The Scalloped Surgical Guide as an Alternative to Flat Bone Reduction Guide in Full-arch Implant Restoration

AIM

The goal of this clinical report was to present an alternative to traditional flat bone reduction guides, using a custom-designed 3D printed guide according to the future gingival margin of the planned dentition.

MATERIALS AND METHODS

A 61-year-old female with concerns regarding her smile appearance was presented. The initial examination revealed excessive gingival show accompanied by excessive overjet. The dentition was in a failing situation. The proposed treatment plan, relying on the sufficient amount of bone and keratinized tissue, consisted of re-contouring of the alveolar ridge and gingiva and placement of six implants and a FP-1 prosthesis after extraction of all remaining maxillary teeth.

RESULTS

Digital smile design was completed, and a fully-digitally-guided surgery was planned. This consisted of utilizing three surgical guides. Starting with the fixation pin guide and continuing with the scalloped hard and soft tissue reduction guide and finally, the implant placement template. Following the surgery, the patient received a temporary restoration and on the 4-month follow-up, a new poly-methyl meta-acrylate temporary prosthesis was delivered. The patient's 7-month follow-up is presented in the paper.

CONCLUSIONS

The report of this triple-template guided surgery indicated that digital 3D planning is a considerably predictable tool to properly establish and evaluate future occlusal plane, smile line, and lip support. Scalloped guides seem to be an excellent alternative to conventional bone reduction guides since they require less bone removal and improve patient comfort during surgery.

The Scalloped Surgical Guide as an Alternative to Flat Bone Reduction Guide in Full-Arch Implant Restoration

The goal of this clinical report was to present an alternative to traditional flat bone reduction guides, using a custom-designed 3-dimensional (3D)-printed guide according to the future gingival margin of the planned dentition. A 61-year-old woman with concerns regarding her smile appearance was presented. The initial examination revealed excessive gingival show accompanied by excessive overjet. The dentition was in a failing situation. The proposed treatment plan, relying on the sufficient amount of bone and keratinized tissue, consisted of recontouring of the alveolar ridge and gingiva and placement of 6 implants and an FP-1 prosthesis after extraction of all remaining maxillary teeth. Digital smile design was completed, and a fully digitally guided surgery was planned. This consisted of using 3 surgical guides, starting with the fixation pin guide, continuing with the scalloped hard- and soft-tissue reduction guide, and finally the implant placement template. Following the surgery, the patient received a temporary restoration, and on the 4-month follow-up, a new polymethyl meta-acrylate temporary prosthesis was delivered. The patient's 7-month follow-up is presented in the article. The report of this triple-template guided surgery indicated that digital 3D planning is a considerably predictable tool to properly establish and evaluate future occlusal plane, smile line, and lip support. Scalloped guides seem to be an excellent alternative to conventional bone reduction guides since they require less bone removal and improve patient comfort during surgery.

Influence of scanbody design and intraoral scanner on the trueness of complete arch implant digital impressions: An in vitro study

This study aimed to compare the accuracy of full-arch digital implant impressions using seven different scanbodies and four intraoral scanners. A 3D-printed maxillary model with six implants and their respective multi-unit abutments was used for this study. Seven scanbodies (SB1, SB2, SB3, SB4, SB5, SB6, and SB7) and four intraoral scanners (Primescan®, Omnican®, Trios 3®, and Trios 4®) were assessed. Each combination group was scanned ten times and a dental lab scanner (D2000, 3Shape) was used as a reference. All scans were exported as STL files, imported into Convince software (3Shape) for alignment, and later into Blender software, where their 3D positions were analyzed using a Python script. The 3D deviation, angular deviation, and linear distance between implants #3 and #14 were also measured. Accuracy was measured in terms of "trueness" (scanbody 3D deviation between intraoral scan and desktop scan). Kruskal-Wallis followed by the Bonferroni correction was used to analyze the data (⍺ = .05). The study found statistically significant differences in digital impression accuracy among the scanners and scanbodies (p<0.001). When comparing different intraoral scanners, the Primescan system showed the smallest 3D deviation (median 110.59 μm) and differed statistically from the others, while Trios 4 (median 122.35 μm) and Trios 3 (median 130.62 μm) did not differ from each other (p = .284). No differences were found in the linear distance between implants #3 and #14 between Trios 4, Primescan, and Trios 3 systems. When comparing different scanbodies, the lowest median values for 3D deviation were obtained by SB2 (72.27μm) and SB7 (93.31μm), and they did not differ from each other (p = .116). The implant scanbody and intraoral scanner influenced the accuracy of digital impressions on completely edentulous arches.

Erratum: Sleeveless guided implant placement compared to conventional approaches: An in vitro study at healed sites and fresh extraction sockets

The following amendments are made to the published article: Int J Oral Implantol (Berl) 2023;16(2): 117-132; First published 9 May 2023.

Digitally Guided Lateral Sinus Floor Elevation With Simultaneous Implant Placement: 3 Case Reports With Technical Considerations

A sinus floor elevation via lateral window (LSFE) is one of the most widely used bone augmentation procedures for implant therapy in the posterior area of the maxilla. Locating and preparing a correct opening window on the lateral sinus wall is a key step of this procedure. Conventionally, the surgeon designs and locates the window after the flap is reflected based on the information obtained from cone-beam computed tomography (CBCT) images or other diagnostic aids. Nevertheless, in spite of the advancements in CBCT imaging, clinicians may still experience hardships in situating and procuring meticulous access to the maxillary sinus by using CBCT alone. Therefore, in cases requiring an LSFE simultaneous to implant placement, a maxillary sinus surgical guide has been tested and reported to be the amiable method to be utilized as a conjunct to prevent unpredictable consequences according to its application in implying both the direction for the implant and the location of the lateral window. This article presents 3 clinical cases with a fully digital approach to guide the opening of the lateral wall of the maxillary sinus as well as the simultaneous placement of a single implant in an ideal 3D position. Based on the CBCT images and intraoral scan, a surgical guide was fabricated based on 3D software. During surgery, this teeth-supported template can be placed intraorally, guiding sinus window opening preparation. This technique makes the sinus window opening procedure simple and predictable, reduces surgical time and the risk of complications, and allows the placement of the implant in the ideal 3D position.

Physical and mechanical properties of four 3D-printed resins at two different thick layers: An in vitro comparative study

OBJECTIVES

This in vitro comparative study aimed to evaluate the physical and mechanical properties of four 3D-printed resins with two different thickness layers.

METHODS

Four printed resins (VarseoSmile Crown Plus, VSC; NexDent C&B MFH, MFH; Nanolab 3D, NNL; and Resilab 3D Temp, RSL) were printed with 50 µm and 100 µm layer thickness, resulting in 80 bars measuring 25 × 2×2 mm. The specimens underwent a Raman spectroscopy for degree of conversion, confocal laser scanning microscopy for surface roughness (Sa), three-point bending test for flexural strength and elastic modulus, and a Vickers hardness test (VHN). Data was tested for normality using the Shapiro-Wilk, two-way ANOVA, and Tukey test (α = 0.05) for statistical analysis.

RESULTS

The layer thickness affected all performed tests, but the elastic modulus (p < 0.001). Specimens with 100 µm showed, in general, worse results outcomes than those with 50 µm (p < 0.001). However, within the limitations of this comparative in vitro study, it could be concluded that the tested resins and layer thicknesses directly influenced physical and mechanical properties.

SIGNIFICANCE

The physical and mechanical properties of three-dimensional printed restorations can be affected by the layer thickness, which can interfere with the choice of the 3D printing resin for a desired clinical outcome.

Effects of crown contour on artificial biofilm removal efficacy with interdental cleaning aids: An in vitro study

OBJECTIVES

To evaluate the efficacy of various interdental cleaning aids for artificial biofilm removal on different implant-supported crown designs.

METHODS

Mandibular models with missing first molar were fabricated and installed with single implant analogs and loaded with crowns of different designs (concave, straight, and convex). Artificial biofilm was made with occlusion spray. Thirty volunteers (periodontists, dental hygienists, and laypersons) were asked to clean the interproximal areas. The crowns were unscrewed and photographed in a standardized setting. The outcome was measured by the cleaning ratio which represents the cleaned surfaces in relation to the area of the tested surface.

