Press-Fit Placement of a Rectangular Block Implant in the Resorbed Alveolar Ridge: Surgical and Biomechanical Considerations.

Rectangular Block Implant (RBIs) were manufactured, using computer-aided-design lathe turning, surface roughened with grit blasting and gamma irradiated. Implants were surgically placed into the resorbed edentulous mandibular ridges of both greyhound dogs (ex vivo and in vivo) and humans; the pooled total was 17 placements. The aim was to achieve mechanical stability and full implant submergence without damage to the mandibular canal and without bone fracture: fulfilment of all of these criteria was deemed to be a successful surgical outcome. Rectangular osteotomy sites were prepared with piezo surgical instrumentation. Sixteen implants were fully submerged and achieved good primary stability without bone fracture and without evidence of impingement of the mandibular canal. One implant placement was deemed a failure due to bone fracture: the event of a random successful outcome was rejected (p < 0.01 confidence, binomial analysis). Technique of placement yielded excellent mechanical retention: key biomechanical factors that emerged in this process included under preparation of the osteotomy site with the use of specifically designed trial-fit gauges, the viscoelastic property of the peri-implant bone, the flat faces and cornered edges of the block surfaces which enhance stress distribution and mechanical retention, respectively. It was concluded that the surgical protocol for the RBI placement in the resorbed alveolus is a predictable clinical procedure tailored to its specific, unique biomechanical profile.

The Biomechanical Profile of an Osseo-Integrated Rectangular Block Implant: A Pilot In Vivo Strain Analysis.

Aim: To load-test the osseo-integrated rectangular block implant (RBI), measure the generated cortical peri-implant strains, and relate these findings to known human physiological parameters. Materials and methods: Two RBIs were placed into the posterior mandibular saddle in a mature greyhound dog and allowed to osseo-integrate. The half mandible (implants in situ) was mounted in a servohydraulic system. Four triple-stacked rosette gauges were placed cortically (mesial, distal, buccal, and lingual). A modified ISO-14801 protocol was used (1000 N, 300, 2 Hz, 1 h) and the generated principal strains (ep, eq) and their angular orientations (F), were calculated. Results: (1) Bucco-lingual "horizontal" dimension: dominant "horizontal" compressive stresses were on the lingual aspect and "horizontal" tensile stresses on the buccal aspect. The buccal cortex was elastically tensile-stretched, while the lingual cortex was elastically compressed. (2) Bucco-lingual "vertical" dimension: dominant vertical torsional stresses were oriented buccally and apically, with an overall buccally inclined torsional effect. This was also evidenced on the lingual aspect, where there remained high torsional rotation elements (high F and e2). (3) Mesio-distal "horizontal" dimension: dominant torsional stresses oriented as a distal-lingual "counter-clockwise" rotation. Conclusions: The applied off-axial loads generated a heterogeneous pattern of bucco-lingual and mesio-distal cortical strains, both vertically and horizontally. The short dimensioned osseo-integrated RBI design appeared to biomechanically withstand the applied loads and to maintain the strains generated to levels that were within physiological limits. More studies and statistical analyses are needed to confirm these findings.

Effect of Aging on the Load-to-Failure of Molar Implant-Supported Monolithic Zirconia Crowns: A Laboratory Study.

PURPOSE: To evaluate the effect of hydrothermal aging on the load to failure and number of cycles to failure of implant-supported monolithic zirconia molar crowns under cyclic loading. MATERIALS AND METHODS: Twenty identical implant-supported monolithic zirconia crowns with molar morphology were produced. Half of the crowns were aged according to ISO standard 13356 to simulate 5 years in vivo. The non-aged crowns served as a control group. All crowns were subjected to cyclic loading with increasing increments of load until failure. The load to failure, the number of cycles to failure, and the failure pattern were determined for each crown. RESULTS: The load to failure values were 3,630 N (SD: 547.8 N) and 3,640 N (SD: 389.3 N) for the non-aged and aged crowns, respectively. The non-aged crowns failed after 33,480.1 cycles (SD: 23,138.4 cycles), and the aged crowns failed after 28,456.1 cycles (SD: 10,158.7 cycles). There was no significant difference between the two groups for the load to failure or number of cycles to failure. The predominant form of failure was catastrophic crown fracture, which was observed for all the non-aged crowns and 9 of the aged crowns. CONCLUSION: Within the limitations of this study, aging of the implant-supported monolithic zirconia crowns with molar morphology did not affect the load to failure or the number of cycles to failure under cyclic loading. Since all the crowns failed at much higher loads than the expected physiologic loads, clinical application of implant-supported monolithic zirconia crowns to replace missing molars seems reasonable.

