Sequential Drilling Research Articles

Thermal Evaluation of Bone Drilling with a One-Drill Protocol.

This study evaluates the thermal impact of a one-drill protocol for osteotomy preparation in dental implant surgery. Our findings demonstrate a significant reduction in heat generation compared to traditional sequential drilling, suggesting potential benefits for implant osseointegration and patient comfort. Specifically, the one-drill protocol was associated with lower peak temperatures and a reduced duration of elevated temperatures. These findings suggest that the one-drill protocol may contribute to improved implant stability and reduce the risk of thermal-induced bone damage. While further research is needed to confirm these findings in clinical settings, the results of this study provide promising evidence for the potential advantages of the one-drill protocol in dental implant surgery. Additionally, the one-drill protocol may offer simplified surgical workflows and reduced instrument management, potentially leading to improved efficiency and cost-effectiveness in dental implant procedures.

STUDY OF THE USE OF THERMAL DRILLING IN MECHANICAL JOINING OF MG SHEET AND GFRP/CFRP COMPOSITES WITH THERMOSOFTENING MATRIX

The paper discusses the joining of magnesium based metallic sheet and composites with thermosoftening polypropylene matrix reinforced with bi-directional continuous glass and carbon fibers by thermal drilling technology. The bushing formation has been investigated by separately drilling AZ91 Mg alloy sheet at two rotational speeds and feed rates to find out the parameters at which a bushing with optimum length and thickness, suitable for joining with the composite, is formed. Under these conditions, the joining of the metal sheet and composite was then carried out by simple thermal drilling. During simple drilling, delamination of the composite occurred in the vicinity of the hole, which was resolved by flanging the bushing with a penetration of the tool from the opposite side. When AZ91 was joined to carbon fibers reinfirced composite, there was a lack of bushing formation due to the higher resistance of the carbon fibers, which are present in the composite in greater numbers compared to the glass fibers. This problem was solved by sequential drilling, which means that a flowdrill tool was used to create a hole in the composite itself, then overlaid with Mg sheet and again drilled, forming the bushing and flanging the bushing from the opposite side. The sequential drilling resulted in joints with a load capacity of 0.8 - 1.4 kN, which exhibit the characteristics of a hybrid - mechanical and adhesive joint.

Thermal Evaluation of Bone Drilling: Assessing Drill Bits and Sequential Drilling.

Sequential drilling is a common practice in dental implant surgery aimed at minimizing thermal damage to bone. This study evaluates the thermal effects of sequential drilling and assesses modifications to drilling protocols to manage heat generation. We utilized a custom drill press and artificial bone models to test five drill bits under various protocols, including sequential drilling with different loads, spindle speeds, and peck drilling. Infrared thermography recorded temperature changes during the drilling process, with temperatures monitored at various depths around the osteotomy. The results reveal sequential drilling does not eliminate the thermal damage zone it creates (well over 70 °C). It creates harmful heat to surrounding bone that can spread up to 10 mm from the osteotomy. The first drill used in sequential drilling produces the highest temperatures (over 100 °C), and subsequent drill bits cannot remove the thermal trauma incurred; rather, they add to it. Modifying drill bit design and employing proper drilling techniques, such as reducing drilling RPM and load, can reduce thermal trauma by reducing friction. Inadequate management of heat can lead to prolonged recovery, increased patient discomfort, and potential long-term complications such as impaired bone-to-implant integration and chronic conditions like peri-implantitis. Ensuring healthy bone conditions is critical for successful implant outcomes.

Vertical Mouth Opening Requirements for CAD/CAM Fully Guided Implant Surgery: An Analysis of Different Implant Systems.

