Cavity Margins Research Articles

Endocrown : from preparation to bonding : Case report /// L'endocouronne : de la préparation au collage : à propos d'un cas clinique

The restoration of endodontically treated teeth is a real challenge, particularly teeth with extensively damaged coronal tissues. The use of post-retained restorations has been discussed because of the potential tooth weakening due to the additional removal of sound dental structures. In fact, long-term prognosis of a devitalized tooth is closely related to the coronal restoration’s quality and the remaining dental structure.With the development of adhesive dentistry and minimally invasive preparation, new approaches have emerged. Among them, the endocrown which is monolithic ceramic bonded restoration, anchored to the internal portion of pulp chamber and cavity margins that have been used as an alternative to conventional post and core.

HGG-49. INTERNEURONS THAT BITE: A CELLULAR DELIVERY SYSTEM FOR PEDIATRIC HIGH-GRADE GLIOMA

Abstract BACKGROUND High-grade gliomas (HGG) represent the leading cause of cancer-related mortality in children due to a lack of curative therapies. Challenges of cellular therapies in brain tumors include the lack of unique tumor antigens, downregulation of targeted antigens, and immune suppressive tumor microenvironment. To circumvent these obstacles, we devised a cellular delivery system using post-mitotic migratory cortical inhibitory interneuron precursors (MCIPs) to deliver therapeutic payloads in an antigen-independent manner. Notably, HGGs secrete the same chemoattractants stimulating long-distance MCIP migration as during normal fetal development, leading to the hypothesis that MCIPs would preferentially migrate to HGG cells. METHODS MCIP to HGG cell migration was assessed in vitro using transwell migration assays, and in vivo via stereotactic injection of MCIP and glioma xenografts in nude mice. As proof of principle, MCIPs were equipped with an EGFR or CD19 control bispecific T-cell engager (BiTE) which activates T-cells upon their linkage to the tumor cells resulting in glioma elimination. Equipped MCIPs were co-cultured with HGG cells and CD8 T-cells at an effector to target ratio of 4:1. Results were validated in vivo via xenografts of HGG, MCIPs, and either a single dose of CD8 T-cells or repeated T-cell dosing via intraventricular cannula. Survival was evaluated via Kaplan-Meier curves. RESULTS MCIPs migrated preferentially to the majority of HGG cell lines in vitro and in vivo. This migration was mediated, at least in part, via CXCR4 ligands. MCIPs secreting an EGFR-BiTE potently killed HGG cells in vitro versus CD19-BiTE controls. Furthermore, nude mice xenografted with HGG and EGFR-expressing MCIPs experienced prolonged survival versus controls. CONCLUSION These data suggest that MCIPs form a viable cellular delivery system and can be equipped with various agents targeting HGG. Modified MCIPs could be differentiated from induced pluripotent stem cells and injected into the resection cavity margins to eliminate residual cells.

Abstract PO5-22-09: Positive pegulicianine fluorescence rate in the lumpectomy cavity correlates with tumor distance to margins in excised tissue

