Crestal Area Research Articles

TADJIKABAD EARTHQUAKE of JULY 4, 2020 with Мs=5.2, I0=7 (TAJIKISTAN)

Instrumental and macroseismic data are presented for the Tadjikabad earthquake on July 4, 2020 with intensity in the epicenter I0=7 and surface wave magnitude Ms=5.2, which has happened in the eastern part of Tajikistan, in the crest area of Peter the Great Ridge. This seismic event has been accompanied by numerous aftershocks (NΣ=137), which spread area has the form of ellipse stretched in sub-meridional direction with axes 83 and 96 km. The information about the earthquake perceptibility has been collected in 32 settlements and the map with isoseist of I=7, 6, 5, 4 has been created. Description of seismotectonic position of the origin and historical seismicity of the area is given. The areas of the strongest shaking in the focal zone from earthquakes in the study area were determined and a probabilistic model of the earthquake isoseist map of the earthquake of May 4, 2020 was compiled.

Three-dimensional finite element analysis of maxillary molar distalization treated with clear aligners combined with different traction methods

BackgroundThis study aimed to analyze the effects of maxillary molar distalization using clear aligners with different intramaxillary and intermaxillary traction via the three-dimensional (3D) finite element method.MethodsA 3D finite element model consisting of the maxilla, mandible, dentitions, periodontal ligaments (PDLs), attachments, and clear aligners was constructed. Five groups were established based on different traction modalities: group 1 (control group); group 2 (orthodontic mini-implants (OMIs) were implanted between the maxillary first molars and the second premolars on the buccal side); group 3 (OMIs were implanted in the infrazygomatic crest area between the maxillary first and second molars on the buccal side); group 4 (OMIs were implanted between the maxillary first molars and the second premolars on the palatal side); and group 5 (class II elastics were utilized between the maxillary canines and the mandibular first molars). OMIs were implanted 4 mm away from the alveolar crest in each experimental group. A force of 1.5 N was applied to each experimental group. The 3D displacement of the target teeth and stress distribution around the PDLs were analyzed.ResultsGroup 4 exhibited the least amount of torque change in the upper anterior teeth and the highest displacement of the maxillary second molars. Group 3 showed smaller changes in anterior teeth torque and higher molar distalization efficiency compared to group 2. Group 5 showed adverse effects such as anterior teeth extrusion and mandibular anchorage loss.ConclusionOMIs implanted on the palatal side have advantages in preserving anterior teeth anchorage and improving the efficiency of molar distalization compared to those positioned on the buccal side. OMIs implanted in the infrazygomatic crest area between the first and second molars on the buccal side demonstrate benefits in the aforementioned aspects when compared to OMIs implanted between the first molars and the second premolars on the buccal side.

Evaluation of Two Mini-implant Lengths in the Infrazygomatic Crest Region: A Randomized Clinical Trial.

Temporary anchorage devices (TADs) have revolutionized fixed orthodontic appliance treatment through anchorage controlling in the clinic and play an essential role in resolving many complex cases. Due to the limited space, there is a risk of injury to the roots while using interradicular microimplants. Therefore, the infrazygomatic crest (IZC) area can be an alternative mini-implant insertion site in the maxillary arch. The aim of the study was to evaluate the primary stability, pain perception, sinus penetration, late stability, and failure rate with two mini-implant lengths in the IZC area. Forty-eight mini-implants (Tusk Dental Co., Ltd., Canada) with two different lengths (length/diameter: 12/2 and 14/2 mm) were grouped by length (24 per group) and inserted bilaterally into the IZC area of 24 patients. The data were statistically analyzed, considering a significance level of p < 0.05. Sinus penetration prevalence did not differ significantly between 12-mm (54.2%) and 14-mm (62.5%) mini-implants (p > 0.05). Primary stability was significantly higher with the 14-mm mini-implants (p < 0.05). The failure rate did not differ significantly between the 12-mm (20.8%) and 14-mm (16.7%) mini-implants (p > 0.05). While the failure rate was similar between 12- and 14-mm mini-implants, the 14-mm mini-implants were more likely to damage adjacent structures. Therefore, shorter mini-implants should be preferred over longer mini-implants for most cases requiring IZC TADs. ClinicalTrials.gov identifier: NCT06293872.