To determine the vertical space required for implant osteotomy preparation when utilizing a CAD/CAM fully guided surgical template. A total of 14 surgical osteotomy drills (individual and sequential drills) were collected and measured individually using a digital caliper, as well as the total length when the drills were positioned in a surgical handpiece. The height of the surgical guide sleeves and the offset of 14 implant systems in the market were also collected. The vertical dimension of the drills included in this study ranged from 28.2 to 46.3 mm. When these drills were inserted into the handpiece, the total length ranged from 30.0 to 49.5 mm. The height of the surgical guide sleeve and the offset required for the guide had a range of 3.2 to 7.0 mm and 5.0 to 13.5 mm, respectively. This dimension resulted in the total vertical space required for CAD/CAM fully guided surgical templates for each implant system, which ranged from 30.0 to 58.5 mm. Limited mouth opening can pose challenges and limitations in both guided and nonguided dental implant surgery. It can affect the accessibility of surgical implant placement and may result in increased patient discomfort, surgical implant positioning errors, and postoperative complications. Clinicians should determine the patient's mouth opening capabilities during the treatment planning phase prior to deciding on the appropriate implant system to be used and the implant placement technique.

Evaluation of the effect of chemical disinfection and ultraviolet disinfection on the dimensional stability of polyether impression material: an in-vitro study

BackgroundVarious methods, chemical and physical, disinfect dental impressions. Common chemicals include 1% Sodium Hypochlorite and 2% glutaraldehyde, while UV radiation is a prevalent physical method. Few studies compare their effects on dimensional stability in polyether impressions. This study aims to assess such stability using different disinfection methods. Therefore, this study was planned to evaluate the dimensional stability of polyether impression material using different disinfection methods.MethodsThis in vitro study compared the effects of chemical disinfectants (1% Sodium Hypochlorite and 2% glutaraldehyde) and UV irradiation on the dimensional stability of polyether impression material. Groups A, B, C, and D, each with ten samples (N = 10), were studied. Group A was untreated (control). Group B was treated with 2% glutaraldehyde for 20 min, Group C with 1% Sodium Hypochlorite for 20 min, and Group D with UV rays for 20 min. A pilot milling machine drill was used to make four parallel holes labeled A, B, C, and D in the anterior and premolar regions from right to left. After sequential drilling, four implant analogs were positioned using a surveyor for accuracy. Ten open-tray polyether impressions were made and treated as described in the groups, followed by pouring the corresponding casts. Distortion values for each disinfection method were measured using a coordinate measuring machine capable of recording on the X- and Y-axes.ResultsA comprehensive analysis was conducted using the one-way ANOVA test for distinct groups labeled A, B, C, and D, revealing significant differences in the mean distances for X1, X2, X4, X5, and X6 among the groups, with p-values ranging from 0.001 to 0.000. However, no significant differences were observed in X3. Notably, mean distances for the Y variables exhibited substantial differences among the groups, emphasizing parameter variations, with p-values ranging from 0.000 to 0.033. The results compared the four groups using the one-way ANOVA test, revealing statistically significant distance differences for most X and Y variables, except for X3 and Y4. Similarly, post-hoc Tukey’s tests provided specific pairwise comparisons, underlining the distinctions between group C and the others in the mean and deviation distances for various variables on both the X- and Y-axes.ConclusionsThis study found that disinfection with 1% sodium hypochlorite or UV rays for 20 min maintained dimensional stability in polyether impressions.

Comparative evaluation on wear resistance of metal sleeve, sleeve-free resin, and reinforced sleeve-free resin implant guide: An in vitro study.