Abstract Title: Positive pegulicianine fluorescence rate in the lumpectomy cavity correlates with tumor distance to margins in excised tissue Background: A randomized, two-arm pivotal study of pegulicianine fluorescence guided surgery (pFGS) at 14 US sites was conducted using the Lumicell Direct Visualization System (DVS) to identify residual cancer in the lumpectomy cavity after the standard of care (SoC) tumor excision. We reported that the Lumicell DVS detects residual cancer in the lumpectomy cavity, including in orientations pathologically negative on the SoC specimen. In addition, 15% (9 of 62) of patients with positive SoC margins were converted to final negative margins by taking Lumicell DVS directed cavity margins, avoiding a second unnecessary surgery. Interestingly, 8 of these 9 patients had no tumor found in the Lumicell DVS guided specimens. We hypothesize that fluorescence decreases as the distance from the tumor boundary increases. We analyzed data from the pivotal study (NCT03686215) to assess correlation of pegulicianine signal with tumor-to-margin distance, and its potential clinical value. Methods: The pivotal study enrolled 406 patients undergoing breast conserving surgery (BCS) for stage 0-III breast cancers. Patients received an IV injection of pegulicianine 2-6 hours prior to surgery. After the standard of care lumpectomy was completed, additional Lumicell DVS-guided cavity margins were excised at sites of positive pegulicianine fluorescence signal in the lumpectomy cavity walls using a hand-held imaging device and patient-calibrated cancer detection software. The positive fluorescence rate, that is, the rate at which the Lumicell DVS indicates areas suspected to contain cancer, was calculated as the ratio of orientations with positive pegulicianine signal to the total number of orientations with (1) negative margins, (2) positive margins and (3) positive margins with ink on tumor, on the initial SoC lumpectomy specimen. Calculations were made on a per-margin basis. Positive margins were defined as ink on tumor for invasive cancer and tumor less than 2 mm from the margin for ductal carcinoma in situ (DCIS) alone. Results: Results are presented in Table 1. We found a statistically significant higher positive fluorescence rate in orientations with positive margins (p=0.044). The positive fluorescence rate was even higher (21.1%) when only considering cases with ink on tumor (a subset of the positive margin group). Discussion: By design, pegulicianine is activated by enzymes within the tumor and in stromal cells at the invasive front surrounding the tumor. Thus, when tumor is closer to the edge of the lumpectomy specimen, the rate of positive pegulicianine fluorescence in the cavity increases, being highest when there is tumor present at the inked margin. This feature of pegulicianine fluorescence guides the surgeon to resect more tissue in these areas in order to achieve a negative margin of the required width. The conversion of positive margins after the SoC lumpectomy to appropriately wide final negative margins prevents a second surgery, even when there is no tumor in the DVS guided margins. These findings have strengthened our understanding of the utility of this technology. Table 1 Positive cavity wall fluorescence rate for SoC lumpectomy positive margins, SoC lumpectomy negative margins and SoC lumpectomy ink on tumor margins Citation Format: Irene Wapnir, E Shelley Hwang, Kelly Hunt, David Carr, Peter Blumencranz, Manna Chang, Kate Smith, Jorge Ferrer, Barbara Smith. Positive pegulicianine fluorescence rate in the lumpectomy cavity correlates with tumor distance to margins in excised tissue [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-22-09.

Abstract PO2-23-01: Selective cavity margin shaving: effective method to maintain balance between cosmesis and negative margin in breast conserving surgery

Abstract Background: Breast conserving surgery (BCS), which became the mainstay of breast cancer surgery, both cosmesis and margin negativity are significant issues. Firstly, it is well known that negative resection margin is crucial for reducing local recurrence after BCS. Therefore, there has been numerous attempts to secure negative margin, such as specimen mammography, frozen section margin analysis, and cavity margin shaving. Regarding cosmesis, wider excision to secure negative margin could disrupt cosmesis especially in Asian patients with relatively smaller breast, and minimizing excision volume is necessary for optimal cosmetic outcome. Our center adopted the concept of selective cavity margin shaving (SCMS) to achieve negative margin while optimizing cosmetic result. Method: 606 female patients with non-metastatic, unilateral breast cancer were prospectively collected and underwent BCS with SCMS from October, 2012 to December, 2020. The medical record was retrospectively reviewed, and we assessed positive margin rate and local recurrence. During BCS, the surgeon excised gross margin of 1~2cm around the cancer, and assessed the proximity of the margin through gross examination. If sufficient margin was not obtained, cavity shaving was performed in the close margin, while shaving from retrieved specimen was conducted on the sufficient margin side. Additionally, circumferential margin frozen analysis was carried out, and further excision was performed until a negative margin was achieved or when only focal DCIS involvement remained. Result: The mean ± SD age of the patients was 52.47 ± 9.92 years and mean follow-up period was 59.98 ± 26.59 months. 56 patients (9.24%) received neoadjuvant chemotherapy. 123 patients (20.29%) got positive margin for invasive cancer or DCIS in frozen section margin analysis and 97 patients (16.01%) underwent intraoperative re-excision. There was discordance between frozen and permanent section margin analysis in 48 patients (7.92%), and 7 patients (1.16%) underwent post-operative re-excision operation. Local recurrence occurred in 11 patients (1.82%), which is significantly lower compared to previously reported outcomes after BCS. Presence of lympho-vascular invasion, neoadjuvant chemotherapy, and margin involvement of invasive cancer in permanent section analysis were strongly related with local recurrence. Conclusion: In conclusion, SCMS and frozen section margin analysis demonstrated low positive margin rate and reduced re-excision rate. The local recurrence was also lower compared to conventionally reported rate after BCS. Selective cavity margin shaving is an oncologically safer and effective surgical method with minimized cosmetic deformity. Table 1. Baseline patient characteristics Table2. Univariate and multivariate analysis of factors associated with local recurrence Table2. Univariate and multivariate analysis of factors associated with local recurrence by Cox proportional hazard model. Citation Format: Dabin Kim, Zisun Kim, Sung Mo Hur, Cheol wan Lim. Selective cavity margin shaving: effective method to maintain balance between cosmesis and negative margin in breast conserving surgery [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-23-01.

