Biomechanical Effects of Ti-Base Abutment Height on the Dental Implant System: A Finite Element Analysis.

This study aims to analyse, using a finite element analysis, the effects of Ti-base abutment height on the distribution and magnitude of transferred load and the resulting bone microstrain in the bone-implant system. A three-dimensional bone model of the mandibular premolar section was created with an implant placed in a juxta-osseous position. Three prosthetic models were designed: a 1 mm-high titanium-base (Ti-base) abutment with an 8 mm-high cemented monolithic zirconia crown was designed for model A, a 2 mm-high Ti-base abutment with a 7 mm-high crown for model B, and a 3 mm-high abutment with a 6 mm-high crown for model C. A static load of 150 N was applied to the central fossa at a six-degree angle with respect to the axial axis of the implant to evaluate the magnitude and distribution of load transfer and microstrain. The results showed a trend towards a direct linear association between the increase in the height of the Ti-base abutments and the increase in the transferred stress and the resulting microstrain to both the prosthetic elements and the bone/implant system. An increase in transferred stress and deformation of all elements of the system, within physiological ranges, was observed as the size of the Ti-base abutment increased.

Orthopantomography Detection of Atheroma Plaques and Its Relationship with Periodontal Disease and Missing Teeth.

Background: The aim of this study is to determine the atheromatous plaques' prevalence in orthopantomography and their relationship with periodontal disease and missing teeth. Material and Methods. Orthopantomographs of 1,254 patients over 18 years of age from Clínica Arlanza in Lerma, Burgos, were examined between 2017 and 2021. A Planmeca ProOne® orthopantomograph (68 kV, 7 mA, and 10 sg) was used. Statistical analysis was carried out using SPSS Statistics® version 25. The results of the categorical variables were described as frequencies (%). Contingency tables were made with the qualitative variables, and the chi-square test was applied to study the relationship among them. The measure of statistical power used was the relative risk (RR), which was described with its respective 95% confidence interval (CI). Student's t-test was applied to study the relationship between the qualitative variable "presence or absence of atheroma plaque" and the quantitative variable "number of teeth." Results: A 6.2% prevalence of atheroma plaques was obtained from 1,079 selected X-rays. The risk in patients with periodontal disease increased as periodontal disease worsened. The risk in patients with periodontal disease increased as periodontal disease worsened as follows: healthy patients vs. periodontal patients with less than 30% bone loss in radiography: RR 0.434, 95% CI 0.181-1.041, p = 0.053 healthy patients vs. patients with between 30%-60% bone loss: RR 0.177, 95% CI 0.075-0.418, p < 0.05 healthy patients vs. patients with more than 60% bone loss: RR 0.121, 95% CI 0.041-0.355, p < 0.05. Patients with calcifications on their orthopantomograms had a lower mean teeth number (20.9 teeth) compared to patients without calcifications (24 teeth), which was statistically significant, t (1077) = -3.125, p < 0.05. Conclusions: Orthopantomography can be considered a screening method to detect patients at increased cardiovascular risk who are referred for individualized study. It is important to continue research to know the real significance of these findings. Dentists should be aware of the importance of our work in our patients' systemic health.

Comparision between cortico-cancellous allograft and bovine xenograft for sinus augmentation: a radiographic, histologic and histomorphometric clinical study.