In-office three-dimensional (3D) printers and metal sleeveless surgical guides are becoming a major trend recently. However, metal sleeve-free designs are reported to be more prone to distortion which might lead to variation in the inner diameter of the drill hole and cause deviation and inaccuracy in the placement of the implant. Carbon fiber nanoparticles are reported to improve the properties of 3D printing resin material in industrial application. The purpose of the study is to evaluate and compare the wear resistance of 3D-printed implant guides with metal sleeve, sleeve-free, and reinforced sleeve-free resin to the guide drill. A total of 66 samples with 22 samples in each group. Three groups including 3D-printed surgical guide with metal sleeve (Group A), without metal sleeve (Group B), an carbon fiber reinforced without metal sleeve (Group C) were included in the study. All samples were evaluated before sequential drilling and after sequential drilling using Vision Measuring Machine. The data were tabulated and statistically evaluated. The data obtained were statistically analyzed with one-way analysis of variance and posthoc test. The data obtained for wear observed in the samples showed that the wear was highest in Group B with a mean of 0.5036 ± 0.1118 and the least was observed in Group A with a mean of 0.0228 ± 0.0154 and Group C was almost similar to Group A with mean of 0.0710 ± 0.0381. The results showed there was a significant difference between Group B with Group A and C, respectively (P < 0.05). The results showed that there was no significant difference regarding the wear observed between Groups A and C (P > 0.05). The wear observed in the guide with a metal sleeve and carbon fiber reinforced without a metal sleeve was almost similar. The carbon fiber-reinforced guide showed better tolerance to guide drill equivalent to metal sleeve. Thus, carbon fiber nanoparticles reinforced in 3D printing resin have shown improved strength and can be used as a good replacement for a metal sleeve for an accurate placement of the implant.

Geosteering based on resistivity data and evolutionary optimization algorithm

Currently, the oil and gas industry faces numerous challenges in addressing geosteering issues in horizontal drilling. To optimize the extraction of hydrocarbon resources and to avoid penetration in aquifers, industry experts frequently modify the drilling trajectory using real-time measurements. This approach involves quantifying subsurface uncertainties in real-time, enhancing operational decision-making with more informed insights but also adding to its complexity. This paper demonstrates an approach to decision making for trajectory correction based on real-time formation evaluation data and the differential evolution algorithm. The approach uses volumetric resistivity log data and data from reservoir models, such as porosity. The provided methodology suggests corrections for planned well trajectories by maximization of the objective function. The objective function operates with a calculated hydrocarbon saturation environment as the decision-making system in a virtual sequential drilling process. To demonstrate the accuracy and reliability of our approach, we compared the simulations of the corrected trajectory with the preliminary trajectory drilled in the same area. In addition, we conducted several experiments to tune the hyper-parameters of the differential evolution algorithm to select the optimal parameter set for our case study and compared proposed differential evolution algorithm with particle swarm optimization and pattern search algorithms. The results of our experiments showed that the real-time formation evaluation data combined with the differential evolution algorithm outperformed a trajectory provided by the drilling engineers. Differential evolution algorithm demonstrated strong performance compared to others optimization algorithms. We have implemented a complete pipeline from generating resistivity and porosity cubes, using the Archie equation to estimate oil saturation, and consequently generating a corrected trajectory in this cube based on near-well data, angle constraints and predefined hyper-parameters set prior to well trajectory planning. The methods developed were validated on synthetic and real datasets. Our decision-making system shows better cumulative oil saturation values than the preliminary provided horizontal well.

Comparative evaluation of open tray impression technique: investigating the precision of four splinting materials in multiple implants