Evaluation of intra-operative cavity shave and margin re-excision in SAVI SCOUT versus wire-guided localization in non-palpable breast lesions

Evaluation of intra-operative cavity shave and margin re-excision in SAVI SCOUT versus wire-guided localization in non-palpable breast lesions

Comparative study of the adaptation of alkasite versus self-adhesive flowable restorations

Aim To compare the adaptation of self-adhesive flowable composite versus alkasite restorations with or without the use of an adhesive system. Materials and Methods A total of 30 noncarious maxillary premolars were selected and mounted 2 mm below the cemento–enamel junction in acrylic blocks. Trapezoidal class V cavities were prepared on the buccal surface of each tooth. The gingival margins of the prepared cavities were located 1 mm above cemento–enamel junction. All cavity margins were not bevelled. During the experiment time, all samples were kept in artificial saliva renewed daily at 37°C in an incubator to prevent dehydration. These were randomly divided into three groups (n = 10). Alkasite restorative material was applied in a bulk fill technique using a universal adhesive in samples of group I, while those of group II did not have any adhesive using the same restorative material and those of group III were restored using self-adhesive flowable composite (vertise flow). Specimens of the three tested groups were subjected to 500 thermal cycles from 5 to 55°C with 30 s. Dwell time and 15 s transfer time. They were all immersed in methylene blue dye 2% for 24 h in an incubator. Then all samples were examined under stereomicroscopy at ×40 to determine the percentage of gap free length along the entire margins. All specimens were then sectioned buccolingually to detect the percentage of internal gap length along the restoration/tooth interface. Results Regarding the marginal adaptation, the highest % of marginal free gap was recorded for group I, while the lowest was recorded for group II. Concerning the internal adaptation, it was found that the highest % of free gap was related to group I and III while the lowest was related to group II. Comparing the marginal versus internal % of gap free margins it was found that group I versus II showed a statistically significant difference. Also, group III versus II showed a significant difference. While group I versus III recorded no statistically significant difference. This was true at both marginal and internal % of free gaps. These findings indicated the responsibility of group II for the recorded differences since group II showed the least % of free gap margins and the highest percentage of total dye penetration values. Conclusions Within the limitations of this in vitro study, the adhesive system was effective in increasing the percentage of free gaps of tested groups whether marginal or internal. Recommendations The use of any composite material is not recommended without an adhesive system. Further in vitro studies providing more precise gap measurement are required.

Effect of artificial aging on the stability of color match of Omnichroma composite resin

Purpose To evaluate the effect of artificial aging on the stability of color match between the teeth and Omnichroma composite resin compared to that in the teeth restored with Tetric EvoCeram nanohybrid composite resin. Materials and methods Twenty sound, freshly extracted human maxillary premolars were mounted in acrylic blocks. The baseline shade of the selected teeth was A2 as measured from the middle third of the buccal surface by spectrophotometer (Vita Easyshade Advance). Trapezoidal Class V cavity was prepared on the buccal surface of each tooth 0.5 mm coronal to CEJ. Cavity dimensions were width of 4 mm occlusally and 3 mm gingivally, 2 mm occluso-gingival length and 1.5 mm depth. A 45-degree bevel was placed on the occlusal cavity margin. Results Specimens were randomly divided into two equal groups (n = 10) representing the materials used to restore the cavities. Group I: Tetric EvoCeram while Group II: Omnichroma. Specimens were artificially aged by storage for 6 months in artificial neutral saliva in an incubator at 37 ± 5°C during which the saliva was replaced daily. Color measurements and ΔE values were recorded before cavity preparation representing the baseline tooth color to be used for detection of the initial color match between the tooth and restoration where their color was measured after storage in saline for 24 h. Conclusion At the end of the storage period, the color of both the teeth and the restorations was remeasured to detect the stability of color match between the restoration and the tooth due to storage.

