Salivary gland tumor is one of the most common tumors in oral and maxillofacial regions. The diagnosis and treatment of salivary gland tumors had been a clinical characteristic project in Peking University School and Hospital of Stomatology since long time ago. Here we introduced the research progress in diagnosis and treatment of salivary gland tumors during the past 10 years. Among 7 190 cases of salivary gland tumors treated in this institution, 4 654 cases (64.7%) were benign, and 2 536 (35.3%) were malignant, with benign ∶ malignant ratio of 1.84 ∶ 1. Parotid was the most common location, followed by minor salivary gland and submandibular gland, while sublingular gland tumor was seldom seen. The proportion of minor salivary gland tumor was relatively high. Among 1 874 cases with primary malignant tumors, the cases with T3 and stage Ⅲ accounted for only 9.6% and 10.3%, respectively, which indicated that there was shortcoming in the T classification and clinical stage formulated by Union for International Cancer Control (UICC), and further revision was required. The 5, 10, and 15 year survival rates of 1 637 cases with postoperative follow-up were 93.1%, 87.2% and 79.3%, respectively, which were much higher than those we reported 30 years ago. The improvement of treatment results was related to more widely used combined treatment with surgery and postoperative radiotherapy, and the increase in patients with early stage. Adenoid cystic carcinoma was the malignant tumor with high rate of distant metastasis. The 5 and 10 year survival rates of the patients with pulmonary metastasis were 76.2% and 51.8%, respectively, which indicated that the pulmonary metastatic carcinomas developed slowly. Recurrent rate of carcinoma ex pleomorphic adenoma was 46.7% after single treatment of sur-gery, while it decreased to 27.5% after combined theraphy with surgery and radiotherapy, indicating that postoperative radiotheraphy could reduce the recurrent rate effectively. The normal myoepithelial cells had the inhibiting role in the invasion and metastasis of carcinoma ex pleomorphic adenoma. The evaluation of integrity of myoepithelial cells surrounding the tumor mass is helpful to understand the invasiveness of the tumors. The new surgical modalities such as extracapsular resection and partial sialoadenectomy were used in treatment of benign tumors of parotid gland and submandibular gland with advantages of decreased tissue damage and preservation of glandular function. Application of digital surgical techniques such as mixed reality combined with surgical navigation and real-time three-dimensional holograms in the surgical treatment of parotid gland tumors showed the benifits of more safety and precision, and less tissue da-mage.
Humans ; Salivary Gland Neoplasms/pathology* ; Carcinoma, Adenoid Cystic/therapy* ; Adenoma, Pleomorphic/therapy* ; Neoplasm Staging

OBJECTIVE: To initially investigate the function of neuronal pentraxin 1 (NPTX1) gene on osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). METHODS: hBMSCs were induced to undergo osteogenic differentiation, and then RNA was collected at different time points, namely 0, 3, 7, 10 and 14 d. The mRNA expression levels of key genes related with osteogenic differentiation, including runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteocalcin (OCN), and NPTX1, were detected on the basis of quantitative real-time polymerase chain reaction (qPCR) technology. In order to establish a stable NPTX1-knockdown hBMSCs cell line, NPTX1 shRNA lentivirus was constructed and used to infect hBMSCs. ALP staining, alizarin red (AR) staining, and qPCR were employed to assess the impact of NPTX1-knockdown on the osteogenic differentiation ability of hBMSCs. RESULTS: The results showed that during the osteogenic differentiation of hBMSCs in vitro, the mRNA expression levels of osteogenic genes RUNX2, ALP and OCN significantly increased compared with 0 d, while NPTX1 expression decreased markedly (P < 0.01) as the osteogenic induction period exten-ded. At 72 h post-infection with lentivirus, the result of qPCR indicated that the knockdown efficiency of NPTX1 was over 60%. After knocking down NPTX1 in hBMSCs, RNA was extracted from both the NPTX1-knockdown group (sh NPTX1 group) and the control group (shNC group) cultured in regular proliferation medium. The results of qPCR showed that the expression levels of osteogenic-related genes RUNX2 and osterix (OSX) were significantly higher in the sh NPTX1 group compared with the shNC group (P < 0.01). ALP staining revealed a significantly deeper coloration in the sh NPTX1 group than in the shNC group at the end of 7 d of osteogenic induction. AR staining demonstrated a marked increase in mineralized nodules in the sh NPTX1 group compared with the shNC group at the end of 14 d of osteogenic induction. CONCLUSION NPTX1 exerts a modulatory role in the osteogenic differentiation of hBMSCs, and its knockdown has been found to enhance the osteogenic differentiation of hBMSCs. This finding implies that NPTX1 could potentially serve as a therapeutic target for the treatment of osteogenic abnormalities, including osteoporosis.
