Evaluation of deviation in implants placed at different depths with a prototype surgical guide: an in vitro study.

The aim of this study was to measure the angular and linear deviations between planned and placed dental implant positions at different depths in an in vitro model. Ten dental manikins of a maxilla without the central and lateral incisors were used. The implants were placed in the tooth positions using a prototype guide based on computed tomographic scans of dental casts. The groups consisted of implants placed at varying depths according to tooth position: 1 mm deep for the right lateral incisor, 2 mm deep for the right central incisor, 3 mm deep for the left central incisor, and 4 mm deep for the left lateral incisor (n = 10 per group). After implant placement, the manikin was scanned again to compare the positioning of the implants to the planned positions. Statistical analysis evaluated the linear deviations between planned and placed implant positions at 3 points (coronal, central, and apical) as well as the angular discrepancies. The analysis showed that the depth of the implant placement proportionally affected the linear deviation of the actual position from the planned position; thus, the deeper implants showed significantly greater linear deviations (P < 0.05; 1-way analysis of variance and Tukey test). There were no statistically significant differences in the mean angular deviations of the groups. Thus, the results suggest that implants placed at greater depths present greater linear deviations than implants placed at shallower depths, but the angular deviation is not affected by implant depth.

Stability of mandibular implants with Morse taper and external hexagon connections placed under immediate loading: a longitudinal clinical study.

The aim of this study was to compare the longitudinal stability of implants with Morse taper and external hexagon connections placed in the anterior mandible and subjected to immediate functional loading. Nine patients each received 4 mandibular implants placed between the mental foramina. In each patient, 2 implants on the left side of the arch had Morse taper prosthetic connections, and 2 implants on the right side had external hexagon prosthetic connections. Mandibular overdentures and opposing removable complete dentures were placed within 72 hours after implant surgery. Clinical evaluation of the implants via magnetic transduction resonance frequency analysis was performed immediately following surgery and 3 months, 6 months, and 2 years following surgery to obtain the implant stability quotient (ISQ). The data obtained were parametric according to the Kolmogorov-Smirnov normality test. The lowest ISQ of any implant was approximately 67, representing reliable osseointegration. The only statistically significant difference between the 2 types of prosthetic connection was found in the initial period (immediately following surgery), when the external hexagon connection in the distal position presented greater stability than did the Morse taper connection in the same position on the opposite side (P < 0.05; Student t test). In intragroup comparisons, no statistically significant differences were found regarding the positions of the implants in the mandible. When the different follow-up periods were evaluated, there were statistically significant differences only in the external hexagon group, with significant reductions in stability of both mesial and distal implants at 6 months compared to other time periods (P < 0.05; Tukey test). Within the limitations of the study, it can be concluded that both Morse taper and external hexagon prosthetic connections provide good stability in an immediate functional loading protocol.

Analysis of Linear and Angular Deviations of Implants Installed With a Tomographic-Guided Surgery Technique: A Prospective Cohort Study.

The aim of this study was to evaluate the linear and angular deviations of the implants installed by the computerized tomography (CT)-guided surgery technique. Eighteen patients who underwent implant insertion by means of CT-guided surgery participated in this study. Ten of these patients had a fully edentulous maxilla, and 8 had a fully edentulous mandible. The patients received a total of 115 implants, of which 81 implants were installed in the maxilla and 34 installed in the mandible. Tomographic guides were made for tomographic examination in both the upper and lower jaws. After the image acquisition, the virtual planning of the positioning of the implants was performed in relation to the previously made prosthesis. The measurement of the linear and angular deviations between the virtual planning and the final position of the implants was performed with the overlap of the planning and postoperative tomography. There were no differences in the linear and angular deviations of the implants installed in the maxilla and mandible. Compared with the coronal region, there was a trend of greater linear deviations in the apical regions of the implants and a greater tendency toward deviations in the posterior regions than in the anterior regions of both arches. The CT-guided surgery promoted the installation of implants with high accuracy and allowed the installation of straight pillars in all cases evaluated. The linear deviations were not different in the different regions of the mouth or in the different portions of the implants.

In vivo evaluation of cp Ti implants with modified surfaces by laser beam with and without hydroxyapatite chemical deposition and without and with thermal treatment: topographic characterization and histomorphometric analysis in rabbits.

