Effect of mineralized dentin matrix on the prognosis of bone defect and retained root after coronectomy.

OBJECTIVE: To investigate the impact of mineralized dentin matrix (MDM) on the prognosis on bone regeneration and migration of retained roots after coronectomy. MATERIALS AND METHODS: Patients were divided into three groups based on the type of bone graft after coronectomy: Group C (n = 20, collagen), Group T (n = 20, tricalcium phosphate (TCP) + collagen), and Group D (n = 20, MDM + collagen). CBCT scans, conducted immediately and 6 months after surgery, were analyzed using digital software. Primary outcomes, including changes in bone defect depth and retained root migration distance, were evaluated 6 months after surgery. RESULTS: After 6 months, both Groups D and T exhibited greater reduction of the bone defect and lesser retained root migration than Group C (p < 0.001). Group D had greater regenerated bone volume in the distal 2 mm (73 mm3 vs. 57 mm3, p = 0.011) and lesser root migration (2.18 mm vs. 2.96 mm, p < 0.001) than Group T. The proportion of completely bone embedded retained roots was also greater in Group D than in Group C (70.0% vs. 42.1%, p = 0.003). CONCLUSIONS: MDM is an appropriate graft material for improving bone defect healing and reducing retained root migration after coronectomy. CLINICAL RELEVANCE: MDM is an autogenous material prepared chairside, which can significantly improve bone healing and reduce the risk of retained root re-eruption. MDM holds promise as a routine bone substitute material after M3M coronectomy.

Alveolar ridge preservation of two-wall bone defects using mineralized dentin matrix: An experimental pre-clinical study.

OBJECTIVES: To study bone healing of two-wall bone defects after alveolar ridge preservation using mineralized dentin matrix. MATERIALS AND METHODS: After distal roots extraction of second and fourth premolars (P2, P4) on one lateral mandible in 12 beagles, two-wall bone defects (5 × 5 × 5 mm) were surgically created distally to the remaining mesial roots of P2 and P4. A total of 24 sites were randomly allocated to three groups (implant material- time of execution): mineralized dentin matrix (MDM)-3 m (MDM + collagen membrane; 3 months), MDM-6 m (MDM particles + collagen membrane; 6 months), and C-6 m (collagen membrane only; 6 months). Clinical, radiographic, digital, and histological examinations were performed 3 and 6 months after surgery. RESULTS: The bone healing in MDM groups were better compared to Control group (volume of bone regenerated in total: 25.12 mm3 vs. 13.30 mm3, p = .046; trabecular volume/total volume: 58.84% vs. 39.18%, p = .001; new bone formation rate: 44.13% vs. 31.88%, p = .047). Vertically, the radiological bone level of bone defect in MDM-6 m group was higher than that in C-6 m group (vertical height of bone defect: 1.55 mm vs. 2.74 mm, p = .018). Horizontally, no significant differences in buccolingual bone width were found between MDM and C groups at any time or at any level below the alveolar ridge. The percentages of remaining MDM were <1% in both MDM-3 m and MDM-6 m groups. CONCLUSIONS: MDM improved bone healing of two-wall bone defects and might be considered as a socket fill material used following tooth extraction.

Accuracy of computer-assisted dynamic navigation when performing coronectomy of the mandibular third molar: A pilot study.

OBJECTIVES: The study represents a preliminary evaluation of the accuracy of the dynamic navigation system (DNS) in coronectomy of the mandibular third molar (M3M). METHODS: The study included participants with an impacted M3M near the inferior alveolar canal. The coronectomy planes were designed before the surgery using cone-beam computed tomography (CBCT) imaging data and then loaded into the DNS program. Intraoperatively, the navigation system was used to guide the complete removal of the target crown. Postoperative CBCT imaging was used to assess any three-dimensional deviations of the actual postoperative from the planned preoperative section planes for each patient. RESULTS: A total of 12 patients (13 teeth) were included. The root mean square (RMS) deviation of the preoperatively designed plane from the actual postoperative surface was 0.69 ± 0.21 mm, with a maximum of 1.45 ± 0.83/-1.87 ± 0.63 mm deviation. The areas with distance deviations < 1 mm, 1-2 mm, and 2-3 mm were 71.97 ± 5.72 %, 22.96 ± 6.57 %, and 4.52 ± 2.28 %, respectively. Most patients showed extremely high convexity of the surface area located in the mesial region adjacent to the base of the extraction socket. There was no observable evidence of scratching of the buccolingual bone plate at the base of the extraction socket by the handpiece drill. CONCLUSIONS: These results provide preliminary support for the use of DNS-based techniques when extracting M3M using a buccal approach. This would improve the accuracy of coronectomy and reduce the potiential damage to the surrounding tissue. CLINICAL SIGNIFICANCE: DNS is effective for guiding coronectomy.