Humans ; Mesenchymal Stem Cells/cytology* ; Osteogenesis/genetics* ; Cell Differentiation/genetics* ; Nerve Tissue Proteins/genetics* ; Cells, Cultured ; C-Reactive Protein/genetics* ; RNA, Small Interfering/genetics* ; Core Binding Factor Alpha 1 Subunit/metabolism* ; Bone Marrow Cells/cytology* ; Gene Knockdown Techniques ; Osteocalcin/metabolism* ; Alkaline Phosphatase/metabolism* ; RNA, Messenger/metabolism*

OBJECTIVE: To analyze RELT gene mutation found in a pedigree with clinical features and inheritable pattern consistent with amelogenesis imperfecta (AI) in China, and to study the relationship between its genotype and phenotype. METHODS: Clinical and radiological features were recorded for the affected individuals. Peripheral venous blood samples of the patient and family members were collected for further study, and the genomic DNA was extracted to identify the pathogenic gene. Whole exome sequencing (WES) was performed to analyze the possible pathogenic genes, and Sanger sequencing was performed for validation. SIFT and PolyPhen-2 were used to predict and analyze the mutation effect. Comparison of RELT amino acids across different species were performed by using Uniprot website. In addition, the three-dimen-sional structures of the wild type and mutant proteins were predicted by Alphafold 2. RESULTS: The proband exhibited typical hypocalcified AI, with heavy wear, soft enamel, rough and discolored surface, and partial enamel loss, while his parents didn ' t have similar manifestations. WES and Sanger sequencing results indicated that the proband carries a homozygous frameshift mutation in RELT gene, NM_032871.3: c.1169_1170del, and both of his parents were carriers. This mutation was predicted to be pathogenic by SIFT and PolyPhen-2. Up to now, there were 11 mutation sites in RELT gene were reported to be associated with AI, and all of the patients exhibited with hypocalcified AI. Compared with the wild-type RELT protein, the mutant protein p. Pro390fs35 conformation terminated prematurely, affecting the normal function of the protein. CONCLUSION Through phenotype analysis, gene sequencing, and functional prediction of a Chinese family with typical amelogenesis imperfecta, this study found that RELT gene frameshift mutation can lead to protein dysfunction in AI patients. Further research will focus on the role and mechanism of RELT in enamel development at the molecular and animal levels, providing molecular biology evidence for the genetic counseling, prenatal diagnosis, and early prevention and treatment of AI.
Humans ; Amelogenesis Imperfecta/genetics* ; Frameshift Mutation ; Male ; Pedigree ; Female ; China ; Exome Sequencing ; Phenotype ; Adult

OBJECTIVE: To explore the function of LIM and calponin homology domains 1 (LIMCH1) in the development and progression of oral squamous cell carcinoma (OSCC), along with their potential clinical applications. METHODS: By utilizing transcriptome sequencing data from two groups of oral squamous cell carcinoma patients, along with bioinformatics analytical techniques such as Gene Ontology (GO) and gene co-expression networks, we identified genes that might play a pivotal role in the pathogenesis of oral squamous cell carcinoma. We employed real-time quantitative PCR and Western blotting to validate the expression patterns of these genes across twelve patient tissue samples. Furthermore, we conducted CCK-8 assays, flow cytometry analyses, and scratch wound healing assays to assess the impact of key genes on the biological behaviors of both the Cal27 oral squamous cell carcinoma cell line and the potentially malignant DOK oral lesion cell line. Additionally, we examined correlations between these key genes and clinical disease parameters in 214 oral squamous cell carcinoma patients using The Cancer Genome Atlas (TCGA) data; gene set enrichment analysis (GSEA) analysis results were also incorporated to enhance our findings from real-time quantitative PCR and Western blotting regarding potential mechanisms underlying the action of these key genes. RESULTS: The integrated analysis of sequencing data and bioinformatics revealed that LIMCH1 exhibited significantly reduced mRNA (P < 0.001) and protein levels (P < 0.01) in the oral squamous cell carcinoma tissues compared with normal control tissues. In the Cal27 cells, the low LIMCH1 level group demonstrated a larger wound healing area within 24 hours than the control group (P < 0.01), enhanced proliferation capacity over 72 hours relative to the control group (P < 0.01), and an increased apoptosis rate within 24 hours compared with the high expression group (P < 0.05). However, no significant differences were observed between the low and high level groups in DOK cells. Furthermore, it was determined that low LIMCH1 level correlated with poor prognosis in the patients (P=0.013) and a higher lymph node metastasis rate (P < 0.05). Investigations into the potential mechanisms of action indicated that LIMCH1 did not influence the onset or progression of oral squamous cell carcinoma via the epithelial-mesenchymal transition pathway. CONCLUSION LIMCH1 level may function as a promising biomarker to aid in the prognostic assessment of oral squamous cell carcinoma; however, its precise mechanistic role requires further investigation.
