Emergence Angle Research Articles

Bone remodeling around dental implants after 1-1.5 years of functional loading: A retrospective analysis of two-stage implants.

ObjectivesThis study aims to retrospectively assess to what extent peri‐implant bone level changes occur from exposing the implant to the oral environment at the second stage of surgery (SSS) to the baseline assessment and, additionally, after 1–1.5 years of functional loading. Further, this study aims to examine the role of the emergence angle in marginal bone changes.Material and MethodsThis retrospective study included 46 patients treated between 2012 and 2019. These patients received 64 bone‐level dental implants. After implant placement, SSS, and baseline assessment, relevant clinical peri‐implant conditions and radiographical data were collected. A radiographic examination of the marginal bone level was performed after SSS, the baseline assessment, and 1–1.5 years of follow‐up.ResultsThe peri‐implant periodontal probing depth increased significantly from 3.08 ± 0.7 mm at the baseline to 3.27 ± 0.81 mm at the 1–1.5‐year follow‐up. The mean marginal bone level at the implant level was 0.12 ± 0.23, 0.35 ± 0.43, and 0.47 ± 0.47 mm at the SSS, baseline, and the 1–1.5‐year follow‐up, respectively. Most changes occurred at the implant's distal site. A significant relationship was found between the emergence angle and the extent of change in the marginal bone level between the SSS and baseline (r = .430, p ≤ .001).ConclusionsMost changes in the marginal bone level occurred between SSS and baseline assessments. For diagnostic purposes, it is advised to obtain a standardized radiograph after SSS to monitor peri‐implant bone‐level alterations.

Influence of buccal emergence profile designs on peri-implant tissues: A randomized controlled trial.

The prosthetic emergence profile design might be an important factor in postsurgical mucosal recession etiology. Therefore, a restorative buccal emergence profile designed correctly might reduce gingival margin recession. To compare the marginal gingival level and the width/height (W/H) ratio between two profile configurations of single implant-supported restorations at molar sites. Twenty-one patients requiring a single mandibular molar tooth replacement with supracrestal mucosal thickness ≥2 mm were recruited and randomly assigned to a prosthesis buccal emergence profile design based on the buccal mucosal W/H ratio (Test Group) or maintained the original emergence profile of the healing abutment (Control Group). Assessments were made before delivery of the definitive restoration (T0), at prosthesis placement (T1), one (T2), and 12 (T3) months after loading. The gingival margin level change (△GM), initial emergence angle, buccal mucosal W/H ratio, marginal bone loss (MBL), implant failure, and complications were assessed. The gingival recession in the test group (0.13 ± 0.32 mm) was significantly lower than in the control group (0.63 ± 0.38 mm) at T3 (p=0.006). The initial emergence angle in the test group (31.4 ± 7.22 degrees) was significantly lower than the control group (40.0 ± 7.60 degrees) (p=0.025). The W/H ratio in the test group at T2 was significantly higher than at T0 but remained stable thereafter. The W/H ratio presented a continued rising trend in the control group. When the initial supracrestal soft tissue thickness was ≥2 mm, a restorative emergence profile based on the W/H ratio significantly reduced gingival margin recession. An emergence angle of 32.4 degrees showed better behavior in maintaining the gingival margin than 40 degrees. ChiCTR190002210.

Marginal Bone Maintenance and Different Prosthetic Emergence Angles: A 3-Year Retrospective Study.

The aim of the present retrospective study was to assess marginal bone changes around implants restored with different prosthetic emergence profile angles. Patients were treated with implants supporting fixed dentures and were followed for 3 years. Marginal bone levels (MBL) measured at the prosthesis installation (t0) and at the 3-year follow-up visit (t1) were considered. The MBL change from t0 to t1 was investigated. Two groups were considered: Group 1 for restorations with an angle between implant axis and prosthetic emergence profile >30°, and Group 2 for those with an angle ≤30°, respectively. Moreover, peri-implant soft tissue parameters, such as the modified bleeding index (MBI) and plaque index (PI) were assessed. Seventy-four patients were included in the analysis and a total of 312 implants were examined. The mean EA in groups 1 and 2 was 45 ± 4 and 22 ± 7 degrees, respectively. The mean marginal bone level change (MBL change) of 0.06 ± 0.09 mm and 0.06 ± 0.10 mm were, respectively, in groups 1 and 2. The difference in the MBL change between the two groups was not statistically significant (p = 0.969). The MBL change does not seem to be influenced by the emergence angle for implants with a stable internal conical connection and platform-switching of the abutment diameter.