RESULTS

A significant difference in favor of concave crown (p < .001) on the basal surface was cleaned by all tools, except the water flosser. There was evidence of an overall effect of "cleaning tool," "surface," and "crown design" (p < .0001) except for the "participant" factor. The mean cleaning ratio for each cleaning tool and overall combined surfaces were (in%): dental floss: 43.02 ± 23.93, superfloss: 42.51 ± 25.92, electric interspace brush: 36.21 ± 18.78, interdental brush: 29.10 ± 15.95, and electric water flosser: 9.72 ± 8.14. Dental floss and superfloss were significantly better (p < .05) than other tools in removing plaque.

CONCLUSIONS

Concave crown contour had the greatest artificial biofilm removal, followed by straight and convex crowns at the basal surface. Dental floss and superfloss were the most effective interdental cleaning devices for artificial biofilm removal. None of the tested cleaning devices were able to completely remove the artificial biofilm from the interproximal/basal surfaces.

Volumetric Outcomes of Peri-implant Soft Tissue Augmentation with a Xenogeneic Cross-Linked Collagen Scaffold: A Comparative Clinical Study

Performing soft tissue augmentation (STA) at implant sites to improve esthetics, patient satisfaction, and peri-implant health is common. Several soft tissue grafting materials can be used to increase soft tissue thickness at the second-stage surgery, including human dermal matrices and xenogeneic collagen scaffolds. This study assessed and compared the volumetric outcomes, from second-stage surgery to crown delivery, around implants that received STA with a xenogeneic cross-linked collagen scaffold (XCCS) vs nonaugmented implant sites. Thirty-one patients (31 implant sites) completed the study. Intraoral digital scans were taken at the second stage and prior to crown delivery, and the STL files were imported in an image-analysis software to assess volumetric changes. XCCS-augmented implants showed significantly greater volumetric changes compared to control sites, which showed volume loss. The mean thickness of the XCCS-augmented area was 0.73 mm. There was no difference in patient-reported esthetic evaluations between groups. STA with XCCS provided significantly greater volumetric outcomes compared to nonaugmented sites. Further studies are needed to evaluate the long-term behavior of the augmented peri-implant mucosa and the effects of STA on peri-implant health.

Comparative physical and mechanical properties of a 3D printed temporary crown and bridge restorative material

Background

The objective was to compare physic-mechanical properties of different materials used for temporary restorations.

Material and Methods

Protemp 4/bisacrylic resin, Jet/acrylic resin, and Nexdent C&B/3D-printed resin samples (10mm diameter x 2mm thickness) were analyzed for surface roughness and color stability tests (baseline, after 5 thousand brushing cycles; and after artificial aging in water at 60oC for 24 hours) and Knoop microhardness. All data were checked for normality using Shapiro-Wilk test. Surface roughness and color stability were analyzed using two-way repeated measurements ANOVA, microhardness data was subjected to one-way ANOVA. All tests were followed by Tukey test and were performed with α=0.05.

Results

For roughness, material (p=.002), time points (p=.002) and interaction between both (p<.001) were significant. All groups presented similar roughness for measurements of baseline and after brushing. After artificial aging, 3D printed resin showed decreased roughness when compared with other resins, and with its baseline reading. Acrylic resin showed an increase in surface roughness (when compared with measurement after brushing cycles). Considering color stability, only the material (p=.039) and the time (p<0.001) were significant. All groups showed similar color variation before and after artificial aging. There was an increase in color alteration after artificial aging for all groups. Considering microhardness test (p<.001), the 3D printed resin showed the highest values and acrylic resin the lowest. Bysacylic resin was similar to both 3D printed and acrylic resins.

Conclusions

The tested 3D printed resins present similar or better properties than other tested temporary materials while being integrated with the digital workflow. Key words:Disinfection methods, hydroxyl radical, environment, surfaces, dentistry.

Sleeveless guided implant placement compared to conventional approaches: An in vitro study at healed sites and fresh extraction sockets

PURPOSE

To investigate the accuracy of a novel sleeveless implant surgical guide by comparing it with a conventional closed-sleeve guide and a freehand approach.

MATERIALS AND METHODS

Custom resin maxillary casts with corticocancellous compartments were used (n = 30). Seven implant sites were present per maxillary cast, corresponding to healed (right and left first premolars, left second premolar and first molar) and extraction sites (right canine and central incisors). The casts were assigned into three groups: freehand (FH), conventional closed-sleeve guide (CG) and surgical guide (SG) groups. Each group comprised 10 casts and 70 implant sites (30 extraction sites and 40 healed sites). Digital planning was used to design 3D printed conventional and surgical guide templates. The primary study outcome was implant deviation.

RESULTS

At extraction sites, the largest difference between groups occurred in angular deviation, where the SG group (3.80 ± 1.67 degrees) exhibited ~1.6 times smaller deviation relative to the FH group (6.02 ± 3.44 degrees; P = 0.004). The CG group (0.69 ± 0.40 mm) exhibited smaller coronal horizontal deviation compared to the SG group (1.08 ± 0.54 mm; P = 0.005). For healed sites, the largest difference occurred for angular deviation, where the SG group (2.31 ± 1.30 degrees) exhibited 1.9 times smaller deviation relative to the CG group (4.42 ± 1.51 degrees; P < 0.001), and 1.7 times smaller deviation relative to the FH group (3.84 ± 2.14 degrees). Significant differences were found for all parameters except depth and coronal horizontal deviation. For the guided groups, there were fewer significant differences between healed and immediate sites compared to the FH group.

CONCLUSION

The novel sleeveless surgical guide showed similar accuracy to the conventional closed-sleeve guide.

Bacterial Leakage Evaluation Through DNA-DNA Checkerboard Hybridization Technique in Morse Taper Implant-Abutment Connections: An In Vitro Study

Purpose: The objective of this in vitro study was to evaluate the activity of local gel containing metronidazole (MN) in the leakage area, which was analyzed by the DNA-DNA checkerboard hybridization method. Materials and Methods: Thirty-six sets of Morse taper/mini-pillar implants were used in this study. These implants were equally divided into the following three groups: MN gel (test group), no MN gel (negative test group), and no gel (control). The gel was prepared with metronidazole (15%). Unstimulated saliva samples were collected, transferred to a Falcon tube, and stored at 37°C. The sets were partially immersed in microtubes containing 300 μL of saliva and were incubated at 37°C ± 1°C for 7 days. Microbial infiltration was evaluated (37 bacterial species and 5 species of Candida). The results were analyzed with Wald-Type, ANOVA, and multiple comparisons analysis between groups. Results: After comparing the quantity of microorganisms, both gel-treated groups (no MN gel and MN gel) had more significant microorganism presence than the control group (P < .001), and no significant result was found between the no MN gel and MN gel groups (P > .05). Regarding the bacteria found, the most common were Aggregatibacter actinomycetemcomitans, Prevotella melaninogenica, Bacteroides fragilis, and Candida tropicalis. Conclusion: Within the limitations of this study, it was concluded that the gel containing metronidazole used in this study was not effective in preventing the infiltration of microorganisms through the Morse taper implant-abutment interface.

Digital planning for two-implant-supported overdenture and bone reduction guide using cone-beam computed tomography: Simple features for predictable outcomes

The two-implant-supported mandibular overdenture is considered a reliable treatment option to restore masticatory function. Digital planning has been shown to improve the precision and accuracy of the surgical procedure. The outcomes are indeed pertinent to the ideal three-dimentional positioning of the implant placement. Recently, the uses of cone-beam computed tomography (CBCT) and intraoral scan have improved greatly the workflow of digital planning; however, the sophisticated technology caused confusion among clinicians. The purpose of this case series was to exhibit the efficacy of a bone-supported guide in applying simultaneous implant placement and bone reduction, solely based on CBCT data. The bone reduction can therefore be determined accordingly, by adding windows to the guide, allowing the clinician to decide the amount of bone reduction as well as the location for implant placement. This novel surgical guide would not only fit properly on the bone but also provide the benefits of less-invasive surgery and the opportunity to place implants parallel. The  digital workflow described not only simplifies the fabrication process but also yields predictable surgical outcomes.

