Removal of broken abutment screws using ultrasonic tip - a heat development in-vitro study.

BACKGROUND: Dental implants can cause complications, including the loosening of the abutment screw or fracture. However, there is no standardized technique for removing broken abutment screws. This necessitates further research. OBJECTIVE: This study aimed to measure heat generation during screw removal to better understand its implications for dental implant procedures. MATERIAL AND METHODS: The experimental setup involved using synthetic bone blocks and titanium implants. An ultrasonically operated instrument tip was utilized for screw removal. Infrared thermometry was employed for accurate temperature measurement, considering factors such as emissivity and distance. Statistical analysis using linear regression and ANOVA was conducted. RESULTS: The findings revealed an initial rapid temperature increase during the removal process, followed by a gradual decrease. The regression model demonstrated a strong correlation between time and temperature, indicating the heat generation pattern. CONCLUSION: Heat generation during screw removal poses risks such as tissue damage and integration issues. Clinicians should minimize heat risks through an intermittent approach. The lack of a standardized technique requires further research and caution. Understanding the generated heat optimizes implant procedures.

Comparative Mechanical Testing for Digitally Produced Provisional Fixed Partial Dentures vs the Conventional Method: An In Vitro Study

PURPOSE: To examine and compare the fracture strength of implant-cemented fixed partial denture (FPD) prostheses fabricated with digital vs conventional chairside methods. MATERIALS AND METHODS: Three groups of seven specimens each were produced: group A (3D printing); group B (milling); and group C (conventional chairside manufacturing), which served as a control. All groups were cemented to standard implant abutments placed in artificial bone blocks. Fracture strength testing was performed using a universal testing machine. Statistical analysis of the resultant maximum forces was performed using SPSS version 25 software (Mann- Whitney U test, P < .05). RESULTS: The mean fracture load value of the group A FPDs was 260.14 N ± 28.88, for group B was 663.57 N ± 140.55, and for group C was 266.65 N ± 63.66. CONCLUSIONS: Milled provisional FPDs showed a higher fracture resistance compared to 3D-printed and control groups. However, no such difference could be detected between the 3D-printed and control groups.

Comparison of temperature changes in different irrigation methods used in guided piezosurgery: in vitro study.

PURPOSE: The study aimed to investigate the cooling performance of three different surgical methods for bone splitting during implant dentistry procedures. METHODS: An in vitro study was conducted on bovine ribs to test the cooling performance of three osteotomy methods: conventional osteotomy with standard cooling irrigation, template-assisted osteotomy with standard cooling irrigation, and modified template-assisted osteotomy with additional cooling fluid through internal irrigation channels in the surgical guide. A negative control group without cooling was also included. Temperature measurements were taken during the procedures using a contactless infrared thermometer. RESULTS: The results showed that the conventional osteotomy without cooling resulted in the highest mean of the peak temperatures (114.7 °C ± 45.4), while the modified template-assisted osteotomy with additional cooling achieved the lowest mean of the peak temperatures (29.4 °C ± 7). Statistically significant differences in temperature were observed among the groups (p < 0.001). CONCLUSION: The study rejected the null hypothesis and demonstrated that the cooling method used during bone splitting procedures significantly affected the temperature development at the surgical site. The modified template-assisted osteotomy with additional cooling provided the best cooling performance. However, caution should be exercised in interpreting the results due to the limitations of the in vitro study. Further research with stronger external validity is needed to confirm these findings and explore their applicability in clinical settings to benefit patients.

The fracture resistance of 3D-printed versus milled provisional crowns: An in vitro study.