Emergence angle: Comprehensive analysis and machine learning prediction for clinical application.

To analyze and compare the emergence angle (EA) using two measurement methods, conventional and modified (EA-GPT and EA-R), the EAs of all-natural teeth were evaluated and classified to derive a suitable and predictable clinically applicable measurement method. Natural human teeth (n=600) were classified, cleaned, and thoroughly inspected. Teeth were scanned using an intraoral scanner. The scanned data were analyzed using three-dimensional analysis software for both methods with several points per surface. A Bland-Altman analysis was used for statistical analysis and a heat map and a nonparametric density plot to assess the repetition and distribution. An XGBoost regression model was used for prediction. The EA-R method showed significantly different values compared to the EA-GPT method, representing an increase of 17.5-20.7% for the proximal surfaces. An insignificant difference between the two methods was observed for other surfaces. Different teeth classes showed variation in the normal range, thereby resulting in a new classification of the EA for all-natural teeth based on the interquartile range. The machine learning gradient boosting model predicted conventional data with an average mean absolute error of 0.9. Variations in the natural teeth EA and measurement methods, suggest a new classification for EA. The established artificial intelligence method demonstrated robust performance, which could aid in implementing EA measurement in prosthetic designs.

Quantifying the Abundances of Minerals of Granitic Composition Using the Hapke Model of Bidirectional Reflectance

Quantitatively assessing the abundances of the composite minerals in terrestrial granite is crucial to understanding the evolutionary history of the earth’s crust and to mineral exploration as well. Prevalent methods of estimating mineral abundances based on the Hapke model by setting the optical constants of the endmembers ahead of time are no longer applicable to terrestrial granite because of the complexity of natural granite, which leads to remarkable uncertainties in these estimations. In this study, we retrieved specific photometric parameters from the bidirectional reflectance spectra measured at a range of incidence, emergence, and phase angles before they were input into the Hapke model and used to estimate the mineral abundances. Four types of granite samples containing the main granitic minerals (quartz, alkali feldspar, and plagioclase) were used to test the effectiveness of our proposed method. The effects of the particle size and dark minerals on the inversion results using the visible near and shortwave infrared (VNIR-SWIR) wavelengths were also examined. The results show that using the photometric parameters retrieved from multiangle measurements as inputs to the Hapke model can produce accurate estimations of the abundances of quartz, alkali feldspar, and plagioclase in both natural and synthetic granite samples. Furthermore, the results demonstrate that the retrieved particle sizes of the particulate samples are close to the ground measurements. Thus, the proposed approach provides a more accurate and efficient estimation of the compositions of terrestrial granites, making it feasible to quickly assess the abundances of the minerals contained in granite.

The impact of asteroid shapes and topographies on their reflectance spectroscopy

Here we report the comparison between unresolved reflectance spectroscopy of Solar System small bodies and laboratory measurements on reference surfaces. We measure the bidirectional reflectance spectroscopy of a powder of howardite and a sublimation residue composed of a Ceres analogue. The spectra are then inverted using the Hapke semi-empirical physical model and the MRTLS parametric model to be able to simulate the reflectance of the surfaces under any geometrical configuration needed. We note that both models enable an accurate rendering of the reflectance spectroscopy, but the MRTLS model adds less noise on the spectra compared to the Hapke model. Using the parameters resulting from the inversions, we simulate two spherical bodies and the small bodies (1)Ceres and (4)Vesta whose surfaces are homogeneously covered with the Ceres analogue and powder of howardite respectively. We then simulate various scenarios of illumination and spectroscopic observations, i.e. spot-pointing and fly-bys, of these small bodies for phases angles between 6° and 135°. The unresolved reflectance spectroscopy of the simulated bodies is retrieved from the resulting images, and compared to the reflectance spectroscopy of the reference surface measured in the laboratory. Our results show that the photometric phase curves of the simulated bodies are different from the reference surfaces because of the variations of the local incidence and emergence angles due to the shape and topography of the surface. At low phase angle, the simulated bodies are brighter than the reference surfaces, with lower spectral slope and shallower absorption bands. We observe the maximum differences at wide phase angles with the various simulated observations of (4)Vesta due to its high surface topography. Finally, we highlight the differences in the spectral parameters derived from the unresolved observations at 30° with laboratory measurements acquired under a single geometrical configuration.