Accuracy of partially and fully guided surgical techniques for immediate implant placement: An in vitro assessment

STATEMENT OF PROBLEM

Optimal implant positioning is essential to achieving predictable results. Computer-guided surgery has been reported to be an accurate technique for implant placement in healed sites, but the accuracy of guided techniques for immediate implant placement into fresh sockets is still unclear.

PURPOSE

The purpose of this experimental randomized split-mouth study in pig jaws was to determine the accuracy of partially and fully guided surgical techniques for immediate implant placement into fresh sockets and to compare 2 different methods of implant position deviations analysis.

MATERIAL AND METHODS

Twenty implants were installed in 10 pig jaws using 2 different techniques: partially guided (n=10) and fully guided (n=10). Cone beam computed tomography and digital scanning were performed before and after the surgical procedure to plan the virtual implant position and fabricate the surgical guide, as well as to determine implant position deviations. Two methods were used to evaluate implant deviations: tomographic and digital scanning. The Shapiro-Wilk test of normality was used. Deviation comparisons were carried out by using paired t tests (α=.05), and intraclass correlation coefficient (ICC) was computed to assess the agreement between the 2 methods of implant deviation analysis.

RESULTS

In the tomographic analysis, the partially guided technique resulted in significantly higher global apical and lateral coronal deviations (2.25 ±0.59 mm; 0.96 ±0.55 mm) than fully guided (1.52 ±0.89 mm; 0.75 ±0.52 mm) (P<.01 and P<.05, respectively). The analysis performed using digital scanning showed significantly higher angular, global apical, and lateral apical deviations in the partially guided (6 ±3.28 degrees; 2.49 ±1.03 mm; 2.16 ±1.07 mm) technique than in the fully guided (3.32 ±1.84 degrees; 1.5 ±0.58 mm; 0.98 ±0.67 mm) (P<.05). An ICC of 0.522 between the 2 methods of implant deviation analysis was obtained.

CONCLUSIONS

The partially guided technique was less accurate than the fully guided technique for immediate implant placement into fresh sockets. A moderate concordance was observed between cone beam computed tomography and digital scanning analyses, suggesting that more studies are required to validate and to define the most reliable method of measuring implant deviation.

Cost and effectiveness of 3-dimensionally printed model using three different printing layer parameters and two resins

STATEMENT OF PROBLEM

When 3-dimensional printing casts, the operator can change the type of resin and the printing layer thickness, reducing the fabrication time. However, how these parameters affect the accuracy of 3-dimensionally printed casts is unknown.

PURPOSE

The purpose of this in vitro study was to evaluate the accuracy of 3-dimensionally printed casts by using a stereolithography (SLA) 3-dimensional printer (Forms2) with 3 different layer thickness (25, 50, and 100 μm) and 2 different resins (Gray and Cast) and by comparing the time to obtain each cast.

MATERIAL AND METHODS

One master cast was scanned, and a single file was printed several times. The printed casts were then scanned by using a laboratory scanner. The standard tessellation language (STL) files provided by the laboratory scanner were superimposed and compared by using a software program (Geomagic Control; 3D Systems). The 2-way ANOVA test was used for the trueness evaluation, followed by the Tukey test to identify differences among the groups (α=.05).

RESULTS

No statistically significant differences in accuracy were found among the 3 different layers for either resin (P>.05). Printing time doubled as layer thickness decreased.

CONCLUSIONS

This study showed that when printing casts, the fastest printing settings can be used without losing accuracy and that the laboratory digital workflow can be accelerated with selection of the resin and cast layer, as the type of resin and layer thickness did not influence the quality of the casts.

Survival and prosthetic complications of monolithic ceramic implant-supported single crowns and fixed partial dentures: A systematic review with meta-analysis

STATEMENT OF PROBLEM

Monolithic ceramic implant-supported restorations have been used to rehabilitate partially edentulous patients. However, knowledge of the survival and prosthetic complications of single crowns (SCs) and fixed partial dentures (FPDs) is limited.

PURPOSE

The purpose of this systematic review with meta-analysis was to evaluate the clinical performance of monolithic ceramic implant-supported SCs and FPDs in terms of survival and prosthetic complication rates.

MATERIAL AND METHODS

The systematic review was registered on the prospective register of systematic reviews (PROSPERO) (CRD42017078568). Five electronic databases were independently searched by 2 authors for articles published until May 2022. In addition, a hand search was performed in the nonpeer-reviewed literature, specific journals, and reference lists of included articles. A single-arm meta-analysis was performed by using the R program. The risk of bias and quality were assessed using the Cochrane risk of bias tools and the Newcastle-Ottawa scale.

RESULTS

Twenty-eight studies were included in the quantitative synthesis. A total of 1298 monolithic ceramic implant-supported restorations (1116 SCs and 182 FPDs) were evaluated in 1193 participants, with a median observation time of 24 months (range: 12 to 72 months). Meta-analysis indicated the proportion of failures and prosthetic complication rates of 2% (95% confidence interval [CI]: 1% to 4%) for SCs. No difference was observed for monolithic zirconia and lithium disilicate SCs. In the FPDs, only monolithic zirconia was considered, with 1 failure reported totaling the proportion of failures of 0% (0% to 1%) and complication rates of 4% (0% to 12%). The most complications reported for both types of restorations were screw loosening, debonding, and minor chipping and were considered repairable. The included studies showed a low risk of bias and good quality.

CONCLUSIONS

The use of monolithic ceramic implant-supported SCs, independent of ceramic material, and monolithic zirconia implant-supported FPDs should be considered an effective and safe treatment option because of favorable short-term survival and low prosthetic complications. However, additional well-conducted studies with a longer-term follow-up and direct comparison between veneered restorations are recommended to reassess clinical performance.

Accuracy of conventional and 3D printed casts for partial fixed prosthesis

PURPOSE

To evaluate and compare the accuracy of conventional and 3D-printed casts using five different 3D printers.

MATERIALS AND METHODS

In the control group (CG group, n = 5), five conventional impressions using light- and heavy-body polyvinyl siloxane were obtained from the master model, resulting in five stone models. In the test groups, five different scans were performed by a well-trained and experienced clinician using a TRIOS intraoral scanner. All data were exported as an STL file format, processed, and sent to five 3D printers. Five casts were manufactured in each group: SG (CARES P20, Straumann); FG (Form 2, Formlabs); WG (Duplicator 7, Wanhao); ZG (Zenith D, Zenith); and MG (Moonray S100, Moonray). Measurements of the accuracy (trueness and precision) of the casts obtained from conventional elastomeric impressions and 3D-printing methods were accomplished using a 3D analysis software (Geomagic Control).

RESULTS

The FG group showed the lowest values for trueness (closer to real dimensions), which were similar to the SG group only (P > .05). Groups MG, WG, and ZG presented higher values and were similar compared to each other. Data on precision demonstrated that all 3D-printed groups showed lower values for precision (smaller deviation) when compared to the control group.

CONCLUSION

The trueness depends on the chosen 3D printer. All of the tested 3D printers were more precise than cast models obtained from conventional elastomeric impressions.

PSIX-2 Residual Effect of Narasin on Ruminal Fermentation Characteristics in Steers

This study aimed to evaluate the effect of narasin withdrawal on steers ruminal fermentation characteristics. Nellore steers [n = 30; initial body weight (BW) = 281 ± 21 kg] cannulated at the rumen were assigned to individual pens in a randomized complete block design according to their initial shrunk BW. The trial lasted 156 days, divided into 2 periods. The first period lasted 140 days and consisted of the daily supply of narasin. In the second period (last 16 days) the animals were not supplemented with narasin, when the residual effect of the additive was evaluated. The diet was composed by 99% haylage Tifton-85, and 1% concentrate used as a delivery vehicle for narasin. The experimental diets were: 1) no feed additives (CON); 2) 13 mg of narasin/kg of DM (N13); 3) 20 mg of narasin/kg of DM (N20). The dry matter intake (DMI) was evaluated daily and the ruminal fluid was obtained on day 0, 1, 3, 5, 8 and 16 after narasin withdrawal. The data were analyzed using the MIXED procedure, and the effect was considered significant when P ≤ 0.05. The DMI was not affected after narasin withdrawal (P ≥ 0.27). There was a treatment and day interaction after narasin removal for the molar ratio of acetate (P &lt; 0.01), propionate (P &lt; 0.01), ac:prop ratio (P &lt; 0.01) and ammonia nitrogen (P = 0.03). The inclusion of narasin linearly reduced acetate (P &lt; 0.01), increased propionate (P ≤ 0.04), and linearly decreased the ac:prop ratio (P &lt; 0.01) up to 5 days after narasin withdrawal. Narasin linearly decreased ammonia nitrogen up to 1 day after withdrawal (P &lt; 0.01). It is concluded that use of narasin results in a residual effect on the rumen fermentation process after removal of the additive from the diets.