The biomechanical profile of an osseo-integrated rectangular block implant: A pilot in vivo experimental study.

OBJECTIVE: A novel implant design, the rectangular block implant (RBI), was investigated as a possible solution to the restoration of the posterior resorbed ridge. AIM: To maximally load test the osseo-integrated RBI in shear and tensile loads and relate these findings to known human masticatory loads as biomechanical proof of the study concept. MATERIALS AND METHODS: Twelve RBIs were design-manufactured and placed into posterior mandibular saddles in 3 mature greyhound dogs.-2 per left and right. After 12 weeks of healing, osseo-integration was confirmed using resonance frequency analysis (RFA) and wrench torque tests. Three bone blocks each with two RBIs were dissected and mounted in acrylic. Micro-computerized tomography (µ-CT) was performed to assess bone to implant contact (BIC), and load analysis was performed using a Universal Test System. Three force applications were conducted until failure: pull-out (tensile), buccal push from the lingual (shear) and distal push from the mesial (shear). The osteotomy sites were examined using light magnification and scanning electron microscopy (SEM). RESULTS: Pull-out, buccal and distal force failures occurred at differing levels. Post-detachment sites showed complex patterns of bone failure, including trabecular and cortical fracture, as well as shearing at varying distances from the BIC. Interfacial shear strength was calculated at 14.4 MPa. CONCLUSION: The osseo-integrated RBIs were able to withstand simulations of the demanding axially, bucco-lingually and mesio-distally oriented biomechanical challenges of the posterior saddle, under conditions of reduced bone volume. These values exceeded equivalent force components of maximal masticatory loads in humans.

Influence of the application of a pre-sintered surface augmentation on zirconia and lithium disilicate bonding using an adhesive composite resin cement.

OBJECTIVE: The purpose of this laboratory study is to evaluate the application of a pre-sintered surface augmentation to zirconia (Zir) and lithium disilicate (LDS) ceramics on the delamination strength of adhesive resin cement. The applied surface augmentation was the ruling of lines to the pre-sintered surface of the ceramics. METHODS: Ninety milled Zir and sixty pressed LDS specimens (3mm×0.5mm×25mm) were created and divided into five groups (n=30). Group 1: Zir no surface treatment (control Zir-NT); Group 2: Zir airborne particle abraded (Zir-APA) with 30µm CoJet; Group 3: Zir pre-sintered surface augmentation (Zir-SA); Group 4: LDS etched (control LDS-etched) and; Group 5: LDS with pre-sintered surface augmentation and etching (LDS-SA). A resin adhesive cement (3mm×1mm×8mm) was then applied and cured to the ceramic specimens. The delamination strength values of the resin cement from the ceramic were recorded. The delamination strength data were analysed statistically using one-way ANOVA and Turkey post hoc analysis. RESULTS: The mean delamination strength and standard deviation, when comparing only the Zir-SA to the resin cement were statistically different (p<0.001); Zir-SA 63.42±11.85, Zir-NT 26.82±12.07, and Zir-APA 48.11±17.85MPa. Comparison between LDS groups were not significantly different (p=0.193); LDS-etched 33.49±16.07 and LDS-SA 28.83±10.15MPa. The delaminated Weibull modulus was highest for surface augmentation Zir specimens (m=13.56) but decreasing to less than half for Zir-APA (m=6.27) and Zir-NT (m=5.68). The Weibull values for the LDS-SA and LDS-etched specimens was 5.63 and 3.38 respectively. SIGNIFICANCE: Incorporating the pre-sintered surface augmentation to zirconia improved the delamination strength and reliability of Zir to the resin cement but not for LDS.

A 5-Year Retrospective Assay of Implant Treatments in Private Practice: The Restorative Complications of Long-Span Implant-Supported Fixed and Removable Dental Prostheses.