An Itemized Study on Peri-implant Diseases after Insertion of Restorations

Regardless of the type of implant, the loss of the implant crestal bone in the first year during post-implant-treatment and after functioning by prosthetic treatment is often greater than that of the following year. Possible causes for early implant bone loss include surgical trauma, occlusal overload, peri-implantitis, microgap, biological width, and crest modules of the implant itself. Plaque index and Gingival index values were also foundsignificantly higher for implants without KM(keratinized mucosa). KM of at least 2 mm should be maintained.Contour of implant restoration is known as one of the risk indicators of peri-implantitis.Prevalence of peri-implantitis was significantly greater in the bone-level group when the emergence angle was >30 degrees compared to an angle ≤30 degrees. Emergence angle of >30 degrees is a signific ianndti cra-istokr for peri-implantitis and convex profile creates an additional risk for bone-level implants, but not fo rtis-suelevel implants. Biocom-patible materials should be used for all implant prosthetics, especially f otrhmeation of high polished surfaces with a reasonable appearance on the transmucosal part of the imp rlaensttorations.Bacterial products of the biofilm provoke an immune response in the gingival tissues. As btihoefilm matures-more complex inter-reactions occur and bacteria with more virulent qualities apprpoevaork,ing a more compleximmune system response. Inflammation and immune response cannot be resolved until the bacteria biofilm is removed. To minimize the incidence of complications, dental professionals should make great effort in choos-ing reliable components and materials for implant- supported FDPs and the patients should be placed in wellstructured maintenance system after treatment.

Universal design rules for 2π phase trapezoidal metasurface based on Fabry–Perot resonance in visible and near-infrared

Our work proposes universal rules for simplifying the numerical design of phase metasurface, which alleviates the problem of lots of iterative calculations and low design efficiency due to the consideration of dispersion and phase distribution of materials and so on. According to the different effects of structure sizes and materials on metasurface, the parameters can be divided into two categories: one affects the 2π phase shifting mechanism and phase linearity, and the other affects the anomalous deflection performance of the device, such as bandwidth, reflection, and angle of emergence. Through the proposed design rules, the uncertain parameters can be reduced by more than 60%, greatly improving the numerical design efficiency. To verify the rules, we design several metasurfaces: the large angle deflector at 430 to 630 nm waveband and the broadband (more than 700 nm) high-efficiency reflective metasurface in the near-infrared, where the perfect 2π phase linearity is achieved at the communication wavelength 1550 nm. Moreover, we simply combine two trapezoids in one unit, so that the metasurface can be used as a beam splitter to verify the generality of the rules. The optimal conversion efficiency of equal power beam splitter is more than 95%, and the reflectivity is more than 0.85 at near-infrared. It is of guiding significance to the theoretical design of phase metasurface with excellent performance.

Impact of design elements of the implant supracrestal complex (ISC) on the risk of peri-implant mucositis and peri-implantitis: A critical review.