Assessment of Deviations of Implants Installed with Prototyped Surgical Guide and Conventional Guide: In Vitro Study

OBJECTIVE

 The study aimed to assess the angular and linear deviations of implants installed in mannequins aided by surgical guides produced with the techniques of dual tomography (DT), model-based tomography (MT), and nonprototyped guide.

MATERIALS AND METHODS

 Implants were installed in mannequins of a partially edentulous maxilla and divided into three groups: Group C (n = 20), implants installed using the conventional technique with flap opening and conventional guide; Group DT (n = 20), implants installed using guided surgery with the dual tomography technique; and Group MT (n = 20), implants installed using the model-based tomography technique. After implant installation, the mannequin was subjected to a computed tomography (CT) to measure the linear and angular deviations of implant positioning relative to the initial planning on both sides.

RESULTS

 There was a higher mean angular deviation in group C (4.61 ± 1.21, p ≤ 0.001) than in groups DT (2.13 ± 0.62) and MT (1.87 ± 0.94), which were statistically similar between each other. Similarly, the linear deviations showed group C with the greatest discrepancy in relation to the other groups in the crown (2.17 ± 0.82, p = 0.007), central (2.2 ± 0.77, p = 0.004), and apical (2.34 ± 0.8, p = 0.001) regions.

CONCLUSION

 The techniques of DT and MT presented smaller angular and linear deviations than the conventional technique with the nonprototyped guide. There was no difference between the two-guided surgery techniques.

Does guided level (fully or partially) influence implant placement accuracy at post-extraction sockets and healed sites? An in vitro study

OBJECTIVES

The aim of this study is to evaluate the effect of guide level on the accuracy of static computer-aided implant surgery (sCAIS) at post-extraction sockets and healed sites.

MATERIALS AND METHODS

A total of 30 duplicate dental models, with 300 potential implant sites, were used. All the models were equally randomized into three groups: fully guided (FG, n = 100), partially guided (PG, n = 100), and free handed (FH, n = 100) surgeries. After implant placement, the mean global, horizontal, depth, and angular deviations between the virtually planned and actual implant positions were measured automatically by a Python script within software Blender.

RESULTS

Both FG and PG surgeries showed significantly higher accuracy than FH surgery at post-extraction sockets and healed sites. In both sCAIS groups, there were nearly 50% more deviations from implants placed at sockets than those from delayed placement. For the immediate implant placement, the accuracy of sCAIS was significantly affected by the level of guidance. The FG group exhibited lower deviations than the PG group, with a significant difference in coronal global and horizontal deviations (p < .05). For the healed sites, two guided groups exhibited similar outcomes (p > .05).

CONCLUSIONS

sCAISs provide more accuracy than the free-handed approach in position transferring from planning to a model simulation. Full guidance can significantly increase the accuracy, especially at post-extraction sites.

CLINICAL RELEVANCE

Guided protocols showed significantly higher accuracy than free-handed surgery regardless of implantation timing, but both had nearly 50% more deviations in immediate implant placement.

Nanoscale hybrid implant surfaces and Osterix-mediated osseointegration

Endosseous implant surface topography directly affects adherent cell responses following implantation. The aim of this study was to examine the impact of nanoscale topographic modification of titanium implants on Osterix gene expression since this gene has been reported as key factor for bone formation. Titanium implants with smooth and nanoscale topographies were implanted in the femurs of Osterix-Cherry mice for 1-21 days. Implant integration was evaluated using scanning electron microscopy (SEM) to evaluate cell adhesion on implant surfaces, histology, and nanotomography (NanoCT) to observe and quantify the formed bone-to-implant interface, flow cytometry to quantify of Osterix expressing cells in adjacent tissues, and real-time PCR (qPCR) to quantify the osteoinductive and osteogenic gene expression of the implant-adherent cells. SEM revealed topography-dependent adhesion of cells at early timepoints. NanoCT demonstrated greater bone formation at nanoscale implants and interfacial osteogenesis was confirmed histologically at 7 and 14 days for both smooth and nanosurface implants. Flow cytometry revealed greater numbers of Osterix positive cells in femurs implanted with nanoscale versus smooth implants. Compared to smooth surface implants, nanoscale surface adherent cells expressed higher levels of Osterix (Osx), Alkaline phosphatase (Alp), Paired related homeobox (Prx1), Dentin matrix protein 1 (Dmp1), Bone sialoprotein (Bsp), and Osteocalcin (Ocn). In conclusion, nanoscale surface implants demonstrated greater bone formation associated with higher levels of Osterix expression over the 21-day healing period with direct evidence of surface-associated gene regulation involving a nanoscale-mediated osteoinductive pathway that utilizes Osterix to direct adherent cell osteoinduction.

Early soft tissue changes following implant placement with or without soft tissue augmentation using a xenogeneic cross-link collagen scaffold: A volumetric comparative study

OBJECTIVE

Soft tissue augmentation (STA) at implant sites has the potential of improving peri-implant health, esthetics, and marginal bone level stability. The present study aimed at evaluating the volumetric changes occurring following implant placement in sites that received STA compared to non-augmented sites.

METHODS

A total of 26 subjects received a dental implant in a posterior edentulous site. Simultaneous STA with a xenogeneic cross-linked collagen scaffold was performed for the first 13 patients, while the remaining subjects served as the negative control. An intraoral optical scanner was used at baseline and at 12 weeks to generate digital models.

RESULTS

The mean volume (Vol) gain of the test group was 38.43 mm³ , while a mean Vol of -16.82 mm³ was observed for the control group (p < 0.05). The mean thickness of the reconstructed volume (ΔD) was 0.61 and -0.24 mm, for the test and control group, respectively (p < 0.05). Higher linear dimensional changes were observed for the test group (p < 0.05), while no significant differences were observed in terms of keratinized mucosa width and pocket depth changes between the two groups.

CONCLUSIONS

Simultaneous STA with xenogeneic collagen scaffold obtained statistically significant higher volumetric outcomes compared to the non-augmented group.

CLINICAL SIGNIFICANCE

STA at the time of implant placement using a xenogeneic cross-linked collagen scaffold can prevent remodeling of the ridge during the first 12 weeks, as compared to non-grafted implant sites.

Intraoral scanning reduces procedure time and improves patient comfort in fixed prosthodontics and implant dentistry: a systematic review

OBJECTIVES

The primary aim of this systematic review was to evaluate whether intraoral scanning (IOS) is able to reduce working time and improve patient-reported outcome measures (PROMs) compared to conventional impression (CI) techniques, taking into account the size of the scanned area. The secondary aim was to verify the effectiveness of IOS procedures based on available prosthodontic outcomes.

MATERIALS AND METHODS

Electronic and manual literature searches were performed to collect evidence concerning the outcomes of IOS and CI performed during the treatment of partially and complete edentulous patients for tooth- or implant-supported restorations. Qualitative analysis was conducted to evaluate the time efficiency and PROMs produced by the two different techniques. Clinical prosthodontic outcomes were analyzed among the included studies when available.

RESULTS

Seventeen studies (9 randomized controlled trials and 8 prospective clinical studies) were selected for qualitative synthesis. The 17 included studies provided data from 430 IOS and 370 CI performed in 437 patients. A total of 7 different IOS systems and their various updated versions were used for digital impressions. The results demonstrated that IOS was overall faster than CI independent of whether quadrant or complete-arch scanning was utilized, regardless of the nature of the restoration (tooth or implant supported). IOS was generally preferred over CI regardless of the size of the scanned area and nature of the restoration (tooth- or implant-supported). Similar prosthodontic outcomes were reported for workflows implementing CI and IOS.