Composite Restoration Design Effect During Curing and Chewing.

The purpose of this work is to observe the effect of the cavity design of the direct composite restoration on a real case of the patient's tooth structures after applying his mandibular kinematics with finite element analysis. Four complex maxillomandibular models of teeth 17 and 47 were constructed from the patient's cone-beam acquisition and the patient's kinematic data recorded with Modjaw® were added. Different shapes and sizes of mesio-occluso-distal (M.O.D.) composite restorations were simulated, including the polymerization shrinkage of this material. Finite element analyses were used to observe the Von Mises stresses occurring during polymerization and mastication. The stresses were observed at the cavity margin and the amplitude of the stresses was higher when the enamel volume was lower. The reduction in occlusal enamel volume with the open-angle vestibular and palatal walls resulted in a greater increase in stresses observed on the structures. The occlusal enamel is the area that bears the maximum masticatory stress, the loss of this enamel volume generates a much greater concentration of stress on the underlying structures. It is important to preserve as much enamel tissue as possible when designing a cavity for a direct composite restoration.

Evaluation of surface microhardness and gingival marginal adaptation of three different bulk-fill flowable resin composites: A comparative study.

To evaluate surface microhardness and gingival marginal adaptation of three different bulk-fill flowable resin composites (FB-RBCs) in Class V cavities with enamel or dentin margins before and after thermocycling (TMC). Three available FB-RBCs were used; Palfique Bulk Flow (PaBF) (Tokuyama Dental), SDR Flow+ Bulk Fill Flowable (Dentsply Sirona), and I-Flow Bulk Fill (I-Dental). Thirty discs were prepared from each type of FB-RBCs. The discs were subjected to Vickers microhardness tester machine. Class V cavities were prepared on 180 molars. Gingival margins of half the specimens were prepared above CEJ and the other half below CEJ. Cavities were restored with FB-RBCs for gingival marginal adaptation test. Two-way ANOVA was used in microhardness, while three-way ANOVA was used for marginal adaptation. The used materials showed statistically significant differences in microhardness and marginal adaptation. Regarding microhardness, PaBF showed the highest value before TMC and SDR was the highest after TMC. Regarding marginal adaptation, SDR revealed the best marginal adaptation than PaBF and I-flow, either subjected to TMC or not. The longevity of cervical restorations depend on both the location of the cavity margin and the material used. The microfractures in resin composite surface due to low surface microhardness as well as marginal gaps seen in laboratory studies could be considered as an indicative parameter for clinical problem associated with marginal differences.

Retrospective Study on 57 Direct Interproximal Restorations with Supracrestal Tissue Attachment Violation: Follow-ups Between 10 and 23 Years.

A total of 57 interproximal restorations invading the supracrestal tissue attachment were evaluated in terms of crestal bone loss over a mean period of 15 years (10 to 23 years). The distance from the cavity margin to the bone was measured at T0 (after the restoration; baseline) and controlled using radiographs and a measurable landmark. The mean vertical bone loss was 0.46 mm, with a 96.49% survival rate. Smoking habits (P = .02) and tooth type (P = .03) significantly affected bone loss. The proposed technique could help the clinician in adopting a minimally invasive approach in the treatment of heavily compromised teeth. Future research with rigorous study designs would be interesting to guide the clinical decision-making.

Effect of different storage media on elemental analysis and microhardness of cervical cavity margins restored with a bioactive material.

This study aimed to investigate the elemental analysis and microhardness of a bioactive material (Activa) and marginal tooth structure after storage in different media. Fifteen teeth received cervical restorations with occlusal enamel and gingival dentin margins using the tested material bonded with a universal adhesive, 5 of them on the 4 axial surfaces and the other 10 on only the 2 proximal surfaces. The first 5 teeth were sectioned into 4 restorations each, then stored in 4 different media; deionized water, Dulbecco's phosphate buffered saline (DPBS), Tris buffer, and saliva. The storage period for deionized water was 24 hours while it was 3 months for the other media. Each part was analyzed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis for different substrates/distances and the wt% of calcium, phosphorus, silica, and fluoride were calculated. The other 10 teeth were sectioned across the restoration, stored in either Tris buffer or saliva for 24 hours or 3 months, and were evaluated for microhardness of different substrates/areas. Data were analyzed using analysis of variance and Tukey's post hoc test. Enamel and dentin interfaces in the DPBS group exhibited a significant increase in calcium and phosphorus wt%. Both silica and fluoride significantly increased in tooth structure up to a distance of 75 μm in the 3-month-media groups than the immediate group. Storage media did not affect the microhardness values. SEM-EDS analysis suggests an ion movement between Activa and tooth structure through a universal adhesive while stored in DPBS.

