Drilling Protocol Research Articles

Using Haptic Feedback in a Virtual Reality Bone Drilling Simulation to Reduce Plunge Distance.

BackgroundBone drilling is a procedure that demands a high level of dexterity, fine motor skills and spatial awareness from the operating surgeon. An important consideration when drilling bone is minimising soft tissue damage. There are numerous causes of drilling associated soft tissue injury, of which most concerning is drilling into the tissue beyond the far cortex as unseen injury can occur. This is known as plunging.ObjectivesThe objective of this study was to evaluate the impact of haptic feedback in virtual reality (VR) simulation-based training. The acquisition of drilling skill was assessed by changes to their drill plunge depth.Study Design & MethodsThe participants in the study were medical students, doctors and biomedical scientists. Participants were randomly allocated into two groups. One group had simulation with haptic feedback as part of their VR simulated learning, whereas the second group undertook the same VR simulation but did not receive haptic feedback during the simulation. Following completion of the simulated bone drilling protocol, a bone drilling exercise took place. Each participant was allowed to drill a synthetic tibia bone five times and then the plunge depth was measured. We quantified outcome in the form of plunge depth.Results There were four participants in each group. The average plunge distance in the group who were able to practice with haptic assisted VR simulation was 46mm (range: 37-56mm), the average plunge distance in the non-haptic group was 79mm (range: 44-136mm). Results showed an average reduction of 33mm in plunge depth from users in the haptic group compared to the non-haptic group.Conclusion Bone drilling simulation with haptic feedback may be an effective simulator of the motor skills that would be required to perform this action on a live patient. The study results suggest that there could be a reduction in soft tissue damage for users trained in VR simulations with haptic feedback.

Radiographic Assessment of Bone Changes Around Implants Placed using Computer-Guided Approach with Single Drilling Protocol: A Randomised Clinical Trial

Radiographic Assessment of Bone Changes Around Implants Placed using Computer-Guided Approach with Single Drilling Protocol: A Randomised Clinical Trial

Radiographic comparisons of crestal bone levels around implants placed with low-speed drilling and standard drilling protocols: Preliminary results

BackgroundThe present study aimed to investigate the mean crestal bone loss (CBL) by placing implants using two different drilling-protocols, i.e., standard drilling with saline irrigation and low-speed drilling without saline irrigation. Material and MethodsThe patients were enrolled in the present study from a university teaching institute. Patients who fulfilled the inclusion criteria were randomly placed in two study groups: 1) control group: Standard drilling with saline irrigation and 2) test group: low-speed drilling without saline irrigation. The radiographic mean crestal bone loss (CBL) was evaluated at 3 months of follow-up before implant loading. Data analysis was performed using SPSS 20.0 (IBM product, Chicago, USA) and a p-value ≤ 0.05 was considered statistically significant. ResultsSixteen patients (10 males and 6 females) participated in the study. Thirty Camlog®-screw-line implants were placed (15 implants per study group). After 3 months of follow-up, the means CBL of implants placed with standard drilling and low-speed drilling protocols were 1.01 ± 0.49 mm and 0.74 ± 0.62 mm, respectively. No statistically significant difference could be recorded between two groups (p = 0.206). ConclusionsDental implants placed with low-speed drilling without saline irrigation exhibited a similar CBL to implants installed with the standard drilling protocol. However, further randomised clinical trials are recommended to obtain stronger evidence and a better understanding of the effect of the low-speed drilling protocol without saline irrigation on mean CBL and long-term implant survival.

COMPARATIVE EVALUATION OF OSSEODENSIFICATION EFFECT ON PERI-IMPLANT STRAIN WHILE LOADING A FOUR UNIT CERAMIC FIXED PARTIAL DENTURE (IN VITRO STUDY)