CONCLUSIONS

Within the limitations of this systematic review, IOS is faster than CI, independent of whether a quadrant or complete arch scan is conducted. IOS can improve the patient experience measured by overall preference and comfort and is able to provide reliable prosthodontic outcomes.

CLINICAL RELEVANCE

Reduced procedure working time associated with the use of IOS can improve clinical efficiency and the patient experience during impression procedures. Patient-reported outcome measures (PROMs) are an essential component of evidence-based dental practice as they allow the evaluation of therapeutic modalities from the perspective of the patient. IOS is generally preferred by patients over conventional impressions.

Personalized and Defect-Specific Antibiotic-Laden Scaffolds for Periodontal Infection Ablation

Periodontitis compromises the integrity and function of tooth-supporting structures. Although therapeutic approaches have been offered, predictable regeneration of periodontal tissues remains intangible, particularly in anatomically complex defects. In this work, personalized and defect-specific antibiotic-laden polymeric scaffolds containing metronidazole (MET), tetracycline (TCH), or their combination (MET/TCH) were created via electrospinning. An initial screening of the synthesized fibers comprising chemo-morphological analyses, cytocompatibility assessment, and antimicrobial validation against periodontopathogens was accomplished to determine the cell-friendly and anti-infective nature of the scaffolds. According to the cytocompatibility and antimicrobial data, the 1:3 MET/TCH formulation was used to obtain three-dimensional defect-specific scaffolds to treat periodontally compromised three-wall osseous defects in rats. Inflammatory cell response and new bone formation were assessed by histology. Micro-computerized tomography was performed to assess bone loss in the furcation area at 2 and 6 weeks post implantation. Chemo-morphological and cell compatibility analyses confirmed the synthesis of cytocompatible antibiotic-laden fibers with antimicrobial action. Importantly, the 1:3 MET/TCH defect-specific scaffolds led to increased new bone formation, lower bone loss, and reduced inflammatory response when compared to antibiotic-free scaffolds. Altogether, our results suggest that the fabrication of defect-specific antibiotic-laden scaffolds holds great potential toward the development of personalized (i.e., patient-specific medication) scaffolds to ablate infection while affording regenerative properties.

Analysis In Vivo of Bone Modulation in Hydrophilic and Hydrophobic Titanium Implant Surfaces

PURPOSE

To evaluate whether a hydrophilic surface treatment compared with a hydrophobic implant surface can enhance osseointegration by analysis of calcium deposition, bone-to-implant contact (BIC), bone volume (BV), and upregulation of genes involved in bone formation.

MATERIALS AND METHODS

Sixty implants (n = 60) with a hydrophobic (SAE) or hydrophilic (SAE-HD) surface treatment were placed bilaterally in each femur of 3-month-old male mice (n = 30). Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) were utilized for quantifying the presence of calcium on the implant surface 7 days after implant placement. The specimens were analyzed after 14 and 21 days for BIC and BV by Nano CT scanning followed by histologic evaluation. Additionally, 1, 3, and 7 days postsurgery, femurs were harvested, implants were explanted, and gene expression (Sp7, Bsp, Sost, IL-1α, and IL-10) by quantitative real-time polymerase chain reaction was studied. Moreover, implants were characterized for surface roughness area. Data were statistically analyzed with two-way analysis of variance (ANOVA) followed by the Tukey test (P < .05).

RESULTS

The amount of calcium on the surface was higher for SAE-HD after 7 days. Nano CT revealed significantly more BV in the SAE-HD than the SAE surface. The histologic assessment showed increased BIC in SAE-HD in comparison to SAE. SAEHD showed significantly increased levels of genes involved in bone formation.

CONCLUSION

Both surfaces were able to modulate bone responses toward osteoblast differentiation. SAE-HD presented a better response compared with SAE.

Flapless Guided Implant Surgeries Compared with Conventional Surgeries Performed by Nonexperienced Individuals: Randomized and Controlled Split-Mouth Clinical Trial

PURPOSE

The study aimed to evaluate the outcomes of flapless guided surgery related to surgery, patient, operator, assistant, and advisor, comparing it with conventional surgery performed by undergraduate students who had never placed implants in patients.

MATERIALS AND METHODS

A randomized controlled split-mouth clinical trial was carried out. Ten patients with bilateral mandibular posterior tooth loss received an implant on each side with conventional flap surgery or flapless guided surgery that was performed by undergraduate students. Surgery time, pain, patient satisfaction, quantity of consumed medications, time of procedure, ease of procedure, anxiety, and stress were assessed.

RESULTS

Conventional surgery showed statistically significantly inferior results compared with flapless guided surgery in terms of procedure time (56 minutes, 36 seconds ± 8 minutes, 38 seconds vs 30 minutes, 1 second ± 6 minutes, 2 seconds), consumption of analgesic medications (49 tablets vs 15 tablets), intraoperative (1.75 ± 1.56 vs 0.65 ± 0.64) and postoperative pain (4.62 ± 2.17 vs 1.17 ± 0.72), and operator anxiety (4.76 ± 1.66 vs 3.47 ± 1.50), respectively.

CONCLUSION

Flapless guided implant surgeries performed by individuals with no previous clinical experience showed reduced surgery time and delivered better patient-reported outcomes both in the intraoperative and postoperative periods; reduced medication consumption; and showed better results in the operator and assistant perspectives.

A fully digital approach for implant fixed complete dentures: A case report

INTRODUCTIONS

Intraoral scanner has been widely used for implant impression in partially edentulous cases; however, its accuracy in the impression of full-arch implant is still questionable.

CLINICAL REPORT

This clinical report presents a technique to check the accuracy of intraoral scanning for complete-arch implant restorations using an implant index cast (The Glossary of Prosthodontic Terms 9th Edition) and a three-dimensional printed cast. A clinical case of immediate loading on a maxillary edentulous patient illustrates the application of an implant index cast in implant fixed complete dentures (IFCDs).

DISCUSSION

The implant index cast was fabricated based on the immediate interim prosthesis and provides effective control of the fit of scanned files and printed models. Therefore, this approach allows a more predictable and accurate fit of the final prosthesis.

CLINICAL SIGNIFICANCE

In this article, we present a technique to check the accuracy of the final prosthesis without the need for a conventional impression and final cast in a digital workflow. This proposed approach is demonstrated through a case report of a maxillary edentulous patient restored with immediate loaded IFCDs.

The Impact of Surgical Guide Fixation and Implant Location on Accuracy of Static Computer-Assisted Implant Surgery

PURPOSE

To evaluate the accuracy of static computer-assisted implant surgery (sCAIS) for tooth-supported free-end dental implantation with the aid/and without the aid of fixation pins to secure the surgical template through comparison between planned, 3D printed guide position and placement implant position.

MATERIALS AND METHODS

Thirty-two duplicated maxillary resin models were used in the present in vitro study. Digital planning was performed and fabrication of a surgical template that allowed implant placement on the distal extension edentulous site of the model (maxillary left side). A first optical scan was performed after fitting the surgical template on the model to assess the deviation at the surgical guide level. After placing implants in the model using the surgical guide, scan bodies were attached to the implants, and a second scan was performed to record the position of placed implants. The digital representations were later superimposed to the pre-operative scan and measurements of implant deviations were performed. Global (coronal and apical), horizontal (coronal and apical), depth and angular deviations were recorded between planned implant position, guide position, and placement implant position. Three-way ANOVA was used to compare implant location (#13, 14, and 15), fixation pin (with or without pin), and guide comparison (planned, guided, and placement).

RESULTS

Final implant placement based on the digital plan and based on the 3D printed guide were very similar except for depth deviation. Use of fixation pin had a statistically significant effect on the depth and angular deviation. Overall, without fixation pins and based on guide versus placement, mean global coronal (0.88 ± 0.36 mm), horizontal coronal (0.55 ± 0.32 mm), and apical (1.44 ± 0.75 mm), and angular deviations (4.28 ± 2.01°) were similar to deviations with fixation pins: mean global coronal (0.88 ± 0.36 mm); horizontal coronal (0.67 ± 0.22 mm) and apical (1.60 ± 0.69 mm); and angular deviations (4.53 ± 2.04°). Horizontal apical without pins (1.63 ± 0.69 mm) and with fixation pins (1.72 ± 0.70 mm) was statistically significant (p = 0.044). Depth deviation without pins (-0.5 ± 0.5 mm) and with fixation pins (-0.16 ± 0.62 mm) was also statistically significant (p = 0.005). Further analysis demonstrated that the final sleeve position on the 3D printed guide was on average 0.5 mm more coronal than the digital plan.

