Endoscopically-assisted extraction of broken roots or fragments within the mandibular canal: a retrospective case series study.

PURPOSE: To assess the impact of endoscope-assisted fractured roots or fragments extraction within the mandibular canal, along with quantitative sensory testing (QST) alterations in the inferior alveolar nerve (IAN). METHODS: Six patients with lower lip numbness following mandibular third molar extraction were selected. All patients had broken roots or fragments within the mandibular canal that were extracted under real-time endoscopic assistance. Follow-up assessments were conducted on postoperative days 1, 7, and 35, including a standardized QST of the lower lip skin. RESULTS: The average surgical duration was 32.5 min, with the IAN exposed in all cases. Two of the patient exhibited complete recovery of lower lip numbness, three experienced symptom improvement, and one patient remained unaffected 35 days after the surgery. Preoperative QST results showed that the mechanical detection and pain thresholds on the affected side were significantly higher than those on the healthy side, but improved significantly by postoperative day 7 in five patients, and returned to baseline in two patients on day 35. There were no significant differences in the remaining QST parameters. CONCLUSIONS: All endoscopic surgical procedures were successfully completed without any additional postoperative complications. There were no cases of deterioration of IAN injury, and lower lip numbness recovered in the majority of cases. Endoscopy allowed direct visualization and examination of the affected nerve, facilitating a comprehensive analysis of the IAN.

Bone regeneration using titanium plate stabilization for the treatment of peri-implant bone defects: A retrospective radiologic pilot study.

AIM: To 3-dimensional radiographically assess the effect of titanium plate in guided bone regeneration (GBR) for the treatment of peri-implant ridge defects in esthetic zone. MATERIAL AND METHODS: Nineteen patients with buccal peri-implant defects in the maxillary esthetic zone were treated with GBR using xenograft, autogenous bone, and collagen membrane. Subjects were divided into two groups: control (conventional GBR, 10 patients with 16 implants) and test (GBR with an adjunctive titanium plate; nine patients with 15 implants). Cone-beam computed tomography (CBCT) images obtained immediately after and 5-7 months following GBR were used to assess buccal crestal bone level (BBL) and buccal bone thickness (BBT) at different implant levels. RESULTS: Thirty-one implants in 19 patients were evaluated. Titanium plate exposure occurred in three cases (33.33%) of the test group. After 5-7 months, the mean BBL was located 1.48 ± 0.71 mm coronal to the platform in the test group and 0.90 ± 3.03 mm coronal to the platform in the control group (p = 0.03). The mean over all BBT (BBT-M) was 4.16 ± 0.48 mm in the test group and 2.38 ± 0.97 mm in the control group (p < 0.01). More resorption occurred in the control group than in the test group regarding mean BBL (3.00 ± 3.11 mm vs. 0.78 ± 0.79 mm, respectively; p = 0.04), BBT-M change (1.87 ± 1.59 mm vs. 0.56 ± 0.33 mm, respectively; p = 0.02), and percentage change in BBT-M (40.69 ± 24.01% vs. 11.53 ± 5.86%, respectively; p < 0.01). CONCLUSION: In the short-term, titanium plate-enhanced GBR maintained ridge dimensions better than conventional GBR did.

A three-in-one alveolar process reconstruction protocol for maxillary molar sites with severe residual bone height deficiency: A proof-of-concept pilot study.