Sinus floor augmentation is one of the most used approaches to obtain sufficient bone availability to place dental implants in cases with severe bone atrophy in the posterior maxilla. Several bone substitutes are indicated for sinus augmentation but they may obtain different clinical outcomes. This study aims to compare bovine bone mineral (BBM) with freeze dried bone allograft (FDBA) in two- stage lateral window sinus grafting approach. 20 patients received a lateral window sinus lift with either FDBA or BBM. Post-operative graft height was measured with a cone-beam computerized tomography (CBCT). 6 months later implants were placed. Biopsies were taken for histological analysis and new CBCts were performed to measure graft height at this point. 6 months after procedure, there was a height reduction of 20,27 ± 4,94 % for the FDBA sample and 5,36 ± 2,41% for the BBM group. The histological analysis revealed a ratio of newly formed bone of 43,70 ± 5,29% for the FDBA and 38,11 ± 4,03% for the BBM group. The FDBA also showed a higher amount of residual biomaterial 17,25 ± 10,10% and connective tissue 14,63 ± 4,38% compared to the BBM 15,53 ± 5,42% and 13,11 ± 4,42%. The differences between groups were statistically significant for the height reduction and for the newly formed bone (p ≤ 0.05) but not for the residual biomaterial amount and the non-mineralized connective tissue (p ≥ 0.05). It could be concluded that the percentage of newly formed bone 6 months after performing a lateral window sinus lift using FDBA was significantly higher than when using BBM, although the graft height reduction was also significantly higher for the FDBA group.

Mechanical Characterization of Dental Prostheses Manufactured with PMMA-Graphene Composites.

The use of a PMMA composite with graphene is being commercialized for application as dental prostheses. The different proportions of fibers provide a wide range of colors that favors dental esthetics in prostheses. However, there are no studies that have explained the influence that graphene has on the mechanical properties. In this contribution, we studied the PMMA and PMMA material with graphene fibers (PMMA-G) in the form of discs as supplied for machining. The presence of graphene fibers has been studied by Raman spectroscopy and the Shore hardness and Vickers micro hardness were determined. Mechanical compression tests were carried out to obtain the values of maximum strength and Young's modulus (E) and by means of pin-on-disc wear tests, the specific wear rate and the friction coefficients were determined following the established international standards. Finally, the samples were characterized by field emission scanning electron microscopy (FESEM) to characterize the graphene's morphology inside the PMMA. The results showed the presence of graphene in PMMA and was estimated in an amount of 0.1027% by weight in G-PMMA. The Shore hardness and Vickers microhardness values did not show statistically significant differences. Differences were observed in the compression maximum strength (129.43 MPa for PMMA and 140.23 for PMMA-G) and E values (2.01 for PMMA and 2.89 GPa for PMMA-G) as well as in the lower wear rate for the G-PMMA samples (1.93 × 10−7 for PMMA and 1.33 × 10−7 mm3/N·m) with a p < 0.005. The coefficients of friction for PMMA-G decreased from 0.4032 for PMMA to 0.4001 for PMMA-G. From the results obtained, a slight content in graphene produced a significant improvement in the mechanical properties that could be observed in the prosthesis material. Therefore, we can state that the main attraction of this material for dental prosthesis is its esthetics.

In Vitro Evaluation of the Retentive Effectiveness of Axial Attachments Used in Implant-Retained Overdentures After 1 Year of Function.

PURPOSE: The aim of this study was to measure and compare the retention degrees of different attachment systems before and after 1 year of mastication and removal/insertion simulations. MATERIALS AND METHODS: A 4 × 10-mm implant embedded in self-curing acrylic resin was placed inside a rectangular metal frame installed in a plastic container with artificial saliva at 37°C. Three different attachment systems were connected to the implants: Dalbo Classic, Locator (with blue, pink, and clear inserts), and Klockner Rotula. A loading test at 100 N and 1.25 Hz frequency was repeated 10 times for each attachment (changing the matrix component or plastic insert) until a total of 300,000 cycles and 1,095 removal/ insertion sequences. The retention force was assessed at baseline until the end of the test (1 year) after 3-month intervals of simulation. One-way analysis of variance (ANOVA) and post hoc Tukey test (P < .05) were performed for statistical analyses. RESULTS: Klockner Rotula showed the highest retention values at the beginning (69.6 ± 9.2 N; 7.1 ± 0.9 kg) and the end of the test (51.4 ± 5.4 N; 5.2 ± 0.6 kg), while Dalbo Classic showed the lowest values both at the beginning (13.1 ± 1.7 N; 1.3 ± 0.2 kg) and the end of the test (6.7 ± 1.6 N; 0.7 ± 0.2 kg). Locator with clear insert exhibited the lowest retention loss ratio (20.4%), while Locator with blue insert showed the highest (50.8%). At the end of the test, all attachment systems showed a significant decrease in retention force in comparison with the initial retention (P < .001). CONCLUSION: Locator attachments with clear and pink inserts and the Klockner Rotula attachment system showed retention forces > 20 N (2 kg) after 1 year of mastication and prosthesis insertion/removal simulation. All attachment systems showed a progressive loss of retention, which was higher for Locator attachments with blue and pink inserts and Dalbo Classic. The Klockner Rotula attachment system showed the highest retention values both at the beginning and the end of the test.