Data Science Enables Management of Stealth Asphaltene Flow-Assurance Risk

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 216216, “Managing Stealth Asphaltene Flow-Assurance Potential Risk in Gas-Injection Field Based on Data Science Using Over 20-Year Accumulated Data Set,” by Hideharu Yonebayashi, SPE, and Takeshi Hiraiwa, SPE, Japan Oil Development, and Khuloud T. Al Khlaifi, SPE, ADNOC, et al. The paper has not been peer reviewed. _ Gas injection is recognized generally not only to improve oil recovery but also to increase the risk of asphaltene destabilization. The recent discovery of asphaltene deposits in a subject field motivated the operator to launch an immediate investigation to evaluate what critical risks might exist and consider appropriate mitigation. It was found that precipitated but invisible asphaltenes still can be flowable. This stealth asphaltene behavior could explain a possible mechanism of the first asphaltene observation in the upper reservoir. Introduction The subject giant offshore field in the Arabian Gulf has not experienced asphaltene-induced production deterioration during long-term lean hydrocarbon gas injection. The gas has been injected into the crestal area of two reservoirs (upper and lower) with peripheral powered seawater injection. Both reservoir fluids contain a small amount of asphaltenes (0.1–1.5 wt%) distributed at higher concentration at deeper locations. In May 2022, the first discovery of asphaltene deposits from the historical no-issued area in the upper reservoir motivated an immediate investigation for risk assessment and mitigation. A resulting study captured stealth asphaltenes, which were detected by a laser-light-scattering technique while high-pressure microscopy detected no visible asphaltene solid particles. Historical Asphaltene Data Accumulation The permeability range and pore-throat size of the subject field are relatively low in the lower reservoir compared with the upper. Both reservoirs are under highly unstable asphaltene-stability conditions. The reservoir pressure-maintenance scheme, consisting of dump-floodwater injection followed by peripheral powered seawater injection and crestal gas injection, however, has maintained asphaltene-free production except for the gas-injection pilot (GIP) during 2005–2009. No asphaltenes have been observed in the crestal gas-injection area; however, asphaltene deposits were observed in the GIP area in 2007. The injected gas was enriched gradually by a vaporizing gas-drive process. The previous studies involving numerical modeling analysis and laboratory experiments reported that enriched hydrocarbon gas can more easily allow asphaltene precipitation compared with lean hydrocarbon gas. GIP Asphaltene Risk Analysis (Upper Reservoir). In 2009, an asphaltene flow-assurance risk evaluation was conducted using the single-phase bottomhole sample collected from Well 6, which is 90 ft shallower that the GIP area and far from the crestal gas-injection area. Therefore, the Well 6 reservoir fluid was not affected by injection gas. The bottomhole condition of the GIP production well was entered into the asphaltene precipitation envelope (APE) that was expanded by injection-gas enrichment but never covered by the APE without an enrichment process. Latest Laboratory Analysis (Lower Reservoir). In 2022, an asphaltene flow-assurance risk evaluation was conducted. After the location was narrowed to a depth range, Well 1 was selected by taking an asphaltene gradient into account.

Spatial and temporal variation of Syrian Arc structures in the onshore and offshore Eastern Mediterranean region

Syrian Arc structures form a belt of folds and faults oriented northeast to southwest and north-northeast to south-southwest extending from the Western Desert of Egypt (and farther westward to Tunisia) via northern Sinai to Levant eastward. Detailed studies of surface and subsurface areas in onshore Egypt as well as the offshore Eastern Mediterranean show evidence for continued deformation since the Santonian with local mild start during the Turonian. Santonian deformation was the strongest, whereas the later continued deformation was less. Previous studies of Syrian Arc structures proposed discrete phases of deformation, but the present study shows evidence that deformation was continuous since the Santonian. The lack of a continuous rock record, erosion of the crestal areas of some folds, nondeposition of younger sediments, and the scattered nature of younger rocks at the exposed Syrian Arc folds led some investigators to propose a short period(s) of Syrian Arc deformation. The relatively well-preserved subsurface stratigraphic record of Syrian Arc structures in some onshore and offshore areas led to the conclusion that the Syrian Arc folding continued to present time. However, the intensity of deformation and the associated structural relief have varied through time and space with its climax during Santonian time. We consider the Late Cretaceous–Cenozoic Syrian Arc structures to be the manifestation of the closure history of the Neo-Tethys Ocean and its successor, the Mediterranean Sea.