The application of an intraoral banana peel suturing model in surgical training of dental students.

OBJECTIVES: This study investigated the application of an intraoral banana peel suturing model in helping students to acquire intraoral surgical techniques. METHODS: This is a self-control study conducted from January 2021 to March 2021. An intraoral banana peel suturing model was implemented to provide oral suture experience for undergraduates majoring in stomatology. The sutures students placed in the model were photographed and evaluated blindly by a professional team using an established scoring system. Training scores were recorded before (training 1) and after 2 months of training (training 2). Linear regression was used to examine factors related to the scores. Suturing training was conducted in the School and Hospital of Stomatology at Peking University. A total of eighty-two students in Peking University School and Hospital of Stomatology were in their fourth pre-clinical year and followed a workshop on surgical sutures according to the curriculum. All students who should take this course were included, and the response rate was 100%. RESULTS: The mean training 2 score (23.04 ± 3.83) was higher than the mean training 1 score (13.94 ± 3.15). The training 1 score was not significantly correlated with any of the students' general characteristics. The training 2 score was correlated with the training 1 score and the cumulative duration of practice outside of class. CONCLUSION: The intraoral banana peel suturing model can be used for suture training, and dental students' suture ability was improved after using the banana peel for suture practice.

Endoscopic visualization of the inferior alveolar nerve associated with somatosensory changes after impacted mandibular third molar extraction.

The aim of this study is to assess the relationship between somatosensory functional changes and inferior alveolar nerve (IAN) exposure after impacted mandibular third molars (M3M) removal. We recruited 35 patients who underwent impacted M3M extraction near the IAN. The M3Ms were extracted by combined endoscopy, piezosurgery, and contra-angle high-speed turbine handpiece. All IAN canal perforations and exposed regions were recorded and measured by endoscopy after extraction and on cone-beam computed tomography (CBCT) images before extraction. The patients were followed up 1, 7, and 35 days after surgery. A standardized quantitative sensory testing (QST) battery was performed on the lower lip skin. All of 35 cases had exposed IAN on CBCT images, 5 of which had no exposed IAN under endoscopy. For the other 30 cases, the endoscopy-measured IAN length and width were shorter than the CBCT measurements (P < 0.001). The warm and mechanical detection thresholds (MDT) on the operation side were significantly higher than the contralateral side after surgery (P < 0.05). Thermal sensory limen, MDT, and cold pain threshold were strongly correlated with the exposed IAN length and MDT also with the exposed IAN width one day after surgery. In conclusion, it was found that not all exposed IAN in CBCT images were real exposure after surgery. The intraoperative exposed IAN endoscopic measurements were smaller than by CBCT and strongly correlated with some QST parameters.

Feasibility and Efficacy of a Degradable Magnesium-Alloy GBR Membrane for Bone Augmentation in a Distal Bone-Defect Model in Beagle Dogs.