BackgroundThis study aimed to determine the relative positioning accuracy of multiple implants utilizing four distinct types of splinting materials.MethodsThe purpose of this in-vitro study was to compare the precision of four splinting materials in an open tray impression technique in multiple implant situations. Based on the material used for splinting, four groups were made (n = 40)- Group A: Conventional Method, Group B: Prefabricated Pattern Resin Framework, Group C: Prefabricated Metal Framework, Group D: Light Cured Pattern Resin, these groups were compared with the master model. A heat-cured clear acrylic resin and a master model were constructed. A pilot milling machine drill was used to drill four parallel holes in the anterior and premolar regions, which were later labeled as A, B, C, and D positions from right to left. Then, sequential drilling was carried out, and four 3.75‑mm diameter and 13-mm long ADIN implant analogs with internal hex were placed in the acrylic model using a surveyor for proper orientation. The impression posts were then manually screwed to the implant analogs using an open tray, and they were secured to the implants using 10 mm flat head guide pins with a 15 N.cm torque. 10 Open tray polyether impressions were made, and casts were poured. Each splinting method’s distortion values were measured using a coordinate measuring machine capable of recordings in the X-, Y-, and Z-axes. Comparison of mean distances for X1, X2, and X3 was made using the Kruskal-Wallis test, and Pairwise comparison was done using Post Hoc Tukey’s Test.ResultsThe differences between the groups were significant when assessing the distances X1, X2, and X3 (p < 0.05). The comparison of deviations between the groups revealed a statistically significant difference (p < 0.05) for the deviation distance X3 but not for the deviation distances X1 and X2. For distance Y1, the difference between the groups was statistically significant (p0.05), but it was not significant for distances Y2 and Y3. A statistically significant difference was seen in the comparison between the groups (p < 0.05) for the deviation distances Y1, Y2, and Y3. The results were statistically significant for the distance Z1 comparisons, namely, control vs. Group A (p = 0.012), control vs. Group B (p = 0.049), control vs. Group C (p = 0.048), and control vs. Group D (p = 0.021), and for distance Z3 comparison for control vs. Group A (p = 0.033). The results were statistically insignificant for the distance Z2 comparisons (p > 0.05).ConclusionsAll splinting materials produced master casts with measurements in close proximity to the reference model. However, prefabricated pattern resin bars splinting showed the highest accuracy among the studied techniques. The most recent splinting techniques using prefabricated metal framework and light-cure pattern resin showed similar accuracy.

An Investigation of the Sequential Micro-Laser Drilling and Conventional Re-Drilling of Angled Holes in an Inconel 625 Ni-Based Alloy

The conventional (mechanical) micro-drilling of Inconel 625 alloys suffers from premature breakage of the drill bit due to its brittle nature and limited cutting tool life. Even greater problems are encountered when micro-drilling holes at an acute angle to the machining plane. In such a process, there are great difficulties associated with the low stiffness of the tool, which leads to the frequent breakage of the drill during machining. Therefore, in this type of mechanical drilling operation, the hole surface is usually milled with an end mill to provide a flat surface on the entry side of the drill bit. The aim of this article is to recognise the process of sequential micro-drilling and to assess the possibility of its use as an effective and efficient method of micro-drilling in hard-to-cut metals. The paper describes the process of initial laser drilling followed by final mechanical micro-drilling. Inconel 625 Ni-based alloy sheets were used as the test material. The shape and microstructure of pre-holes made with a laser, the volumetric efficiency of laser processing, the energy in the mechanical drilling process, and tool wear were analysed. The research results show that in the sequential drilling process, mechanical re-drilling eliminates the geometrical discrepancies resulting from the laser pre-drilling. In addition, it was found that, compared to mechanical micro-drilling, the use of sequential micro-drilling resulted in a two-fold increase in drill life. It has been also observed that sequential machining reduces the energy demand by 60% compared to mechanical micro-drilling. In addition, it was found that the edge of the drill bit is a key factor in deciding the target diameter of the laser-drilled pilot hole, and thus in selecting the micro-drilling parameters.

Effects of a simplified drilling protocol at 50 rpm on heat generation under water-free conditions: an in vitro study.