BACKGROUND: Implant placement in maxillary molar sites with severe height deficiency often requires multiple surgeries, which was time-consuming, invasive, and subject to serious postoperative complications. PURPOSE: To introduce and assess a three-in-one technique (extraction, alveolar ridge preservation [ARP], and sinus elevation) for augmenting deficiency maxillary molar alveolar ridges. MATERIAL AND METHODS: Fourteen patients with severe posterior maxillary ridge height deficiency underwent extraction, sinus elevation via an intrasocket window and ARP using sticky bone and then covered with acellular dermal matrix (ADM). Primary closure was intentionally not obtained. Cone-beam computed tomography and periapical radiography were used to measure dimensional ridge changes over time. Bone biopsies were taken at implant placement 7-21 months after surgery, which proceeded without additional grafting. Peri-implant soft tissue was assessed after 8-12 months of functional loading. RESULTS: Maxillary molar sites (13 first molars, 1 second molar) with a mean sinus floor height of 1.73 ± 0.86 mm and mean buccal plate thickness of 1.62 ± 1.15 mm were elevated and grafted. Immediately after surgery, the mean sinus floor height was 14.03 ± 1.97 mm and the alveolar thickness at virtual implant platform level was 12.99 ± 1.88 mm. After 5-9 months healing, those measurements decreased by 2.45 ± 1.73 mm (p = 0.000) and 3.88 ± 3.95 mm (p = 0.006), respectively. Healed ridges were composed of 18.74% ± 4.34% mean vital bone and 19.08% ± 9.10% mean residual graft. After 8-12 months of functional loading, the peri-implant tissue appeared healthy, and there was a mean marginal bone loss of 0.12 ± 0.11 mm. CONCLUSIONS: For maxillary first molar sites with severe sinus floor height deficiency, this minimally invasive three-in-one treatment allows for uncomplicated implant placement and short-term functional stability.

Implications of Virtual CBCT-Based Immediate Implant Planning for Maxillary and Mandibular First Molars.

The purpose of his study was to investigate the projected ridge-implant dimensions derived from virtual superimposition of implants on intact first molars mimicking immediate implantation in the mandible (Md1) and maxilla (Mx1) using cone-beam computed tomography (CBCT). The CBCT records of 41 patients (19 males and 22 females) with Md1 or Mx1 were collected. Ten-millimeter-long cylindrical implants with different diameters were virtually positioned at prosthetically ideal angles into interradicular septum using CBCT software. Radiographic alveolar ridge height (ARH), alveolar ridge width (ARW), gap distance, and vertical distance from the implant platform to the alveolar crest were measured. Twenty Mx1s (48.8%) and 21 Md1s (51.2%) were included. The mean ARH values were 7.13 ± 4.32 and 15.64 ± 1.80 mm for Mx1 and Md1, respectively; 87.8% of mesiobuccal sites had gap distance of >2 mm when 6-mm-diameter implants were used. Increasing implant diameter from 6 to 9 mm decreased the percentage of sites with ARW > 2 mm from 80.5% to 41.5% buccally and from 86.4% to 26.8% lingually. The mean vertical distance from the implant platform to the alveolar crest was 1.41 ± 1.09 mm buccally and 1.11 ± 1.10 mm lingually. Immediate implant placement of first molars, especially in the maxilla, requires stringent presurgical evaluation. Implants no wider than 6 mm placed into the interradicular septum may meet acceptable running room and alveolar plate thickness criteria if the jumping distance is grafted. Further clinical trials are needed to confirm these findings in this virtual study.

Alveolar Ridge Preservation in Severely Damaged Molar Socket Using a Polylactic Acid Membrane Without Primary Wound Closure: A Case Series.

PURPOSE: Untreated severely damaged molar sockets often complicate implant placement. This study evaluated membrane degradation, soft tissue healing, and alveolar crest dimensional changes after alveolar ridge preservation (ARP) in severely damaged molar sockets using a polylactic acid membrane (PLA) and xenograft without primary wound closure. MATERIALS AND METHODS: A total of 14 damaged molar sockets in 12 patients were grafted with deproteinized bovine bone mineral, which was covered with a PLA membrane without primary wound closure. Wound healing was evaluated at set times. Three sets of CBCT data taken before surgery, at 1 to 2 weeks, and at 6 to 12 months after surgery were reconstructed and superimposed to analyze dimensional changes of the alveolar crest with volumetric imaging software. RESULTS: Two weeks after ARP, no degradation of PLA membrane was present, and the xenograft had either no exfoliation (7 sites, 50%) or mild exfoliation (6 sites, 42.9%). One to 2 months following ARP, the membrane was partially degraded in 6 sites (42.9%) and completely degraded in 8 sites (57.1%). Nine sites (64.3%) presented with mild graft particle exfoliation, and four sites (28.6%) had granulation tissue covering the bone graft. All sites were fully covered by keratinized mucosa by 6 to 12 months. Compared with baseline measurements, the vertical bone graft height decreased by 2.2 ± 2.2 mm, and central alveolar ridge thickness measured at the level of the virtual implant platform decreased by 5.0 ± 5.1 mm after 6 to 12 months. CONCLUSION: The exposed PLA membrane maintains some barrier function for at least 3 to 4 weeks after ARP in severely damaged molar extraction sites. This technique allowed for implant placements without additional grafting. Future studies should include histologic assessment of the augmented bone and nongrafted control sockets.