Humans ; Mouth Neoplasms/metabolism* ; Prognosis ; Carcinoma, Squamous Cell/metabolism* ; Biomarkers, Tumor/metabolism* ; LIM Domain Proteins/metabolism* ; Cell Line, Tumor ; Cell Proliferation ; Male ; Female

OBJECTIVE: To investigate the effects of LncRNA SNHG20 on epithelial mesenchymal transition (EMT) and microtubule formation in human oral squamous cell carcinoma (OSCC) cells through targeted regulation of the miR-520c-3p/RAB22A pathway. METHODS: After real-time fluorescence quantitative detection of LncRNA SNHG20, miR-520c-3p, RAB22A mRNA expression levels in OSCC tissues and cells, dual luciferase reporter assay was used to detect the relationship between the three. OSCC cells were randomly separated into control group, sh-NC group, sh-SNHG20 group, sh-SNHG20+anti NC group, and sh-SNHG20+anti miR-520c-3p group. Western blotting was used to detect the expression of N-cadherin, vimentin, and E-cadherin proteins in the OSCC cells. The morphology of HSC-3 cells was observed under microscope. Changes in the number of microtubules formed were detected. The effect of LncRNA SNHG20 on the growth of OSCC tumors and the expression levels of LncRNA SNHG20, miR-520c-3p and RAB22 A in the transplanted tumors were detected by nude mice tumorigenesis experiment. RESULTS: LncRNA SNHG20 and RAB22A mRNA were upregulated in the OSCC tissues and cells, while miR-520c-3p was downregulated (P < 0.05). There were binding sites between LncRNA SNHG20 and miR-520c-3p, RAB22A and miR-520c-3p, which had targeted regulation relationship. Compared with the sh-NC group, the sh-SNHG20 group had fewer stromal like cells, more epithelial like cells, incomplete microtubule structure, and fewer nodules. LncRNA SNHG20, RAB22A, N-Cadherin, and vimentin were downregulated, while miR-520c-3p and E-cadherin were upregulated (P < 0.05). Compared with the sh-SNHG20+anti-NC group, the sh-SNHG20+anti-miR-520c-3p group had a higher number of stromal like cells, a lower number of epithelioid cells, tighter microtubule arrangement, and more microtubule nodules. miR-520c-3p and E-cadherin were downregulated, while RAB22A, N-cadherin, and vimentin were upregulated (P < 0.05). The transplanted tumor of OSCC in sh-SNHG20 group was smaller and lower than that in sh-NC group. The expression levels of LncRNA SNHG20 and RAB22A in the transplanted tumor tissues were lower than those in sh-NC group, and the expression level of miR-520c-3p was higher than that in sh-NC group (P < 0.05). CONCLUSION LncRNA SNHG20 promotes epithelial-mesenchymal transition and microtubule formation in human oral squamous cell carcinoma cells by targeting the miR-520c-3p/RAB22A pathway. Inhibiting the expression of LncRNA SNHG20 can target and regulate the miR-520c-3p/RAB22A pathway to inhibit EMT and microtubule formation in OSCC cells.