The aim of this review was to investigate the evidence correlating the emergence profile (EP) and emergence angle (EA), peri-implant tissue height, implant neck design, abutment and/or prosthesis material, retention and connection types with risk of peri-implant mucositis and peri-implantitis. Seven focus questions were identified, and seven electronic search queries were conducted in PubMed. Human studies reporting on bleeding on probing, probing depth or case definitions of peri-implant mucositis and peri-implantitis were included. Emerging evidence with bone-level implants suggests a link between EA combined with convex EP and peri-implantitis. Depth of the peri-implant sulcus of ≥3mm is shown to be reducing the effectiveness of treatment of established peri-implant mucositis. Modification of the prosthesis contour is shown to be an effective supplement of the anti-infective treatment of peri-implant mucositis. Limited evidence points to no difference with regard to the risk for peri-implant mucositis between tissue- and bone-level implants, as well as the material of the abutment or the prosthesis. Limited evidence suggests the use or not of prosthetic abutments in external connections and does not change the risk for peri-implantitis. Literature with regard to prosthesis retention type and risk for peri-implantitis is inconclusive. Limited evidence indicates the involvement of EA, EP, sulcus depth and restricted accessibility to oral hygiene in the manifestation and/or management of peri-implant mucositis/peri-implantitis. Conclusions are limited by the lack of consensus definitions and validated outcomes measures, as well as diverse methodological approaches. Purpose-designed studies are required to clarify current observations.

Peri-implantitis: Summary and consensus statements of group 3. The 6th EAO Consensus Conference 2021.

To evaluate the influence of implant and prosthetic components on peri-implant tissue health. A further aim was to evaluate peri-implant soft-tissue changes following surgical peri-implantitis treatment. Group discussions based on two systematic reviews (SR) and one critical review (CR) addressed (i) the influence of implant material and surface characteristics on the incidence and progression of peri-implantitis, (ii) implant and restorative design elements and the associated risk for peri-implant diseases, and (iii) peri-implant soft-tissue level changes and patient-reported outcomes following peri-implantitis treatment. Consensus statements, clinical recommendations, and implications for future research were discussed within the group and approved during plenary sessions. Data from preclinical in vivo studies demonstrated significantly greater radiographic bone loss and increased area of inflammatory infiltrate at modified compared to non-modified surface implants. Limited clinical data did not show differences between modified and non-modified implant surfaces in incidence or progression of peri-implantitis (SR). There is some evidence that restricted accessibility for oral hygiene and an emergence angle of >30combined with a convex emergence profile of the abutment/prosthesis are associated with an increased risk for peri-implantitis (CR). Reconstructive therapy for peri-implantitis resulted in significantly less soft-tissue recession, when compared with access flap. Implantoplasty or the adjunctive use of a barrier membrane had no influence on the extent of peri-implant mucosal recession following peri-implantitis treatment (SR). Prosthesis overcontouring and impaired access to oral hygiene procedures increases risk for peri-implantitis. When indicated, reconstructive peri-implantitis treatment may facilitate the maintenance of post-operative peri-implant soft-tissue levels.

Restoration of a wide edentulous posterior site with two small-diameter implants: Biologically-driven alternative treatment

Crestal bone stability, implant rigidity and occlusal loading are issues with small-diameter implants. This article demonstrates the use of two small-diameter implants replacing a missing wide edentulous site and discusses factors that may affect bone changes. Patients who wanted to restore an edentulous space measuring from 12 to 14mm wide in the posterior region were offered an alternative treatment option, using two narrow or regular-diameter implants instead of one wide implant. In the study, the crestal bone stability of 12 implants in 6 edentulous sites was assessed by cone beam CTs and periapical radiographs in follow-up visits for up to 4 years. The bone level of all the implants was stable at buccal, lingual, mesial and distal sites, with mean values<1mm. The average buccal bone thickness was 1.15±1.07mm and lingual was 1.86±0.89mm, meaning that implants were surrounded by a sufficient amount of bone. The good treatment outcome may be attributed to the capability of fabricating better emergence profiles, angles (Mean: 20.67±7.82°at the mesial and 20.25±8.23°at the distal site) and cleansable embrasures of prostheses which are key to maintaining good oral hygiene and implant health. Using two narrow or regular-diameter implants to replace a single edentulous site measured around 12-14mm wide in posterior region seemed to be a feasible treatment option. It is especially suitable for sites with ridge atrophy and/or patients suffering from systemic diseases.