Introduction: Primary stability and bone quality are key factors in implant success in early stages of placement while osseointegration comes further on. Objectives: The aim of this study was to compare the effect of osseodensification on peri-implant strain during functional loading of a 4-unit monolithic zirconia bridge as well as its effect on primary stability and insertion torque. Materials and Methods: Sixteen IS-II active implants were used in this study, the implants were divided into 2 groups. Group (A) were placed in conventionally drilled osteotomy sites with progressive subtractive enlargement and Group (B) were placed in osseo-densified osteotomy sites. All implants were inserted in unicortical polyurethane test blocks mimicking medium quality bone while recording insertion torque and implant stability quotient (ISQ) using Osstell for all implants. Each block contained two parallel implants carrying a 4-unit fixed partial denture (FPD). FPD were cemented then thermocycled for 5000/cycle and mechanically loaded at 100N, 2.5×10*5 cycles. A load of 400N and 600N and 800N was applied at connector areas in FPD. Strain gauges were connected to strain meter to record the peri-implant strain for both implants in all groups. Results: Regarding insertion torque and peri-implant insertion torque strain Group (A) had significantly lower values than group B (p < 0.05) while insignificant Osstell values. Concerning peri-implant strain after loading group A had significantly higher strain values than Group (B) (p < 0.05). Conclusions: Osseodensification drilling protocol increased insertion torque values and peri-implant insertion torque strain in comparison to conventional drilling protocol while decreasing peri-implant strain after loading.

Comparison of the accuracy of implant placement using different drilling systems for static computer-assisted implant surgery: A simulation-based experimental study.

Different designs of surgical drilling systems have been developed for the purpose of static Computer-Assisted Implant Surgery (sCAIS), but there is at present little understanding of how design principles affect the accuracy of implant placement. The aim of this in vitro study was to compare the accuracy of implant placement among five drilling systems of sCAIS in a controlled experimental setting. Twenty-five 3D printed models with two edentulous bilateral premolar spaces were allocated to five different drilling systems: group A: sleeve-in-sleeve, group B: sleeve-in-sleeve with self-locking, group C: mounted sleeve-on-drill, group D: integrated sleeve-on-drill with metal sleeve in the guide, group E: integrated sleeve-on-drill without metal sleeve. Models were scanned with CBCT and optical scanner. All implants were digitally planned and 10 implants placed with sCAIS in each group. Postoperative 3D deviation of placed vs planned position was measured by means of platform, apex and angular deviation. Data was analyzed using Kruskal-Wallis test (P ≤ .05). Pairwise comparisons were tested with Dunn's test with adjusted P values. The overall platform deviation ranged from 0.42 ± 0.12 mm (group B) to 1.18 ± 0.19 mm (group C). The overall apex deviation ranged from 0.76 ± 0.22 mm (group B) to 1.95 ± 0.48 mm (group D). The overall angular deviation ranged from 2.50 ± 0.89 degree (group B) to 5.30 ± 1.04 degree (group E). Group A and B showed significantly less angular deviation than groups D and E (P < .05). There was no statistically significant differences in all parameters between group A and B, as well as between group D and E (P > .05). Significant differences were found with regards to accuracy among the five sCAIS systems tested, suggesting that the drilling protocol, the devices used and the design principles of the guides could influence the accuracy of implant placement.

SHORT IMPLANTS- AN EVOLVING TREND- A REVIEW

Short implants have been proposed as one of the positive treatment options for compromised edentulous regions. Decreased bone height, poor bone quality often limit the use of conventional implants and usually necessitate complex surgical procedures like sinus lift or bone augmentations which are associated with increased morbidity, treatment time and cost. Though the crown root ratio of short implants is controversial, they have demonstrated a high success rate with innovations that have bolstered its effectiveness through the modifications in micro and macro surface topography, surgical bone drilling protocols and implant diameter. Photo functionalization of implants and customized implants using 3D printing are some of the promising developments in short implants. KEYWORDS: Short Implants, Implant surface topography, Bone grafting, Photo functionalization, Customized Implants

The Effect of Coronal Implant Design and Drilling Protocol on Bone-to-Implant Contact: A 3-Month Study in the Minipig Calvarium.

Background: Stress concentrated at an implant’s neck may affect bone-to-implant contact (BIC). The objective of this study was to evaluate four different implant neck designs using two different drilling protocols on the BIC. Methods: Ninety-six implants were inserted in 12 minipigs calvarium. Implants neck designs evaluated were: type 1–6 coronal flutes (CFs), 8 shallow microthreads (SMs); type 2–6 CFs,4 deep microthreads (DMs); type 3–4 DMs; type 4–2 CFs, 8 SMs. Two groups of forty-eight implants were inserted with a final drill diameter of 2.8 mm (DP1) or 3.2 mm (DP2). Animals were sacrificed after 1 and 3 months, total-BIC (t-BIC) and coronal-BIC (c-BIC) were evaluated by nondecalcified histomorphometry analysis. Results: At 1 month, t-BIC ranged from 85–91% without significant differences between implant types or drilling protocol. Flutes on the coronal aspect impaired the BIC at 3 m. c-BIC of implant types with 6 CFs was similar and significantly lower than that of implant types 3 and 4. c-BIC of implant type 4 with SMs was highest of all implant types after both healing periods. Conclusions: BIC was not affected by the drilling protocol. CFs significantly impaired the -BIC. Multiple SMs were associated with greater c-BIC.

