Automated freeform imaging system design with generalized ray tracing and simultaneous multi-surface analytic calculation.

Recently, freeform optics has been widely used due to its unprecedented compactness and high performance, especially in the reflective designs for broad-wavelength imaging applications. Here, we present a generalized differentiable ray tracing approach suitable for most optical surfaces. The established automated freeform design framework simultaneously calculates multi-surface coefficients with merely the system geometry known, very fast for generating abundant feasible starting points. In addition, we provide a "double-pass surface" strategy with desired overlap (not mutually centered) that enables a component reduction for very compact yet high-performing designs. The effectiveness of the method is firstly demonstrated by designing a wide field-of-view, fast f-number, four-mirror freeform telescope. Another example shows a two-freeform, three-mirror, four-reflection design with high compactness and cost-friendly considerations with a double-pass spherical mirror. The present work provides a robust design scheme for reflective freeform imaging systems in general, and it unlocks a series of new 'double-pass surface' designs for very compact, high-performing freeform imaging systems.

Bone microRNA-21 as surgical stress parameter is associated with third molar postoperative discomfort.

OBJECTIVE: To evaluate an association between bone levels of inflammation/oxidative stress mediators and postoperative discomfort after third molar conventional or piezosurgery. MATERIAL AND METHODS: Twenty-six subjects with bilaterally impacted mandibular third molars, who underwent either piezo or conventional surgery, were included in a split-mouth design study. MicroRNA-21 (miR-21) expression, interleukin-1 beta (IL-1ß), and vascular endothelial growth factor (VEGF) proteins, as well as superoxide dismutase (SOD) activity in alveolar bone, were evaluated. Pain intensity, the first pain appearance, analgesic first use and total dose taken, trismus, and swelling were clinically recorded. RESULTS: MiR-21 expression was higher while VEGF protein was lower in piezosurgery vs. conventional groups. The differences in IL-1ß protein and SOD activity were not significant between groups. The pain intensity on the first day was significantly decreased in piezosurgery group. The first pain appearance and the first analgesic taken were reported sooner in conventional vs. piezosurgical group. Significantly pronounced trismus on the third day following conventional surgery was found. In conventional group, significantly increased trismus was observed on the third compared to the first postoperative day. MiR-21 showed significant correlation with the first pain appearance. CONCLUSION: Delayed onset of less pronounced postoperative pain after piezosurgical vs. conventional extraction of impacted lower third molar was significantly associated with expression of bone miR-21. CLINICAL RELEVANCE: Alveolar bone miR-21 may reflect surgical stress and is associated with third molar postoperative pain onset.

Which substances loaded onto collagen scaffolds influence oral tissue regeneration?-an overview of the last 15 years.

BACKGROUND: Collagen scaffolds are widely used for guided bone or tissue regeneration. Aiming to enhance their regenerative properties, studies have loaded various substances onto these scaffolds. This review aims to provide an overview of existing literature which conducted in vitro, in vivo, and clinical testing of drug-loaded collagen scaffolds and analyze their outcome of promoting oral regeneration. MATERIALS AND METHODS: PubMed, Scopus, and Ovid Medline® were systematically searched for publications from 2005 to 2019. Journal articles assessing the effect of substances on oral hard or soft tissue regeneration, while using collagen carriers, were screened and qualitatively analyzed. Studies were grouped according to their used substance type-biological medical products, pharmaceuticals, and tissue-, cell-, and matrix-derived products. RESULTS: A total of 77 publications, applying 36 different substances, were included. Collagen scaffolds were demonstrating favorable adsorption behavior and release kinetics which could even be modified. BMP-2 was investigated most frequently, showing positive effects on oral tissue regeneration. BMP-9 showed comparable results at lower concentrations. Also, FGF2 enhanced bone and periodontal healing. Antibiotics improved the scaffold's anti-microbial activity and reduced the penetrability for bacteria. CONCLUSION: Growth factors showed promising results for oral tissue regeneration, while other substances were investigated less frequently. Found effects of investigated substances as well as adsorption and release properties of collagen scaffolds should be considered for further investigation. CLINICAL RELEVANCE: Collagen scaffolds are reliable carriers for any of the applied substances. BMP-2, BMP-9, and FGF2 showed enhanced bone and periodontal healing. Antibiotics improved anti-microbial properties of the scaffolds.