We explored the feasibility and efficacy of a degradable magnesium (Mg) alloy guided bone regeneration (GBR) in the treatment of bone defects after tooth extraction. A GBR membrane (MAR-Gide (MG)) was used to treat a mandibular second molar (M2M)-distal bone defect (DBD). In eight beagle dogs, bilateral mandibular second and fourth premolars were hemi-sected. The distal roots were removed to create a two-wall bony defect of dimension 5 mm × 5 mm × 5 mm to simulate M2M-DBD. Thirty-two bone defects were assigned randomly into four groups according to GBR membranes (MG and Bio-Gide (BG)) applied and the time of killing (3 months and 6 months after surgery). The osteogenesis of bone defects and MG degradation were analyzed using micro-CT, histology (staining, tartrate-resistant acid phosphatase), and inductively coupled plasma mass spectrometry. MG did not increase the prevalence of infection, wound dehiscence, or subcutaneous emphysema compared with those using BG. Trabecular volume/total volume at 3 months (63.71 ± 10.4% vs. 59.97 ± 8.94%) was significantly higher in the group MG than that in the group BG. Implanted MG was degraded completely within 3 months, and "island-shaped" new bone was found near MG degradation products. A significant difference was not found in vertical bone height or percent of new bone formation (45.44 ± 12.28% vs. 43.49 ± 7.12%) between the groups. The concentration of rare-earth elements in mandibular lymph nodes of the group MG was significantly higher than that of the group BG (P ≤ 0.017) but did not lead to histopathological changes. In summary, MG exhibited good biocompatibility and clinical applicability compared with BG in vivo. The osteogenic effect of MG could be enhanced by regulating the degradation rate of Mg-alloy.

Navigation in bone-impacted premaxillary supernumerary tooth removal: a preliminary clinical trial.

AIM: The present clinical trial aimed to preliminarily assess whether navigation could help to position impacted supernumerary teeth (STs) and reduce surgical trauma. MATERIALS AND METHODS: Subjects with an impacted supernumerary tooth (ST) in the premaxillary area were enrolled in the study and randomly distributed into a navigation group and a control group. In the navigation group, STs were positioned and extracted under real-time optic navigation. In the control group, STs were extracted depending on the surgeon's experience. Subjects were followed up for 12 to 24 weeks postsurgery. Operating time, futile bony trauma, and the positioning precision of the STs were the major outcomes assessed. Multivariate correlation analysis was performed. RESULTS: In 24 subjects, 32 STs were removed and no severe complications occurred in either group. The proportion of ST exposure at the planned access point was 100% in the navigation group and 68.75% in the control group (χ² = 5.926, P = 0.015). Futile length, futile width, and the distance between the point where the ST was initially exposed and the bony point planned for accessing it were related to both navigation/control grouping and bone thickness in the access side. For challenging STs with bone thickness of > 0.5 mm in the access side (N = 22), the futile length in the navigation group (0.0 [0.0, 4.0] mm) was significantly smaller than that in the control group (3.0 [0.0, 8.0] mm, P = 0.028). Similarly, the futile width in the navigation group (0.0 [0.0, 2.0] mm) was significantly smaller than that in the control group (2.0 [0.0, 4.0] mm, P = 0.018). CONCLUSIONS: Navigation helped to position impacted STs precisely and reduced surgical bony trauma to some extent, especially in challenging cases in which the bone in the access side was thicker than 0.5 mm.

Somatosensory changes in Chinese patients after coronectomy vs. total extraction of mandibular third molar: a prospective study.

OBJECTIVES: This study aimed to quantitatively compare the somatosensory function changes of inferior alveolar nerve (IAN) after mandibular third molar extraction with a surgery protocol of coronectomy, as opposed to the conventional method. MATERIALS AND METHODS: Patients with a lower third molar directly contacting IAN were recruited and assigned either to a test group (coronectomy group) or a control group (conventional extraction). A standardized quantitative sensory testing (QST) battery was performed for four times: one week before surgery and the second, seventh, and 28th days after surgery. Z-scores and the loss/gain coding system were applied for each participant. RESULTS: A total of 140 molars (test group: n = 91, control group: n = 49) were enrolled. The sensitivity of the mechanical detection threshold (MDT) and pressure pain threshold (PPT) significantly increased after surgery more than before surgery in both groups (P ≤ 0.001). After the surgery, the sensitivities of the cold detection threshold (CDT), cold pain threshold (CPT), and heat pain threshold (HPT) were significantly higher in the test group than in the control group (P ≤ 0.027). The risk of IANI was significantly larger (P = 0.041) in the test group than in the control group. CONCLUSIONS: QST was a sensitive way to detect somatosensory abnormalities even with no subjective complaint caused by surgery. Coronectomy had less influence on IAN function than conventional total extraction. CLINICAL RELEVANCE: The somatosensory function changes after mandibular third molar extraction were quantitatively studied, and coronectomy was proved a reliable alternation to reduce IAN injury rate.