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.

Effects on Ridge Dimensions, Bone Density, and Implant Primary Stability with Osseodensification Approach in Implant Osteotomy Preparation.

To compare the amount of bone expansion, bone density change, and implant primary stability with an osseodensification technique to a conventional drilling protocol. Twenty-four bovine rib segments (20 × 25 × 4 mm) with a 1-mm outer layer of cortical bone were randomly divided into two groups: an osseodensification group and a conventional drilling group. Each bone sample received one 4.1 × 10-mm implant. The density of the peri-implant bone before and after osteotomy was measured. After implant placement, primary stability was assessed. A laser surface scanner was used before and after implant placement to compare the dimension of crestal bone width and volumetric expansion. Histomorphometric analysis was performed to compare the bone-to-implant contact percentage (BIC%) of the two groups. The peripheral and apical bone mineral density around the implants was significantly increased, and a statistically significantly higher peripheral BIC% was found in the osseodensification group. A significant increase in volume and bone width after implant placement was found in both groups. However, there were no significant differences in volume and bone width change at all three locations and in implant stability between the osseodensification and conventional drilling protocols. Within the limitations of this study, the osseodensification protocol increased the bone mineral density and primary bone-to-implant contact. Also, this study suggests that implant placement by osseodensification or conventional drilling can increase ridge dimensions in narrow alveolar ridges.

Does the Modification of the Apical Geometry of a Dental Implant Affect Its Primary Stability? A Comparative Ex Vivo Study.

(1) Background: Primary stability—one fundamental criterion for the success of dental implants—is influenced by implant geometry even if the effect of apical shape modifications on implant primary stability has not yet been examined. Therefore, the aim of the ex vivo study was to compare primary stability of implants differing in apically located screw threads (J-line) or a flat tip (K-line) only. (2) Methods: 28 implants of each group of the same diameter (4.3 mm) were randomly inserted into porcine bone blocks. The first group (9, 11 and 13 mm) was inserted into “hard”, the second (11 mm) into “soft” bone, here using a normal and an undersized drilling protocol. Insertion torque (Ncm), Periotest® value, resonance frequency (implant stability coefficient, ISQ) and push-out force (N) were measured. (3) Results: In “hard” bone, primary stability increased with increasing length in both groups but it was significantly higher in J-line (p < 0.03). An undersized preparation of the implant bed in “soft” bone resulted in a significant increase in primary stability in both groups. Here, J-line also showed a significantly increased primary stability when compared to equally prepared K-line (insertion torque: 37 Ncm vs. 26 Ncm; Periotest®: −6.5 vs. −4.3; push-out force: 365 N vs. 329 N; p < 0.05 each). (4) Conclusions: Primary stability is significantly higher with increasing implant length and apically located screw threads as well as with undersized drilling protocols. When preparing the implant site and subsequently selecting the implant system, modifying factors such as implant geometry (also at the tip) should be taken into account.

“Effect of low friction chromium surface coating of drills on heat generation during simulated implant osteotomy preparation: an in vitro study”

Brief Background To evaluate the effect of low friction chromium surface coating of drills on heat generation during implant osteotomy preparation in standardized simulated bone blocks. Materials and Methods 32 Artificial polyurethane bone blocks were used as the study models. 32 twisted stainless-steel design drills of three different sizes 2.0mm, 2.4mm and 2.8mm x 18mm were used. Drills were divided into two groups as control (Group 1) and low friction chromium coated (Group 2) drills. Surface coatings of drills were made for Group 2 drills with Low friction chromium. Standardized drilling protocol was used to avoid influence of other drilling factors on heat generation. Osteotomies were performed and temperatures were recorded during drilling procedure using thermocouples at different depths of 4mm, 8mm and 12mm. Method In this study, it was observed that the temperature changes in the thermocouples reading were significant (p&lt;0.001) when compared with control and test group drills, proving that LFC coated drills reduced the heat generated during implant osteotomy preparation due to reduction in frictional contact between the drills and bone. Also, the temperature changes recorded at different depths of drill site showed an increase in temperature with increase in depth of drill site but the values were not statistically significant (p&gt;0.5) to prove the result. Summary and Conclusions Drill depth did not have a significant (p&gt;0.5) effect on heat generation during implant osteotomy preparation. Low friction chromium surface coating can reduce heat generated during implant osteotomy preparation by reducing the frictional contact between the bone and the drill surface. Key Words: dental implants; low friction; heat; polyurethane