OBJECTIVE: We aimed to assess the surfaces of commercially pure titanium implants (cp Ti) with modified surfaces by laser beam (LS) with and without hydroxyapatite (HA) deposition, without (HAB) and with (HABT) thermal treatment. Furthermore, we have compared them with implants with surfaces modified by acid treatment (AS) and with machined surfaces (MS) utilizing histomorphometric and descriptive histologic analyses. MATERIAL AND METHODS: Surface topography characterization was analyzed by scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDX), and surface roughness (Ra) before implant installation. Forty-five rabbits received seventy-five implants in their left and right tibias and were randomly divided into five groups (n = 5 implants per group): (1) cp Ti implant modified by LS, (2) cp Ti implant modified by laser beam associated with HA deposition without heat treatment (HAB), (3) cp Ti implant modified by laser beam associated with HA deposition with heat treatment (HABT), (4) cp Ti implant with modified surface by means of acid treatment (Master Porous) commercially available (AS), and (5) cp Ti implant with MS commercially available. After 30, 60, and 90 days, the animals were euthanized and the implants and surrounding bone were removed and prepared by a non-decalcified histological process. The percentage of bone-to-implant contact (BIC) and the bone area fraction occupancy (BAFO) between the first three threads was evaluated to the higher cortical region. RESULTS: BIC (%) was statistically superior (p < 0.001) on the LS (69.36 ± 7.91, 71.67 ± 8.79, and 79.69 ± 3.3), HAB (73.22 ± 3.75, 69.48 ± 1.89, and 75.7 ± 4.62), and HABT (65.41 ± 5.51, 71.3 ± 2.5, and 79.68 ± 5.01) compared with AS (49.15 ± 5.76, 41.94 ± 2.85, and 57.18 ± 7.81) and MS (36.69 ± 7.24, 52.52 ± 2.75, and 51.31 ± 6.96) in the 30, 60, and 90-day periods, respectively. BAFO (%) of HAB at 30 days (90.17 ± 6.24) was statistically superior (p < 0.01) to all the other groups. At 60 and 90 days, BAFO of LS (87.17 ± 5.9 and 87.99 ± 2.52), HAB (85.95 ± 3.93 and 82.17 ± 3.65), and HABT (83.27 ± 1.44 and 88.67 ± 2.67) was higher than the AS (77.49 ± 5.83 and 76.42 ± 5.98) and MS (74.01 ± 4.68 and 73.81 ± 4.91). CONCLUSIONS: Collectively, our data indicate that the modified surfaces LS, HAB, and HABT favored the interaction between bone and implant and increased bone formation. In addition, HAB showed higher biological behavior favoring the osseointegration. CLINICAL RELEVANCE: Our study provides evidence that LS, HAB, and HABT-modified surfaces improved bone-to-implant contact and increased bone formation around osseointegrated implants compared to conventional machined implants favoring the osseointegration process.

Evaluation of Short and Regular Implants after Prosthesis Placement in the Mandible: A Nonrandomized Controlled Clinical Trial.

AIM: The aim of this nonrandomized controlled preliminary clinical trial was to compare treatment using short and conventional implants in the posterior region of the mandible after prosthesis installation by means of clinical, resonance frequency, and radiographic analyses. MATERIALS AND METHODS: A total of 10 patients with 40 dental implants already installed were included in this study. Four implants were installed for each subject, in which the length of the implants (short and conventional) was distributed according to the reminiscent alveolar bone in the left and right side of the mandible. All implants received splinted prosthesis after the osseointegration period. Analyses were performed immediately after prosthesis installation (T1), and 3 (T2) and 6 months (T3) after prosthesis placement. RESULTS: The 6-month survival and success rates were 100% for the short and conventional implants. Probing depths (PDs) after 6 months did not show statistical differences between short and conventional implants. All groups showed mean implant stability quotient (ISQ) values above 60 in all periods evaluated, demonstrating great implant stability, and no differences were found between groups at T3. Radiographic measurements showed an increased bone loss for conventional implants compared with short implants in all the three periods evaluated. CONCLUSION: Our findings suggest that treatment of resorbed posterior regions in the mandible with shorter dental implants is as reliable as treatment with conventional implants after 6 months of splinted prosthesis installation. CLINICAL SIGNIFICANCE: Short implants might be considered a predictable treatment alternative to bone augmentation or extensive surgical techniques in regions of restricted vertical bone height in the posterior region of the mandible.

Guided Surgery in Esthetic Region.