A Comparative Assessment of Various Turbulence Models Applied for Simulation of Air-Water Flow Over Chute Spillway

Chute aerators have been largely used to reduce cavitation hazard in high head spillways. There is no definite turbulence model for simulating these devices in smooth spillways in spite of its importance in critical conditions. A simulation in two-phase air-water chute flow and its aerator with five different turbulence models (RNG, Standard and Realizable k–ε Models, SST and Standards k–ω Models) has been numerically investigated by Fluent software. Finite Volume and VOF methods were used for discretization of flow equations and free surface modeling. Flow depth, velocity and bottom pressure comparison were made along with the air cavity length determination by numerical, experimental and reference equations. The best model with the minimum value of error percentage for flow depth and velocity was RNG k–ε turbulence model. The realizable and RNG k–ε turbulence models showed better results for the pressure head at the bottom of the chute. The RNG k–ε model results for the jet length have a very slight difference with the experimental results. The length of the cavity is closely associated with the flow emergence angle θ’ over aerators. The bottom air concentration of spillway chute simulated by all the turbulence models, except for the RNG k–ε model, can be overestimated and therefore may affect the designing of aerator geometry.

Mitigating the ill-posedness of first-arrival traveltime tomography using slopes: application to the eastern Nankai Trough (Japan) OBS data set

SUMMARYFirst-arrival traveltime tomography is one of the most used velocity model building techniques especially in sparse wide-angle acquisitions for deep crustal seismic imaging cases. Relying on the inversion of a picked attribute, the absolute traveltimes, the approach is ill-posed in terms of non-uniqueness of the solution. The latter is remedied by proper regularization or the introduction of prior information. Indeed, since traveltime kernels are vulnerable to the velocity–depth ambiguity, the inversion is stabilized by the introduction of complementary data like reflections and explicit reflectors in the velocity models. Here, we propose to supplement first-arrival traveltimes by their slopes, in other words the horizontal component of the slowness vectors at the sources and/or receivers. Slopes are a crucial attribute in state of the art scattering-based or reflection-based tomographic methods like slope tomography or wavefront tomography where the differential information is needed in order to locate the scattering events position or to parametrize the wavefront. The optional but valuable injection of slopes as an objective measure in first-arrival traveltime tomography stabilizes the problem by constraining the emergence angle or in turn implicitly the turning point depth of the rays. We explain why slopes have a tremendous added value in such a tomographic problem and highlight its remedial effect in cases where the medium is unevenly illuminated. We also show that the contribution of slopes become even more significant when the acquisition is sparse as it is generally the case with ocean-bottom seismometer surveys. The inferred models from such an extended time-attributes tomography will be used as initial guesses in a full-waveform inversion workflow context. The proposed strategy is benchmarked in 2-D media against a dip section of the SEG/EAGE overthrust model and then followed by a revisit of ocean bottom seismometers data from the eastern-Nankai subduction margin as a real deep crustal case study.

Waves Propagation at an Interface of Two Liquid Saturated Porous Solid Half Spaces

This manuscript is concerned with reflected and refracted elastic waves when transverse waves are incident at the interface between two fluid-saturated porous solid half-spaces. Perfect and imperfect both types of contact of the interfaces are discussed. It has observed that for a specific model the behaviour of different reflected, refracted waves and the ratio of their amplitudes depend on the physical properties of the medium, angle of emergence, the porosity of the fluid, the porosity of fluid drenched incompressible porous medium and stiffness of imperfect boundary. The computer numerically results for this model have been presented graphically by taking a particular case of empty porous solid.

Synthesis of Bessel Beam Using Time-Reversal Method Incorporating Metasurface

In this paper, a synthesis and implementation method for generating Bessel beams based on time-reversal theory incorporating electromagnetic (EM) meta-lens is proposed. As is known, time-reversal EM waves has the unique characteristic of adaptive backtracking. Therefore, with this characteristic, the EM characteristics of the radiation aperture can be obtained and further utilized to generate Bessel waves with any departure angle. Based on this concept, two meta-lenses for generating Bessel beams tilted in different directions were designed. Both meta-lenses were designed at the center frequency of 15 GHz, and the simulation results were consistent with the target expectation. A representative meta-lens was fabricated and measured. The final size of the meta-lens was 350 mm × 350 mm, and a Bessel beam with a 30° emergence angle was generated by this structure. The experimental results were in good agreement with the simulation results and the theoretical derivation. This synthetic method of Bessel beam generation using the time-reversal operation may be of great use for the application of Bessel beams in microwave communications, and it can broaden the application scope of non-diffracting beams.