The Effectiveness of Osseodensification Drilling Protocol for Implant Site Osteotomy: A Systematic Review of the Literature and Meta-Analysis.

Many different osteotomy procedures has been proposed in the literature for dental implant site preparation. The osseodensification is a drilling technique that has been proposed to improve the local bone quality and implant stability in poor density alveolar ridges. This technique determines an expansion of the implant site by increasing the density of the adjacent bone. The aim of the present investigation was to evaluate the effectiveness of the osseodensification technique for implant site preparation through a literature review and meta-analysis. The database electronic research was performed on PubMed (Medline) database for the screening of the scientific papers. A total of 16 articles have been identified suitable for the review and qualitative analysis—11 clinical studies (eight on animals, three on human subjects), four literature reviews, and one case report. The meta-analysis was performed to compare the bone-to-implant contact % (BIC), bone area fraction occupied % (BAFO), and insertion torque of clockwise and counter-clockwise osseodensification procedure in animal studies. The included articles reported a significant increase in the insertion torque of the implants positioned through the osseodensification protocol compared to the conventional drilling technique. Advantages of this new technique are important above all when the patient has a strong missing and/or low quantity of bone tissue. The data collected until the drafting of this paper detect an improvement when the osseodensification has been adopted if compared to the conventional technique. A significant difference in BIC and insertion torque between the clockwise and counter-clockwise osseodensification procedure was reported, with no difference in BAFO measurements between the two approaches. The effectiveness of the present study demonstrated that the osseodensification drilling protocol is a useful technique to obtain increased implant insertion torque and bone to implant contact (BIC) in vivo. Further randomized clinical studies are required to confirm these pieces of evidence in human studies.

An in vitro evaluation on polyurethane foam sheets of the insertion torque, removal torque values, and resonance frequency analysis (RFA) of a self-tapping threads and round apex implant

The dental implant primary stability and micromovement absence represent critical factor for dental implant osseointegration. The aim of the present in vitro investigation was to simulate the bone response on different polyurethane densities the effect of self-tapping threads and round apex implant geometry. A total of 40 implants were positioned in D1, D2, D3 and D4 polyurethane block densities following a calibrated drilling protocol. The Insertion, removal Torque and resonance frequency analysis (RFA) means were calculated. All experimental conditions showed insertion torque values &gt;30 Ncm. A significant higher insertion torque, removal and RFA was present in D1 polyurethane. Similar evidences were evidenced for D3 and D4. The effectiveness of the present study suggested a valuable clinical advantage for self-tapping threads and round apex implant using, such as in case of reduced bone density in the posterior maxilla

A retrospective case series report on a novel aggressively threaded and tapered implant

Background: Firm primary implant stability is considered as one determinant of success with implant therapy. A novel tapered implant with aggressive threading aiming at high primary stability, also in low bone densities, using a simplified drilling protocol has recently been developed. Aim/Hypothesis: To retrospectively evaluate the primary stability, clinical and radiographic performance of 25 tapered and aggressively threaded implants in 15 consecutive patients after one year of follow-up. Materials and Methods: The study comprised of the first 15 consecutive patients (13 female, 2 male) treated with 25 implants (Proactive Edge, Neoss AB, Gothenburg, Sweden) using a one-stage protocol and loaded for at least one year (Figures 1 and 2). Five implants had been placed in the mandible and 20 in the maxilla for seven single tooth replacements, seven partial bridges and one full bridge. Insertion torque/time curves were registered during placement with an Elcomed drilling unit (W&H Austria GmbH, Bürmoos, Austria). RFA measurements were taken after implant placement using a PenguinRFA instrument (IDSAB, Gothenburg, Sweden). The implants were either restored immediately (n = 5) or after 6 to 8 weeks of healing (n = 20). Marginal bone levels were evaluated in baseline and one-year intraoral radiographs. Results: All implants achieved firm primary stability as assessed with insertion torque (42.6 + 17.0 Ncm, range 13-80 Ncm) and RFA (76.9 + 3.7 ISQ, range 66-84 ISQ) measurements. Thirteen of the implants (all 3.5 mm in diameter) could be placed after the use of one spiral drill only. The remaining implants (4.0 mm, n = 10, 5.0 mm, n = 2) were placed after using two spiral drills. No implant was lost during the one-year of follow-up. The mean marginal bone resorption was 0.5 + 0.6 mm after one year. Conclusions and Clinical Implications: The present case series report showed that the novel implant and simplified drilling protocol resulted in firm primary implant stability. Promising clinical and radiographic outcomes were seen after one year. However, clinical studies including more patients and implants are needed. Keywords: dental implants, primary stability, clinical follow-up, case series Figure 1: The Neoss Proactive Edge implant in different diameters, Figure 2: Postoperative (left) and one-year (right) intraoral radiograph of one implant used for a maxillary molar replacement.