The placement of dental implants and subsequent placement of immediate temporary dentures after extractions has become a treatment modality accepted by the scientific community. In addition to the functional factor, the surgical procedure in a single stage in the anterior region of the maxilla offers an esthetic appearance, and relieves the psychological concerns of patients. To guarantee the success and longevity of treatments performed, the fabrication of surgical guides is a helpful method in these situations. Guided surgery has gained attention because it restores esthetics with immediate restoration, provides the patient with comfort in addition to dispensing with the need for performing surgical flaps. This auxiliary method allows the position and design of the implant, as well as the perforation sequence to be programmed, thus optimizing the clinical results. In this study, the authors present a clinical case of a patient who was submitted to extraction and subsequent implant placement with immediate loading in the anterior region of the maxilla, performed in a satisfactory manner.

Clinical study on survival rate of short implants placed in the posterior mandibular region: resonance frequency analysis.

OBJECTIVE: Short implants are increasingly used, but there is doubt about their performance being similar to that of regular implants. The aim of this study was to compare the mechanical stability of short implants vs. regular implants placed in the edentulous posterior mandible. MATERIAL AND METHODS: Twenty-three patients received a total of 48 short implants (5 × 5.5 mm and 5 × 7 mm) and 42 regular implants (4 × 10 mm and 4 × 11.5 mm) in the posterior mandible. Patients who received short implants had <10 mm of bone height measured from the bone crest to the outer wall of the mandibular canal. Resonance frequency analysis (RFA) was performed at time intervals T0 (immediately after implant placement), T1 (after 15 days), T2 (after 30 days), T3 (after 60 days), and T4 (after 90 days). RESULTS: The survival rate after 90 days was 87.5% for the short implants and 100% for regular implants (P < 0.05). There was no significant difference between the implants in time intervals T1, T2, T3, and T4. In T0, the RFA values of 5 × 5.5 implants were higher than values of 5 × 7 and 4 × 11.5 implants (P < 0.05). A total of six short implants that were placed in four patients were lost (three of 5 × 5.5 mm and three of 5 × 7 mm). Three lost implants started with high ISQ values, which progressively decreased. The other three lost implants started with a slightly lower ISQ value, which rose and then began to fall. CONCLUSIONS: Survival rate of short implants after 90 days was lower than that of regular implants. However, short implants may be considered a reasonable alternative for rehabilitation of severely resorbed mandibles with reduced height, to avoid performing bone reconstruction before implant placement. Patients need to be aware of the reduced survival rate compared with regular implants before implant placement to avoid disappointments.

Rehabilitation of the maxillary arch after bone graft using immediate loading with implant-supported fixed restoration.

Moderate and controlled loading environments support or enhance osteogenesis, and, consequently, a high degree of bone-to-implant contact can be acquired. This is because when osteoprogenitor cells are exposed to limited physical deformation, their differentiation into osteoblasts is enhanced. Then, some range of microstrain is considered advantageous for bone ingrowth and osseointegration. The primary stability has been considered one of the main clinical means of controlling micromotion between the implant and the forming interfacial tissue, which helps to establish the proper mechanical environment for osteogenesis. Based on the biological aspects of immediate loading (IL), the objective of this study is to present a clinical case of maxillary arch rehabilitation using immediate loading with implant-supported fixed restoration after bone graft. Ten dental implants were placed in the maxilla 6 months after the autogenous bone graft, removed from the mandible (bilateral oblique line and chin), followed by the installation of an immediate-load fixed cross-arch implant-supported restoration because primary stability was reached for 8 implants. In addition, instructions about masticatory function and how it is related to interfacial micromotion were addressed and emphasized to the patient. The reasons for the IL were further avoidance of an interim healing phase, a potential reduction in the number of clinical interventions for the patient, and aesthetic reasons. After monitoring the rehabilitation for 8 years, the authors can conclude that maxillary IL can be performed followed by a well-established treatment planning based on computed tomography, providing immediate esthetics and function to the patient even when autogenous bone graft was previously performed in the maxilla.

Mechanical behavior of dental implants in different positions in the rehabilitation of the anterior maxilla.