Humans ; RNA, Long Noncoding/genetics* ; MicroRNAs/metabolism* ; rab GTP-Binding Proteins/metabolism* ; Epithelial-Mesenchymal Transition/genetics* ; Cell Line, Tumor ; Carcinoma, Squamous Cell/metabolism* ; Animals ; Microtubules/metabolism* ; Mouth Neoplasms/genetics* ; Mice, Nude ; Mice ; Gene Expression Regulation, Neoplastic ; Mice, Inbred BALB C

OBJECTIVE: To evaluate the clinical and radiographic efficacy of micro crestal flap-alveolar ridge preservation following extraction of mandibular molars with severe periodontitis compared with natural healing, and to preliminarily propose the surgical indication. METHODS: A retrospective analysis was conducted on clinical data from patients with mandibular molars with severe periodontitis either receiving micro crestal flap-alveolar ridge preservation (MCF-ARP group) or undergoing natural healing in department of periodontology, Peking University School and Hospital of Stomatology from September 2013 to June 2021. Cone-beam computed tomography scannings performed before/immediately after extraction (as baseline) and repeated before implantation (after the extraction socket healing) were used to measure the ridge width, height and volumetric changes of the sockets, and the proportion of guided bone regeneration (GBR) during implant therapy were compared between the two groups. RESULTS: Between baseline and healing, significant differences in changes of MCF-ARP group [(8.34±2.81) mm] and natural healing group [(3.82±3.58) mm] in the distances from mandibular canal to center of the tooth socket were recorded (P < 0.001). The ridge width at 1 mm below the most coronal aspect of the crest increased by (3.50±4.88) mm in the MCF-ARP group but decreased by (0.16±5.70) mm in the natural healing group, respectively (P=0.019). After healing, the MCF-ARP group showed the distances from mandibular canal to center of the tooth socket >8 mm in all the cases, with 97.1% exceeding 10 mm. Natural healing group displayed 23.1% of the cases with center bone height < 8 mm and 61.5% exceeding 10 mm. Volume changes at the buccal and lingual aspect as well as the total socket were significantly greater in the MCF-ARP group compared with natural healing group (P < 0.001).At the time of implantation, GBR was performed in 5 out of 68 subjects (8.3%) in the MCF-ARP group, whereas 8 out of 26 subjects (30.8%) in the natural healing group required GBR, reflecting significant difference (P=0.003). CONCLUSION In the sites of mandibular molars with severe periodontitis, when the distances from mandibular canal to center of the tooth socket was not enough (less than 7 mm), clinicians could consider performing the micro crestal flap-alveolar ridge preservation to achieve augmentation for alveolar ridge and reduce the proportion of guided bone regeneration during implant therapy to reduce the difficulty and risk of injuries during implant therapy.
Humans ; Tooth Extraction ; Retrospective Studies ; Surgical Flaps ; Molar/surgery* ; Mandible/surgery* ; Female ; Periodontitis/surgery* ; Male ; Adult ; Middle Aged ; Cone-Beam Computed Tomography ; Alveolar Ridge Augmentation/methods* ; Alveolar Process/surgery* ; Tooth Socket/diagnostic imaging* ; Dental Implantation, Endosseous/methods*

OBJECTIVE: To clarify the role of concentrated growth factors (CGF) in the treatment of periodontal cement defects using calcium phosphate cement (CPC) with self-curing properties. METHODS: Thirty-six intrabony defects were randomly divided into two groups. The experimental group received CGF+CPC treatment (n=18), while the control group received CPC treatment alone (n=18). The probing depth, clinical attachment loss, and hard tissue filling as measured by cone beam CT (CBCT) were evaluated at baseline and 1 year postoperatively in both groups, and the levels of major growth factors in CGF and serum were compared [platelet-derived growth factor-BB (PDGF-BB), transforming growth factor-β1 (TGF-β1), insulin-like growth factor-1 (IGF-1), and vascular endothelial growth factor (VEGF)]. RESULTS: At baseline, there were no statistically significant differences in probing depth, clinical attachment loss and CBCT measurements between the two groups (P>0.05). At 1 year postoperatively, significant improvements were observed in parameters mentioned above in both groups (P < 0.05). The CGF+CPC group seemed more effective compared with the CPC group in reduction of probing depth [(4.5±1.3) mm vs. (3.2±1.1) mm] and clinical attachment gain [(3.8±0.9) mm vs. (2.0±0.5) mm, P < 0.05]. Compared with the group treated with CPC alone, the hard tissue filling degree shown by CBCT in the CGF+CPC group was significantly increased [the reduction of the depth of the intrabony defects was (3.9±1.2) mm vs. (2.1±0.7) mm, respectively, P < 0.01]. At 1 year post-operatively, the volume of the intrabony defects shown by CBCT in the CGF+CPC group was reduced by (0.031 8±0.004 1) mL, which was significantly more than that in the CPC group [(0.019 7±0.001 2) mL, P < 0.05]. In addition, the concentration of the main growth factors (PDGF-BB, TGF-β1, IGF-1, and VEGF) in CGF were higher than those in serum (P < 0.001). CONCLUSION After 1 year of follow-up, the results of the present study indicated that CGF could significantly improve the clinical and radiological effects of CPC on the treatment of periodontal intrabony defects.