Fracture Toughness of Monolithic Zirconia and Lithium Disilicate CAD/CAM Endocrown


 Introduction: Endocrown is an indirect restoration following the endodontic treatment made of ceramic material as a substitute for post core crown. The endocrown is cemented to the inner wall of the pulp chamber and to the cavity margins to increase the macromechanical retention. Material commonly used are monolithic zirconia and lithium disilicate; both can be obtained using the CAD/CAM technique. Good endocrown restoration must be able to handle the chewing workload especially on the posterior tooth. Objective: To determine the difference in fracture toughness of monolithic zirconia and lithium disilicate CAD/CAM endocrown. Methods: This study used 6 endocrown CAD/CAM samples, attached to typodont prototype in 3D resin printing model produced by the printing machine. Samples were divided into 2 groups. Group A were monolithic zirconia endocrowns and group B were lithium disilicate endocrowns. The fracture toughness was calculated using the Universal Testing Machine (UTM). Results: Fracture toughness of the monolithic zirconia endocrown were 2.747 N and lithium disilicate were 769 N. The unpaired t test showed that there was significant difference in fracture toughness between groups (p < 0,05). Conclusion: Monolithic zirconia endocrown has a higher fracture toughness compared to the lithium disilicate endocrown, but lithium disilicate is more recommended as an endocrown restoration material because its fracture toughness is closer to masticatory load of posterior teeth.

Outcome of Placenta Percreta Management by Planned Peripartum Hysterectomy in a Tertiary Level Hospital

The incidence of placenta accreta spectrum is gradually increasing due to increased rate of caesarean sections (CS). Due to torrential haemorrhage, placenta percreta is one of the main reasons for emergency peripartum hysterectomies and mostly results in subsequent maternal mortalities and morbidities. In such cases, caesarean hysterectomy leaving the placenta in situ without any separation of placenta is preferred. We observed the outcome of such patients managed with planned caesarean hysterectomy. This cross-sectional observational study was conducted at the Department of Obstetrics, Faridpur Medical College Hospital, Bangladesh. A total of 14 patients who underwent planned caesarean hysterectomy due to placenta percreta were studied. We performed delivery of the baby through upper segment transverse incision without placental separation. The umbilical cord was ligated leaving the placenta in the uterine cavity and cut margins of the uterus was closed with few interrupted sutures and then hysterectomy was performed. Among 14 cases, the mean age was 30 years, mean gestational age at the time of delivery was 36 weeks, and all had a history of one or more CS. Before operation, mean Hb% was 8.9 g/dl. A mean of 1.5 units pre-operative and 1.2 units post-operative blood transfusions was needed. Post-operative mean Hb% was 10.5 gm/dl. Half of the women were discharged on their 3rd post-operative day. None of them had serious pre- and post-operative complications. In light of our findings, we recommend managing placenta percreta by planned caesarean hysterectomy with the placenta left in situ to minimise blood loss and subsequent maternal mortality and morbidity.
 Bangabandhu Sheikh Mujib Med. Coll. J. 2022;1(2):80-84

Risk Factors for Positive Margins in Breast-Conserving Surgery.

Introduction Breast-conserving surgery (BCS) followed by adjuvant radiotherapy has similar overall survival compared to mastectomybut is associated with higher rates of local recurrence. Positive surgical margins in BCS are the most important predictor of local recurrence. The aim of our study was to assess the risk factors associated with positive margins in women undergoing BCS for breast cancerin order to inform our clinical practice and minimize re-operation rates. Methods Patients with a diagnosis ofbreast cancer who underwent BCS from January 2013 to January 2021 were identified from our pathology database and included in the study. All patients underwent a lumpectomy with the removal of additional shaved cavity margins. Statistical analysis was used toassess the effect of patient clinical and pathological risk factors on the rate of positive margins. Results One hundred and twenty patients underwent BCS for breast cancer. Twenty-four percent of patients had positive margins. Of the 29 patients that underwent subsequent re-excisions, only 13 (45%) hadresidual disease in the re-excision specimen. In younger patients, tumors localized in lower quadrants and the presence of extensive intraductal component within invasive breast cancer increased the risk of positive margins. In addition, positive margins were encountered more significantly in patients with ductal carcinoma in situ (DCIS) compared to invasive tumors. Multivariate analysis showed that DCIS and young age were the only factors independently associated with positive margins. Conclusion DCIS and younger patients have a higher rate of positive margins during BCS than invasive breast cancer. For such patients at higher risk of positive margins, excision of cavity shave margins and intraoperative inking may be done to lower positive margin rates.Preoperative review of breast imaging, core biopsies, and counseling of patients about the likelihood of positive margins is important.