STATEMENT OF PROBLEM: In dental rehabilitations that involve implants, the number of implants is sometimes smaller than the number of lost teeth. This fact can affect the biomechanical behavior and success of the implants. PURPOSE: The purpose of this study was to investigate the mechanical behavior of different implant positions in the rehabilitation of the anterior maxilla. MATERIAL AND METHODS: Three-dimensional models of the maxilla were created based on computed tomography images for 3 different anterior prosthetic rehabilitations. In group IL, the implants were placed in the lateral incisor positions with pontics in the central incisor positions; in group IC, the implants were in the central incisor positions with cantilevers in the lateral incisor positions; and, in group ILIC, one implant was in a lateral incisor position and one was in a central incisor position, with a pontic and a cantilever in the remaining positions. A 150 N load was distributed and applied at the center of the palatal surface of each tooth at a 45-degree angle to the long axis of the tooth. The resulting stress-strain distribution was analyzed for each group. RESULTS: The lowest displacement of the prosthetic structure was observed in group IC, although the same group exhibited the largest displacement of the bone tissue. In the bone tissue, the von Mises stress was mainly observed in the cortical bone in all groups. The maximum value of the von Mises stress shown in the cortical tissue was 35 MPa in the implant that neighbors the cantilever in group ILIC. The maximum von Mises stress in the trabecular bone was 3.5 MPa. CONCLUSION: The prosthetic configuration of group IC limited the displacement of the prosthetic structure but led to greater displacement of the bone structure. The use of a cantilever increased the stress concentration in the implant and in the bone structure adjacent to the cantilever under the conditions studied here.

Repair technique for fractured implant-supported metal-ceramic restorations: a clinical report.

The fracture of porcelain structures have been related in either natural dentition or implant-supported restorations. Techniques using a composite resin or indirect methods can be used. This article presents a porcelain fracture on implant-supported metal-ceramic restoration. IPS Empress e.max laminate veneer restoration was used to repair the fracture. With this technique, it was possible to restore aesthetics and function, combined with low cost and patient satisfaction.

Effect of different thread configurations on hydrophilic implant stability. A split-mouth RCT.

This split-mouth randomized controlled trial aimed to evaluate the primary and secondary stability of hybrid implants with different thread configurations and hydrophilic surfaces. Twenty patients with a partially edentulous maxilla were selected. These patients received two types of implants with the same hydrophilic surface: CTP group: Cylindrical-Tapered implant with perforating threads; CTH: Cylindrical-Tapered implant with hybrid threads configuration (perforating and condensing threads). The primary and secondary stability parameters were measured by insertion torque and resonance frequency analysis at the time of implant placement and 7, 28, 56, and 90 days after the surgical procedure. The paired t-test was used to compare the data on the implant's stability between the groups. The statistical analysis was performed with a confidence level set at 95%. It was found that the implants in the CTH group presented higher primary stability values ​​at the time of implant placement, due to the higher ISQ (63.61 ± 9.44 vs. 40.59 ±7.46) and insertion torque (36.92 ± 16.50 Ncm vs. 28.00 ± 14.40 Ncm), than the implants in the CTP group. The CTH group presented higher ISQ values ​​in all follow-up periods: 7 days (68.67 ± 7.60 vs. 41.55 ± 9.07), 28 days (68.61 ± 5.98 vs. 47.90 ±13.10), 56 days (74.09 ± 3.96 vs. 55.85 ± 13.18), and 90 days (75.45 ± 4.02 vs. 63.47 ± 6.92) after implant placement. Hybrid implants with perforating and condensing threads demonstrated greater stability than hybrid implants with only perforating threads.

Commercially pure titanium implants with surfaces modified by laser beam with and without chemical deposition of apatite. Biomechanical and topographical analysis in rabbits.

OBJECTIVES: The purpose of this study was to evaluate the surfaces of commercially pure titanium (cp Ti) implants modified by laser beam (LS), without and with hydroxyapatite deposition by the biomimetic method (HAB), without (HAB) and with thermal treatment (HABT), and compare them with implants with surfaces modified by acid treatment (AS) and with machined surfaces (MS), employing topographical and biomechanics analysis. METHODS: Forty-five rabbits received 75 implants. After 30, 60, and 90 days, the implants were removed by reverse torque and the surfaces were topographically analyzed. RESULTS: At 30 days, statistically significant difference (P < 0.05) was observed among all the surfaces and the MS, between HAB/HABT and AS and between HAB and LS. At 60 days, the reverse torque of LS, HAB, HABT, and AS differed significantly from MS. At 90 days, difference was observed between HAB and MS. The microtopographic analysis revealed statistical difference between the roughness of LS, HAB, and HABT when compared with AS and MS. CONCLUSIONS: It was concluded that the implants LS, HAB, and HABT presented physicochemical and topographical properties superior to those of AS and MS and favored the osseointegration process in the shorter periods. In addition, HAB showed the best results when compared with other surfaces.

Guided implant surgery: what is the influence of this new technique on bone cell viability?