PURPOSE: To describe and analyze the restorative complications of long-span (> three units) implant-supported dental prostheses (LIDPs) in 27 private practices in the state of Victoria, Australia, during the period from January 1, 2005, to December 31, 2009. MATERIALS AND METHODS: Private dental practitioners providing implant treatment were invited to enroll in this study, which was conducted through a dental practice-based research network. Clinical records of the implant treatments, which were provided during the specified period, were accessed for data collection. LIDPs included implant-supported prostheses of fixed or removable design; namely, fixed partial dentures (IFPDs), fixed complete dentures (IFCDs), removable partial dentures (IRPDs), and complete overdentures (IODs). Descriptive statistics and generalized linear mixed modeling were used for data analysis. RESULTS: The range of observation time for 627 LIDPs was 3 to 72 months (mean ± SD: 3.22 ± 1.49 years). For fixed prostheses, the complication with the highest annual rate was veneer fracture (acrylic: 21%; ceramic: 2.9%), followed by loss of retention for cement-retained IFPDs (14.7%). For mandibular IODs, the highest annual complication rate was for retention complications, whereas for maxillary IODs, it was for acrylic veneer fracture (11.5% and 6.4%, respectively). The peak incidence of complications was during the first year of function in fixed protheses and in IODs. Acrylic veneer fracture in IFCDs and IOD base fracture were more common in patients with preoperative clinician-reported attrition (estimated odds ratios [ORs] = 4.5 and 11.3, respectively; P < .05). Ceramic veneer fracture in fixed protheses and acrylic veneer fracture in IODs were reported more commonly for maxillary compared to mandibular prostheses (ORs = 5 and 22, respectively; P < .05). Mandibular IODs had more frequent retention complications when supported by two compared to four implants (OR = 5.9, P < .05). CONCLUSION: Restorative complications were observed in all categories of LIDPs at various annual rates. Clusters of these complications occurred during the first year of prosthesis function. Patient- and prosthesis-related variables influenced the incidence rate of some of these complications.

Laboratory Evaluation of Novel Implant Metal-Acrylic Prosthesis Design: Influence of Monolithic Acrylic Veneer.

PURPOSE: To test a novel implant metal-acrylic prosthesis design in comparison to a conventional prosthesis design through simulation of cyclic masticatory loading. The novel design involved digital designing and fabrication of the framework and the matched veneering acrylic resin material. MATERIALS AND METHODS: Ten prostheses were fabricated for each group. All the prostheses exhibited a similar external design on two implants with a distal cantilever. The conventional group comprised a milled metal framework with mechanically retained acrylic denture teeth via vertical pins. The digital prosthesis group incorporated an inverted T-shape bar and a monolithic milled acrylic resin veneer. The resin veneer was subsequently adhesively attached on the bar. All prostheses were thermally aged and subjected to laboratory cyclic loading at the cantilever region. The load-to-failure and the number of cycles until failure were collected. Furthermore, failed specimens were analyzed to determine the mode of failure. RESULTS: The digital prostheses failed at significantly greater load-to-failure (1,570.0 N ± 116.0 N) and number of cycles (124,857 ± 21,608) than the conventional prostheses (load-to-failure = 1,015.0 N ± 47.4 N; number of cycles = 28,452 ± 6,559). The conventional prostheses failed by fracturing of the acrylic teeth and veneering material that led to exposure of the metal framework. Half of the digital prostheses failed by superficial chipping of the veneering material, while the other half failed by the deformation and fracture of screws. CONCLUSION: Within the limitations of this study, the digital prostheses with the novel design and monolithic veneering material showed significantly higher strength compared with the conventional prostheses. The mode of acrylic failure of the digital prostheses was more favorable.

Body dysmorphia in dentistry and prosthodontics: A practice based study.