BACKGROUND: CAD/CAM has considerably transformed the clinical practice of dentistry. In particular, advanced dental materials produced via digital technologies offer unquestionable benefits, such as ideal mechanical stability, outstanding aesthetics and reliable high precision. Additive manufacturing (AM) technology has promoted new innovations, especially in the field of biomedicine. AIMS: The aim of this study is to analyze the fracture resistance of implant-supported 3D-printed temporary crowns relative to milled crowns by compression testing. METHODS: The study sample included 32 specimens of temporary crowns, which were divided into 16 specimens per group. Each group consisted of eight maxillary central incisor crowns (tooth 11) and eight maxillary molar crowns (tooth 16). The first group (16 specimens) was 3D printed by a mask printer (Varseo, BEGO, Bremen, Germany) with a temporary material (VarseoSmile Temp A3, BEGO, Bremen, Germany). The second group was milled with a millable temporary material (VitaCAD Temp mono-color, Vita, Bad Säckingen, Germany). The two groups were compression tested until failure to estimate their fracture resistance. The loading forces and travel distance until failure were measured. The statistical analysis was performed using SPSS Version 24.0. We performed multiple t tests and considered a significance level of p <0.05. RESULTS: The mean fracture force of the printed molars was 1189.50 N (±250.85) with a deformation of 1.75 mm (±0.25). The milled molars reached a mean fracture force of 1817.50 N (±258.22) with a deformation of 1.750 mm (±0.20). The printed incisors fractured at 321.63 N (±145.90) with a deformation of 1.94 mm (±0.40), while the milled incisors fractured at 443.38 N (±113.63) with a deformation of 2.26 mm (±0.40). The milled molar group revealed significantly higher mechanical fracture strength than the 3D-printed molar group (P<0.001). However, no significant differences between the 3D-printed incisors and the milled incisors were found (p = 0.084). There was no significant difference in the travel distance until fracture for both the molar group (p = 1.000) and the incisor group (p = 0.129). CONCLUSION: Within the limits of this in vitro investigation, printed and milled temporary crowns withstood masticatory forces and were safe for clinical use.

Influence of Multiple Used Implant Drills on Their Cutting Performance and Fracture Resistance.

This study aimed to analyze the influence of multiple uses of zirconia implant drills on their cutting performance and bending strength. The hypothesis was that drill usage and sterilization cycles would not affect drilling time or flexural strength. Sixty zirconia twist drills from Z-Systems were used to drill in the angulus mandibulae region of fresh porcine jaws. The drills were divided into four groups based on the cycle count, and the drilling time was measured. Bending strength tests were conducted using a universal testing machine, and statistical analysis was performed using ANOVA tests. The results showed that drilling times followed a normal distribution, and significant differences were observed in drilling times between group 1 and the other groups for the pilot drill. However, no significant differences were found for ø3.75 mm and ø4.25 mm drills, and drilling times also varied significantly among different drill diameters, regardless of the cycle count. Flexural strength did not significantly differ among drill diameters or sterilization cycles. Overall, using and sterilizing zirconia implant drills had no significant impact on drilling time or flexural strength. Nevertheless, drilling times did vary depending on the diameter of the drill. These findings provide valuable insights into the performance and durability of zirconia implant drills, contributing to the optimization of dental implant procedures.

Comparing Original and Universal Screwdrivers and How They Affect Friction in the Screw.

The present study focused on investigating whether universal screwdriver kits cause less friction between the screwdriver and the abutment screw than original screwdrivers. For this purpose, 2 original screwdrivers (Straumann and BEGO) and a universal screwdriver kit (bredent) were investigated. On 1 implant per screwdriver, 26 abutments were properly attached one after the other with the corresponding abutment screws. After tightening the abutment screw, the force required to pull the screwdriver off the screw head was determined with a spring balance. For both manufacturers, greater pull-off forces were measured when using the original screwdrivers than when using the universal screwdriver. The pull-off force (mean ± SD) required for the Straumann original screwdriver was 3.7 ± 1.4 N, while that required for the universal screwdriver was 0.1 ± 0.1 N (P < .001). The pull-off force was 1.5 ± 1.5 N for the BEGO original screwdriver and 0.7 ± 0.9 N for the universal screwdriver (P = .19). Using original manufacturer-supplied screwdrivers could thus minimize the risk of the screwdriver slipping out of the screw head during dental treatment and being swallowed or aspirated by the patient.

Artificial intelligence system for training diagnosis and differentiation with molar incisor hypomineralization (MIH) and similar pathologies.