PURPOSE: To evaluate the effect of implant osteotomy on immediate bone cell viability, comparing guided surgery for implant placement with the classic drilling procedure. MATERIALS AND METHODS: For this study, 20 rabbits were used. The animals were divided into a guided surgery group (GG) and a control group (CG) and were then divided into 4 subgroups--subgroups 1, 2, 3, and 4--corresponding to drills used 10, 20, 30, and 40 times, respectively. All animals received 5 osteotomies in each tibia, by use of the classic drilling procedure in one tibia and guided surgery in the other tibia. The osteotomized areas were removed and processed immunohistochemically for detection of osteocalcin, receptor activator of nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), and caspase 3. RESULTS: Immunohistochemical analysis showed that osteocalcin expression was initially higher in the CG and remained constant after drill reutilization. Although the expressions of RANKL and OPG were not statistically different for the GG and CG, the RANKL/OPG ratio tended to be higher for the GG. Moreover, caspase 3 expression was elevated in the GG, proportionally to the number of osteotomies, indicating an increase in the apoptosis index in the GG. CONCLUSIONS: The classic drilling procedure is more favorable to cell viability than guided surgery.

Bone augmentation and autogenous transplantation of premolar to the site of the fissure in a cleft palate patient.

This article presents a case report of autogenous tooth transplantation to the site of the fissure, in addition to bone augmentation with graft of autogenous bone harvested from the iliac crest, performed in a cleft palate patient, who had insufficient bone volume. A non-syndromic 10-year-old girl, with a unilateral cleft lip and palate, incisal transforamen fissures, agenesis of the maxillary left central incisor and both maxillary lateral incisors, was treated with autogenous bone graft in the cleft area. The orthodontic treatment plan was to replace the missing lateral incisors with the maxillary canines and to extract the mandibular first premolars. One of the mandibular premolars was extracted from its site with 2/3 of its root formation completed and transplanted to the maxillary left central incisor area. After orthodontic treatment, the anatomic crowns were characterized with composite resin. Autogenous tooth transplantation can be performed in the area of the fissure in young cleft palate patients, by performing bone graft augmentation before transplantation of the tooth, to gain sufficient recipient alveolar bone volume. A multidisciplinary approach is mandatory for the success of this clinical procedure, especially in cleft palate patients.

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

OBJECTIVE: The study aimed to assess the angular and linear deviations of implants installed in mannequins aided by surgical guides produced with the techniques of dual tomography (DT), model-based tomography (MT), and nonprototyped guide. MATERIALS AND METHODS: Implants were installed in mannequins of a partially edentulous maxilla and divided into three groups: Group C (n = 20), implants installed using the conventional technique with flap opening and conventional guide; Group DT (n = 20), implants installed using guided surgery with the dual tomography technique; and Group MT (n = 20), implants installed using the model-based tomography technique. After implant installation, the mannequin was subjected to a computed tomography (CT) to measure the linear and angular deviations of implant positioning relative to the initial planning on both sides. RESULTS: There was a higher mean angular deviation in group C (4.61 ± 1.21, p ≤ 0.001) than in groups DT (2.13 ± 0.62) and MT (1.87 ± 0.94), which were statistically similar between each other. Similarly, the linear deviations showed group C with the greatest discrepancy in relation to the other groups in the crown (2.17 ± 0.82, p = 0.007), central (2.2 ± 0.77, p = 0.004), and apical (2.34 ± 0.8, p = 0.001) regions. CONCLUSION: The techniques of DT and MT presented smaller angular and linear deviations than the conventional technique with the nonprototyped guide. There was no difference between the two-guided surgery techniques.

Effectiveness of Hyaluronic Acid Injection for Interdental Papillae Recovery in Esthetic Areas: A Randomized Clinical Trial.

The aim of this study was to evaluate the effectiveness of hyaluronic acid (HA) injections used to reduce defects in the gingival papillae in esthetic areas. This randomized study included six patients requiring black triangle treatment in 19 defective papillae. After local anesthesia, less than 0.2 mL of HA was injected 2 to 3 mm into the tip of the deficient papilla in the apical direction. Analysis of the target regions with standardized photographs and 3D intraoral scanning (CEREC 4.5 software with RST files, Dentsply Sirona) was performed at baseline (T0) and at 1 month (T1), 2 months (T2), 3 months (T3), and 4 months (T4) after the initial application of HA. At each time period, the photographic analysis showed no statistically significant differences in linear tissue gain after HA gel application. The 3D analysis showed improvements in the vertical papillae tissue recovery at T3 (0.41 ± 0.21 mm) and T4 (0.38 ± 0.21 mm) when compared to T1 (0.13 ± 0.08 mm; P < .0001). Regarding the reconstruction of the interdental papillae, the general dimensions of the tissue in the black triangle areas showed a significant increase in size percentage at T3 (58% ± 32.9%) compared to T1 (30.41% ± 23.4%; P = .0054). Thus, the application of injectable HA was effective for filling papillae in the esthetic area. Int J Periodontics Restorative Dent 2023;43:e73-e80. doi: 10.11607/prd.5814.