The prevalence of Body Dysmorphic Disorder (BDD) and dysmorphic concern in dentistry and prosthodontics have not been properly assessed, yet the mouth and the teeth are amongst the top preoccupation for these individuals. OBJECTIVES: To evaluate the prevalence of dysmorphic symptoms and BDD using validated tools in patients presenting to general and specialist prosthodontic practice. METHODS: Patients were recruited by two prosthodontics practices and three general dentist practices. Patients were given a Dysmorphic Concern Questionnaire (DCQ) integrated into a medical history form. Treating clinicians also completed a Baseline Rating Form assessing the patients´ reason for presentation. Two DCQ score cut-offs were used (9 and 12). RESULTS: Two hundred and thirteen patients were recruited, the majority of patients showed DCQ scores below 9 (84%). The prevalence of BDD was 7% (cut-off ≥ 9) or 4% (cut-off ≥12). Women were more likely to present with high DCQ scores as well as people with a history of mental health problems. The cosmetic practice, the implant clinic, and the prosthodontic practice received a higher proportion of patients with high DCQ scores when compared with the general family practice. The type of procedure was not related to DCQ scores. The defect severity assessment and whether this was amenable to correction was moderately correlated with DCQ scores. CONCLUSIONS: The DCQ seems to be a suitable tool to be used by dentists as part of history taking and patient examination due to its brevity, simplicity and the good sensitivity/specificity reported in the literature. CLINICAL SIGNIFICANCE: Identifying patients with dysmorphia is important before irreversible treatment is carried out due to high levels of dissatisfaction, poor patient centred outcomes and the question of whether these individuals have the capacity to consent.

A Five-Year Retrospective Assay of Implant Treatments and Complications in Private Practice: Restorative Treatment Profiles of Long-Span, Implant-Supported Fixed and Removable Dental Prostheses.

PURPOSE: To describe the restorative treatment profiles of long-span (> three units), implant-supported dental prostheses (LIDPs) prescribed in 27 private practices in the state of Victoria, Australia, during the period from January 1, 2005, to December 31, 2009. The restorative treatment profiles of these prostheses refer to the framework/veneering materials, number of prosthetic units/supporting implants, location in the oral cavity, retention methods, and cantilever designs. LIDPs refer to implant-supported prostheses of fixed or removable design; namely, fixed partial dentures (IFPDs), fixed complete dentures (IFCDs), removable partial dentures (IRPDs), and complete overdentures (IODs). MATERIALS AND METHODS: Private dental practitioners providing implant treatment in Victoria, Australia, were invited to enroll in this study, which was conducted through a dental practice-based research network (the eviDent Foundation). The enrolled practitioners' clinical records of the implant treatments provided during the specified period were accessed for data collection. Descriptive statistics, cross-tabulations, and linear mixed models were conducted for data analyses. RESULTS: During the study period, 627 LIDPs were prescribed to 556 patients by 18 general dentists and 5 prosthodontists. LIDPs were more common in the maxilla than in the mandible except in the case of IODs. Of the fixed prostheses, 60% replaced missing teeth in more than one sextant, 33% in the anterior sextant, and 7% in the posterior sextant. The average number of prosthetic units per implant was higher in mandibular compared to maxillary IFPDs/IFCDs (2.5 vs 1.9, respectively, P < .001). Cantilever pontic(s) were present in 68% of IFCDs (more often in the mandible than in the maxilla) compared to 28% of IFPDs (use of cantilever pontics was about the same in the maxilla and mandible). Screw retention was the most commonly reported retention method in IFPDs/IFCDs (95%). Locator attachment was used for the majority of IRPDs/IODs (83%). CONCLUSION: The clinicians enrolled in this study preferred fixed over removable LIDPs for partially dentate and maxillary edentulous cases. For mandibular edentulous patients, IODs were prescribed more often than IFCDs. A retrievable retention design was favored for IFPDs/IFCDs. IFPDs were predominantly metal-ceramic, and metal-acrylic designs were more popular for IFCDs.

Implications of implant framework misfit: a systematic review of biomechanical sequelae.

PURPOSE: The objective of this study was to review all biomechanical investigations that have evaluated the implications of implant framework misfit with fixed prostheses. MATERIALS AND METHODS: A detailed electronic search was conducted of PubMed (MEDLINE), Google Scholar, and Cochrane Library with the aid of Boolean operators to combine relevant key words. The search was confined to articles published in English through April 2013. The literature search was enlarged by manual searches of the peer-reviewed literature and the reference lists of the selected articles. RESULTS: A total of 633 articles were retrieved from the initial search; however, only 28 articles met the determined inclusion criteria of the review. According to the study design, the selected articles were classified into two categories: laboratory studies (finite element analyses, actual model analyses, and screw stability analyses) and animal studies. The studies evaluated the effects of alterations in the magnitude and configuration of misfit, framework rigidity, type of retaining screws, and implant loading time. In addition to a lack of clear criteria of what constitutes an accurate implant framework fit, the biomechanical implications of framework misfit are unclear. CONCLUSIONS: Although implant framework misfit alters the biomechanical situation, negative biomechanical sequelae could not be confirmed from the included studies. Biologically, bone resorption cannot develop as a result of framework misfit. From a mechanical perspective, the framework stresses and screw stresses and instability increase with misfit, but the clinical significance of this remains unclear.

