production of CCL19 and CCL21.

Functional and biomechanical assessment of the hand following ulnar forearm free flap transfer: Prospective self-controlled study.

BACKGROUND: There is a shortage of well-designed self-controlled studies evaluating hand biomechanics following ulnar forearm flap (UFF) harvest. This study was conducted to evaluate objective and subjective functional outcomes of the donor's hand following UFF harvest. METHODS: All patients undergoing UFF were included for analysis. Grip strength, wrist movement, forearm supination and pronation, pinch strengths, sensation to light touch and temperature, and hand dexterity were assessed preoperatively and at 1, 3, and 6 months postoperatively. In addition, DASH score (disabilities of the arm, shoulder, and hand score) and Patient and Observer Scar Assessment Scale (POSAS) were analyzed. RESULTS: A total of 18 patients were enrolled. A significant reduction in grip strength for donor's hand was observed between preoperative and postoperative 1 and 3 months (mean difference = 14 kg, 7.38 kg, respectively, p = 0.000 for all). A similar trend was observed for pinch strength and range of motion (p < 0.05). Three months after surgery, there is still a significant reduction in tip pinch, tripod pinch, wrist extension, and supination. All biomechanics outcomes returned to preoperative baseline at 6 months after surgery. No patients suffered significant changes in sensation to light touch, temperature, and numbness by 6 months. There was a significant increase in DASH score by 3.37 points 6 months after operation (p = 0.000). The POSAS score indicates satisfaction with the appearance of the donor site. CONCLUSIONS: UFF is a safe and reliable option for oral cavity reconstruction with minimum donor site morbidities, mainly when cosmesis is paramount. Furthermore, objective hand biomechanics ultimately returns to its preoperative state within 6 months after surgery.

The Overexpression of Fibronectin 1 Promotes Cancer Progression and Associated with M2 Macrophages Polarization in Head and Neck Squamous Cell Carcinoma Patients.

Purpose: This study aimed to investigate the biological roles of fibronectin 1 (FN1) in head and neck squamous cell carcinoma (HNSCC) and its effects on macrophage M2 polarization. Methods: We analyzed FN1 expression pattern and examined its clinical relevance in HNSCC progression by bioinformatic analysis. Small interfering RNA (siRNA) was utilized to silence FN1 in HNSCC cells. Cell counting kit-8 (CCK-8) assay, colony formation assay, Transwell assay and wound healing assay were performed to reveal the effect of FN1 on malignant behaviors of HNSCC cells. Moreover, a co-culture model of macrophages and HNSCC cells was established to investigate whether FN1 induce macrophage M2 polarization. Finally, we used bioinformatic methods to explore the possible FN1-related pathways in HNSCC. Results: FN1 is significantly overexpressed in HNSCC patients and has been obviously correlated with higher pathological stage and poor prognosis. Downregulation of FN1 suppressed the proliferation, migration and invasion of HNSCC cells, and inhibited macrophage M2 polarization in vitro. In addition, "PI3K-Akt" and "MAPK" signaling pathways may be involved in the malignant process of FN1 in HNSCC. Conclusion: The overexpression of FN1 promotes HNSCC progression and induces macrophages M2 polarization. FN1 may serve as a promising prognostic biomarker and therapeutic target in HNSCC.

Superficial parotidectomy with or without great auricular nerve preservation. Is there a difference in postoperative sensory recovery rates and quality of life?

The clinical implications of great auricular nerve (GAN) preservation or sacrifice during parotid surgery have long been a topic of controversy. This study aimed to compare sensory recovery rates and quality of life (QoL) in patients who had undergone superficial parotidectomy and had their GAN preserved or sacrificed. Fifty patients were prospectively analysed, 28 with the GAN preserved, and 22 with it sacrificed. The primary outcomes were tactile sensitivity and QoL. The secondary outcomes were operating times and other complications. There was a gradual improvement in tactile sensitivity in both groups, which showed a statistically significant difference favouring the preserved group at 1, 3, 6, and 9 months postoperatively (p<0.05). There was no statistically significant difference in tactile sensation for both groups at 12 months postoperatively. The overall sensory recovery rates in the GAN preserved and sacrificed groups after 1, 3 ,6, 9 and 12 months were 42.8%, 42.8%, 57.1%, 57.1%, and 78.5%, and 0%, 0%, 13.6%, 27.3%, and 59.1%, respectively. According to the QoL assessment, there was a significant difference in mean (SD) loss of sensation scores (sacrificed group 0.86 (0.94) and preserved group 0.39 (0.62), p= 0.039). However, there were no statistical differences between the groups regarding other categories of the questionnaire. No significant difference was seen between groups regarding operating time and other complications. This study concluded that when evaluated objectively, sensory impairment ultimately lessened in severity in the second half of the first postoperative year. GAN preservation minimised sensation disturbance in long-term results, but overall QoL seemed to be unaffected following GAN preservation or sacrifice.