Fabricating a dual-material, vat-polymerized, additively manufactured static implant surgical guide: A dental technique.

Protocols with static computer-aided implant placement provide more tangible clinical advantages than conventional implant placement methods. A technique to manufacture a dual-material implant surgical guide by using a vat-polymerization printer is described. The implant surgical guide combined a resilient intaglio and hard exterior surface. The technique should minimize the clinical adjustments needed to ensure fit and improve patient comfort.

Prevalence of Favorable Anatomy for Palatal Emergence of an Immediate Implant in the Maxillary Central Incisor Post-Extraction Site.

The purpose of this study was to determine the prevalence of favorable anatomy for palatal emergence of an immediate flapless implant in the maxillary central incisor post-extraction site. Implants were virtually placed into maxillary central incisor sites using 3-dimensional implant planning software. Following a strict implant placement criterion to keep a safe distance to the buccal plate and other anatomical structures, sockets were assessed to determine their suitability for an implant emerging from the palatal aspect. From 321 patients included in this study, 62.3% presented a suitable socket anatomy for an immediate implant to be placed with an angulation suitable for a screw-retained crown. In 29% of the cases, the implants had to be labially tilted to maintain a minimum distance to the buccal plate; 8.7% were unsuitable for immediate implants due to anatomic limitations. The position and angulation for an immediate implant in the maxillary central incisor socket should be carefully assessed preoperatively with 3-dimensional images, as many sites will not be candidates for a palatal emergence and thus a screw-retained restoration.

Logistic Regression Analysis of the Factors Involved in the Failure of Osseointegration and Survival of Dental Implants with an Internal Connection and Machined Collar: A 6-Year Retrospective Cohort Study.

BACKGROUND: Although the long-term success rate of dental implants is currently close to 95%, it is necessary to provide more evidence on the factors related to the failure of osseointegration and survival. PURPOSE: To establish the risk factors associated with the failure of osseointegration and survival of dental implants with an internal connection and machined collar and to establish a predictive statistical model. MATERIALS AND METHODS: An analytical, retrospective, and observational clinical study of a sample of 297 implants with a follow-up of up to 76 months. Independent variables related to the implant, patient, and surgical and rehabilitative procedures were identified. The dependent variables were failure of osseointegration and failure of implant survival after prosthetic loading. A survival analysis was carried out by applying the Kaplan-Meier model (significance for p < 0.05). The log-rank test and the Cox regression analysis were applied to the factors that presented differences. Finally, the regression logit function was used to determine whether it is possible to predict the risk of implant failure according to the analyzed variables with the data obtained in this study. RESULTS: The percentages of osseointegration and survival were 97.6 and 97.2%, respectively. For osseointegration, there were significant differences according to gender (p = 0.048), and the risk of nonosseointegration was 85% lower in women. Regarding survival, the Cox analysis converged on only two factors, which were smoking and treatment with anticoagulant drugs. The risk of loss was multiplied by 18.3 for patients smoking more than 10 cigarettes per day and by 28.2 for patients treated with anticoagulants. CONCLUSIONS: The indicated risk factors should be considered, but the analysis of the results is not sufficient to create a predictive model.