OBJECTIVES: Molar incisor hypomineralization (MIH) is a difficult-to-diagnose developmental disorder of the teeth, mainly in children and adolescents. Due to the young age of the patients, problems typically occur with the diagnosis of MIH. The aim of the present technical note was to investigate whether a successful application of a neural network for diagnosis of MIH and other different pathologies in dentistry is still feasible. MATERIALS AND METHODS: For this study, clinical pictures of four different pathologies were collected (n = 462). These pictures were categorized in caries (n = 118), MIH (n = 115), amelogenesis imperfecta (n = 112) and dental fluorosis (n = 117). The pictures were anonymized and a specialized dentist taking into account all clinical data did the diagnosis. Then, well-investigated picture classifier neural networks were selected. All of these were convolutional neural networks (ResNet34, ResNet50, AlexNet, VGG16 and DenseNet121). The neural networks were pre-trained and transfer learning was performed on the given datasets. RESULTS: For the vgg16 network, the precision is the lowest with 83.98% as for the dense121 it shows the highest values with 92.86%. Comparing the different pathologies between the investigated neural networks, there is no trend detectable. CONCLUSION: In the long term, an implementation of artificial intelligence for the detection of specific dental pathologies is conceivable and sensible. CLINICAL RELEVANCE: Finally, this application can be integrated in the area of training and teaching in order to teach dental students as well as general practitioners for MIH and similar dental pathologies.

Implant Placement in the Esthetic Zone: More Efficiency in Guided Surgery.

The aim of this case report is to describe the combination of a surgical guide with a temporary restoration to streamline the implant process. A 54-year-old male patient presenting with partial edentulism underwent computer-aided template-guided implant placement for the replacement of the missing upper second right incisor. The presented technique was used during the surgical procedures; it introduced the integration of a surgical guide into the temporary fixed partial denture. Using computer-aided design, computer-aided manufacturing technology and virtual implant planning, a temporary-implantation fixed partial denture was constructed, and a guidance sleeve was implemented into it. The implant bed preparation was then performed using the bridge as a surgical guide. After osteotomy, the guidance sleeve within the bridge was sealed, and the bridge was temporarily incorporated for submerged healing of the implant. The use of a temporary restoration as a surgical guide seems to make the digital workflow of guided implant placement more efficient by achieving a representative clinical outcome.

Mechanical evaluation for three-dimensional printed orthodontic springs with different heights-in vitro study.

BACKGROUND: The orthodontic spring materials in use have a significant influence on the applied forces. The prerequisite to identify the in vitro< force deflection of the CAD/CAM fabricated springs is considered mandatory to identify the material characteristics. The purpose of the present investigation was to evaluate the mechanical load on 3D printed springs using different coil heights. MATERIAL AND METHODS: The springs were digitally designed with different coil heights using Autodesk Netfabb CAD software (San Rafael, CA, USA). Test specimens were manufactured using 3D printable experimental flexible material (Code: BM2008, GC, Tokyo, Japan). The specimens were divided according to the coil height into five groups, group A (n=4mm), group B (n=6mm), group C (n=8mm), group D (n=10mm) and group E (n=12mm). All group specimens were mechanically tested using a universal testing machine. Statistical analysis was performed using K-S-Test to compare the values of each to the control group (p< 0.001). RESULTS: The highest value in all groups was achieved by 5.43 N/mm in group A, while the lowest value was achieved by 0.11 N/mm in group E. CONCLUSIONS: 3D printed springs are mechanically affected by the coil heights and there is a direct correlation to the resulting force. Furthermore, the variations within the investigated groups must be thoroughly investigated prior to clinical application. Key words:CAD/CAM, 3D printing, Orthodontics, mechanical testing, material evaluation.

Pull-off resistance of a screwless implant-abutment connection and surface evaluation after cyclic loading.

PURPOSE: The aim of this study was to investigate to what extent cyclic load affects the screwless implant-abutment connection for Morse taper dental implants. MATERIALS AND METHODS: 16 implants (SICvantage max) and 16 abutments (Swiss Cross) were used. The screwless implant-abutment connection was subjected to 10,000 cycles of axial loading with a maximum force of 120 N. For the pull-off testing, before and after the same cyclic loading, the required force for disconnecting the remaining 6 implant-abutment connections was measured. The surface of 10 abutments was examined using a scanning electron microscope 120× before and after loading. RESULTS: The pull-off test showed a significant decrease in the vertical force required to pull the abutment from the implant with mean 229.39 N ± 18.23 before loading, and 204.30 N ± 13.51 after loading (P<.01). Apart from the appearance of polished surface areas and slight signs of wear, no visible damages were found on the abutments. CONCLUSION: The deformation on the polished abutment surface might represent the result of micro movements within the implant-abutment connection during loading. Although there was a decrease of the pull-off force values after cyclic loading, this might not have a notable effect on the clinical performance.