Fracture force of cantilevered zirconia frameworks: an in vitro study.

STATEMENT OF PROBLEM: Little evidence is available showing the effect of connector dimension and cantilever length on the ultimate fracture force of computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia implant frameworks. PURPOSE: The purpose of the study was to determine the impact of variations in the cross-sectional dimension of connector sites and variations in the effective cantilever length (load point) on zirconia implant frameworks. This would allow verification of the fracture force with 2 proposed mathematical models. MATERIAL AND METHODS: Forty zirconia implant-supported frameworks with 12-mm distal cantilevers were divided into 4 equal test groups (n=10). Connector dimensions (3×5 mm, 3×4 mm) and cantilever loading distance (7 mm, 10 mm) were tested for ultimate fracture force. A 2-way analysis of variance (ANOVA) was used to examine the ultimate fracture force and examine the relationship between connector dimension and ultimate fracture force. The data obtained from all 4 groups were compared and verified with calculations from 2 theoretical mathematical models. RESULTS: Two-way ANOVA revealed significant effects for cross-sectional area connector dimension on fracture force (P<.001) and cantilever length (P=.009). No statistically significant interaction was observed between the 2 factors (P=.229). The observed data were consistent with the data from the proposed mathematical models, with group comparisons showing no statistical significance. The largest difference between the mathematical results and mathematical models was in the 7 mm 3×5 mm group of the fixed cantilever bending model (P=.032). The predominant mode of failure was fracture of the zirconia framework, without damage or plastic deformation of the abutment screws or implant analogs. The 10 mm 3×5 mm specimens fractured at a mean load of 923.7 ±234.5 N; the 10 mm 3×4 mm specimens at a mean load of 474.8 ±122.9 N; the 7 mm 3×5 mm specimens at a mean load of 1011.7 ±185.3 N; and the 7 mm 3×4 mm specimens at a mean load of 700.9 ±152.4 N. CONCLUSIONS: Zirconia implant frameworks loaded 7 mm from the distal abutment failed at higher fracture loads than specimens loaded 10 mm from the distal abutment. Zirconia implant frameworks with cross-sectional area connector dimensions of 3×5 mm failed at higher fracture loads than specimens with cross-sectional area connector dimensions of 3×4 mm. No statistically significant interaction was observed between the cross-sectional connector area dimension and cantilever length. Calculations from the mathematical models closely approximated the observed data, which supports the use of the mathematical models as a predictor of fracture force.

In vitro bone strain analysis of implant following occlusal overload.

OBJECTIVES: To enumerate peri-implant bone strain pattern under quantified occlusal load and verify the bone response through comparison with the critical strain thresholds defined by Frost's bone mechanostat theory. MATERIAL AND METHODS: Mandibular unilateral recipient sites in two greyhound dogs were established with posterior teeth extractions. After 6 weeks, four titanium implants were placed in each dog mandible. Following 12 weeks of healing, successfully osseointegrated implants were placed in supra-occlusal contact via screw-retained non-splinted metal crowns. Plaque control and a dental health enhancing diet were prescribed. A bite force detection device was used to quantify in vivo occlusal load as the dogs functioned with supra-occlusal contact. After 8 weeks, the dogs were sacrificed. In vitro peri-implant bone strain under quantified occlusal load was measured using bonded stacked rosette strain gauges. RESULTS: The average and peak in vivo occlusal load measured were 434 and 795 newton (N). When individually and simultaneously loaded in vitro (≤476 N), absolute bone strains up to 1133 and 753 microstrains (µÎµ) were measured at implant apices, respectively. Bone strain reaching 229 µÎµ was recorded at distant sites. For bone strain to reach the pathological overload threshold defined by Frost's bone mechanostat theory (3000 µÎµ), an occlusal load of 1344 N (greater than peak measured in vivo) is required based on the simple linear regression model. CONCLUSION: Under the in vivo and in vitro conditions investigated in this study, peri-implant bone was not found to be under pathological overload following supra-occlusal contact function. Strain dissipation to distant sites appeared to be an effective mechanism by which implant overload was avoided.