Consequences of Peri-Implant Bone Loss in the Occlusal Load Transfer to the Supporting Bone in terms of Magnitude of Stress, Strain, and Stress Distribution: A Finite Element Analysis.

METHODS: Three models of a single internal connection bone level-type implant inserted into a posterior mandible bone section were constructed using a 3D finite element software: one control model without marginal bone loss and two test models, both with a circumferential peri-implant bone defect, one with a 3 mm high defect and the other one 6 mm high. A 150 N static load was tested on the central fossa at 6° relative to the axial axis of the implant. RESULTS: The results showed differences in the magnitude of strain and stress transferred to the bone between models, being the higher strain found in the trabecular bone around the implant with greater marginal bone loss. Stress distribution differed between models, being concentrated at the cortical bone in the control model and at the trabecular bone in the test models. CONCLUSION: Marginal bone loss around dental implants under occlusal loading influences the magnitude and distribution of the stress transferred and the deformation of peri-implant bone, being higher as the bone loss increases.

Effect of implantoplasty on the elastic limit of dental implants of different diameters.

BACKGROUND: Implantoplasty reduces both implant diameter and the thickness of its walls, subsequently reducing the ability of the implant to resist fracture in response to functional load. In combination with an increase in the crown-implant ratio due to bone loss, this could increase the lever effect, which in presence of high masticatory forces or parafunctional habits, could lead to complications such as fracture of the implant or loosening of the prosthetic screw. OBJECTIVES: To determine the elastic limits of internal connection, dental implants of different designs and diameters after an implantoplasty. MATERIALS AND METHODS: This in vitro study included 315 tapered internal connection titanium dental implants, the threads of which were removed with an industrial milling machine-for standardized implantoplasty (IMP1; n = 105)-or with the conventional approach-manually, using high-speed burs (IMP2; n = 105). The remaining 105 implants were used as controls. The final implant diameters were recorded. The quality of the newly polished surfaces was assessed by scanning electron microscopy. All implants were subjected to a mechanical pressure resistance test. A Tukey's test for multiple comparisons was used to detect differences in the elastic limit and final implant diameters between the implant groups. RESULTS: There were statistically significant differences in the elastic limit between the IMP1, IMP2, and control groups (p < 0.05). Furthermore, the implant diameter was significantly smaller in the IMP1 and IMP2 groups (p < 0.05). Scanning electron microscopy revealed smooth implant surfaces in the IMP1 and IMP2 groups, with some titanium particles visible in the IMP1 group. CONCLUSIONS: Implantoplasty significantly decreased the elastic limit of internal connection titanium dental implants, especially in those with a smaller diameter (3-3.5 mm).

Evaluation of the primary stability in dental implants placed in low density bone with a new drilling technique, Osseodensification: an in vitro study / Evaluación de la estabilidad primaria en implantes dentales colocados en baja densidad hueso con una nueva técnica de perforación, Osteodensificación: un estudio in vitro

Background: Primary stability is an important key determinant of implant osseointegration. We investigated ap-proaches to improve primary implant stability using a new drilling technique termed osseodensification (OD),which was compared with the conventional under-drilling (UD) method utilized for low-density bones.Material and Methods: We placed 55 conical internal connection implants in each group, in 30 low-density sec-tions of pig tibia. The implants were placed using twist drill bits in both groups; groups Under Drilling (UD)and Osseodensification (OD) included bone sections subjected to conventional UD and OD drilling, respectively.Before placing the implants, we randomized the bone sections that were to receive these implants to avoid samplebias. We evaluated various primary stability parameters, such as implant insertion torque and resonance fre-quency analysis (RFA) measurements.Results: The results showed that compared with implants placed using the UD technique, those placed using theOD technique were associated with significantly higher primary stability. The mean insertion torque of the im-plants was 8.87±6.17 Ncm in group 1 (UD) and 21.72±17.14 Ncm in group 2 (OD). The mean RFA was 65.16±7.45ISQ in group 1 (UD) and 69.75±6.79 ISQ in group 2 (OD).Conclusions: The implant insertion torque and RFA values were significantly higher in OD group than in UD.Therefore, compared with UD, OD improves primary stability in low-density bones (based on torque and RFAmeasurements).(AU)

Zirconia and radioactivity: An in vitro study to establish the presence of radionuclides in dental zirconia.