Humans ; Calcium Phosphates/therapeutic use* ; Male ; Female ; Bone Cements/therapeutic use* ; Middle Aged ; Cone-Beam Computed Tomography ; Alveolar Bone Loss/therapy* ; Becaplermin ; Adult ; Insulin-Like Growth Factor I ; Intercellular Signaling Peptides and Proteins/therapeutic use* ; Proto-Oncogene Proteins c-sis/blood* ; Transforming Growth Factor beta1/blood* ; Vascular Endothelial Growth Factor A/blood*

OBJECTIVE: To evaluate the clinical efficacy of clear aligner therapy in patients with severe periodontitis accompanied by pathological tooth displacement in the anterior region. METHODS: This retrospective study analyzed patients diagnosed with severe periodontitis and pathological displacement in the anterior region, who visited both the Periodontics and Orthodontics Departments at Peking University School and Hospital of Stomatology between 2019 and 2022. A total of 26 eligible cases were included in this study. All the patients underwent regular periodontal maintenance throughout the treatment process, and clear aligners were used for orthodontic treatment. Intraoral scans were analyzed by dedicated software to measure and compare occlusal distribution and proximal contact scores before and after orthodontic treatment. Periodontal clinical indicators were assessed at three key time points: before periodontal treatment (T0), before orthodontic treatment (T1), and after orthodontic treatment (T2). All the cases were treated with clear aligner. RESULTS: A total of 217 pathologically displaced anterior teeth from 26 patients were analyzed. Among these, 105 teeth exhibited periodontal pockets [probing depth (PD) ≥5 mm] before periodontal treatment. After clear aligner therapy, the occlusal score improved significantly from 10.35±8.61 to 23.62±9.73 (P < 0.001), and the proximal contact score increased from 13.62±4.73 to 31.62±10.37 (P < 0.001). The median PD decreased significantly from 3.33 mm [interquartile range (IQR)=0.92] at T0 to 2.50 mm (IQR=0.67, P < 0.001) at T1 and remained stable at 2.50 mm (IQR=0.50) after treatment (T2). A significant reduction in PD was observed between T0 and T2 (P < 0.001), but no significant difference was found between T1 and T2 (P=0.948). CONCLUSION Clear aligner therapy demonstrates favorable clinical efficacy in patients with severe periodontitis and pathological anterior tooth displacement. It effectively improves occlusal distribution and proximal contact while maintaining periodontal health in these patients. However, further large-scale prospective controlled studies are needed to verify its long-term clinical outcomes.
Humans ; Retrospective Studies ; Periodontitis/therapy* ; Female ; Male ; Adult ; Tooth Migration/therapy* ; Tooth Movement Techniques/methods* ; Treatment Outcome ; Middle Aged ; Young Adult ; Orthodontic Appliances, Removable

OBJECTIVE: To evaluate the wound healing of recipient and donor sites following keratinized mucosa augmentation (KMA) around implants in reconstructed jaw areas and to compare these outcomes with gingival grafts in native jawbone, so as to provide clinical guidance for postoperative maintenance, and to investigate the impact of clinical experience on the evaluation of KMA postoperative healing through subgroup comparisons. METHODS: This study included patients who underwent resection of maxillofacial tumors, fibular or iliac flap reconstruction, and implant placement at Peking University Dental Hospital from October 2020 to April 2023. Three months post-implant placement, the patients were referred for KMA procedures. Clinical photographs of the reconstructed area were taken preoperatively, immediately postoperatively, and 3 weeks and 3 months post-surgery. Additionally, photographs of the palatal donor site were obtained preoperatively and 3 weeks later. Wound healing was assessed by four junior and three senior clinicians utilizing the early healing index (EHI), early wound healing score (EHS), and pink esthetic score (PES).And senior clinicians evaluated the healing effect compared with gingival transplantation on natural jawbone using a 10-point scale. RESULTS: A total of 26 patients with jawbone reconstruction were included, with an average age of (34.2±10.2) years, 11 males (42.3%) and 15 females (57.7%). Among them, 13 cases (50.0%) underwent fibula flap reconstruction, and 13 cases (50.0%) underwent iliac flap reconstruction. The average number of implants per patient was 3.2±0.7. In the recipient area, 3 weeks postoperatively, the EHS was 7.0 (4.0, 9.0), with sub-item scores as follows: Clinical signs