Clinical Factors Affecting the Accuracy of Guided Implant Surgery-A Systematic Review and Meta-analysis.

OBJECTIVES: To systematically review the current dental literature regarding clinical accuracy of guided implant surgery and to analyze the involved clinical factors. MATERIAL AND METHODS: PubMed and Cochrane Central Register of Controlled Trials were searched. Meta-analysis and meta-regression analysis were performed. Clinical studies with the following outcome measurements were included: (1) angle deviation, (2) deviation at the entry point, and (3) deviation at the apex. The involved clinical factors were further evaluated. RESULTS: Fourteen clinical studies from 1951 articles initially identified met the inclusion criteria. Meta-regression analysis revealed a mean deviation at the entry point of 1.25 mm (95% confidence interval [CI]: 1.22-1.29), 1.57 mm (95% CI: 1.53-1.62) at the apex, and 4.1° in angle (95% CI: 3.97-4.23). A statistically significant difference (P < .001) was observed in angular deviations between the maxilla and mandible. Partially guided surgery showed a statistically significant greater deviation in angle (P < .001), at the entry point (P < .001), and at the apex (P < .001) compared with totally guided surgery. The outcome of guided surgery with flapless approach indicated significantly more accuracy in angle (P < .001), at the entry point (P < .001), and at apex (P < .001). Significant differences were observed in angular deviation based on the use of fixation screw (P < .001). CONCLUSIONS: The position of guide, guide fixation, type of guide, and flap approach could influence the accuracy of computer-aided implant surgery. A totally guided system using fixation screws with a flapless protocol demonstrated the greatest accuracy. Future clinical research should use a standardized measurement technique for improved accuracy.

Implant-guided supracrestal alveolar bone growth using scaffolds, BMP-2, and novel scaffold-retaining device.

OBJECTIVE: To evaluate the efficacy of various scaffold systems and a Ti scaffold-retaining device with and without non-glycosylated rhBMP-2 (BMP-2) for increasing the vertical alveolar bone growth in the intra-oral mini-pig model. METHODS: Forty-eight Straumann Bone Level implants with hydrophilic (SLActive) surfaces were partially embedded in mandibles of 12 adult mini-pigs with the shoulder of the implant located 3 mm above the bone crest. Twenty-four implants were placed in conjunction with BMP-2 (50 µg) incorporated within resorbable scaffolds. Twenty-four additional control implants were placed with scaffolds only. Scaffolds were placed around the implant and stabilized with a newly developed Ti "umbrella" scaffold retainer. Scaffolds included (i) HA-coated collagen (Healos); (ii) biphasic HA/ß-TCP crystals (Straumann Bone Ceramic, SBC); and (iii) SBC crystals infused with polyethylene glycol (PEG) hydrogel. Eight test and control pairs for each scaffold group were implanted. At 9 weeks, soft tissue healing was assessed and the extent of new vertical bone was evaluated with microCT and histomorphometry. RESULTS: microCT analysis revealed a mean of 167 ± 47 mm3 new supracrestal mineralized tissue volume formation around the test sites where BMP-2 was released from the scaffold whereas the control group (no BMP-2) showed a significantly lower mineralized tissue volume of 106 ± 55 mm3 . The SBC+BMP-2 group had the highest mineralized tissue volume of 189 ± 36 mm3 . Histomorphometry showed bone-to-implant contact of 54.5% for the test groups and 33.3% for the control groups and new vertical bone growth of 2.2 ± 1.0 and 1.0 ± 0.9 mm, respectively. The SBC+BMP-2 group again demonstrated the best outcome (2.7 ± 0.4 mm). The qualitative scoring of soft tissue dehiscence showed that the presence of BMP-2 yielded far superior outcomes, 0.63 vs. 1.75 for all control implant sites (with scores ranging from 0, reflecting no soft dehiscence, to 4, showing a completely exposed umbrella). CONCLUSION: The release of BMP-2 from a SBC scaffold adjacent to a hydrophilic, rough Ti implant and scaffold retention umbrella consistently regenerated the greatest volume and height of new vertical bone along the length of the implant.