STATEMENT OF PROBLEM: Dental zirconia possesses concentrations of radionuclides, but their possible radioactivity is unknown. PURPOSE: The purpose of this in vitro study was to evaluate the radioactivity and radionuclide concentration in dental zirconia. MATERIAL AND METHODS: Three specimens were obtained from commonly used dental yttria-stabilized tetragonal zirconia polycrystal materials: Vita In-Ceram YZ, Zirkonzahn, and Zirkonzahn Prettau-producing a powder for the evaluation of radioactivity through gamma spectrometry. For the determination of radioactivity, a group of radionuclides (Ac-228, Pb-212, Tl-208, Pb-214, Bi-214, and Be-7) was evaluated. RESULTS: The measurements of all the specimens reported that most activity came from the decay chain of uranium, radium, and thorium, obtaining a radioactivity of 11.082 Bq/kg for Vita In-Ceram YZ, <11.63 Bq/kg for Zirkonzahn, and <34.91 Bq/kg for Zirkonzahn Prettau. CONCLUSIONS: Although all specimens contained radionuclides, their radioactivity was below the limit established by the International Atomic Energy Agency.

The Bone Buttress Theory: The Effect of the Mechanical Loading of Bone on the Osseointegration of Dental Implants.

OBJECTIVES: To determine the effect of mechanical loading of bone on the stability and histomorphometric variables of the osseointegration of dental implants using an experimental test in an animal model. MATERIALS AND METHODS: A total of 4 human implants were placed in both tibiae of 10 New Zealand rabbits (n = 40). A 6-week osseointegration was considered, and the rabbits were randomly assigned to two groups: Group A (Test group) included 5 rabbits that ran on a treadmill for 20 min daily during the osseointegration period; Group B (Controls) included the other 5 that were housed conventionally. The monitored variables were related to the primary and secondary stability of the dental implants (implant stability quotient-ISQ), vertical bone growth, bone to implant contact (BIC), area of regenerated bone and the percentage of immature matrix. RESULTS: The results of the study show a greater vertical bone growth (Group A 1.26 ± 0.48 mm, Group B 0.32 ± 0.47 mm, p < 0.001), higher ISQ values (Group A 11.25 ± 6.10 ISQ, 15.73%; Group B 5.80 ± 5.97 ISQ, 7.99%, p = 0.006) and a higher BIC (Group A 19.37%, Group B 23.60%, p = 0.0058) for implants in the test group, with statistically significant differences. A higher percentage of immature bone matrix was observed for implants in the control group (20.68 ± 9.53) than those in the test group (15.38 ± 8.84) (p = 0.108). A larger area of regenerated bone was also observed for the test implants (Group A 280.50 ± 125.40 mm2, Group B 228.00 ± 141.40 mm2), but it was not statistically significant (p = 0.121). CONCLUSIONS: The mechanical loading of bone improves the stability and the histomorphometric variables of the osseointegration of dental implants.

The Utility of Implant-Supported Fixed Dental Prosthesis Material for Implant Micromovement and Peri-implant Bone Microstrain: A Study in Rabbit Tibia.