Intraoperative Fluorescence Guidance for Breast Cancer Lumpectomy Surgery

BackgroundAlthough lumpectomy and mastectomy provide equivalent survival for patients with breast cancer, local recurrence after lumpectomy increases breast cancer mortality. Positive lumpectomy margins, which imply incomplete tumor removal, are the strongest predictor of local recurrence and are identified days after surgery, necessitating a second surgery.MethodsIn this prospective trial, we assessed margin status with or without pegulicianine fluorescence-guided surgery (pFGS) for stages 0 to 3 breast cancers. To prevent surgeons from performing smaller than standard lumpectomies in anticipation of pFGS assistance, patients were randomly assigned 10:1 to pFGS or control groups, thus randomization was not designed to provide a control group for evaluating device performance. In patients undergoing pFGS, additional pFGS-guided cavity margins were excised at sites of pegulicianine signal. We evaluated three coprimary end points: the percentage of patients for whom pFGS-guided margins contained cancer, sensitivity, and specificity.ResultsOverall, 406 patients received 1.0 mg/kg intravenous pegulicianine followed by lumpectomy. Among 392 patients randomly assigned, 316 had invasive cancers, and 76 had in situ cancers. In 27 of 357 patients undergoing pFGS, pFGS-guided margins removed tumor left behind after standard lumpectomy, 22 from cavity orientations deemed negative on standard margin evaluation. Second surgeries were avoided by pFGS in 9 of 62 patients with positive margins. On per-margin analysis, pFGS specificity was 85.2%, and sensitivity was 49.3%. Pegulicianine administration was stopped for adverse events in six patients. Two patients had grade 3 serious adverse events related to pegulicianine.ConclusionsThe use of pFGS in breast cancer surgery met prespecified thresholds for removal of residual tumor and specificity but did not meet the prespecified threshold for sensitivity. (Funded by Lumicell, Inc. and the National Institutes of Health; Clinicaltrials.gov number, NCT03686215.)

Abstract P2-14-01: MOLECULAR FLUORESCENCE-GUIDED SURGERY USING BEVA800 FOR THE ASSESSMENT OF TUMOR MARGINS DURING BREAST CONSERVING SURGERY OF PATIENTS WITH PRIMARY BREAST CANCER (MARGIN-II)