Comparison of bone morphogenetic protein-2 delivery systems to induce supracrestal bone guided by titanium implants in the rabbit mandible.

OBJECTIVE: To compare the ability of three non-glycosylated/rhBMP-2 (BMP-2) delivery systems to induce supracrestal bone. MATERIAL AND METHODS: Thirty-six custom SLActive dental implants were partially embedded in transverse orientation into the posterior mandibles of 18 adult rabbits with the head of the implant located 3 mm supracrestal. Delivery of BMP-2 (30 µg) from the following materials was studied: (1) Ti implant + BMP-2 with hydroxyapatite (HA)-coated collagen (Col/HA) scaffold, (2) Ti implant with Col/HA infused with PEG hydrogel + BMP-2, or (3) Ti implant with HA/ß-TCP/PEG hydrogel scaffold + BMP-2. Scaffolds were secured with a metal "umbrella." Non-BMP-2 contralateral controls were included. MicroCT imaging and histological analysis was performed after 10 weeks to assess new supracrestal bone formation. In vitro BMP-2 release studies were conducted. RESULTS: All treatment groups displayed new supracrestal bone formation. Ti + BMP-2 with Col/HA (3.0 ± 0.2 mm) and Ti with Col/HA/PEG hydrogel + BMP-2 (2.7 ± 0.4 mm) had significantly greater (P < 0.05) outcomes than without BMP-2. Maximum bone volume occurred in the Ti implant with HA/ß-TCP/PEG hydrogel scaffold + BMP-2 group. CONCLUSIONS: The use of an implant system composed of a partially inserted Ti implant, adjacent scaffold and scaffold stabilizer resulted in the formation of new supracrestal bone across all test groups with and without BMP-2. Delivery of BMP-2 directly from the Ti implant increased bone height, BIC and bone volume as compared to no BMP-2 when a Col/HA was used, but did not improve performance of the HA/ß-TCP/PEG scaffold.

Tight Placement of Erich Arch Bar While Avoiding Wire Fatigue Failure.

PURPOSE: To determine the number of wire twists needed to acquire ideal Erich arch bar tightness before wire fatigue failure (fracture) in relation to different distances and angles at which different gauge wires are grasped to provide information to improve the efficiency of arch bar application. MATERIALS AND METHODS: This study mimicked surgical placement of arch bars with 24- and 26-gauge wires. The number of twists to tightness and failure was evaluated when the wire distance between the arch bar and wire holder tip changed (5 vs 10 mm) and when the degree at which the wire was held relative to the tooth axis was changed (45° vs 90°). A wire shearing test also was used to investigate the fatigability of wires tightened under these same conditions. Wires twisted to tightness, past tightness, and after shearing test movements were visualized with electron microscopy. RESULTS: For 24-gauge wire held at 5 mm, 2.6 to 2.8 twists were needed for wire tightness, with failure after 1.7 to 1.9 twists past tightness; for 24-gauge wire held at 10 mm, 4.4 to 4.9 twists produced tightness, with failure after 2.3 to 2.9 twists past tightness. For 26-gauge wire held at 5 mm, 3.3 to 3.5 twists provided tightness, with 1.6 to 1.8 twists past tightness causing failure; for 26-gauge wire held at 10 mm, 5.1 to 5.5 twists produced tightness, with 3.1 to 3.7 twists past tightness causing failure. At a 45° angle, the wire tightened with fewer twists and showed more resistance to failure with twists past tightness compared with 90° using 24- and 26-gauge wires. In contrast, 24-gauge wire held at a 5-mm distance showed the opposite result, with decreased resistance to failure at the 45° angle. However, the differences were not statistically meaningful. Scanning election microscopy showed no wire fatigue for either angle for 26-gauge wire held at a 5-mm distance and twisted to tightness. After overtightening and oscillation, the 90° angle trials showed fatigue, whereas the 45° angle trials did not. CONCLUSIONS: Holding a 24-gauge wire at 45° to the tooth axis is recommended owing to fewer twists to tightness and more resistance to failure. A 5-mm grasping distance is recommended for experienced surgeons owing to fewer twists to tightness, whereas a 10-mm grasping distance is recommended for novice surgeons owing to a greater tolerance for over-twisting before failure.