PURPOSE: To evaluate and compare the effects of two restorative materials with different stiffness on peri-implant bone microstrain and implant micromovements during occlusal loading in implant-supported single and adjacent splinted crowns. MATERIALS AND METHODS: Two 3 × 10-mm implants were inserted into the tibia of four rabbits. During the osseointegration process, prosthetic restorations were performed. Before suturing the flap, each implant's position and direction were obtained by fastening two splinted transfer abutments, onto which implant analogs were placed and fastened; the splinted transfer abutments were subsequently unfastened. Splinted transfer abutment/analog complexes were cast using type IV plaster to obtain eight different working models. Two single mandibular premolar crowns of monolithic zirconia and acrylate polymer composite were generated using CAD/CAM technology, and 16 adjacent splinted crowns (eight of each material) with the same design were also generated. After 6 weeks of implant osseointegration, the animals were sacrificed. Tibial sections with the implants were extracted, and prosthetic restorations (performed during implant osseointegration) were fastened to the implants. Static loading tests were performed with 100-N force application and an inclination of 6 degrees over the central fossa of the premolars. Implant micromovement was measured using an image analysis technique. Bone microstrain was quantified using two strain gauges placed on the crestal bone around the implants. Data were analyzed using two-way analysis of variance. RESULTS: The mean implant micromovement values were lower for monolithic zirconia single and splinted crowns (61.5 ± 26.3 µm and 57.7 ± 8.8 µm, respectively) than for acrylate polymer composite-based single and splinted crowns (78.9 ± 37.3 µm and 59.61 ± 11.5 µm, respectively). No significant differences between the materials were noted. Bone microstrain around the implants was lower for splinted crowns (303.7 ± 281.3 µÎµ for acrylate polymer composite; 312.4 ± 226.8 µÎµ for monolithic zirconia) than for single crowns (539.7 ± 8.8 µÎµ for acrylate polymer composite; 574.6 ± 271.9 µÎµ for monolithic zirconia). CONCLUSION: Using restorative materials of different stiffness did not significantly affect the micromovement of already-osseointegrated implants supporting single or splinted crowns. Independent of material stiffness, single crowns transfer significantly more microstrain than splinted crowns.

Monolithic and Minimally Veneered Zirconia Complications as Implant-Supported Restorative Material: A Retrospective Clinical Study up to 5 Years.

OBJECTIVE: Long-term clinical data on the success and complication rates of monolithic or minimally veneered zirconia implant-supported restorations are lacking. Hence, the purpose of this retrospective clinical study was to analyze the complications of monolithic or partially veneered zirconia implant-supported restorations up to 5 years follow-up. Material and Methods. Single crowns, bridges, and full-arch rehabilitations were included. The selection process was achieved by reviewing data from the prosthetic laboratory and excluding cases in which zirconium and full-ceramic coating restorations were used. A total of 154 restorations were included (82 monolithic and 72 with buccal ceramic stratification). All the complications encountered, and the solutions applied, were explained. RESULTS: A total of 93 restorative units had a follow-up of between 24 and 60 months, and 61 restoration units had a follow-up of between 12 and 24 months. A total of 7 complications were encountered (14.58% of cases; 95.45% per prosthetic unit). The technical complication rate was 2.08% (one case of minor chipping in one prosthetic unit); regarding the mechanical complications, four decementations (8.33% of the cases) and two screw loosening (4.17% of the cases) were encountered. CONCLUSIONS: Considering the limitations of this study, it can be concluded that monolithic or partially veneered zirconia implant-supported restorations have a good clinical behavior during a follow-up period of up to 5 years.

The Impact of Compaction Force on Graft Consolidation in a Guided Bone Regeneration Model.