Evaluation of Insertion Energy as Novel Parameter for Dental Implant Stability.

Insertion energy has been advocated as a novel measure for primary implant stability, but the effect of implant length, diameter, or surgical protocol remains unclear. Twenty implants from one specific bone level implant system were placed in layered polyurethane foam measuring maximum insertion torque, torque–time curves, and primary stability using resonance frequency analysis (RFA). Insertion energy was calculated as area under torque–time curve applying the trapezoidal formula. Statistical analysis was based on analysis of variance, Tukey honest differences tests and Pearson’s product moment correlation tests (α = 0.05). Implant stability (p = 0.01) and insertion energy (p < 0.01) differed significantly among groups, while maximum insertion torque did not (p = 0.17). Short implants showed a significant decrease in implant stability (p = 0.01), while reducing implant diameter did not cause any significant effect. Applying the drilling protocol for dense bone resulted in significantly increased insertion energy (p = 0.02) but a significant decrease in implant stability (p = 0.04). Insertion energy was not found to be a more reliable parameter for evaluating primary implant stability when compared to maximum insertion torque and resonance frequency analysis.

Implant primary stability with an osteocondensation drilling protocol in different density polyurethane blocks

The implant primary stability is a fundamental condition for avoiding implant micro-motions that might result in fibrous encapsulation; its achievement is facilitated by macro- and micro-geometry of the implant, and by the bone density and architecture at the intended implant site. The aim was to evaluate an osteocondensing drilling protocol for dental implant positioning compared to standard protocol on polyurethane block. A total of 40 implants, 20 for each osteocondensing group (Test) and 20 for standard drilling group (Control), were positioned. Insertion torque (IT), removal torque (RT), and Periotest were measured. A IT, RT, and Periotest significant difference was present in favor of the implant osteocondensing protocol. The results suggested that osteocondensing protocol represents a useful technique for implant placement in poor density bone.

Effect of insertion factors on dental implant insertion torque/energy-experimental results

Anchorage of dental implants is quantified with a mechanical engagement to insertion, for example maximum insertion torque (MIT) and insertion energy (IE). Good anchorage of dental implants highly correlates to positive clinical outcomes. However, it is still unclear how bone density, drill protocol, surface finish and cutting flute affect anchorage. In this study, effects of the insertion factors on both MIT and IE were investigated using a full-factorial experiment at two levels: bone surrogate density (0.32 g/cm3 versus 0.48 g/cm3), drill protocol (Ø2.4/2.8 versus Ø2.8/3.2 mm), implant surface finish (machined versus anodized surface) and cutting flute (with versus without). Osteotomies were prepared on rigid polyurethane foam blocks with dimensions of 40 × 40 × 8 mm. Screw shaped dental implants with variable tapered body were consecutively inserted into and removed from the polyurethane foam blocks three times under constant axial displacement and rotational speed. Axial force and torque were recorded synchronously. Insertion energy was calculated from the area under the torque-displacement curve. In this study, we found the main insertion mechanics were thread forming for the first insertion. For the second and third insertions, the main mechanics shifted to thread tightening. Maximum insertion torque (MIT) responded differently to the four insertion factors in comparison to IE. Bone surrogate density, drill protocol and surface finish had the largest main effects for first MIT. For the first IE, drill protocol, surface finish and cutting flute were significant contributors. These results suggest that MIT and IE are influenced by different mechanics: the first MIT and the first IE were sensitive to thread tighten and forming, respectively. Together MIT and IE provide a complete assessment of dental implant anchorage.