CONCLUSIONS

The use of surgical guides with or without fixation pins can provide clinically acceptable outcomes in terms of accuracy in implant position. There was a statistically significant difference in the accuracy of implant position when utilizing fixation pins only for horizontal apical and depth deviation. Additionally, a statistically significant difference between the planned and the 3D printed surgical guide when considering the sleeve position was detected.

Potential of Using an Implant Fixture as a Ridge Expander for Minor Ridge Augmentation: An Ex Vivo Randomized Controlled Study

To place implants with minimal trauma is what the patient and clinician are seeking. Hence, the aim of this study was to quantify the potential of using an implant fixture as a ridge expander in an underprepared osteotomy. Thirty-eight edentulous sites in 12 human cadaver jaws with ridge widths ranging from 4 to 6 mm and with type 3 or type 4 bone density were randomly assigned into 2 groups. In the ridge expansion group (RE), each osteotomy was drilled to a width of 2.8 mm and depth of 11.5 mm. In the non-ridge expansion (NE) control group, each osteotomy was drilled to a width of to 3.4 mm and depth of 11.5 mm. A 3.7 mm × 11.5 mm tapered implant was inserted into each site. The ridge width before (RW1) and after (RW2) implant placement as well as the buccal plate thickness (BPT) post-insertion were measured and analyzed. In the RE group, the average RW1 and RW2 were 4.69 ± 0.45 mm and 5.54 ± 0.35 mm, respectively, corresponding to a statistically significant ridge expansion of 0.85 mm (P < .01). In the NE group, no ridge width gain was observed (RW1: 4.79 ± 0.40 mm, RW2: 4.88 ± 0.42 mm). Compared to NE, RE resulted in a statistically greater BPT (1.08 ± 0.28 mm after RE vs 0.71 ± 0.37 mm after NE, P < .001). Our study determined that it was physically possible to widen a ridge by an average of 0.85 mm by osteotomy underprepation in ridge with type 3 or type 4 bone density, which effectively turned the implant upon insertion into a ridge expander. The physiological consequences of this method of ridge expansion in a living person must be established before drawing further conclusions about its clinical indications or efficacy.

Dual Digitally Guided Crown Lengthening in Esthetic Area Compromised by Disharmonic Implant Crown

INTRODUCTION

A disharmonious smile results from excessive gingival exposure or gingival margin misalignment is a frequent finding in patients. The most common cause is altered passive eruption; however, in the case presented here, the esthetics of the smile is compromised also due to an inadequate implant placement and crown fabrication.

CASE PRESENTATION

This case presented a combination of altered passive eruption and a buccally as well as deeply placed implant crown (#10) that led to disproportionate dimensions of an upper lateral incisor. Dual digitally guided crown lengthening surgical procedure for teeth #5 to #12 was performed aiming a better harmony of the smile. Treatment also included placement of tooth veneers and re-made of implant crown. A pleasant smile with appropriate colors and proportions was achieved. All esthetic and periodontal health parameters were maintained throughout the follow-up period (1 year).

CONCLUSION

The use of dual digitally guided crown lengthening help to accomplish precision and stability of esthetic outcome, as it guides for both, bone and soft tissue removal. Particularly, in challenging cases with high esthetic demand and complicated factors present, such as the case presented here, the digital approach provides tools to attain excellent treatment outcome.

Does the use of an adhesive improve conventional complete dentures? A systematic review of randomized controlled trials

STATEMENT OF PROBLEM

A consensus on whether the use of a complete-denture adhesive provides a clinical benefit remains unclear.

PURPOSE

The purpose of this systematic review of randomized controlled trials was to evaluate the use of adhesive in complete dentures in terms of retention and stability, patient-reported outcomes measures, and masticatory performance.

MATERIAL AND METHODS

A search was performed in PubMed, Web of Science, and Cochrane Library for articles up to October 2020. The Cochrane collaboration tool was used to analyze the risk of bias. The grading quality of evidence and strength of recommendations (GRADE) tool was used to assess the certainty of the evidence.

RESULTS

Thirteen studies were included with a total of 516 participants with a mean age of 65.5 years. Most studies reported a significant improvement in the retention and stability, patient-reported outcomes measures, and masticatory performance of complete dentures with the use of denture adhesive compared with no-denture adhesive. Newly developed denture adhesives were reported to have promising results. Most studies presented a low risk of bias, but the certainty of the evidence was classified as low to moderate.

CONCLUSIONS

Participants had improved treatment outcomes when using denture adhesives because they significantly improve the retention and stability, patient-reported outcomes measures, and masticatory performance. However, further high-quality studies are needed to confirm these results with newly developed denture adhesives.

Digital Immediate Complete Denture for a Patient with Rhabdomyosarcoma: A Clinical Report

Fabricating an immediate complete denture can be very challenging in some clinical situations. This clinical report describes a digital workflow to fabricate a printed maxillary immediate complete denture for a patient with a severely compromised maxilla. Digital data obtained by using an intraoral scanner was utilized to reconstruct the three-dimensional (3D) image of the jaws at the desirable vertical dimension of occlusion. After performing the virtual teeth extraction and alveoloplasty, the denture base and teeth were designed. The resulting data were exported to a 3D printer for denture fabrication and the 3D printed (additively manufactured) denture was successfully inserted immediately after the surgery. After initial healing and confirmation of good retention and function, a new printed denture was fabricated by digitally duplicating the relined denture maintaining the same teeth positions but adjusting the base to a new intraoral scan of the healed ridge.

Hydrophilic titanium surface modulates early stages of osseointegration in osteoporosis

OBJECTIVE

Using a mouse osteoporotic model, this study aimed to determine the influence of hydrophilic titanium surfaces on gene expression and bone formation during the osseointegration process.

BACKGROUND

Based on the previous evidence, it is plausible to assume that osteoporotic bone has a different potential of bone healing. Therefore, implant surface modification study that aims at enhancing bone formation to further improve short- and long-term clinical outcomes in osteoporosis is necessary.

MATERIAL AND METHODS

Fifty female, 3-month-old mice were included in this study. Osteoporosis was induced by ovariectomy (OVX, test group) in 25 mice. The further 25 mice had ovaries exposed but not removed (SHAM, control group). Seven weeks following the ovariectomy procedures, one customized implant (0.7 × 8 mm) of each surface was placed in each femur for both groups. Implants had either a hydrophobic surface (SAE) or a hydrophilic treatment surface (SAE-HD). Calcium (Ca) and phosphorus (P) content was measured by energy-dispersive X-ray spectroscopy (EDS) after 7 days. The femurs were analyzed for bone-to-implant contact (BIC) and bone volume fraction (BV) by nano-computed tomography (nano-CT) after 14 and 28 days. Same specimens were further submitted to histological analysis. Additionally, after 3 and 7 days, implants were removed and cells were collected around the implant to access gene expression profile of key osteogenic (Runx2, Alp, Sp7, Bsp, Sost, Ocn) and inflammatory genes (IL-1β, IL-10, Tnf-α, and Nos2) by qRT-PCR assay. Statistical analysis was performed by ANOVA and paired t test with significance at P < .05.

RESULTS

The amount of Ca and P deposited on the surface due to the mineralization process was higher for SAE-HD compared to SAE on the intra-group analysis. Nano-CT and histology revealed more BV and BIC for SAE-HD in SHAM and OVX groups compared to SAE. Analysis in OVX group showed that most genes (ie, ALP, Runx2) involved in the bone morphogenetic protein (BMP) signaling were significantly activated in the hydrophilic treatment.

CONCLUSION

Both surfaces were able to modulate bone responses toward osteoblast differentiation. SAE-HD presented a faster response in terms of bone formation and osteogenic gene expression compared to SAE. Hydrophilic surface in situations of osteoporosis seems to provide additional benefits in the early stages of osseointegration.