Comparison of original and universal screwdrivers: Damage to the surface of the socket within the screw head of the abutment screw / Original- und Universalschraubendreher im Vergleich. Beschädigungen der Oberfläche der Fassung innerhalb des Schraubenkopfes der Abutmentschraube

The aim of the study was to investigate the potential damage the usage of universal screwdrivers could cause to the abutment screw. In this study the original versus the universal screwdriver have been compared. 26 original abutment screws, 13 from Straumann and 13 from BEGO, were screwed in with the original and the universal screwdriver. For optical evaluation, the potential damage to the screw head was documented in two different areas. For this purpose, photos were taken with a scanning electron microscope. At Straumann, surface damage was only seen in area 1 (top of the screw head) when using the universal screwdriver. BEGO showed surface damage in area 1 regardless of which screwdriver was used and in area 2 (bottom of the screw head) when using the universal screwdriver. It can be assumed that the use of the original screwdriver might cause little or no damage to the screw heads. In contrast, based on the SEM images, it can be assumed that the surface can be damaged when using the universal screwdriver.

The Influence of Implant Site Preparation and Sterilization on the Performance and Wear of Implant Drills.

PURPOSE: The aim of this study was to investigate if repeated use of pilot and depth drills for implant site preparation in combination with resterilization leads to any significant changes in cutting edges or in preparation times. MATERIALS AND METHODS: With drills of different lengths and widths (pilot, parallel, and tapered), osteotomies were performed under constant conditions in pig jaws. After each osteotomy, the drills were processed and sterilized. The required time for finishing the osteotomy was noted and analyzed. At the end of each osteotomy cycle, consisting of 10 osteotomies and 10 sterilizations, the cutting edge wear of the drill was analyzed using scanning electron microscopy. Unused but sterilized drills served as a control group. RESULTS: There was no statistically significant difference in the evaluated wear between pilot drills and depth drills as well as between the test and the control group. After 60 osteotomies, implant drills showed considerable signs of wear at the major cutting edge (P > .05). Osteotomy led to a significant increase in the drilling time. While pilot drills showed an increase of drilling time of the factor 33.3, and the tapered drills of the factor 5.37, the parallel drills remained constant in their performance. CONCLUSION: Within the limitations of this study, it can be concluded that the process of sterilization as well as the number of performed osteotomies play a major role in the wear of the cutting edge and the performance of implant drills.

Ridge augmentation-The new field of computerized guided surgery: A technical note for minimal-invasive bone splitting.

Different instrumentation procedures of the alveolar ridge expansion technique (ARST) with or without Guided Bone Regeneration have proven to be effective for successful implant placement in cases of alveolar bone width between 3mm and 6mm. Conventional bone splitting techniques require flap arising. This technical note demonstrates a method for flapless guided bone splitting. For this purpose, a newly developed surgical guide with internal irrigation channels was used. Using CAD-CAM additive technology, a narrow slot along the field of interest and a pin of a cooling pipe was designed and implemented in a surgical guide template. The bone split was performed flapless through the surgical guide while the cooling pipe was connected to it. During surgery, the piezo-driven instrument was moved within that slot, and the irrigation solution was directly rinsing it at point of entry through the irrigation channel. This procedure was performed on a 3.3 mm wide alveolar ridge achieving over 3 mm of bone gain. The described method combines several positive aspects. The micro-invasive flapless surgical procedure might improve postoperative healing. Additionally, sufficient cooling of the bone might lead to less thermal affection of bone cells and less resorption of the cortical bone. However, systematic studies are needed to confirm the observations of the presented case report.

Comparative mechanical testing for the digitally produced provisional fixed partial denture prostheses to the conventional method: in-vitro study.