In recent years, guided implant surgery has been widely used for the convenience of patients and surgeons. Further streamlining the surgical procedure would make implant surgery more convenient. Low-speed water-free conditions are often used in guided implant surgery. Therefore, in this study, we attempted to confirm once again whether drilling was safe at a low speed without water. The main purpose of this study was to evaluate whether a simplified drilling protocol that omits some intermediate steps in the drilling process was safe from the viewpoint of heat generation. D1 density artificial bone blocks were drilled under 50 rpm, 10 N·cm water-free conditions, and the surface temperature was measured using a digital infrared camera. First, drilling was performed with the sequential drilling method, which is the most widely used technique. Second, for each drill diameter, the temperature change was measured while performing simplified drilling with omission of the previous 1, 2, or 3 steps. In sequential drilling, the heat generated during drilling at all diameters was less than the critical temperature of osteonecrosis (47°C) except for the ⌀2 drill. Statistical significance was observed in all groups when comparing sequential and simplified drilling in the ⌀3.2, ⌀3.8, and ⌀4.3 drills (P<0.001). However, in the simplified drilling procedures, the temperature was below the osteonecrosis threshold temperature (47°C) except for the ⌀4.3 drill with the omission of the previous 3 steps (⌀3.0, ⌀3.2, and ⌀3.8). In general, drilling under low-speed, water-free conditions has shown stable results in terms of heat generation. Simplified drilling showed statistically significantly greater heat generation than sequential drilling. However, most of the diameters and omitted steps seem to be clinically acceptable, so it will be useful if an appropriate selection is made according to the patient's clinical condition.

Dynamic Navigation: A Novel Tool for Dental Implant Surgery

Dynamic navigation is an advanced technology that has revolutionized dental implant surgeries. Before being used in implant dentistry, navigation technique has been practiced in neurosurgery for performing minimally invasive brain surgeries. Navigation surgery for implant placement can be broadly categorized as dynamic and static navigation. The static navigation uses a static surgical guide for the sequential drilling of the osteotomy site and the implant placement. The static navigation can either be fully guided or partial/half-guided. Dynamic navigation is a computer-assisted implant placement technique that uses real-time imaging to guide the implant placement procedure. In dynamic navigation, three-dimensional (3D) software monitors and tracks the bone drilling and implant placement in real-time during the entire procedure. This technique involves prosthetically driven virtual implant placement planning with Cone Beam Computed Tomography (CBCT) before the implant surgery. The 3D image of the patient is analyzed in a CBCT scan. This image is then used to plan the placement of the implant and create a surgical guide. A resin guided template is 3D printed or milled which is used during the surgery. The CBCT scan images are transferred into a 3D virtual image using digital software, which allows 3D viewing of the structures using Computer Aided Design (CAD). A calibrated special navigation instrument with specific software guides the bone drilling sequence and the implant placement. The drilling procedure is completely tracked and the patient’s anatomy and the surgical procedures in real time is shown in a 3D software. The use of real-time imaging and computer-aided technology ensures that the implant is placed precisely in the desired location, reducing the risks associated with conventional implant placement. Dynamic navigation is an effective and precise method that allows for more accurate placement of dental implants, which reduces the chance of damaging anatomical structures. It also gives clinicians the possibility to modify the planned surgical approach during the surgery. Additionally, because the implant is placed more accurately, there is less risk of implant failure. However, a learning curve and a training period are required before one masters this novel technology. Dynamic navigation can potentially become a preferred method for dental implant placement in the near future.

Freehand Pre-drilling Technique for Lateral Mass Screw Fixation Is More Efficient and Reliable Versus Sequential Drilling Technique: A Sawbone Analysis.

Background Since posterior cervical fixation with lateral mass screws was introduced in 1979, multiple techniques have been described in the literature. However, no study to date has determined whether pre-drilling all lateral masses prior to screw insertion has a benefit over the traditional sequential drilling and screw insertion on the alignment of the screw-rod construct. This study sought to determine the efficacy and efficiency in achieving alignment with a novel pre-drilling technique compared to the traditional sequential drilling technique. The authors hypothesized that the novel pre-drilling technique could be applied more quickly and precisely than the traditional sequential drilling technique. Methods Eight cervical spine sawbones models were utilized to place 64 lateral mass screws by two surgeons. The pre-drilling technique was utilized to place 32 screws in four models, and the sequential drilling technique was utilized to place the 32 screws in the remaining four models. In the traditional sequential drilling technique, each lateral mass underwent screw tract preparation and insertion before proceeding to the subsequent vertebra. In the pre-drilling technique, all lateral masses were marked and drilled sequentially before screw placement. CT imaging with 3D reconstructions was generated for all models. Variability in screw placement and time taken to fully instrument the models were compared. Results The mean time to completion of the pre-drilling technique was 337 ± 22 seconds compared to 490 ± 22 seconds with the traditional technique (p<0.01). There was a significantly higher variability in the coronal plane within the traditional group between C5 and C6 compared to other adjacent vertebrae (p<0.05). There was no significant difference in the start point variability and the overall tightness of line fit between the techniques. Conclusions Our study suggests that a novel pre-drilling technique for lateral mass screw insertion may be more efficient and reliable than the traditional sequential drilling technique. In addition, this technique may reduce the need for rod contouring or additional implants to optimize the alignment of cervical instrumentation. However, further clinical studies are necessary to validate the potential clinical and radiologic benefits of this described technique.

