Implant Placement using Mixed Reality-Based Dynamic Navigation: a Proof of Concept.

OBJECTIVES: To present the first clinical application of a novel mixed reality-based dynamic navigation (MR-DN) system in the rehabilitation of a single tooth gap. METHODS: The protocol consisted of the following: (1) three-dimensional patient data acquisition using intraoral scanning (IOS) and cone-beam computed tomography (CBCT), (2) implant planning using guided surgery software, (3) holography-guided implant placement using the novel MR-DN system (ANNA®, MARS Dental, Haifa, Israel) and (4) placement accuracy verification. RESULTS: The novel MR-DN system was safe and time-efficient, as the surgery took 30 minutes from anaesthesia to suturing. The accuracy of implant placement was high with minimal deviations recorded in the three planes of space compared to the presurgical planning: the error at the entry point planar distance (XY) was 0.381 mm, and the entry point planar distance (Z) was 0.173 mm, for a 3D entry point distance (En) of 0.417 mm. A 3D apex deviation (An) of 0.193 mm was registered, with an angle difference of 1.852°. CONCLUSIONS: This proof-of-concept study demonstrated the clinical feasibility of MR-DN for guided implant placement in single tooth gaps. Further clinical studies on a large sample of patients are needed to confirm these positive preliminary results. Statement of clinical relevance: The use of MR-DN can change the perspectives of guided dental implant surgery as a possible alternative to the classic static and dynamic guided surgical techniques for the rehabilitation of single tooth gaps.

Accuracy of implant placement using a mixed reality-based dynamic navigation system versus static computer-assisted and freehand surgery: An in Vitro study.

PURPOSE: This in vitro study aimed to compare the accuracy of dental implant placement in partially edentulous maxillary models using a mixed reality-based dynamic navigation (MR-DN) system to conventional static computer-assisted implant surgery (s-CAIS) and a freehand (FH) method. METHODS: Forty-five partially edentulous models (with teeth missing in positions #15, #16 and #25) were assigned to three groups (15 per group). The same experienced operator performed the model surgeries using an MR-DN system (group 1), s-CAIS (group 2) and FH (group 3). In total, 135 dental implants were placed (45 per group). The primary outcomes were the linear coronal deviation (entry error; En), apical deviation (apex error; Ap), XY and Z deviations, and angular deviation (An) between the planned and actual (post-surgery) position of the implants in the models. These deviations were computed as the distances between the stereolithographic (STL) files for the planned implants and placed implants captured with an intraoral scanner. RESULTS: Across the three implant sites, the MR-DN system was significantly more accurate than the FH method (in XY, Z, En, Ap and An) and s-CAIS (in Z, Ap and An), respectively. However, S-CAIS was more accurate than MR-DN in XY, and no difference was found between MR-DN and s-CAIS in En. CONCLUSIONS: Within the limits of this study (in vitro design, only partially edentulous models), implant placement accuracy with MR-DN was superior to that of FH and similar to that of s-CAIS. STATEMENT OF CLINICAL RELEVANCE: In vitro, MR-DN showed greater accuracy in implant positioning than FH, and similar accuracy to s-CAIS: it could, therefore, represent a new option for the surgeon. However, clinical studies are needed to determine the feasibility of MR-DN.

Radiographic findings of space-occupying lesions in sialo-CBCT of the major salivary glands.