PURPOSE: To examine and compare the fracture strength of digitally produced interim materials to the conventional chairside method for implant-cemented fixed partial denture prostheses. MATERIALS AND METHODS: Three groups of seven specimens each were produced: group A, 3D-printed with VarseoSmile Temp material (Bego); group B, milled using Telio CAD material (Ivoclar Vivadent), and group C, conventional chairside manufacturing method using Luxatemp material (DMG). All groups were cemented using FujiCEM 2 (GC) to Standard Abutments (SIC) placed in artificial Sawbones blocks. The fracture strength was performed using universal testing machine Z010 (ZwickRoell). Statistical analysis of the resultant maximum forces was performed using SPSS (version 25.0, IBM) software (Mann- Whitney U test, P < .05). RESULTS: The mean fracture strength of the printed provisional fixed partial dentures was 260.14 ± 28.88 N, of the milled interim fixed partial dentures was 663.57 ± 140.55 N, and for the control group reached 266.65 ± 63.66 N. Data showed a significant deviation of the normal distribution Kolmogorov-Smirnov test > .05 for all groups. CONCLUSION: Milled provisional fixed partial dentures showed a higher fracture resistance compared to 3D-printed and control chairside groups. However, for 3D-printed and control groups, no such difference could be detected.

Use of interactive instructional tools in virtual 3D planning.

OBJECTIVES: The aim of this study is to analyze the effectiveness of screencast training videos for users from different professional backgrounds on the basis of the quality and quantity of virtual 3D implant planning as evaluated using assessment software. METHODS: Participants in the study were dental students (n = 21), dental technicians (n = 16), or practicing dentists (n = 16) with no knowledge of the implant planning software CoDiagnostiX or any experience in virtual implant planning. They were randomly divided into 2 groups: The participants of the control group were presented training videos on CBCT (cone beam computed tomography) and implant planning, additional to the traditional software manual. The participants of the experimental group received, additionally, a training video on the planning software, produced in the form of a screencast. Then 3 implant planning procedures were performed by all participants. The quality of implant planning was assessed using the Treatment Evaluation Tool software, and time for planning was measured. RESULTS: Paired sample tests showed significantly shorter planning times for the experimental groups consisting of dentists and students (P < 0.001). A comparison of the results of the individual groups reveals that students and dental technicians who had not received prior screencast training were significantly less precise in their planning (P < 0.001). CONCLUSION: This study suggests a promising outcome for the future use of screencasts in the acquisition of software skills for dental software. There is a need for tools for objective self-assessment of effectiveness in software training.

Shear force comparative evaluation for surface treated and non- treated 3D interim printed materials with different types of glass-ionomer cements.

BACKGROUND: The purpose of this investigation was to compare shear force of different glass-ionomer cements on 3D printed interim material in combination with and without surface pretreatment. MATERIAL AND METHODS: 120 rectangular specimens made of printable provisional material (Bego, Bremen, Germany) were used. After post-processing the specimens were blasted with aluminum oxide 110µm (Bego, Bremen, Germany). Extra 120 non-surface treated specimens were used as an experimental negative test group. All 240 specimens were divided randomly into 6 groups. All were cemented with a compressive load of 20 N using universal testing machine Z010 (Zwick/Roell, Ulm, Germany) to ensure a comparable cementing process. Each of the six groups were cemented with different cements (CX Plus (Shofu, Ratingen, Germany), Vivaglass CEM PL (Ivoclar Vivadent AG, Schaan, Liechtenstein), Aqua Cem (Dentsply Sirona, Bensheim, Germany), Ketac Cem (3M, Neuss, Germany), Meron Plus AC (Voco, Cuxhaven, Germany), and Fuji 1 (GC, Tokyo, Japan). Shear force test was performed, and forces were statistically analyzed via Anova test (significance level p<0.001). RESULTS: All the pre-treated specimens showed a significantly higher bonding strength compared to not pretreated. Meron Plus AC showed the highest shear overall force. The Anova test showed a significant difference between all pretreated study groups (p<0.001). CONCLUSIONS: An increase of the necessary forces for all groups was shown in pretreated group. Within the limitations of this study, a surface pretreatment is recommended when bonding a 3D interim material with glass ionomer cements. Key words:Shear force, 3D printing, glass ionomer cement, mechanical evaluation, CAD/CAM. .

The color stability and wear resistance of provisional implant restorations: A prospective clinical study.