Reducing macrophage numbers alleviates temporomandibular joint ankylosis.

Temporomandibular joint (TMJ) ankylosis is a severe joint disease mainly caused by trauma that leads to a series of oral and maxillofacial function disorders and psychological problems. Our series of studies indicate that TMJ ankylosis development is similar to fracture healing and that severe trauma results in bony ankylosis instead of fibrous ankylosis. Macrophages are early infiltrating inflammatory cells in fracture and play a critical role in initiating fracture repair. We hypothesize that the large numbers of macrophages in the early phase of TMJ ankylosis trigger ankylosed bone mass formation and that the depletion of these macrophages in the early phase could inhibit the development of TMJ ankylosis. By analysing human TMJ ankylosis specimens, we found large numbers of infiltrated macrophages in the less-than-1-year ankylosis samples. A rabbit model of TMJ bony ankylosis was established and large numbers of infiltrated macrophages were found at 4 days post-operation. Local clodronate liposome (CLD-lip) injection, which depleted macrophages, alleviated the severity of ankylosis compared with local phosphate-buffered saline (PBS)-loaded liposome (PBS-lip) injection (macrophage number, PBS-lips vs. CLD-lips: 626.03 ± 164.53 vs. 341.4 ± 108.88 n/mm2; ankylosis calcification score, PBS-lips vs. CLD-lips: 2.11 ± 0.78 vs. 0.78 ± 0.66). Histological results showed that the cartilage area was reduced in the CLD-lip-treated side (PBS-lips vs. CLD-lips: 6.82 ± 4.42% vs. 2.71 ± 2.78%) and that the Wnt signalling regulating cartilage formation was disrupted (Wnt5a expression decreased 60% and Wnt4 expression decreased 73%). Thus, our study showed that large numbers of macrophages infiltrated during the early phase of ankylosis and that reducing macrophage numbers alleviated ankylosis development by reducing cartilage formation.

Correction to: Reducing macrophage numbers alleviates temporomandibular joint ankylosis.

The article "Reducing macrophage numbers alleviates temporomandibular joint ankylosis", written by Lu Zhao, E Xiao, Linhai He, Denghui Duan, Yang He, Shuo Chen, Yi Zhang and Yehua Gan, was originally published electronically on the publisher's internet portal.

Graft-Free Maxillary Sinus Floor Elevation: A Systematic Review and Meta-Analysis.

BACKGROUND: This systematic review and meta-analysis aims to investigate survival rates of dental implants placed simultaneously with graft-free maxillary sinus floor elevation (GFSFE). Factors influencing amount of vertical bone gain (VBG), protruded implant length (PIL) in sinus at follow-up (PILf), and peri-implant marginal bone loss (MBL) are also evaluated. METHODS: Electronic and manual searches for human clinical studies on simultaneous implant placement and GFSFE using the lateral window or transcrestal approach, published in the English language from January 1976 to March 2016, were conducted. The random-effects model and mixed-effect meta-regression were used to analyze weighted mean values of clinical parameters and evaluate factors that influenced amount of VBG. RESULTS: Of 740 studies, 22 clinical studies were included in this systematic review. A total of 864 implants were placed simultaneously with GFSFE at edentulous sites having mean residual bone height of 5.7 ± 1.7 mm. Mean implant survival rate (ISR) was 97.9% ± 0.02% (range: 93.5% to 100%). Weighted mean MBL was 0.91 ± 0.11 mm, and it was significantly associated with the postoperative follow-up period (r = 0.02; R2 = 43.75%). Weighted mean VBG was 3.8 ± 0.34 mm, and this parameter was affected significantly by surgical approach, implant length, and PIL immediately after surgery (PILi) (r = 2.82, 0.57, 0.80; R2 = 19.10%, 39.27%, 83.92%, respectively). Weighted mean PILf was 1.26 ± 0.33 mm (range: 0.3 to 2.1 mm). CONCLUSION: Within limitations of the present systematic review, GFSFE with simultaneous implant placement can achieve satisfactory mean ISR of 97.9% ± 0.02%.