Deep Learning Approach of Drilling Decision for Subhorizontal Drain Geosteering Based on APC-LSTM Model

SummarySteering drilling is used for exploring oil, natural gas, and other liquid and gaseous minerals. Steering drilling consists of high-efficiency drill bits, steering power drilling tools, and logging while drilling (LWD) and is used in petroleum drilling engineering. This paper mainly discusses subhorizontal drain geosteering, one of the methods of guided subhorizontal drilling. We use the currently popular deep learning method to conduct intelligent guided drilling. Geosteering is a sequential drilling decision process under uncertain stratum environment. However, the current geosteering drilling process relies heavily on manual work and has no use of temporal context. This paper aims to solve decision-making of geosteering in deep well (between 4500 and 6000 km) or ultradeep well (between 6000 and 9000 km). To this end, we make three contributions: (1) a wide-angle eye mechanism to obtain more geological information; (2) an asymmetric peephole convolutional long short-term memory (APC-LSTM) approach for geosteering drilling decision, whose input data were assembled with the wide-angle eye mechanism; and (3) use of the deep convolution generative adversarial networks (DCGAN) model to generate simulated logging data and conduct experiments in the simulation environment to verify our proposed method. APC-LSTM can capture the spatial-temporal correlation better between different strata for decision-making. Meanwhile, the APC-LSTM drilling decision model achieved better performance than other advanced methods in two drilling data sets. Tested in a simulative drilling environment, our proposed model achieves excellent application effect. Moreover, our method has been applied to the wells of oil field in practice.

Undersized Implant Site Preparation to Enhance Primary Stability in Computer-Guided Flapless Surgery: Sequential Drilling Protocol

Achieving primary implant stability in areas with poor bone density is often challenging for the clinician. This modified surgical protocol might be beneficial in such situations in computer-guided surgery. The purpose of the present clinical application is to give the clinician the sequence and steps for undersized implant site preparation in areas with poor bone density. After an evaluation of the bone density with the software on the CT scan, the implant site is prepared with drilling while remaining undersized. The implant is then inserted by setting the torque of the implant motor to 35 N-cm. When the desired torque is achieved, the distance between the implant and the bushing is measured. The rule suggests that if more than 3 mm are missing at the lower limit, it is advisable to remove the implant and prepare again with the next diameter drill, if it is less than 3 mm it is possible to use the method of self-tapping directly with the implant. The surgical drilling protocol allows the clinician to limit the number of drills and to use the implant mounter as a reference point when it stops at a certain distance from the bushing. The results of this clinical application suggest that undersized implant site preparations may help enhance primary implant stability in computer-guided surgery and that there are significant correlations among bone density, maximum insertion torque, implant mounter and drilling kit.

Sequential Laser-Mechanical Drilling of Thick Carbon Fibre Reinforced Polymer Composites (CFRP) for Industrial Applications.