Mandibular rehabilitation using immediate implant loading after computer-guided surgery.

Computed tomographic scan is a precise complementary examination of diagnostic imaging and a noninvasive surveying technique that enables the professional to improve precision of implant placement by building a prototype that allows the confection of surgical guides. The authors present a clinical case of mandible rehabilitation based on computed tomography of a patient; the cross sections were reformatted and used to construct a virtual planning of the implants and a guide template in Dental Slice. Immediate loading of 5 titanium implants were placed in the mandible using a Slice Guide System. This technique allows a better surgical planning, makes the procedures more accurate, and reduces surgery time.

Osteoconductive properties of ß-tricalcium phosphate matrix, polylactic and polyglycolic acid gel, and calcium phosphate cement in bone defects.

Extensive bone defects in maxillofacial region can be corrected with autogenous grafts; otherwise, the disadvantages of the therapeutics modality take the research for new bone substitutes. The aim of the study was to evaluate and compare the osteoconductive properties of 3 commercial available biomaterials. A total of 30 calvarial defects (5-mm diameter) were randomly divided into 5 treatment groups, with a total of 6 defects per treatment group (n = 6). The treatment groups were as follows: 500 to 1000 µm ß-tricalcium phosphate (ß-TCP), polylactic and polyglycolic acid (PL/PG) gel, calcium phosphate cement, untreated control, and autograft control. The evaluations were based on histomorphometric analysis at 60 postoperative days. The results have shown that ß-TCP and autograft control supported bone formation at 60 postoperative days. ß-Tricalcium phosphate showed the highest amount of mineralized area per total area and statistically significant compared with PL/PG, calcium phosphate cement, and untreated control groups. The PL/PG gel does not have osteoconductive properties and performed similar to empty control. Calcium phosphate cement showed higher number of multinucleated giant cells around the sites of the biomaterial and showed newly formed bone only at the edges of the biomaterial, without bone formation within the biomaterial. The findings presented herein indicate that bone formation reached a maximum level when rat calvarial defects were filled with ß-TCP at 60 postoperative days. Further studies should be conducted with ß-TCP to understand the potential of this biomaterial in bone regeneration.

Anterior tooth rehabilitation with frozen homogenous bone graft and immediately loaded titanium implant using computer-guided surgery.

Computed tomographic scanning is a precise, noinvasive surveying technique that enables the professionals to improve the precision of implant placement by building a prototype that allows the confection of surgical guides. The authors present a clinical case of anterior tooth rehabilitation with frozen homogenous bone graft and immediately loaded titanium implant using computer-guided surgery. A multislice computed tomography was realized, and a prototype was built. All the procedures were previously realized in the prototype before started in the patient. This technique allows a better surgical planning, makes the procedures more accurate, and reduces surgery time.

Compromised primary implant stability.

The aim of this study was to evaluate implants installed with compromised primary stability associated or not with polylactide and polyglycolide copolymer (PLA/PGA). Two 0.4-mm overdrilled defects (3 mm in diameter and 6 mm long) were produced in the right tibia of 25 rabbits. Half of the defects were left untreated, and the other half was filled with PLA/PGA. Implants of 2.6 mm in diameter and 6 mm long were placed into all defects. Animals were killed at 5, 15, 40, and 60 postoperative days, and biomechanical analysis (torque-reverse), histomorphometry, and immunohistochemistry (osteoprotegerin, receptor activator of NF-κB ligand [RANKL], osteocalcin, and collagen-1 [COL-I] staining) were performed. All the implants achieved osseointegration. There were no statistically significant differences in the torque-reverse and in linear contact extension between bone tissue and implant surface and no statistically significant difference in osteoprotegerin, RANKL, osteocalcin, and collagen-1 expression between the studied groups in all studied periods (P > 0.05). We can conclude that osseointegration can occur in compromised primary implant stability situations, and the addition of PLA/PGA did not improve the osseointegration process in this experimental model.