Histopathological features of hypertrophic bone mass of temporomandibular joint ankylosis (TMJA): An explanation of pathogenesis of TMJA.

Temporomandibular joint ankylosis (TMJA) is a severe organic disease with progressive limitation of the mouth opening. Histopathologically, a residual joint space is reported to consist of fibrous tissue and/or cartilage, indicating two types of interface (osteo-fibrous and osteo-chondral) of residual joint space. It is well known that adverse mechanical stress results in pathological changes of osteoarthritis and enthesopathy in these interfaces. What would happen pathologically in these interfaces of TMJA under repeated mandible movement has not been elucidated. Fourteen tissue samples of residual joint space and temporal and condylar bone were stained with hematoxylin and eosin and evaluated by collagen I and II immunohistochemistry. A pathological study of 14 TMJA patients showed that the residual joint space presented a fibrocartilage entheses structure and an articular cartilage structure. Moreover, these two structures were associated with pathological alterations of both osteoarthritis and enthesopathy, including degenerated and necrotized tissue, chondrocyte cloning, crack and fissure, various bone scleroses, and inflammatory granulation tissue. It is suggested that the pathological alterations of both osteoarthritis and enthesopathy occurred in TMJA, which hints at mechanical stress on TMJA development.

Brief reports: TRPM7 Senses mechanical stimulation inducing osteogenesis in human bone marrow mesenchymal stem cells.

Mesenchymal stem cells (MSCs) are multipotential stem cells residing in the bone marrow. Several studies have shown that mechanical stimulation modulates MSC differentiation through mobilization of second messengers, but the mechanism of mechanotransduction remains poorly understood. In this study, using fluorescence and laser confocal microcopy as well as patch-clamp techniques, we identified the transient receptor potential melastatin type 7 (TRPM7) channel as the key channel involved in mechanotransduction in bone marrow MSCs. TRPM7 knockdown completely abolished the pressure-induced cytosolic Ca(2+) increase and pressure-induced osteogenesis. TRPM7 directly sensed membrane tension, independent of the cytoplasm and the integrity of cytoskeleton. Ca(2+) influx through TRPM7 further triggered Ca(2+) release from the inositol trisphosphate receptor type 2 on the endoplasmic reticulum and promoted NFATc1 nuclear localization and osteogenesis. These results identified a central role of TRPM7 in MSC mechanical stimulation-induced osteogenesis.

The development of traumatic temporomandibular joint bony ankylosis: a course similar to the hypertrophic nonunion?

The traumatic temporomandibular joint (TMJ) bony ankylosis has generated great interest in the cranio-maxillofacial surgeons yet remains an enigma, due to its unknown pathogenesis. Organization and ossification of hematoma is the classical hypothesis concerning the underlying pathophysiology, but it could not explain all the unique characters of TMJ bony ankylosis. The previous imaging descriptions about bony ankylosis tend to over-emphasize the obliteration of joint space and the overgrowth of new bone around the joint. Our recent study has found that the radiolucent zone in the bony fusion area indicating impaired bone healing is one of the most important imaging features of bony ankylosis, and this imaging feature is similar to that of hypertrophic nonunion of long bone. We also observe that there is close relationship between the mouth opening and the degree of calcification of radiolucent zone. Therefore, we hypothesize that the development of traumatic TMJ bony ankylosis may be the course of bone healing of two injured articular surfaces under the interference of opening movement, which is similar to the hypertrophic nonunion. Our hypothesis could help to explain some unintelligible characters of bony ankylosis, and deserves further studies.