Navigation-Guided Extraction of Impacted Supernumerary Teeth: A Case Report.

Supernumerary teeth usually result in retarded eruption, malocclusion, poor esthetics, and cyst formation. Management involves surgical extraction, which can be challenging in certain complicated cases owing to the risk of injury to young permanent tooth germs or fragile roots. The present report describes a novel preoperative computer-assisted and intraoperative navigation-guided surgical treatment for a case of complicated impacted supernumerary teeth. The report highlights accurate tooth location and minimal invasion with use of the navigation-guided system. Moreover, it discusses various treatment considerations during such a procedure.

[Influence of acellular dermal matrix on differentiation of stem cells from young permanent tooth apical papilla].

OBJECTIVE: To get the stem cells from the young permanent tooth apical papillae, and observe the osteogenic differentiation of the cells after cultured with acellular dermal matrix (ADM). METHODS: Young permanent tooth apical papillae were obtained by the oral surgeon. The cells from the apical papillae were isolated, cultured and analyzed through a flow cytometer. The cells in the experimental group were induced both osteogenic and adipogenic differentiation. The cells were not induced in the control group.Both groups were evaluated by staining and real-time polymerase chain reaction (real-time PCR) to examine the quantity of RNAs in the experimental group. The cells from apical papillae were also cultured with ADM. These cells were also induced both osteogenic and adipogenic differentiation in the experimental group, and not induced in the control group. The measures of staining and real-time PCR were also carried out. RESULTS: The cells from the apical papillae proliferated in a rapid rate. Of which 70.3% in cultures were positive for Stro-1, and 96% positive for CD105 according to flow cytometric analysis. After induction, the RNA level related to osteogenic and adipogenic differentiation expressed higher in the experimental group than those of the control group without induction obviously, such as osteocalcin (OCN), bone sialoprotein (BSP), liver X-recepter α (LXRα), lipoprotein lipase(LPL), peroxisome proliferator activated receptor γ (PPAR-γ), and scavenger receptor class B type 1(SR-B1). The cells cultured with ADM also had a fast proliferation, and grew attached to ADM. After induction, the RNA level of OCN and BSP had a higher expression than the control group (P > 0.05), and LPL also expressed higher (P < 0.05). CONCLUSION: The study approved that there were a big amount of stem cells in the young permanent tooth apical papilla obtained by oral surgery, which had significant osteogenic potential. The cells still proliferated well when they were cultured with ADM as a kind of collagen skelecton. The results showed that ADM could be performed as a base to support the stem cells to survive the environment, and it also could play a role in osteogenic differentiation of stem cells from apical papilla.

[Clinical observation of influence of warfarin on post-operative bleeding after tooth extraction in the elderly].

OBJECTIVE: To investigate the feasibility of continuing warfarin when international normalized ratio (INR) was less than 2.5 before tooth extraction in the elderly. METHODS: One hundred elderly outpatients with prolong use of warfarin and maintaining INR < 2.5 before tooth extraction served as observation group, 200 elderly outpatients without taking anticoagulant and antiplatelet medicine served as control group. All the patients underwent a single non-impacted tooth extraction. Postoperative bleeding at different time was observed. RESULTS: There was significant difference in postoperative bleeding at 5, 10, 30 min, 24 h after extraction and there was no significant difference at 48 h between control group and observation group (P < 0.05) and no bleeding was found in either group at 48 h (incidence of bleeding were 0%). CONCLUSIONS: It was feasible to continue warfarin for the elderly maintaining INR < 2.5 undergoing a single non-impacted tooth extraction by monitoring postoperative bleeding and hemostatic treatment measures.

[Clinical evaluation of influence of aspirin on post-operative bleeding after tooth extraction in the elderly].