Carbon fibre reinforced polymer composites (CFRPs) can be costly to manufacture, but they are typically used anywhere a high strength-to-weight ratio and a high steadiness (rigidity) are needed in many industrial applications, particularly in aerospace. Drilling composites with a laser tends to be a feasible method since one of the composite phases is often in the form of a polymer, and polymers in general have a very high absorption coefficient for infrared radiation. The feasibility of sequential laser–mechanical drilling for a thick CFRP is discussed in this article. A 1 kW fibre laser was chosen as a pre-drilling instrument (or initial stage), and mechanical drilling was the final step. The sequential drilling method dropped the overall thrust and torque by an average of 61%, which greatly increased the productivity and reduced the mechanical stress on the cutting tool while also increasing the lifespan of the bit. The sequential drilling (i.e., laser 8 mm and mechanical 8 mm) for both drill bits (i.e., 2- and 3-flute uncoated tungsten carbide) and the laser pre-drilling techniques has demonstrated the highest delamination factor (SFDSR) ratios. A new laser–mechanical sequence drilling technique is thus established, assessed, and tested when thick CFRP composites are drilled.

An Automatic Well Planner for Complex Well Trajectories

A data-driven automatic well planner procedure is implemented to develop complex well trajectories by efficiently adapting to near-well reservoir properties and geometry. The procedure draws inspiration from geosteering drilling operations, where modern logging-while-drilling tools enable the adjustment of well trajectories during drilling. Analogously, the proposed procedure develops well trajectories based on a selected geology-based fitness measure using an artificial neural network as the decision maker in a virtual sequential drilling process within a reservoir model. While neural networks have seen extensive use in other areas of reservoir management, to the best of our knowledge, this work is the first to apply neural networks on well trajectory design within reservoir models. Importantly, both the input data generation used to train the network and the actual trajectory design operations conducted by the trained network are efficient calculations, since these rely solely on geometric and initial properties of the reservoir, and thus do not require additional simulations. Therefore, the main advantage over traditional methods is the highly articulated well trajectories adapted to reservoir properties using a low-order well representation. Well trajectories generated in a realistic reservoir by the automatic well planner are qualitatively and quantitatively compared to trajectories generated by a differential evolution algorithm. Results show that the resulting trajectories improve productivity compared to straight line well trajectories, both for channelized and geometrically complex reservoirs. Moreover, the overall productivity with the resulting trajectories is comparable to well solutions obtained using differential evolution, but at a much lower computational cost.

Real options approach for a staged field development with optional wells

With the decreasing average size of new discoveries in mature production areas, the uncertainties in the base of oil field investment decisions are continually increasing. Fewer appraisal wells, which allow to decrease the amount of subsurface uncertainty, are typically drilled before the development of a small field compared to large fields. In this context, novel solutions must be established to commercialize small discoveries under technical and market uncertainties. In such conditions, managerial flexibilities, which enable to change the course of the project in the event of new information acquisition, must be critically considered in the investment valuation process. Combining the real options approach and decision analysis, we establish a novel model to identify the additional value created by a sequential drilling strategy for field development under oil price and resource uncertainty. In particular, we capture the sequence of the key investment and operating decisions pertaining to a marginal field development in cooperation with an oil industry partner, which corresponds to a synthetic yet realistic project case. By considering the flexibility in dividing the production well drilling into two stages, we adopt the least-squares Monte Carlo algorithm to evaluate the option to wait to expand the production by drilling additional wells. Furthermore, we identify the conditions in which the staged (phased) development is preferable against standard development. We propose a decision rule to determine the optimal expansion timing based on the acquisition of new information on the reservoir and oil price uncertainty. Our results suggest that staged development carries large upside potential for the marginal field development under extensive reservoir uncertainty. In addition, partial hedging against the downside risks in the staged development can enhance the project's economy in a sufficiently significant manner to justify investment.

Influence of a Novel Drill Design on Heat Generation During Conventional and Guided Implant Osteotomy.