CBCT evaluation of buccal bone regeneration in postmenopausal women with and without osteopenia or osteoporosis undergoing dental implant therapy.

STATEMENT OF PROBLEM: Because alveolar bone augmentation in women with osteoporosis/osteopenia has an uncertain prognosis, objective and reliable methods should be used to study standard surgical approaches. PURPOSE: The purpose of this clinical study was to evaluate bone regeneration 9 months after bone augmentation and implant placement in postmenopausal women with different levels of systemic bone health by using cone beam computed tomography (CBCT) and to test proof of concept for this measurement approach. MATERIAL AND METHODS: A subset of 14 participants was analyzed in a best practice study of postmenopausal women receiving dental implants and simultaneous horizontal ridge augmentation. Women were categorized as osteopenic/osteoporotic or normal based on the results of preoperative dual-energy x-ray absorptiometry. All implant study sites received a particulate graft and/or buccal plate expansion. The study sites were evaluated with CBCT preoperatively, immediately postoperatively, and 9 months postoperatively. Nonparametric statistics were used for all analyses. The related samples Wilcoxon signed rank test was used to assess the differences in bone width between time points (α=.05 for all tests). RESULTS: After 9 months, 13 out of 14 participants showed increased bone width compared to the preoperative baseline measurements. The increase was statistically significant for the participants with osteoporosis/osteopenia (P=.007), but not for those with normal bone health (P=.066). The CBCT scans showed that mineralized tissue buccal to the implant surface had the radiographic appearance of mature bone. CONCLUSIONS: CBCT showed evidence of bone regeneration, with an increase in alveolar ridge width in postmenopausal osteopenic/osteoporotic women subsequent to surgical reconstruction.

Increasing orthodontic and orthognathic surgery treatment efficiency with a modified surgery-first approach.

This case report describes the treatment of a 33-year-old white man who had a skeletal Class III and dental Class II subdivision malocclusion caused by a retrognathic maxilla, with severe maxillary crowding, a highly placed maxillary left canine, mild mandibular crowding, and a bilateral posterior crossbite. Treatment was performed with a modified surgery-first approach, which included a short presurgical alignment phase for the correction of the significant maxillary crowding while controlling the incisal angulation, followed by LeFort I maxillary advancement surgery. The short presurgical orthodontic phase aimed at eliminating the anterior dental interferences before the maxillary advancement, and the use of the inherent increased bone turnover in the postsurgical phase helped to reduce the total orthodontic treatment time to 12 months. Pleasing esthetic results and a good functional occlusion were achieved.

The relationship between implant stability and bone health markers in post-menopausal women with bisphosphonate exposure.