Abstract Introduction: The goal of breast conserving surgery (BCS) for early breast cancer (EBC) is to remove the tumor in toto and preserving as much of the normal breast tissue as possible. In 20-50% of cases a re-excision is necessary because of involved margins. Repeat surgeries are not only a burden to patients physically but also psychologically and can delay recommended adjuvant therapies. Accurate determination of tumor margins during surgery is therefore a critical need. Breast cancer tissue produces significantly higher amounts of VEGF-A than healthy tissue. VEGF-A stimulates tumor angiogenesis and is therefore a target for molecular imaging techniques. The fluorescence imaging agent bevacizumab-IRDye800CW (Beva800) is a conjugate of bevacizumab and IRDye800CW and binds specifically to VEGF-A. Beva800 provides a potentially efficacious approach to imaging specimen and cavity margins during BCS. We are presenting a phase II study that combined Beva800 with the SurgVision Explorer Air camera for intraoperative margin assessment during BCS for EBC. Methods: MARGIN II is a multicenter open-label single arm prospective clinical trial aimed at evaluating Beva800 for assessment of tumor margins in women with EBC scheduled for BCS. The study was a within-patient comparison of positive tumor margin rates using BCS standard of care margin assessment compared to intraoperative assessment with 4.5 mg Beva800 and fluorescence imaging with the SurgVision Explorer Air camera. All patients received an i.-v. bolus injection of 4.5 mg of Beva800 three days before surgery. The fluorescent signal was visualized during surgery using NIR fluorescence imaging (700–1000 nm). Standard of care margin assessment was defined as visual inspection, palpation and, in cases of pre-operative wire marking, specimen sonography or mammography. Beva800 efficacy was determined as the number of patients in which a pathology-confirmed positive margin was identified by fluorescence-guided surgery using Beva800 but not by standard of care BCS. Results: 49 patients were included in 5 centers. 4 training cases were only included in the safety analysis, 45 patients were evaluable for the efficacy analysis. 8 patients (17.8%) had involved margins after standard of care BCS, 4 of which were detected by molecular fluorescence intraoperatively resulting in the reduction of patients with positive margins by 50% (95% CI: 15.7%, 84.3%). 4 patients (8.9%; 95% CI: 2.5%, 21.1%) needed a re-excision because of involved margins. In 27 patients (60.0%) the additional molecular fluorescence guided cavity shaving did not change the resection status from positive to negative (false positive). Adverse events were reported by 16 of 49 patients (32.7%), but only 3 (6.1%) were related to Beva800 (syncope, hot flush, hypertensive crisis). One patient experienced a treatment related SAE (hypertensive crisis). No anti-Beva800 antibodies were detected. Conclusion: In our analysis the rate of necessary second operations was reduced by 50% using Beva800 and the SurgVision Explorer Air camera. The safety analysis confirmed the positive safety profile of Beva800 found in previous studies. Molecular fluorescence-guided surgery may have the potential to change the practice of breast conserving surgery by reducing unnecessary re-excisions. Future studies will have to address the high false positive rates. Citation Format: Hans-Christian Kolberg, Carmen Röhm, Angrit Stachs, Florian Schütz, Jens-Uwe Blohmer, Sarah Wetzig, Steffi Hartmann, Jörg Heil, Markus Hahn. MOLECULAR FLUORESCENCE-GUIDED SURGERY USING BEVA800 FOR THE ASSESSMENT OF TUMOR MARGINS DURING BREAST CONSERVING SURGERY OF PATIENTS WITH PRIMARY BREAST CANCER (MARGIN-II) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-14-01.

The Biomechanical Behaviour and life span of a Three-Rooted Maxillary First Premolar with Different Access Cavity Designs: A Finite Element Analysis.

The present study aimed to evaluate the influence of different access cavity designs on the biomechanical behaviour of a three-rooted maxillary first premolar using finite element analysis (FEA). Three experimental FEA models were generated: the intact tooth (IT) model, the traditional access cavity (TAC) model, and the conservative access cavity (CAC) model. In both TAC and CAC models, root canals preparation was simulated as follows: the mesiobuccal and distobuccal canals with a final tip size of 30 and taper of 0.04 and the palatal canal with a final tip size of 35 and taper of 0.04. Cyclic loading of 50 N was simulated on the occlusal surface of the three models. The number of cycles until failure (NCF), the location of failure, stress distribution patterns, maximum von Mises (VM), and maximum principal stress (MPS) were all evaluated and compared. Both types of access cavity preparation caused a reduction in the lifelog of the tooth; when compared to the IT model the TAC model had a lifelog of 94.82% while the CAC model had a lifelog of 95.80%. The maximum VM stresses value was registered on the occlusal surface of the TAC model (7 MPa), while the minimum was on the occlusal surface of the IT (6.2 MPa). MPS analysis showed that the highest stress value was recorded on the occlusal surface of the CAC model (7.71 MPa), while the least was recorded on the occlusal surface of the TAC model (3.77 MPa). Radicular stresses were always of minimal value regardless the model. The relation between the access cavity margins and the functional load points is a deciding factor that influences the biomechanical behaviour and fatigue life of endodontically treated teeth. (EEJ-2023-01-03).