The Implant Supracrestal Complex and Its Significance for Long-Term Successful Clinical Outcomes

Emerging evidence implies significant interrelations between the condition of the peri-implant tissues and the implant-abutment-prosthesis complex. A new paradigm for studying the peri-implant tissues in close interrelation with the implant-abutment-prosthesis complex in the presence of the oral biofilm is essential. The aims of this paper are to introduce the concept of the "implant supracrestal complex" (ISC) and to describe the critical elements that define it as a unique anatomical and functional system of human tissues, mechanical components, and oral bacteria/biofilm. This paper reviews recent evidence to identify the impact of design features on short-term clinical outcomes and long-term health of the peri-implant bone and soft tissues. Prosthetic-driven implant placement is a prerequisite for proper ISC design, which in turn can indirectly influence the structure and dimensions of the peri-implant soft tissues. Design features of the implant-prosthesis-abutment complex, such as the emergence profile, emergence angle, and cervical margin, as well as the design of the implant-abutment and abutment-prosthesis junctions and their locations in relation to the tissues of the ISC, can have a significant impact on the maintenance of stable and healthy peri-implant tissues in the long term.

Coastal Sand Dunes Monitoring by Low Vegetation Cover Classification and Digital Elevation Model Improvement Using Synchronized Hyperspectral and Full-Waveform LiDAR Remote Sensing

Due to the coastal morphodynamic being impacted by climate change there is a need for systematic and large-scale monitoring. The monitoring of sandy dunes in Pays-de-la-Loire (France) requires a simultaneous mapping of (i) its morphology, allowing to assess the sedimentary stocks and (ii) its low vegetation cover, which constitutes a significant proxy of the dune dynamics. The synchronization of hyperspectral imaging (HSI) with full-waveform (FWF) LiDAR is possible with an airborne platform. For a more intimate combination, we aligned the 1064 nm laser beam of a bi-spectral Titan FWF LiDAR with 401 bands and the 15 cm range resolution on the Hyspex VNIR camera with 160 bands and a 4.2 nm spectral resolution, making both types of data follow the same emergence angle. A ray tracing procedure permits to associate the data while keeping the acquisition angles. Stacking multiple shifted FWFs, which are linked to the same pixel, enables reaching a 5 cm range resolution grid. The objectives are (i) to improve the accuracy of the digital terrain models (DTM) obtained from an FWF analysis by calibrating it on dGPS field measurements and correcting it from local deviations induced by vegetation and (ii) in combination with airborne reflectances obtained with PARGE and ATCOR-4 corrections, to implement a supervised hierarchic classification of the main foredune vegetation proxies independently of the acquisition year and the physiological state. The normalization of the FWF LiDAR range to a dry sand reference waveform and the centering on their top canopy echoes allows to isolate Ammophilia arenaria from other vegetation types using two FWF indices, without confusion with slope effects. Fourteen HSI reflectance indices and 19 HSI Spectral Angle Mapping (SAM) indices based on 2017 spectral field measurements performed with the same Hyspex VNIR camera were stacked with both FWF indices into a single co-image for each acquisition year. A simple straightforward hierarchical classification of all 35 pre-classified co-image bands was successfully applied along 20 km, out of the 250 km of coastline acquired from 2017 to 2019, prefiguring its systematic application to the whole 250 km every year.