OBJECTIVES: The authors assessed the relationship between implant stability and bone turnover markers in patients with and without a history of bisphosphonate (BP) exposure for treatment of osteopenia/osteoporosis. MATERIALS AND METHODS: One dental implant site was evaluated in 58 post-menopausal women with a spectrum of bone health in a "best practice" prospective cohort study. Each site had a previous or simultaneous bone augmentation procedure. BP exposure at enrollment was categorized as "never" or "past/current" exposure. Implant stability was assessed by resonance frequency analysis (RFA ISQ) at surgery and 8 weeks post-implant. Bone turnover markers, C-telopeptide collagen crosslinks (sCTX) and procollagen -1 N-terminal telopeptide (P1NP), were measured pre-treatment, 1, and 8 weeks following implant surgery. RESULTS: Mean age was 62.4 ± 6.8 years; 66 % were osteopenic/osteoporotic. Average RFA ISQ at placement for all participants was 63.5 ± 11.3, at 8 weeks post-surgery 74.2 ± 9.4 (p < 0.01). Among "past/current" BP users, there was a significant negative correlation between RFA ISQ values at 8 weeks post-implant placement and sCTX and P1NP values at 1 week (ρ = -.65 and ρ = -.55, respectively; p < 0.01) and 8 weeks (ρ = -.64 and ρ = -.52, respectively; p < 0.05). CONCLUSION: RFA ISQ values increased between implant placement and 8 weeks post-surgery demonstrating successful osseointegration. Lower bone turnover was associated with better implant stability among patients with a history of BP exposure. CLINICAL RELEVANCE: Further investigation of the relationship between BP exposure and implant stability is warranted in a larger population, as results may strongly impact on clinical practice decisions.

Three-dimensional cone-beam computed tomography-based virtual treatment planning and fabrication of a surgical splint for asymmetric patients: surgery first approach.

Virtual 3-dimensional planning in orthognathic surgery allows for a detailed visualization and analysis of skeletal and dental deformities, especially in patients with asymmetries. This approach also eliminates conventional stone model surgery through computer-aided fabrication of surgical stents. This article presents a new approach with 3-dimensional cone-beam computed tomography-based treatment planning for the surgical correction of facial asymmetry in conjunction with the surgery first approach. Good esthetic and occlusal outcomes were obtained for 2 patients after orthognathic surgery and orthodontic treatment with a short total treatment time.

Bidimensional dentoalveolar distraction osteogenesis for treatment efficiency.

This case report describes the treatment of a 16-year-old girl with a unilateral posterior buccal crossbite, a unilateral Class II molar relationship, and a maxillary right canine high in the labial sulcus. The treatment plan included surgically assisted unilateral maxillary expansion for the correction of the buccal crossbite, with simultaneous dentoalveolar distraction of the maxillary right canine into the extraction space of the first premolar aided by skeletal anchorage. Reduced orthodontic treatment time was facilitated by these 2 surgical procedures. A pleasing esthetic result and a good functional occlusion were achieved in 13 months.

Implant-guided vertical bone growth in the mini-pig.

OBJECTIVE: To attain and describe guided vertical bone regeneration around titanium (Ti) and titanium zirconium (Ti-Zr) dental implants utilizing non-glycosylated recombinant human bone morphogenetic protein-2 (ng/rhBMP-2), biomaterial scaffolds and a scaffold retainer. MATERIALS AND METHODS: Thirty-two modified Straumann TE implants were partially embedded in the mandibles of eight adult mini-pigs. Pre-shaped resorbable scaffolds were placed around the implant and shielded and stabilized with a newly developed Ti custom scaffold retainer (umbrella) or wide-neck (WN) healing caps to stabilize the scaffold. Ng/rhBMP-2 (50 µg) was applied to the supracrestal portion of the implant or incorporated within the scaffold. At 9 weeks, soft tissue healing was assessed. Vertical bone regeneration outcomes including bone height, bone-to-implant contact (BIC) and bone volume were assessed by micro-computed tomography and histology. RESULTS: Soft tissue healing at the test sites (+ng/rhBMP-2/+scaffold) appeared to be substantially better than the control sites (-ng/rhBMP-2/-scaffold). Bone height, BIC percentage and bone volume were all similar regardless of whether WN healing caps or umbrella scaffold stabilization was used for all biomaterial scaffolds tested. WN healing cap test sites showed greater new bone height and BIC as compared with aggregate data from the control sites (P=0.05). Comparison of aggregate data from the umbrella test sites showed greater BIC and new bone volume as compared with aggregate data from the control sites(P=0.05). CONCLUSION: Vertical bone regeneration was successfully attained utilizing ng/rhBMP-2, biomaterial scaffolds and a scaffold retainer.