OBJECTIVE: To investigate the feasibility of continuation of aspirin before tooth extraction in the elderly. METHODS: The patients enrolled in this study were the elderly requiring a single non-impacted tooth extraction. 300 elderly outpatients used lidocaine local infiltration anesthesia, 200 patients without using aspirin before tooth extraction served as control group I, 100 patients with prolong use of aspirin before tooth extraction as observation group I. 300 elderly outpatients used compound articaine local infiltration anesthesia, 200 patients without using aspirin before tooth extraction served as control group II, 100 patients with prolong use of aspirin before tooth extraction as observation group II.Bleedings at 5, 10, 30 min, 24 h after tooth extraction were observed and the relationship between postoperative bleeding and intake of aspirin was analyzed. RESULTS: There was no significant difference at 5, 10, 30 min, 24 h in postoperative bleeding after extraction between control group I and observation group. The incidence of bleeding of observation group II after tooth extraction at 5 min was higher than that of control group II and there was no significant difference at 10, 30 min, 24 h between the two groups. CONCLUSIONS: Continuation of aspirin have no influence on postoperative bleeding. Therefore we suggest that there was no indication to discontinue aspirin for the elderly before a single non-impacted tooth extraction.

[Clinical evaluation of midazolam intravenous sedation under bispectral index monitoring on romoval of anterior supernumerary teeth in children].

OBJECTIVE: To evaluate the efficacy and safety of midazolam intravenous sedation plus local anaesthesia on romoval of children's anterior supernumerary teeth in dental clinic. METHODS: A total of 41 ASA I children with anterior supernumerary teeth aged 6 to 14 were selected for removal surgery, anaesthesia was done by moderate sedation by midazolam intravenous titration plus local anaesthesia. Heart rate (HR), blood pressure (BP), pulse oxygen saturation rate (SpO(2)), bispectral index (BIS) and Ramsay sedation score (RSS) at different time points were recorded (5 min after patient is in operation room, at local anaesthesia injection, at incision, 10 min after incision and at the end of operation). After operation, the overall efficacy of sedation by Houpt rating scale was evaluated by surgeon, anaesthesiologist and anaesthetic nurse. RESULTS: Among the 41 children, 29 were male, 12 were female, mean age (9.76 ± 2.46) years old; The average operation time was (23.83 ± 9.98) min, total dose of midazolam was (2.96 ± 0.92) mg with a dosage rate being (0.084 ± 0.016) mg/kg. There was a positive correlation between age and total dose (r=0.69, P<0.01); and a negative correlation between age and total dosage (r=-0.37, P<0.05). With the decreasing of age, probability for children to move or cry during local anaesthesia can increase, while with the increasing of age, probability for children to memorize the clicking of drill or hammer could increase. The correlation coefficient between RSS and BIS value was r=-0.854 (P<0.01), the median BIS value corresponded to RSS of 3 was 75. Pulse oxygen saturation rate was above 95% in all the cases. CONCLUSION: Sedation by midazolam intravenous titration is a safe and efficient method of anesthesia for removal of children's anterior supernumerary teeth when BIS value is above 75.

[Histochemical and immunohistochemical double staining for osteolytic related factors in keratocystic odontogenic tumor].

OBJECTIVE: To investigate the activities of bone resorption related cytokines at the capsule wall of the keratocystic odontogenic tumor (KCOT) by histochemical and immunohistochemical double staining for tartrate-resistant acid phosphatase staining (TRAP), receptor activator of nuclear factor-kappaB ligand(RANKL), osteoprotegerin(OPG), interleukin1alpha(IL-1alpha)and parathyroid hormone-related protein (PTHrP). METHODS: Twenty paraffin blocks of KCOT were sectioned in sequence into five slices. One slice was stained with hematoxylin and eosin to confirm pathological diagnosis. Each of other four slices was histochemically and immunohistochemically double stained separately by TRAP with RANKL, TRAP with OPG. TRAP with IL-1alpha and TRAP with PTHrP to observe expressions of these factors in KCOT. RESULTS: TRAP positive expression was shown in 10 cases. Positive expression of both TRAP and RANKL were detected in 5 cases. RANKL positive staining mainly scattered in fibrous connective tissue, blood vessels and epithelium was shown in 12 cases. OPG positive staining was detected in 4 cases. IL-1alpha positive cells were also observed in 10 cases and PTHrP positive cells were seen in 6 cases. The TRAP and RANKL positive cells were scattered within the connective tissues near the bone. The IL-1alpha positive staining cells were observed both in epithelium and connective tissues, but predominately in the former. CONCLUSION: The mechanism of osteoclastogenesis of KCOT may also be mediated by osteolytic factors such as RANKL, IL-1alpha and PTHrP. These factors involved in the activation and differentiation of pre-osteoclasts to form osteoclasts, thus finally resulted in jaw bone resorption.