OBJECTIVES: When performing CBCT sialography (sialo-CBCT), space-occupying lesions may be identified incidentally. The objective was to describe their radiologic-clinical-histopathologic correlations. METHOD AND MATERIALS: The archive of sialo-CBCT scans was retrospectively searched for suspected space-occupying lesions. Based on the scan and clinical-histopathologic data, the cases were divided into "pathologic" vs "normal," "intra-parenchymal" vs "extra-parenchymal," and "benign" vs "malignant." Two precalibrated, blinded radiologists performed a survey of the radiographic features of each scan. Cohen kappa, chi-square, Kruskal-Wallis, and Mann-Whitney tests assessed inter-observer agreement and radiologic-clinical-histopathologic correlations. RESULTS: In total, 27 (1.5%) suspected space-occupying lesions were found in 1,758 reports. Full follow-up data were available for 15 cases: four were "malignant," six were "benign," and the remaining five were "normal." Kappa showed substantial inter-observer agreement (0.8 to 1.0). Constant swelling correlated with "pathologic" cases (P = .003). Lesion diameter was greater in "pathologic" than "normal" (P < .001) cases, with a cut-off of 12.6 mm. Clinical and radiographic features were similar in "benign" and "malignant" lesions. "Intra-parenchymal" and "extra-parenchymal" space-occupying lesions correlated with "no-fill-region" (P = .01) and "main-duct-displacement" (P = .002), respectively. CONCLUSIONS: Suspected space-occupying lesions in sialo-CBCT with a diameter greater than 12.6 mm are likely to be "pathologic." No radiographic features were able to differentiate between "malignant" and "benign" space-occupying lesions.

Anosmia and dysgeusia amongst COVID-19 patients are associated with low levels of serum glucagon-like peptide 1.

PURPOSE: Anosmia and dysgeusia (AD) are common amongst COVID-19 patients. These symptoms are not frequently associated with rhinorrhea or nasal congestion and the underlying mechanism is unclear. Previous reports suggested that glucagon-like peptide-1 (GLP-1) signalling plays a role in the modulation of olfaction and ageusia. We aimed to assess the correlation between GLP-1 and COVID-19-associated AD. METHODS: Blood samples obtained from COVID-19 patients with and without AD were tested for serum GLP-1 levels using enzyme-linked immunosorbent assay (ELISA). A second control group comprised of COVID-19-negative volunteers. RESULTS: Forty-nine subjects were included in the study. Nineteen were positive for COVID-19. Of the 19 patients, 10 had AD and 9 declined such complaints. Age and basic metabolic rate were similar amongst all study groups. Serum GLP-1 levels were significantly lower amongst patients with AD compared with patients without AD and COVID-19-negative individuals (1820 pg/mL vs 3536 pg/mL vs 3014 pg/mL, respectively, P < .02). CONCLUSION: COVID-19 patients who reported AD had lower serum levels of GLP-1 compared with those lacking AD symptoms and COVID-19-negative individuals. These results suggest that GLP-1 may be involved in the pathogenesis of AD. However, further larger scale studies should corroborate our findings.

Oral fibroblasts modulate the macrophage response to bacterial challenge.

Tissue damage in chronic periodontal disease is driven by the host response to a dysbiotic microbiota, and not by bacteria directly. Among chronic inflammatory diseases of the oral cavity, inflammation and tissue damage around dental implants (peri-implantitis) is emerging as a major clinical challenge, since it is more severe and less responsive to treatment compared to inflammation around natural teeth. We tested whether oral fibroblasts from the periodontal ligament (PDLF), which are present around natural teeth but not around dental implants, actively regulate inflammatory responses to bacterial stimulation. We show that human PDLF down-regulate TNF-α post-transcriptionally in macrophages stimulated with the oral pathogen Porphyromonas gingivalis. Cell contact and secretion of IL-6 and IL-10 contribute to the modulation of inflammatory cytokine production. Although fibroblasts decreased TNF-α secretion, they enhanced the ability of macrophages to phagocytose bacteria. Surprisingly, donor matched oral fibroblasts from gingival tissues, or fibroblasts from peri-implant inflamed tissues were at least as active as PDLF in regulating macrophage responses to bacteria. In addition, priming fibroblasts with inflammatory mediators enhanced PDLF regulatory activity. A further understanding of the spectrum of fibroblast activities in inflammatory lesions is important in order to design ways to control inflammatory tissue damage.

Nonsurgical treatment of recurrent gingival pyogenic granuloma: A case report.