OBJECTIVES: The aim of the present clinical study was to determine the stability of color and resistance against abrasion and attrition of provisional single implant restorations. MATERIAL AND METHODS: A group of 16 patients were treated with provisional crowns made of Telio CAD. Shortly before the insertion the crowns were photographed and scanned using a 3D-laser scanner. After 8 weeks of clinical usage, the crowns were photographed and scanned again. The vertical occlusal wear and color changes between the restorations were measured. RESULTS: The occlusal plane of the original crown showed a statistically significant reduction of 0.052 mm ± 0.037 mm 8 weeks after placement (p < .05). For the stability of color, a change in red, green and blue was described. All three scopes (red, green and blue) showed a statistically significant reduction (p < .05). CONCLUSIONS: This prospective clinical study showed that Telio CAD experienced a significant occlusal reduction and color change after an intraoral placement of 8 weeks.

Guided Implant Placement Using an Internally Cooling Surgical Template: A Technical Note.

Cooling irrigation during implant bed preparation is mandatory to avoid overheating. Due to the surgical guide design, external cooling systems do not reach the point of entry of the implant burr. Here, a new technique for irrigation during guided implant surgery for direct rinse of the burr is described. Using computer-aided design/computer-aided manufacturing additive technology, a pin of a cooling pipe was designed and implemented in a surgical guide template. The implant bed preparation was performed while the cooling pipe was connected to the surgical guide. During surgery, the irrigation solution was directly rinsing the burr at the point of entry through the irrigation channel. The use of a cooling surgical guide seems to improve the cooling of the bone during implant bed preparation. This might lead to less thermal effect of bone cells. However, systematic studies are needed to confirm the observations of the presented case report.

The Impact of Different Augmentative Methods on the Expression of Inflammatory Factors.

Many animal studies show that an intact periosteum plays an important role in osseous regeneration. The potential effect of an in vivo periosteal barrier membrane on the expression of specific proteins has not been examined sufficiently. The aim of the present study is to investigate the influence of the flap preparation method and collagen membrane on the emission of inflammatory factors. This study examines 20 patients with dental implants who had previously undergone an augmentation. A soft tissue sample was taken during augmentation and 3 months later from the same location. Samples were always taken from the margins of a previously prepared mucoperiosteal flap. The flap was raised with a conventional periosteal elevator in the control group and with a piezoelectric device in the test group. In both groups, we covered half of the augmented bone with a native collagen membrane (NCM; Geistlich Bio-Gide). This allowed us to examine the same incision area with and without a membrane. An immunohistochemical analysis was performed for collagen IV, fibronectin, and inflammatory factors such as cluster of differentiation 31 (CD31), cyclooxygenase-2 (COX-2), and interleukin 6 (IL-6). There was a clear difference in the expression of specific proteins after the piezoelectric device and the periosteal elevator were used. The expression of fibronectin, IL-6, and COX-2 was higher after preparation with the periosteal elevator than after piezoelectric periosteum dissection. The expression of collagen IV was higher after the piezoelectric procedure. No difference was observed for CD31. The membrane had no effect on the expression of collagen IV, fibronectin, IL-6, and COX-2. The type of periosteal preparation influences the expression of specific proteins. With regard to the factors examined here, NCM did not appear to influence the wound healing cascade.

A retrospective study of the accuracy of template-guided versus freehand implant placement: A nonradiologic method.

OBJECTIVE: The aim of this retrospective case study was to evaluate implant placement accuracy in inexperienced clinicians with use of a surgical guide template vs the freehand method for preoperatively planned implant position. STUDY DESIGN: Oral implant therapy was performed by inexperienced dental practitioners (<20 implants placed) on eligible patients after cone beam computer tomography (CBCT)-based software planning. Two patients' groups were formed according to the surgical technique: guided and freehand implant placement. The casts used for the fabrication of reconstructions were scanned by using a 3-dimensional (3D) laser scanner, the implant positions were superimposed with preoperative planning data, and the 3D deviations were calculated. RESULTS: Twenty adult patients were included in this retrospective study (20 guided and 21 freehand implant placements). Mean calculated deviations with use of a surgical guide template were significantly lower compared with those of the freehand method with regard to angulation (P = .002), apical position (P = .002), and basal position (P = .012). No significant differences in implant placement accuracy were detected between the groups according to the implant position (premolars/molars; upper jaw/lower jaw) (P > .05). CONCLUSIONS: Computer-aided planning and the use of surgical guides in accordance with CBCT images may help inexperienced clinicians to place implants with high accuracy.