[A comparative study of two imaging techniques for the diagnosis of sagittal fracture of mandible condyle].

OBJECTIVE: To investigate the relationship between fractured fragment and joint disc displacement after sagittal fracture of mandibular condyle (SFMC). METHODS: based on CT examination, SFMC were classified into fissue, displacement and dislocation type. Based on oblique sagittal MRI examination, the displacement of joint disc was grouped into type A and type B. Abnormal superiorposterior attachment was classified into elongation and avulsion type. RESULTS: CT exmination were taken in 26 patients with 41 SFMC. There were 5 SFMC (12%) with fissue type, 18 SFMC (44%) with displacement type and 18 SFMC (44%) with dislocation type. Both CT and MRI examination were taken in 19 patients with 32 SFMC. There were 27 (84%) SFMC with disc displacement. Five SFMC with type fissue showed no signs of disc displacement. Among 15 SFMC with type displacement, there were 3 cases with type A disc displacement and 12 cases with type B disc displacement. All the dislocated SFMC (12 cases) were type B disc displacement. In term of superiorposterior attachment figures, 4 cases (4/5) of type fissue SFMC showed normal. 14 cases (14/15) of the displacement SFMC showed elongated and all cases with dislocated SFMC showed sign of avulsion. There were 20 cases (63%) showing superior joint effusion. There were 13 cases (13/15) with displaced SFMC and 6 cases with dislocated SFMC showing joint effusion. One case with fissue SFMC showed no sign of joint effusion. CONCLUSIONS: Joint effusion, disc displacement and abnormal superiorposterior attachment were related to the displacement of condyle which was involved with SFMC.

[A meta-analysis of condylar fracture treatment].

OBJECTIVE: To systematically evaluate the surgical and non-surgical treatment of condylar fracture using Meta-analysis system. METHODS: The key words: mandible, condyle, fracture and treatment/therapy were adopted to search for the objective articles from following Data-base: Medline, Embase, CCTR and CNKI. The available data were statistically dealt with by software package (RevMan 4.1). RESULTS: In 172 associated articles, only 10 (5.8%) fulfilled the entrance criteria, involving 711 cases. A total of 307 patients underwent surgical treatment due to severely displacement or dislocation of fragment, 239 of the m (78.0%) being subcondylar fracture. A total of 404 patients received non-surgical management, 278 of them (68.7%) being lower level fracture without significant displacement. Surgical treatment outbalanced non-surgical approach in rehabilitation of occlusional relationship and an adverse outcome was noted in term of maximum mouth opening, but the re was no significant difference in postoperative joint pain. CONCLUSIONS: Severely displaced and dislocated condylar fracture is indicated for surgical treatment.

[A revised scheme for LeFort classification of upper jaw fractures].

OBJECTIVE: To put forward a revised scheme on LeFort classification for the upper jaw fractures. METHODS: 193 consecutive cases with the primary diagnoses of upper jaw fractures were involved in this study, for each one of which water's and CT scan were available to decide the fracture site and pattern. Data were filed in term of classification items as LeFort I, II and III fracture, as well as sagittal fracture and alveolar fracture. Statistical analysis was done to validate the meliorating thought on and revised scheme on LeFort classification. RESULTS: It was validated that of 185 cases with upper jaw fractures only 30.81% which presented single-line fracture and 34.06% which presented multiple-line fracture were covered with LeFort classification. Additional 13.51% with single-line fracture and 21.61% with multiple-line fracture could be included when LeFort classification was extended with increase of items of sagittal fracture and alveolar fracture. Further results revealed that among total 344 sites or fracture lines included in 193 cases, 81.10% could be diagnosed fracture pattern of LeFort classification. Of 65 fracture sites presenting LeFort III type, 92.31% were concomitant with LeFort II type or LeFort I and II type, very few being alone. CONCLUSIONS: A revised classification was proposeded that upper jaw fractures could be classified into four types as follows: (1) high horizontal fracture (corresponding to LeFort II and III type), (2) low horizontal fracture (corresponding to LeFort I type), (3) sagittal fracture (including midline and para-midline fracture) and (4) alveolar fracture.