Influence of Thermal and Thermomechanical Stimuli on Dental Restoration Geometry and Material Properties of Cervical Restoration: A 3D Finite Element Analysis

Cervical restoration of a premolar tooth is a challenging task as it involves structural modification to ensure the functional integrity of the tooth. The lack of retention in the cervical area, with the cavity margins on dentin and the nonavailability of enamel, makes it challenging for restoration. The high organic content of dentin, along with its tubular structure and outward flow of fluid, make dentin bonding difficult to attain. The objective of this study is to evaluate the impact of thermal and thermomechanical stimuli on the geometry of dental restorations in the cervical region. In the present study, a three-layered restorative material made of glass ionomer cement, hybrid layer, and composite resin is considered by varying the thickness of each layer. Group 1 of elliptical-shaped cavities generates von Mises stress of about 14.65 MPa (5 °C), 41.84 MPa (55 °C), 14.83 MPa (5 °C and 140 N), and 28.89 MPa (55 °C and 140 N), respectively, while the trapezoidal cavity showed higher stress of 36.27 MPa (5 °C), 74.44 MPa (55 °C), 34.14 MPa (5 °C and 140 N), and 75.57 MPa (55 °C and 140 N), which is comparable to the elliptical cavity. The result obtained from the analysis helps to identify the deformation and volume change that occurs due to various real-time conditions, such as temperature difference and thermal stress. The study provides insight into the behavior of novel restorative materials of varied thicknesses and temperature levels through simulation.

The Effects of Using Cements of Different Thicknesses and Amalgam Restorations with Different Young’s Modulus Values on Stress on Dental Tissue: An Investigation Using Finite Element Analysis

Background: In this study, it was aimed to use a finite element stress analysis method to determine the amount of stress on enamel, dentin, restoration, resin cement and glass ionomer cement in amalgam class II disto-occlusal (DO) cavities by using two different cements with different thicknesses and amalgams with different Young’ s modulus values, respectively. Methods: A three-dimensional tooth model was obtained by scanning an extracted human maxillary first molar with dental tomography. A class II DO cavity including 95-degree cavity margin angles was created. Resin cement (RC) and glass ionomer (GI) cement with different Young’ s modulus measures (RC: 7.7 GPa, GI: 10.8 GPa) were used in amalgam. Different thickness combination groups were simulated: 50 μm, 100 μm and 150 μm. Additionally, amalgams with different Young’ s modulus values were used with the same thickness of different cements (Amalgam Young’s modulus: 35 GPa and 50 GPa). A load of 600 N was delivered to the chewing area. The stress distributions on enamel, dentin, restoration, resin cement and class ionomer cement were then analyzed using finite element analysis. Results: The most stress accumulation was observed in the enamel tissue across all groups where resin cement or glass ionomer cement were used in different thicknesses and where amalgam restorations were used with different Young’s modulus values. The least stress accumulation was observed in the cement itself. Conclusions: According to the results obtained, there was no difference between the two cement types in terms of stress accumulations in the models. However, when the same cements with different thicknesses were evaluated, it was concluded that the presence of both glass ionomer and resin cement with a thickness of 150 μm causes less stress on the restoration surface. Furthermore, when the cements were combined with different thicknesses and with different amalgam Young’ s modulus values, it was concluded that 50 GPa causes less stress on restoration surface.

Robotic repair of non-midline hernias.

Non-midline abdominal wall hernias present unique anatomic challenges, making repair more complex. The constraints of the peritoneal cavity, pelvis, and costal margin limit the utility of intraperitoneal mesh repair, and extra-peritoneal repairs have traditionally been performed using open techniques, often resulting in higher wound morbidity. Advances in minimally invasive surgery make visualization and dissection of such complex cases feasible, with all the attendant benefits of a minimally invasive over an open approach. In this study, we examined the use of the robotic platform to repair non-midline hernias. Retrospective review of all non-midline abdominal wall hernias was performed robotically at Prisma Health, excluding parastomal hernias. Study conducted and outcomes reported according to STROBE statement. Repair was performed in the retro-rectus (n = 3) or retro-rectus + transversus abdominis release (TAR) (n = 39), pre-peritoneal (n = 22), and intraperitoneal (n = 1). Mean hernia width was 9.4cm, permanent synthetic mesh used for all repairs. Mean LOS was 1.5days. Surgical-site occurrence (SSO) occurred in 49.2%, 78% of which were simple seroma. Three patients (4.6%) developed surgical-site infection (SSI). Two recurrences were identified with a mean follow-up of 11 mos. The robotic platform facilitates complex dissection to allow minimally invasive, extra-peritoneal repair of complex non-midline hernias. This approach overcomes the anatomic constraints of intraperitoneal mesh repair and the wound morbidity of open repair.