Evaluation of the fit of CAD/CAM abutments.

PURPOSE: This study aimed to compare the fit of computer-aided design/computerassisted manufacture (CAD/CAM) abutments provided by a single system with proprietary prefabricated abutments on various implant systems. MATERIALS AND METHODS: Titanium CAD/CAM abutments were compared with prefabricated abutments on five different implant types. The samples were embedded in epoxy resin, sectioned longitudinally, and polished. Scanning electron microscopy was used to measure the gap between the implants and abutments at the connecting flanges and internal features. Independent t tests were used to compare data. RESULTS: A mean difference of 1.86 µm between the gold synOcta and CAD/CAM abutments on the Straumann Standard Plus implant was observed to be statistically significant (P = .002). Less than 0.4 µm of difference was found between the CAD/CAM and prefabricated abutments for the remaining implant types, and statistical significance was not observed. Mean differences of 34.4 µm (gold) and 44.7 µm (titanium) were observed between the CAD/ CAM and prefabricated abutments on the Straumann Standard Plus implants, which were statistically significant (P < .001). A mean difference of 15 µm was also observed between the CAD/CAM and prefabricated abutment on the NobelReplace implant, which was statistically significant (P = .026). All other groups had less that 4 µm of difference, and statistical significance was not observed. CONCLUSION: The CAD/CAM abutments appeared to have a comparable fit with prefabricated abutments for most of the systems evaluated. Design differences between the abutment connections for both Straumann implants were observed that affected the fit of internal components of the implant-abutment connections.

Fracture resistance of titanium and zirconia abutments: an in vitro study.

STATEMENT OF PROBLEM: Little information comparing the fracture resistance of internal connection titanium and zirconia abutments exists to validate their use intraorally. PURPOSE: The purpose of this study was to determine the fracture resistance of internal connection titanium and zirconia abutments by simulating cyclic masticatory loads in vitro. MATERIAL AND METHODS: Twenty-two specimens simulating implant-supported anterior single crowns were randomly divided into 2 equal test groups: Group T with titanium abutments and Group Z with zirconia abutments. Abutments were attached to dental implants mounted in acrylic resin, and computer-aided design/computer-aided manufacturing (CAD/CAM) crowns were fabricated. Masticatory function was simulated by using cyclic loading in a stepped fatigue loading protocol until failure. Failed specimens were then analyzed by using scanning electron microscopy (SEM) and fractographic analysis. The load (N) and the number of cycles at which fracture occurred were collected and statistically analyzed by using a 2-sample t test (α=.05). RESULTS: The titanium abutment group fractured at a mean (SD) load of 270 (56.7) N and a mean (SD) number of 81 935 (27 929) cycles. The zirconia abutment group fractured at a mean (SD) load of 140 (24.6) N and a mean (SD) number of 26 296 (9200) cycles. The differences between the groups were statistically significant for mean load and number of cycles (P<.001). For the titanium abutment specimens, multiple modes of failure occurred. The mode of failure of the zirconia abutments was fracture at the apical portion of the abutment without damage or plastic deformation of the abutment screw or implant. CONCLUSIONS: Within the limitations of this in vitro study, 1-piece zirconia abutments exhibited a significantly lower fracture resistance than titanium abutments. The mode of failure is specific to the abutment material and design, with the zirconia abutment fracturing before the retentive abutment screw.

Description of a photoelastic coating technique to describe surface strain of a dog skull loaded in vitro.

There are several methods of determining strain in the facial skeleton on loading in vitro. This article describes an alternative photoelastic coating technique adapted from the commonly accepted method used by engineers to study surface strains in objects. In applying this method to the stomatognathic system, because the masticatory apparatus is loaded by muscular contraction an opposite reaction load should be distributed throughout the skeletal structure. This load distribution should slightly deform the bones to which the muscles of mastication are attached. An understanding of the resulting strain generated in the facial skeleton is important because strain distribution on loading reflects how the loads applied during mastication are partially dissipated. Preliminary descriptive results are presented, suggesting that anatomic structures influence the distribution of strain on loading. The technique described should allow in vitro investigation of the mechanical environment into which osseointegrated implants are placed and may aid in understanding their behavior.