Extremely high temperature stable nanometric scale multilayer spectrally selective absorber coating: Emissivity measurements at elevated temperatures and a comprehensive study on ageing mechanism

Spectrally selective W/WAlSiN/SiON/SiO2 solar absorber coatings were sputter-deposited on stainless steel and silicon substrates. The optimized as-deposited sample exhibits a high solar absorptance of 0.955 and a low thermal emissivity of 0.10 at 82 °C. The coating exhibits a very low reflectance of 1.2% in the wavelength range of 0.5–1.5 μm in the solar spectrum. The spectral emissivity measurements at various operating temperatures and with varying emergence angles were investigated. Also, the impact of emissivity on the photothermal efficiency at different temperatures of the developed solar absorber coating was calculated. The calculated optical properties of the as-deposited sample exhibited low thermal emissivity of 0.157 (at 500 °C) and a high heliothermal efficiency of 89.5%. Angular reflectance measured at room temperature illustrates an insignificant change in the hemispherical and near normal emissivities of the samples. In addition to these studies, the ageing tests of the as-deposited samples at various operating temperatures were studied in detail. The thermal ageing tests of the samples in air and vacuum environments indicated excellent thermal stability at elevated temperatures, i.e., in air at 400 °C for 500 h, at 450 °C for 175 h and at 500 °C for 100 h, whereas, in a vacuum it was stable at 700 °C for 200 h. The top anti-reflection layers and the fine nano-multilayers of WAlSiN (W2N and AlSiN) prevent the inward diffusion of oxygen and thereby improve the overall thermal stability of the tandem absorber.

Multivariate analysis of the influence of prosthodontic factors on peri-implant bleeding index and marginal bone level in a molar site: A cross-sectional study.

Peri-implant tissue condition can result from prosthodontic, surgical and bacteriological factors. This study investigated the effects of prosthodontic factors on peri-implant tissue. Subjects were 140 patients with 310 implants from Osaka University Dental Hospital. Prosthodontic factors examined were the connection type, the suprastructure retention type, the material of the abutment and the mesiodistal and buccolingual prosthetic form of the superstructure as emergence angle. The objective variables were the modified bleeding index (mBI) and marginal bone level (MBL). Statistical analysis was used as a generalized estimation equation. The taper joint had a significantly smaller MBL than the butt joint (P < .001). There was no significant difference in mBI and MBL between cement and screw retaining. Zirconium and titanium resulted in a significantly smaller mBI than gold alloy (zirconium/gold alloy: P = .037, titanium / gold alloy: P = .021), but there was no significant difference in the MBL. Both mBI and MBL tended to be smaller when the emergence angle was around 20° to 40°, although this difference was not significant. As a result of multivariate analysis, our findings suggest that to reduce MBL from the perspective of prosthodontic factors it is preferable to use an implant with a taper joint connection positioned with an emergence angle of 20° to 40°.

Influence of restorative design on the progression of peri-implant bone loss: A retrospective study.

Clinical data on the restorative designs affecting the early progression of peri-implantitis are scarce. The aim of this retrospective study was to evaluate the influence of several restorative factors (e.g., restoration emergence angle, and internal screw length/diameter) on the marginal bone loss around implants with peri-implantitis. Implants diagnosed with peri-implantitis having 1- (T1) and 2-year (T2) follow-ups were included. In addition, within 6 months pre-diagnosis (Tb), all cases required to have full documentation in which no evidence of peri-implantitis was not indicated. Changes in marginal bone levels (MBLs) from Tb to T1 and from T1 to T2 were evaluated. The effect of several variables on MBLs changes was assessed via univariate and multivariate generalized estimating equations. Eighty-three bone-level implants from 65 patients were selected. The mean follow-up before peri-implantitis diagnosis was 99.47 ± 47.93 months. The radiographic mean marginal bone loss was 1.52 ± 1.33mm (Tb to T1) and 0.58 ± 0.52mm (T1 to T2). Restoration emergence angle and frequency of maintenance visits significantly affected MBLs from Tb to T1. Besides, 66.3% of the included implants' bone levels were in a zone within 1mm of the apical end of the internal screw at T1 and remained in this zone during the second follow-up year. Significant marginal bone loss occurred in the early post-diagnosis period of peri-implantitis, which could be affected by the restoration emergence angle. Peri-implant MBLs were frequently located in a zone within 1mm of the apical end of the internal screw.