Comparison of bone-to-implant contact and bone volume around implants placed with or without site preparation: a histomorphometric study in rabbits

The objective of this in vivo study was to compare bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) values of a new implant, designed to be inserted without bone preparation, using two different preparation protocols: no site preparation and prior limited cortical perforation, versus the values of a control implant using a conventional drilling protocol. Forty-one implants were inserted in 13 rabbits. Thirteen test implants with a new thread design were inserted using no bone preparation (NP), 14 test implants were inserted with limited cortical perforation (CP), and 14 conventional implants served as control. Five animals were sacrificed after 21 days and eight animals after 42 days. Histomorphometric analysis was performed and percentage of BIC and BAFO values were measured. ANOVA with Tukey post hoc and Mann–Whitney nonparametric tests were calculated to compare between the groups. Statistical analysis showed no significant difference in the measured values between any of the groups, neither compered by implant nor by compered day. The results demonstrated that biological osseointegration parameters of implant that was inserted without any bone preparation was non-inferior compared to conventional preparation. The clinical relevance is that novel implant designs may not require bone preparation prior to placement.

Biomechanical Evaluation of Initial Stability of a Root Analogue Implant Design with Drilling Protocol: A 3D Finite Element Analysis

Background: The aim of this study was to biomechanically evaluate the initial stability of a patient-specific root analogue implant (RAI) design with drilling protocol by comparing it to designs without drilling protocol through a 3D finite element analysis (FEA). Methods: A 3D surface model of an RAI for the upper right incisor was constructed. To evaluate the effect of root apex drilling, four modified RAI shapes were designed with the press-fit implantation method: Non-modified, wedge added at root surface, lattice added at root surface, and apex-anchor added at root apex (AA). Each model was subjected to an oblique load of 100 N. To simulate the initial stability of implantation, contact conditions at the implant–bone interface were set to allow for the sliding phenomenon with low friction (frictional coefficient 0.1–0.5). Analysis was performed to evaluate micro-displacements of the implants and peak stress on the surrounding bones. Results: Under all low frictional coefficient conditions, the lowest von Mises stress level on the cortical bone and fewest micro-displacements of the implant were observed in the AA design. Conclusion: In view of these results, the AA design proved superior in reducing the stress concentration on the supporting cortical bone and the micro-displacement of RAI.

A look back, part II: The drilling campaign of the Curiosity rover during the Mars Science Laboratory's second and third martian years

The Mars Science Laboratory (MSL) rover, Curiosity, completed its second Martian year, 1337 sols (1374 Earth days), of operation on May 11, 2016, and its third Martian year, 2006 sols (2061 Earth days), of operation on March 28, 2018. During this time the rover successfully drilled twelve full depth drill holes into the Martian surface and analyzed the recovered material using onboard instruments, giving us new insights into the potential habitability and geologic diversity of ancient Mars. During the second Martian year, four holes were drilled into the mudstones of the Murray formation: ‘Confidence Hills’ (Sol 759), ‘Mojave 2’ (Sol 882), ‘Telegraph Peak’ (908) & ‘Buckskin’ (Sol 1060); while four more holes were drilled into the sandstones of the Stimson formation: ‘Big Sky’ (Sol 1119), ‘Greenhorn’ (Sol 1137), ‘Lubango’ (Sol 1320) & ‘Okoruso’ (Sol 1332). During the third Martian year, four additional holes were drilled into the Murray formation: ‘Oudam’ (Sol 1361), ‘Marimba’ (Sol 1422), ‘Quela’ (Sol 1464) & ‘Sebina’ (Sol 1495). In this paper, we will give a brief overview of the rover sampling hardware and nominal drilling protocols, followed by a discussion of how these protocols were refined and altered early during the course of Curiosity's second year on Mars. In addition, we will describe the ‘Bonanza King’ (Sol 724) drill campaign, the mission's first ‘successful failure’, and how it influenced these changes. We will also briefly discuss the events leading up to the drill feed fault on Sol 1536, which resulted in suspension of all drill activities for the remainder of the third Martian year. Finally, we will present scientific highlights obtained from each drill site utilizing MSL's onboard instrumentation (SAM & CheMin), results enabled by the drill's ability to excavate sample at depth and transfer it to these instruments.