[Osteoclastic bone destruction and its regulating factors in oral squamous cell carcinoma].

OBJECTIVE: To investigate the osteoclastic activity in oral squamous cell carcinoma (OSCC) invading the jaws and to observe the expression of RANKL and OPG, the two bone resorption related cytokines, in these cases. METHODS: Twelve cases of OSCC invading the mandible were studied. After pathological diagnosis, operations were done to remove part of the mandible depending upon the X-ray findings. Fresh soft tissue specimens were frozen-sectioned and other specimens with the bone tissue were fixed and decalcified to make paraffin sections. Tartrate-resistant acid phosphatase(TRAP) staining and immunohistochemical staining were then applied to observe the location of osteoclasts and the expression of RANKL and OPG. RESULTS: TRAP positive multinuclear cells were detected near the interface between the bone and tumor. RANKL positive cells were commonly seen on the endothelium of blood vessel and basement membrane of the epithelium. But OPG reactivities were not seen in these sections. CONCLUSION: The bone destruction caused by OSCC is mediated by osteoclasts but not by cancer cell itself. It appears that the differentiation and activation of osteoclasts were induced by OSCC through cytokines like RANKL.

Patterns of mandibular invasion by gingival squamous cell carcinoma.

PURPOSE: This study examined patterns of invasion of lower gingiva cancer into the mandible. Our goal was to clarify the most common routes for gingival squamous cell carcinoma to enter and spread within the mandible. PATIENTS AND METHODS: The subjects were 176 patients with lower gingival squamous cell carcinoma who underwent mandibulectomy; all tumors were examined histopathologically. The method of mandibulectomy was decided on the basis of conventional plain radiographic and computed tomographic findings. RESULTS: The tumor extended to the periosteum in 33%, to the cortical bone in 23%, and to the bone marrow in 9% of the patients who underwent mandibular resection. The remaining 35% of our patients had no evidence of mandibular invasion. CONCLUSION: The area of bone resorption on preoperative clinical and radiographic examinations often disagreed with the extent of mandibular invasion on histopathologic examination.

Effects of cerulenin on the endogenous fatty acid synthetic activity in squamous cell carcinoma of the oral cavity.

PURPOSES: Inhibition of cerulenin on the endogenous fatty acid synthetic activities of oral squamous cell carcinoma (OSCC) and normal oral mucosa was assayed. METHODS: Squamous cell carcinoma and normal oral mucosa were collected fresh from surgical specimens. The collected tissues were minced in RPMI 1640 and divided into 3 groups: cerulenin treated, dimethylsulfoxide treated, and control. The tissues were incubated in [1(2)-(14)C]acetic acid, sodium salt for the last 2.5 hours of the treatment at 37 degrees C in 5% CO(2). After labeling, total lipids were extracted and counted for (14)C by scintillation counting. RESULTS: Endogenous fatty acid synthetic activities of oral squamous cell caranoma in the cerulenin-treated group decreased by 19% at 1 hour, 64% at 2 hours, and 87% at 4 hours; remained nearly unchanged in the dimethylsulfoxide-treated group; and increased slightly in the control group. The oral mucosa tissues were only mildly affected by cerulenin in fatty acid synthesis. CONCLUSIONS: Cerulenin significantly inhibits fatty acid synthetic activity in squamous cell carcinoma and only mildly affected the oral mucosa, indicating that the fatty acid synthetic pathway may be exploited as a target for developing anticancer drugs.