Surgical interventions for management of benign parotid tumors: Systematic review and network meta-analysis.

The impact of the extent of parotid surgery on postoperative complications has long been considered a topic of controversy. The aim of the current network meta-analysis (NMA) is to answer the following questions: (1) Does the extent of surgical resection of benign parotid tumors increase the risk of postoperative complications? (2) What is the best surgical intervention for treatment of benign parotid tumors that can provide an acceptable balance between tumor recurrence rate and other postoperative complications? A comprehensive search on PubMed, Embase, Scopus, and Cochrane library was conducted to identify the eligible studies. The outcome was the incidence of tumor recurrence, facial nerve weakness (temporary [TFW] or permanent [PFP]), Frey's syndrome (FS), sialocele, and salivary fistula. The Bayesian network meta-analysis (NMA) accompanied by a random effect model and 95% credible intervals (CrI) were calculated using the GeMTC R package. Forty-four studies with a total of 7841 participants were included in the current NMA comparing five surgical interventions, namely enucleation, extracapsular dissection (ECD), partial superficial parotidectomy (PSP), superficial parotidectomy (SP), and total parotidectomy (TP). Enucleation showed the highest recurrence rate compared to ECD, SPS, SP, and TP. No statistical differences were observed concerning the recurrence rate when ECD, PSP, SP, and TP were compared together. There was an increased incidence of TFW and FS with the increase in the extent of parotid resection, while no significant difference was found when comparing enucleation with ECD and PSP. SP showed the highest incidence of PFP, and salivary fistula compared to ECD, PSP, and TP. The tumor recurrence rates in enucleation, ECD, PSP, SP, and TP were 14.3%, 3.6%, 3.7%, 2.8%, and 1.4%, respectively. The current NMA demonstrated that the risk of TFW and FS increases with the increase in the extent of parotid resection and that ECD and PSP can be considered the treatment of choice for benign parotid tumors, as both provide an acceptable balance between the incidence of tumor recurrence and facial nerve dysfunction.

Acellular dermal matrix for prevention of Frey's syndrome after superficial parotidectomy of benign tumors.

PURPOSE: To evaluate: 1) the efficacy of acellular dermal matrix (ADM) to prevent Frey's syndrome (FS) after superficial parotidectomy of benign tumors. 2) the effect of different follow-up intervals on the incidence of FS. METHODS: Fifty-five patients with benign parotid gland tumors underwent superficial parotidectomy were divided into two groups: Non-ADM group (n = 31, 56.3%) and ADM group (n = 24, 43.6%). The primary outcomes measure was the incidence of FS. The secondary outcomes were surgical site depression, infection, salivary sialocele, and salivary fistula. Subjective FS was evaluated using a clinical questionnaire submitted via WeChat at 3, 6, 12, 18, 24, and 32 months postoperatively. Objective FS was evaluated using Minor starch-iodine test at 6 and 12 months postoperatively. RESULTS: There was a statistically significant difference in the incidence of subjective and objective FS when ADM compared with Non-ADM groups (P<0.05). The respective incidence of subjective FS at 3, 6, 12, 18, 24, and 32 months was 4.2%, 8.3%,20.8%, 20.8%, 20.8%, 20.8% in ADM group and 3.2%, 9.7%, 29%, 38.7%, 45.2% in Non-ADM group. The incidence of objective FS after 6 and 12 months was 4.2%, 8.3% in ADM group and 8.3% (2/24), 38.7% (12/31) in Non-ADM group respectively. Five patients in ADM group and 1 patient in Non-ADM group developed sialocele, and all patients resolved with conservative management. Surgical site depression was significantly higher in the Non-ADM group (15/31) compared with (5/24) in ADM (P=0.049). No cases of immune rejection, infection, hematoma, or salivary fistula were observed in ADM group. CONCLUSIONS: The current study demonstrated that 1) ADM could reduce the incidence of FS in the patients undergoing superficial parotidectomy. 2) the peak onset of about 18 months appear to be acceptable follow-up for the development of FS.