Electrical stimulation enhances early palatal wound healing in mice

BACKGROUND/OBJECTIVE

Electrical stimulation (ES) has been used to treat chronic wound and other clinical applications, showing favorable results in wound closure. It was hypothesized that ES can present a positive effect on oral mucosa healing. The aim of this study was to investigate the effects of ES during the palatal mucosa early healing process in Swiss mice.

METHODS

Ninety animals were divided into two groups: Control (C; n = 45), which received Sham ES applications, and Test (ES; n = 45), which received ES (100 μA; 9 kHz; 660 mVpp) once a day for 3 days. A full thickness wound was performed with a 1.5 mm diameter biopsy punch in the hard palate. Histologically, the following parameters were evaluated: palatal wound closure and epithelial and connective wound edge distance (EED and CED). Furthermore, IL-1β, IL-6, IL-10 TNF-α, and VEGF cytokine levels were evaluated by multiplex assay. The percentage of collagen fibers was assessed using the polarization method and the Smad proteins using the immunofluorescence method.

RESULTS

Palatal wound closure presented a significant reduction on day 5 in the ES group (p = 0.01). Additionally, both EED and CED were shorter for all time points in the ES group (p < 0.05), and the inflammatory markers IL-6, IL-10, TNF-α, and VEGF were reduced (p < 0.05). There were no differences in collagen fibers and phospho-Smad2 between the groups.

CONCLUSION

ES had a positive effect on early palatal wound closure outcomes, as well as on inflammatory markers.

Volumetric changes at implant sites: A systematic appraisal of traditional methods and optical scanning-based digital technologies

AIM

To evaluate techniques for assessing soft tissue alterations at implant sites and compare the traditionally utilized methods to the newer three-dimensional technologies emerging in the literature.

MATERIALS AND METHODS

A comprehensive search was performed to identify interventional studies reporting on volumetric changes at implant sites following different treatments.

RESULTS

Seventy-five articles were included the following: 30 used transgingival piercing alone, one utilized calliper, six with ultrasonography, six on cone-beam computed tomography, and 32 utilized optical scanning and digital technologies. Optical scanning-based digital technologies were the only approach that provided 'volumetric changes,' reported as volumetric variation in mm³ , or the mean distance between the surfaces/mean thickness of the reconstructed volume. High variability in the digital analysis and definition of the region of interest was observed. All the other methods reported volume variation as linear dimensional changes at different apico-coronal levels. No studies compared volumetric changes with different approaches.

CONCLUSIONS

Despite the emergence of optical scanning-based digital technologies for evaluating volumetric changes, a high degree of variation exists in the executed workflow, which renders the comparison of study results not feasible. Establishment of universal guidelines could allow for volumetric comparisons among different studies and treatments.

Impact of mucosal phenotype on marginal bone levels around tissue level implants: A prospective controlled trial

BACKGROUND

The aim of this 1-year prospective clinical trial was to compare clinical parameters and marginal bone levels (MBLs) around tissue level implants with a partially smooth collar between patients with thin (≤2 mm) and thick (>2 mm) vertical mucosal phenotypes.

METHODS

Thirty patients needing a single dental implant were recruited and allocated to thin (n = 14) or thick (n = 16) phenotype groups. Post-restoration, clinical (probing depth, recession, width of keratinized mucosa, bleeding on probing, suppuration, implant mobility, plaque index, and gingival index) and radiographic bone level measurements were recorded at different timepoints for 1 year.

RESULTS

Twenty-six patients (13 per group) completed the 1-year examination. No implants were lost (100% survival rate). There were no significant differences (P >0.05) between thin and thick vertical mucosal phenotypes for any clinical parameter or for the radiographic MBL.

CONCLUSIONS

Tissue level implants at 1 year of function placed in thin vertical mucosa achieved similar clinical parameters and radiographic MBLs as those in thick tissue. The formation of the peri-implant supracrestal tissue height plays a key role in MBL than mucosal thickness in tissue level implant.

Covalent Attachment of P15 Peptide to Ti Alloy Surface Modified with Polymer to Enhance Osseointegration of Implants

Titanium (Ti) and its alloys are used in orthopedic and dental implants due to their excellent physical properties and biocompatibility. Although Ti exhibits superior osteoconductive properties compared to those of polymer-based implants, improved bone-on growth properties are required for enhanced surgical outcomes and improved recovery surgical interventions. Herein, we demonstrate a novel surface modification strategy to enhance the osteoconductivity of Ti surfaces through the grafting-from procedure of a reactive copolymer via surface-initiated atom transfer radical polymerization (SI-ATRP). Then, postpolymerization conjugation of the P15 peptide, an osteoblast binding motif, was successfully carried out. Subsequent in vitro studies revealed that the surface modification promoted osteoblast attachment on the Ti discs at 6 and 24 h. Moreover, mineral matrix deposition by osteoblasts was greater for the surface-modified Ti than for plain Ti and P15 randomly absorbed onto the Ti surface. These results suggest that the strategy for postpolymerization incorporation of P15 onto a Ti surface with a polymer interface may provide improved osseointegration outcomes, leading to enhanced quality of life for patients.

Validation of a method of quantifying 3D leakage in dental restorations

STATEMENT OF PROBLEM

A reliable and validated protocol for nondestructive analysis of the entire restorative interface that could be applicable in studies assessing the adaptation of direct and indirect restorations is lacking.

PURPOSE

The purpose of this in vitro study was to validate a 3D protocol for microleakage assessment in class II mesio-occluso-distal (MOD) cavities restored with composite resin.

MATERIAL AND METHODS

Sixteen human third molars received standardized class II MOD preparations with cervical margins located 1 mm apical to the cemento-enamel junction. The specimens were restored with Filtek Bulk Fill Posterior (FBP) or Filtek Bulk Fill Flowable (FBF) and submitted to 10 000 thermocycles (5 °C and 55 °C with a 30-second dwell time at each temperature and 5-second transfer time). The specimens were scanned with microcomputed tomography (μCT) before and after immersion in 50% ammoniacal silver nitrate solution for 12 hours. Scanned data were processed, and the 3D amount of infiltrated silver nitrate was analyzed through the entire adhesive interface. In addition, the linear distance of silver nitrate infiltration was assessed using 3 axial images obtained from each specimen proximal box (2D analysis). Data were tested for homogeneity by using the Shapiro-Wilk test and evaluated by using 1-way ANOVA, followed by the post hoc Tukey HSD test (α=.05).

RESULTS

FBP showed significantly lower leakage than FBF for both 2D and 3D analyses. A low correlation was observed between the assessment methods.

CONCLUSIONS

Three-dimensional analysis of microleakage using μCT is a predictable and more reliable method for nondestructive and comprehensive analysis of the entire specimen.

In vitro osteogenesis process induced by hybrid nanohydroxyapatite/graphene nanoribbons composites

Carbon nanotubes combine high bend and mechanical strength, which is advantageous for many structural and biomedical purposes. Recently, some biomaterials, based on carbon nanostructures and nanohydroxyapatite (nHAp), have been investigated as bone substitutes in order to improve regeneration. The aim of this study was to access the expression of some RNA transcripts (involved in the process of osteoblast differentiation) by mesenchymal stem cells cultured over different nanocomposite surfaces. A multi-walled carbon nanotube (MWCNT) was firstly grown using chemical vapor deposition and then exfoliated using chemical and oxygen plasma treatments to obtain graphene nanoribbons (GNR). The hybrid composites nHAp/GNR were prepared using the wet method assisted by ultrasound irradiation with different amounts of GNR (1.0, 2.0 and 3.0 wt %). Five groups were tested in cell cultures. Group 1: synthesized nHAp; Group 2: synthesized GNR; Group 3: nHAp and 1.0% of GNR; Group 4: nHAp and 2.0% of GNR and group 5: nHAp and 3.0% of GNR. Real time reverse transcription polymerase chain reactions were performed, and all data was submitted to Kruskal Wallis and Dunn tests, at a significance level of 5%. As a result, three nanocomposites with different proportions of GNR were successfully produced. After cell culture, the expression of osteogenic genes demonstrated no significant differences among the groups and periods. However, bone morphogenetic protein II (BMP II), integrin binding sialoprotein (IBSP), and Osterix highest expressions were observed in the group containing 3.0% of GNR. In conclusion, our hybrid composites may be useful in bone interventions requiring mesenchymal stem cell differentiation into osteoblasts for healing.