The aim of this in vitro study was to evaluate the temperature development of a novel, electropolished drill design during conventional and guided implant osteotomy in comparison to conventional drills under standardized conditions. Single and sequential 12-mm-deep drilling protocols (guided and unguided) with a conventional (control groups) and novel drill (test groups) were performed in artificial bone blocks under external irrigation. Each drilling protocol was repeated 30 times with drill diameters of 2.2, 2.8, 3.5, and 4.2 mm. Temperature changes were recorded by an infrared camera, and the accumulated thermal energy was calculated. For group comparison, a one-way analysis of variance (ANOVA) and Tukey post hoc test were used with a level of significance set to = .05. The highest temperatures were measured up to 77.9°C for small-diameter drills in the control and test groups. The 3.5-mm and 4.2-mm novel drills showed significantly lower heat generation during guided and unguided osteotomy preparation for single and sequential drilling. The accumulated thermal energy during guided osteotomy preparation was significantly lower with the electropolished drills. The drill design has an important impact on heat development during osteotomy, which was most pronounced for guided osteotomy with conventional drills and for small-diameter osteotomies.

Thermal exposure of implant osteotomies and its impact on osseointegration-A preclinical in vivo study.

Thermal and mechanical stresses during osteotomy preparation can impair implant osseointegration. This study investigated implant osseointegration following the measurement of temperature exposure during osteotomy drilling, varying drill design, sequence, and drill wear. 36 tapered implants were placed in a mandibular minipig model after guided drilling of implant osteotomies using 4 different groups: (1) control drills with a conservative, sequential drilling sequence, (2) control drills using a shortened drill sequence (PF), (3) novel test drill displaying an optimized drill design and surface treatment, PF, and (4) aged test drill, PF. Intraosseous temperatures during drilling were measured using a temperature probe. BIC, fBIC, and tissue reactions were histomorphometrically derived after 2 and 8weeks of healing. Compared to control drills (1) or (2), test drills (3) resulted in significantly lower maximum temperatures ((35.4 (CI 30.2-40.5)°C vs. (46.5 (CI 41.0-52.0)°C, p=.0021)) and shorter drill times ((4.5 (CI 1.6-7.3)sec vs. 10.3 (7.3-13.4)sec). Lower osteotomy temperature values and shorter drill times corroborated with significantly higher BIC after 2 and 8weeks healing for the test (3) compared to control groups (2) (2weeks: (44.9 (CI 34.1-55. 7)% vs. (31.3 (CI 20.5-42.2)%, p=<.0001 and 8weeks: (73.7 ( CI 64.2-83.2)% vs. (66.2 (CI 57.0-75.4)%, p=<.0455). The improved osseointegration of implants placed after osteotomy preparation with novel test drills using a shortened drill sequence compared to standard drills and conventional drill protocols might be attributed to more favorable thermal profiles and less mechanical stress exerted on the bone surrounding the implant osteotomy.

Implant Placement Following Crestal Sinus Lift with Sequential Drills and Osteotomes: Five Years after Final Loading Results from a Retrospective Study.

The aim of this retrospective study was to clinically evaluate the five-year outcomes of implants placed following a combined approach to the sinus, consisting of sequential drills and osteotomes. Medical records of patients with implants placed in combination with crestal sinus lift using sequential drills and osteotomes, with a residual alveolar bone crest between 4 to 8 mm, and a follow-up of at least five years after final loading, were evaluated. Outcomes were implant and prosthetic survival and success rates, any complication, and marginal bone loss. Data from 96 patients (53 women and 43 men; mean age 54.7 years; range 23–79 years) were collected. A total of 105 single implants were analyzed. After five years of function, two implants were lost and two prostheses failed. No major biological or prosthetic complications occurred. At the five-year examination, the marginal bone loss was 1.24 ± 0.28 mm. Within the limitations of this retrospective study it can be concluded that implants placed following a combined approach to the sinus consisting of sequential drills and osteotomes seem to be a viable option for the treatment of posterior atrophic edentulous maxilla.