Gingival pyogenic granuloma is a relatively common benign form of mucocutaneous lesion. Although surgical excision is considered to be the standard care, several reports have demonstrated a high recurrence rate of the lesion. In this case report a nonsurgical protocol to treat recurring gingival pyogenic granuloma and prevent further recurrence is suggested. The protocol includes strict oral hygiene instructions, scaling, root planing, and maintenance treatment. To the best of our knowledge, this is the first report of conservative nonsurgical management of recurrent gingival pyogenic granuloma lesions.

Actin enables the antimicrobial action of LL-37 peptide in the presence of microbial proteases.

Host defense peptides play an important host-protective role by their microcidal action, immunomodulatory functions, and tissue repair activities. Proteolysis is a common strategy of pathogens used to neutralize host defense peptides. Here, we show that actin, the most abundant structural protein in eukaryotes, binds the LL-37 host defense peptide, protects it from degradation by the proteases of Pseudomonas aeruginosa and Porphyromonas gingivalis, and enables its antimicrobial activity despite the presence of the proteases. Co-localization of LL-37 with extracellular actin was observed in necrotized regions of samples from oral lesions. Competition assays, cross-linking experiments, limited proteolysis, and mass spectrometry revealed that LL-37 binds by specific hydrophobic interactions to the His-40-Lys-50 segment of actin, located in the DNase I binding loop. The integrity of the binding site of both LL-37 and actin is a prerequisite to the binding. Our results demonstrate that actin, presumably released by dead cells and abundant in infected sites, might be utilized by the immune system to enhance spatio-temporal immunity in an attempt to arrest infection and control inflammation.

Mandibular reconstruction using stereolithographic 3-dimensional printing modeling technology.

Mandibular reconstruction can be challenging for the surgeon wishing to restore its unique geometry. Reconstruction can be achieved with titanium bone plates followed by autogenous bone grafting. Incorporation of the bone graft into the mandible provides continuity and strength required for proper esthetics and function and permitting dental implant rehabilitation at a later stage. Precious time in the operating room is invested in plate contouring to reconstruct the mandible. Rapid prototyping technologies can construct physical models from computer-aided design via 3-dimensional (3D) printers. A prefabricated 3D model is achieved, which assists in accurate contouring of plates and/or planning of bone graft harvest geometry before surgery. The 2 most commonly used rapid prototyping technologies are stereolithography and 3D printing (3DP). Three-dimensional printing is advantageous to stereolithography for better accuracy, quicker printing time, and lower cost. We present 3 clinical cases based on 3DP modeling technology. Models were fabricated before the resection of mandibular ameloblastoma and were used to prepare bridging plates before the first stage of reconstruction. In 1 case, another model was fabricated and used as a template for iliac crest bone graft in the second stage of reconstruction. The 3DP technology provided a precise, fast, and cheap mandibular reconstruction, which aids in shortened operation time (and therefore decreased exposure time to general anesthesia, decreased blood loss, and shorter wound exposure time) and easier surgical procedure.

Atraumatic teeth extraction in bisphosphonate-treated patients.

PURPOSE: The purpose of this study was to suggest an alternative technique for atraumatic teeth extraction that would prevent bone exposure and the associated complication of osteonecrosis of the jaws in bisphosphonate (BP)-treated patients, without terminating the treatment. PATIENTS AND METHODS: A total of 10 patients treated with BPs for multiple myeloma, metastatic breast cancer, and osteoporosis, requiring dental extractions of nontreatable teeth, were included in this study. The extractions were performed by means of orthodontic elastics placed around the roots, causing slow and gradual exfoliation of the teeth. RESULTS: The technique was applied to 21 roots of 15 teeth. A total of 19 roots exfoliated spontaneously. Two roots had to be removed with minimal manipulation by forceps. The mean time required for exfoliation was 5.8 weeks. All sockets showed soft tissue secondary healing and there were no signs of inflammation or exposed bone during the 9-month follow-up. CONCLUSIONS: Atraumatic extraction by use of elastics is a safe technique that may be used in BP-treated patients to prevent osteonecrosis of the jaws.