The Role of MicroRNAs in the Osseointegration Process

Regulation of cellular function is key to bone formation at endosseous implant surfaces. Osseointegration was "discovered" prior to the discovery of genetic regulation of osteoinduction or characterization of mesenchymal stem cells. Understanding osseointegration in cellular and molecular terms has benefited from genome-wide characterization of this healing process at endosseous implants in vivo. These in vivo studies also demonstrate a role for osteoprogenitor cells and cells involved in immune regulation and osteoclastogenesis. The identification of noncoding RNAs, including microRNAs, as key factors controlling cell function has highlighted the role of microRNAs in cell differentiation control. This review summarizes emerging in vitro and in vivo investigations emphasizing the role of microRNAs in the osseointegration process. Many microRNAs influence key osteoinductive pathways controlling Osterix, runt-related transcription factor 2 (RUNX2), and bone morphogenetic protein (BMP)/SMAD function. Others influence the monocyte/macrophage lineage. While significant progress has been made in elucidating the mechanisms associated with the regulation of surface modulation of osteoblast differentiation by microRNAs, knowledge gaps are evident in the identification and characterization of microRNAs linked to osseointegration. Given existing knowledge regarding the varied expression of microRNAs and their role in inflammation, it is important to understand how microRNA expression may influence the process of bone accrual at implant surfaces during osseointegration.

Evaluation of lettuce chloroplast and soybean cotyledon as platforms for production of functional bone morphogenetic protein 2

The bone morphogenetic protein BMP2 plays a crucial role in the formation and regeneration of bone and cartilage, which is critical for maintaining skeletal integrity and bone fracture repair. Because of its important role in osteogenic properties it has been commercially produced for clinical use. Here we report attempts to express human BMP2 using two plant systems (lettuce chloroplast and soybean seeds). The rhBMP2 gene (coding for the 13 kDa active polypeptide) was introduced in two regions of the lettuce chloroplast genome. Two homoplasmic events were achieved and RT-PCR demonstrated that the BMP2 gene was transcribed. However, it was not possible to detect accumulation of rhBMP2 in leaves. Two soybean events were achieved to express a full-length hBMP2 gene (coding for the 45 kDa pro-BMP2) fused with the α-coixin signal peptide, under control of the β-conglycinin promoter. Pro-BMP2 was expressed in the transgenic seeds at levels of up to 9.28% of the total soluble seed protein as determined by ELISA. It was demonstrated that this recombinant form was biologically active upon administration to C2C12 cell cultures, because it was able to induce an osteogenic cascade, as observed by the enhanced expression of SP7 (osterix) and ALPI (alkaline phosphatase) genes. Collectively, these results corroborated our previous observation that soybean seeds provide an effective strategy for achieving stable accumulation of functional therapeutic proteins, such as BMP2.

Polymerization shrinkage, microhardness and depth of cure of bulk fill resin composites

The present in vitro study assessed the polymerization shrinkage/PS, Knoop microhardness/KHN and depth of cure/DC of 9 different resin composites : Filtek Bulk Fill Flowable (FBF), Surefill SDR flow (SDR), Xtra Base (XB), Filtek Z350XT Flowable (Z3F), Filtek Bulk Fill Posterior (FBP), Xtra Fill (SF), Tetric Evo Ceram Bulk Fill (TBF), Admira Fusion Xtra (ADM), and Filtek Z350XT (Z3XT). PS was assessed with a µ-CT machine, scanning 64 mm³ samples (n=8) before and after 20 s curing. KHN and DC were performed with a microhardness tester (n=8 for each group) right after 20 s light curing, with 3 readings per depth at every 0.5 mm. Low viscosity resin composites showed lower KHN values when compared with high viscosity resins. Z3XT showed the highest microhardness among the tested resin composites. Z3XT and Z3F showed lower DC when compared with bulk fill resin composites. All bulk fill resin composites presented depth of cure higher than 4.5 mm and similar or lower PS than conventional resin composites.

Shrinkage stress and elastic modulus assessment of bulk-fill composites

Bulk-fill composites were introduced in dentistry to accelerate clinical procedures while providing adequate outcomes. Concerns regarding the use of bigger composite increments rely on the polymerization shrinkage and shrinkage stress, which may generate gaps on the adhesive interface and result in a reduced success rate. Objective: To evaluate the polymerization shrinkage stress of different bulk-fill resin composites and their elastic modulus. Materials and Methods: Fourteen specimens were made for each of the nine different resin composites (seven with 12 mm³ and seven with 24 mm³): Surefill SDR flow (SDR), X-tra Base (XB), Filtek Bulk Fill Flowable (FBF), Filtek Z350XT Flow (Z3F); Tetric Evo Ceram Bulk Fill (TBF), X-tra Fil (XF), Filtek Bulk Fill (FBP), Admira Xtra Fusion (ADM) and Filtek Z350 XT (Z3XT). Linear shrinkage stress was evaluated for 300 s with the aid of a linear shrinkage device adapted to a Universal Testing Machine. For each composite group, seven additional specimens (2x2x25 mm) were made and Young's modulus was evaluated with a 3-point bending device adapted in a Universal Testing Machine with 0.5 mm/min crosshead speed and 50 KgF loading cell. Results: For 12 mm³ specimens, three-way ANOVA showed that only SDR and TBF generated lower stress after 20 s. Considering 300 s, TBF, SDR, and XF generated the lowest stress, followed by ADM, FBP, XB, and FBF, which were similar to Z3XT. Z3F generated the highest stress values for all time points. Considering 24 mm³ specimens after 20 s, all bulk fill composites generated lower stress than Z3XT, except XB. After 300 s, SDR, FBP, and ADM generated the lowest stress, followed by TBF and XF. For elastic modulus, one-way ANOVA showed that FBF, SDR, Z3F, and ADM presented the lowest values, followed by XB and TBF. FBP, Z3XT, and XF presented the highest elastic modulus among the evaluated composites. Conclusions: Bulk-fill resin composites presented equal to lower shrinkage stress generation when compared to conventional composites, especially when bigger increments were evaluated. Bulk-fill composites showed a wide range of elastic modulus values, but usually similar to “regular” composites.

Modulation of Micro RNA Expression and Osteoblast Differentiation by Nanotopography

PURPOSE

This study evaluated the expression pattern of micro RNAs (miRNAs) on a surface with nanotopography compared with a smooth surface (control).

MATERIALS AND METHODS

Human mesenchymal stem cells (hMSCs) were plated on different surfaces and compared at 3, 7, and 14 days for alkaline phosphatase (ALP) activity, expression of genes (osterix [OSX], runt-related transcription factor 2 [RUNX2], bone morphogenetic protein 2 [BMP2], and ALP), and expression of miRNAs. Western blot was also used to detect osteogenic proteins (BMP2, OSX, and osteocalcin [OCN]). Scanning electron microscopy of cells plated onto the surfaces was obtained.

RESULTS

ALP activity on different surfaces was significantly greater in the nanotopography surface. At day 14, there was a 3.5-fold and a 9-fold increase for the RUNX2 and OSX genes, respectively. BMP2 and ALP also increased by fourfold and sevenfold compared with the control. Protein levels for OSX and BMP2 were also upregulated compared with the control group. Using RNA sequencing technology (RNA-Seq), a total of 117 miRNAs were found to be differentially expressed comparing the control (day 7) with the nanosurface (day 14). Forty-five miRNAs were upregulated, and 72 were downregulated. Several of the miRNAs that were differently expressed regulate osteogenic genes. For example, hsa-miR-135b-5p targets OCN, BSP, RUNX2, COL15A1, and OSX; hsa-miR-122-5p targets OPN; hsa-miR-196a-5p targets BMP4; hsa-miR-26b-5p targets BMP2; and hsa-miR-148b-3p targets OPN.

CONCLUSION

Surfaces with nanotopography have the potential to improve the osseointegration response in order to reduce the osseointegration time and also increase bone formation around the implants, improving areas with low bone quality. Within the limitation of this study, nanotopography surfaces affected MSC differentiation to osteoblasts. Several miRNAs were differentially regulated by surface topography. These miRNAs could be related to the differentiation response to help control the osseointegration process.