Opioid-Prescribing Patterns in Connecticut and New Jersey Following Third Molar Extractions.

OBJECTIVE: In recent years, opioid misuse has resulted in much scrutiny on providers' prescribing habits. The purpose of this study was to analyze prescribing habits in the context of third molar extractions as a model for promoting better postsurgical pain management. METHODS: This was a cross-sectional survey of oral maxillofacial surgeons in Connecticut and New Jersey. A total of 291 practitioners were contacted to complete an online survey using Qualtrics Research Services to determine prescribing habits following third molar extractions. RESULTS: The most common approach for postoperative analgesia was nonsteroidal anti-inflammatory drugs (NSAIDs) and an opioid/acetaminophen (APAP) combination as 2 separate prescriptions, reported by 36% of participants. The combination of hydrocodone/APAP was the most common opioid formulation, and an average of 10.93 ± 4.51 opioid pills were prescribed with a maximum of 20 pills reported. Most providers (79%) consistently provided patients with opioid information. Only 22% reported always checking opioid-monitoring programs; however, providers were more likely to check if prescribing more than ∼11 opioid pills (P = .0228). Most reported using dexamethasone (82%) and bupivacaine (56%) intraoperatively, while ketorolac was less common (15%). No association was found between the quantity of opioids prescribed and the use of intraoperative ketorolac, steroids, or bupivacaine (P > .05). CONCLUSION: There remains to be a universal standard for using opioids for postoperative pain management in dentistry. Providers should be mindful when prescribing opioids and consider using NSAIDs and APAP for baseline pain plus a separate opioid prescription for breakthrough pain. Additional focus on minimizing the quantity of opioids prescribed and self-reflecting on prescribing and practice habits to further reduce opioid-related complications is warranted.

A novel approach for implant site development through root tipping.

Implant site development through orthodontic extrusion can regenerate hard and soft tissue volumes lost to periodontal disease. This extrusive procedure is indicated especially when a maxillary incisor is severely compromised and the esthetic demands are high. This article describes a novel approach to alveolar bone development that enhanced the volume of the implant site. The technique involves tipping the maxillary incisor in the direction of the angular defect to increase alveolar bone volume in the implant site; simultaneous improvement of the interproximal papillary height can also be expected. With this procedure, immediate loading of the endosseous implant is possible due to the quality of the bone developed.

Implant system for guiding a new layer of bone. Computed microtomography and histomorphometric analysis in the rabbit mandible.

OBJECTIVE: To prove the concept that an implant system with osteoconductive surface characteristics and an osteoinductive scaffold material has the capacity to guide vertical supracrestal bone growth in a rabbit mandible onlay model. MATERIAL AND METHODS: Thirteen adult white New Zealand rabbits each received custom-designed dental implants. All implants had sandblasted, acid-etched (SLA) surfaces, with the coronal aspect (3 mm) of each implant was left outside the lateral aspect of posterior mandibular bone, but covered by periosteum, muscle, subcutaneous tissue, and skin. Bone formation around implants placed adjacent to osteoinductive demineralized bone matrix (DBM) scaffolds were compared with contralateral implants without scaffolds in six rabbits using micro-CT imaging. Bone formation around implants with scaffolds from seven additional rabbits was measured using both micro-CT imaging and quantitative histology. RESULTS: At 8 weeks, new supracrestal bone was seen adjacent to all implants placed with DBM and two implants without DBM. The mean supracrestal bone heights achieved for implants with and without DBM scaffolds as measured by micro-CT was 2.1+/-0.9 and 0.8+/-0.9 mm, respectively (P=0.008). Histomorphometric analysis illustrated that supracrestal bone-to-implant contact for implants with DBM scaffolds was 58.1+/-14% and that mean supracrestal bone height was 2.4+/-0.6 mm. CONCLUSIONS: Successful implant-guided supracrestal osteogenesis has been demonstrated in a rabbit model with the combined use of osteoconductive implant surfaces, an osteoinductive scaffold, and a device that prevents soft tissue downgrowth and provides scaffold stabilization.