of re-epithelialization (CSR) 6.0 (3.0, 6.0), clinical signs of haemostasis (CSH) 1.5 (1.0, 2.0), and clinical signs of inflammation (CSI) 1.0 (0.0, 1.0), indicating that the average appearance of the wound in the recipient area was characterized by generally well-approximated wound edges with minimal fibrin lines and mild erythema and swelling. The EHI for the recipient area was 2.0 (1.5, 2.5), suggesting that the incision was mostly closed with some fibrin lines 3 weeks postoperatively. The long-term healing evaluation system, PES, was 2.5 (2.0, 3.0), with sub-scores for color [1.0 (1.0, 1.5)] and texture [1.5 (1.0, 2.0)], which were slightly different from the reference values.In the palatal donor area, 3 weeks postoperatively, the EHI score was lower at 1.3 (1.0, 2.5), while the EHS score was higher at 8.5 (6.0, 10.0), indicating better soft tissue healing in the donor area compared with the recipient area. Among the clinicians with different levels of experience, the assessment of wound healing revealed that except for the CSI sub-item, where the junior group scored higher than the senior group, all other sub-items showed significantly higher scores in the senior group compared with the junior group. In the EHS evaluation system, the CSH sub-item demonstrated no significant differences between the groups with varying levels of experience. Experienced clinicians' evaluation outcomes of healing effect compared with gum graft on natural alveolar bone was 8.5 (7.5, 9.5), showing high consistency [intraclass correlation coefficient (ICC): 0.892; 95% confidence interval (CI): 0.791－0.949], suggesting slightly suboptimal healing results after KMA surgery. CONCLUSION The healing process following KMA in the context of jawbone reconstruction is relatively protracted, emphasizing the necessity for comprehensive postoperative management. Moreover, clinician experience plays a significant role in the assessment of wound healing outcomes for KMA in maxillofacial reconstruction.
Humans ; Wound Healing ; Adult ; Male ; Female ; Gingiva/transplantation* ; Plastic Surgery Procedures/methods* ; Middle Aged ; Surgical Flaps ; Keratins

OBJECTIVE: To compare the influence of different emergence profile of implants in mandibular molar on the peri-implant soft tissue. METHODS: Forty-four implants were divided into two equal groups by mucosal thickness, ≥2 mm (group A) or < 2 mm (group B), and were randomly included in the test group and the control group. In the control group, the patients were treated by a prosthesis with no transmucosal modifications (subgroups A1 and B1). In groups A1 and B1, the prostheses maintained the original emergence profile of the healing abutment. In the test group, the prostheses were designed based on a width-to-height ratio (W/H) of 1.3 ∶ 1 (subgroups A2 and B2). In group A2, the buccal transmucosal configuration design was slightly concave, and in group B2, the prostheses were designed with convex buccal transmucosal configuration. Assessments were made before delivery of the definitive restoration (T0), one month (T1) and 12 months (T2) after loading. The soft tissue and prosthesis information were obtained by intraoral scan and were converted to digital models. The digital models of different time were superimposed together. Buccal mucosal W/H, emergence angle (EA) and buccal mucosal margin recession (ΔGM) were measured. RESULTS: One year after loading, the buccal mucosal margin recession in the test group (groups A2 and B2) was significantly lower than that in the control group (groups A1 and B1). The ΔGM in group A2 was significantly lower than that in group A1 (P=0.033), but in groups B1 and B2, it was not significantly different. The W/H in group A2 increased significantly one month after loading, but remained stable at one year. In the A1 group, the W/H changed little from initial to one month, but increased significantly at one year after loading. The W/H in group B2 remained stable from the beginning to one year, while in group B1, it changed little one month after loading, but increased significantly by one year. CONCLUSION When the initial mucosal thickness was ≥2 mm, the slightly concave prosthesis designed based on the biological W/H significantly maintained the level of buccal mucosa. When the mucosal thickness was < 2 mm, the slightly convex prosthesis design maintained a more stable W/H over one year.
Humans ; Mandible/surgery* ; Molar/surgery* ; Male ; Female ; Adult ; Middle Aged ; Dental Prosthesis Design ; Dental Implants ; Dental Implantation, Endosseous/methods*