PURPOSE: Compaction of particulated grafts is done manually; thus, the effect of compression force on bone regeneration remains unclear. The aim of this study was to evaluate the impact of two different compression forces on the consolidation of particulated bovine hydroxyapatite. MATERIALS AND METHODS: Two titanium cylinders were fixed on the calvarium of eight New Zealand rabbits. Both defects were filled with particulated bovine hydroxyapatite subjected to a compression force of 0.7 kg/cm2 or 1.6 kg/cm2 before being covered with a resorbable collagen membrane. A handheld device that uses a spring to control the compression force applied by the plugger was used. At 6 weeks, histomorphometry of the area immediately adjacent to the calvaria bone and to the collagen membrane was performed. RESULTS: It was shown that next to the calvaria, the bone volume per tissue volume (BV/TV) was 29.0% ± 8.8% and 27.6% ± 8.2% at low and high compression force, respectively; the bone-to-biomaterial contact (BBC) was 58.2% ± 25.0% and 69.3% ± 22.9%, respectively (P > .05). In the corresponding area next to the collagen membrane, BV/TV was 4.9% ± 5.1% and 5.7% ± 4.7%, and the BBC was 18.3% ± 20.8% and 20.1% ± 15.9%, respectively (P > .05). In addition, the number and area of blood vessels were not significantly affected by compression force. CONCLUSION: Both compression forces applied resulted in similar consolidation of bovine hydroxyapatite expressed by new bone formation and vascularization based on a rabbit calvaria augmentation model.

Effects of Drilling Protocol and Bone Density on the Stability of Implants According to Different Macrogeometries of the Implant Used: Results of an In Vitro Study.

PURPOSE: To assess the effects of drilling protocol and bone density on the primary stability of implants with different macrogeometries currently used in clinical practice. MATERIALS AND METHODS: This in vitro study compared the designs of two implants: Biomimetic Coral, a parallel-walled design with a slightly expanded platform and a symmetric progressive thread; and tapered Biomimetic Ocean, a reverse coronal design with an asymmetric progressive thread. The drilling alternatives were grouped according to the standard sequence for each type, plus an extra drill for hard bone, using laminated blocks with different densities. The insertion torques and implant stability quotient (ISQ) values were obtained with a surgical motor and resonance frequency analysis (RFA), respectively. RESULTS: A total of 120 implants (n = 60 Ocean, n = 60 Coral) were inserted and analyzed without registering any deviation from the protocol. The Coral implants presented significantly higher insertion torque values (P < .001), consistent with optimal osseointegration, for the standard drill, the dense bone drill, and the screw tap. Insertion torque was not affected by the drilling sequence (P = .124), and the effect of interaction between the implant design and drilling sequence was not significant (P = .940). Statistically significant differences were observed in insertion torque values due to the type of implant but not due to the bone density. The ISQ values were significantly higher (P < .001) for the Coral design. In both the Ocean and Coral implants, ISQ was affected by the drilling sequence (P < .001), as the ISQ values were higher in the standard sequence with screw tap drilling than in the standard sequence with a dense bone drill. A positive correlation was found between the insertion torque and ISQ values. CONCLUSION: The macrogeometry of the implant and the drilling sequence have a significant effect on both primary stability values (ISQ and insertion torque). The values for the Coral implant were statistically higher but still within the range required to achieve proper osseointegration. These results support the drilling sequence recommended by the manufacturer for this type of implant, using larger-diameter drills and screw taps in sites with harder or cortical bone.

Estabilidad primaria en implantes inmediatos versus implantes colocados en hueso maduro: un estudio clínico retrospectivo / Primary stability in immediate implants versus implants placed in mature bone: a retrospective clinical study

La estabilidad primaria es un requisito importante para la supervivencia y éxito de los implantes durante la osteointegración. En los últimos años, los implantes inmediatos postextracción han demostrado ser una opción de tratamiento exitosa y predecible para la reposición de dientes con mal pronóstico, pero surge la duda de si dichos implantes alcanzan valores de estabilidad primaria comparables a aquellos colocados en hueso maduro. Comparar la estabilidad primaria de implantes inmediatos colocados en alveolos postextracción con la de implantes colocados en hueso maduro. Se llevó a cabo un estudio clínico retrospectivo, con los datos recogidos sobre 175 implantes, colocados en 175 pacientes. Todos los implantes colocados pertenecían al modelo Essential Cone (Klockner Implant System) y se dividieron en dos grupos: implantes inmediatos (Grupo A, n=31) e implantes colocados en hueso maduro (Grupo B, n=144). La estabilidad primaria de todos los implantes se midió mediante torque de inserción y análisis de frecuencia de resonancia con Osstell ISQ. No se encontraron diferencias estadísticamente significativas respecto a la estabilidad medida a través del torque de inserción (26,29+10,07 Vs 25,76+9,72 N/cm) pero sí que se encontraron diferencias significativas en la medida de la estabilidad primaria mediante AFR, siendo inferiores los valores correspondientes a los implantes colocados en los alveolos post exodoncia (60,74 ± 6,17 en sentido VL y 62,19 ± 7.64 en sentido MD frente a 68,34 ± 6.26 en sentido VL y 69,29 ± 7.98 en sentido MD obtenidos en los implantes colocados en hueso maduro). El torque de inserción de los implantes inmediatos es similar al de los implantes colocados en hueso maduro, pero sus valores ISQ son significativamente inferiores, lo que demuestra un mayor grado de micromovimiento, y por consiguiente, un mayor riesgo de fracaso durante el período de osteointegración.

Primary stability is an important requirement for the survival and success of implants during osseointegration. In recent years, immediate post-extraction implants have proven to be a successful and predictable treatment option for the replacement of teeth with a poor prognosis, but the question arises as to whether these implants reach primary stability values comparable to those placed in mature bone. The objective of the study was to compare the primary stability of immediate implants placed in post-extraction alveoli with that of implants placed in mature bone. A retrospective clinical study was carried out, with data collected on 175 implants, placed in 175 patients. All implants placed belonged to the Essential Cone model (Klockner Implant System) and were divided into two groups: immediate implants (Group A, n = 31) and implants placed in mature bone (Group B, n = 144). The primary stability of all implants was measured by insertion torque and resonance frequency analysis with Osstell ISQ. No statistically significant differences were found regarding the stability measured through the insertion torque (26.29 + 10.07 Vs 25.76 + 9.72 N / cm) but significant differences were found in the measurement of primary stability by means of AFR, the values corresponding to implants placed in the post-exodontic alveoli being lower (60.74 ± 6.17 in the VL direction and 62.19 ± 7.64 in the MD direction versus 68.34 ± 6.26 in the VL direction and 69.29 ± 7.98 in the MD direction obtained in implants placed in mature bone). The insertion torque of immediate implants is similar to that of implants placed in mature bone, but their ISQ values are significantly lower, which demonstrates a higher degree of micromotion, and therefore, a greater risk of failure during the period of osseointegration.

Influence of cortical bone and implant design in the primary stability of dental implants measured by two different devices of resonance frequency analysis: An in vitro study.

BACKGROUND: This study aimed to evaluate the effect of the implant design and the presence of cortical bone in the primary stability, as well as analyze the differences between the stability measurements obtained by two different resonance frequency analysis (RFA) devices. MATERIAL AND METHODS: A total of 80 Klockner implants of two different models [40 Essential Cone implants (group A) and 40 Vega implants (group B)] were used. The implants were placed in two polyurethane blocks that simulated the mechanical properties of the maxillary bone. One block featured a layer of cortical bone that was absent from the other block. The primary stability of all implants was measured by insertion torque and RFA using two different devices: Penguin RFA and Osstell IDX. RESULTS: Primary stability was superior in the cortical bone in both torque and RFA. In the block containing cortical bone, group A implants obtained a greater insertion torque than did group B. The insertion torque was lesser in the bone lacking cortex. Regarding the ISQ of the implants, group A presented higher values in the block with cortical bone, but the values were lower in the block without cortical bone. There were no significant differences between the values obtained from the Osstell IDX and Penguin RFA. CONCLUSIONS: The presence of cortical bone positively influences the primary stability of dental implants. The design of the implant also has a statistically significant influence on implant primary stability, although the impact depends on whether there is coronal cerclage or not. There were no statistically significant differences in the implant stability measurements obtained by two different devices. Key words:Implant stability, resonance frequency analysis, torque, osstell, penguin, cortical.