Forms and Distribution of Phosphorus along A Toposequence at the University of Benin, Nigeria

The experiment was conducted at University of Benin, Nigeria, involving soil samples from four toposequence sites (Crest, Middle, Lower, and Bottom) at different depths (0-15 cm, 15-30 cm, and 30-45 cm). A total of 36 samples were collected and analyzed for various parameters using standard procedures. The parameters included particle size distribution, pH, total organic carbon (TOC), total nitrogen (N), available phosphorus (P), Carbon (C), Hydrogen (H), Magnesium (Mg), Potassium (K), Sodium (Na), ECEC, and Aluminum (Al). Results indicated that pH was lowest in the Crest area (pH 4.10 at 30-45 cm depth) and highest in the Bottom area (pH 5.80 at 0-15 cm to 30-45 cm depth). Different soil properties showed varying highest values across the toposequence depths. These properties included Total organic C, Total N, Available P, Ca, K, Mg, H, Na, ECEC, sand content, and the various forms of phosphorus. The correlation table revealed significant positive and negative relationships between different forms of phosphorus and various soil physical and chemical properties. The experiment demonstrated distinct variations in soil properties along the toposequence sites and depths. The findings contribute to a better understanding of soil characteristics in the studied region, aiding in informed agricultural practices and land management decisions.

Cone-beam computed tomographic evaluation of mandibular incisor alveolar bone changes for the intrusion arch technique: A retrospective cohort research.

: Alveolar bone loss is a common adverse effect of intrusion treatment. Mandibular incisors are prone to dehiscence and fenestrations as they suffer from thinner alveolar bone thickness. : Thirty skeletal class II patients treated with mandibular intrusion arch therapy were included in this study. Lateral cephalograms and cone-beam computed tomography images were taken before treatment (T1) and immediately after intrusion arch removal (T2) to evaluate the tooth displacement and the alveolar bone changes. Pearson's and Spearman's correlation was used to identify risk factors of alveolar bone loss during the intrusion treatment. : Deep overbite was successfully corrected (P < 0.05), accompanied by mandibular incisor proclination (P < 0.05). There were no statistically significant change in the true incisor intrusion (P > 0.05). The labial and lingual vertical alveolar bone levels showed a significant decrease (P < 0.05). The alveolar bone is thinning in the labial crestal area and lingual apical area (P < 0.05); accompanied by thickening in the labial apical area (P < 0.05). Proclined incisors, non-extraction treatment, and increased A point-nasion-B point (ANB) degree were positively correlated with alveolar bone loss. : While the mandibular intrusion arch effectively corrected the deep overbite, it did cause some unwanted incisor labial tipping/flaring. During the intrusion treatment, the alveolar bone underwent corresponding changes, which was thinning in the labial crestal area and thickening in the labial apical area vice versa. And increased axis change of incisors, non-extraction treatment, and increased ANB were identified as risk factors for alveolar bone loss in patients with mandibular intrusion therapy.

Cortical Bone Thickness and Morphology at the Infrazygomatic Crest Area in Growing Thai Patients with UCLP: A CBCT Study.

To determine and compare buccal cortical bone thickness and morphology (in terms of shape and height) at the infrazygomatic (IZ) crest in growing Thai patients with unilateral cleft lip and palate (UCLP) using cone-beam computed tomography (CBCT) with the ultimate goal of identifying potential sites that are suitable for the placement of miniplates. Prospective study. Institutional research. Twenty-four Thai patients with non-syndromic complete UCLP with Class III skeletal discrepancy aged 10-14 years. A total of 48 CBCT images captured the IZ crest. Five horizontal and six vertical reference planes were established in the IZ crest area. The mean buccal cortical bone thickness of the cleft and non-cleft sides were 1.13 ± 0.45 mm and 1.15 ± 0.46 mm, respectively. The most frequently observed shape for the IZ crest was the external concave contour. There were no statistically significant differences in cortical bone thickness and shape distribution between the cleft and non-cleft sides. (P > .05). The thickness of the buccal cortical bone increased anteriorly and superiorly from V + 0 and H + 0. The average height of IZ crest on the cleft side was 16.20 ± 1.59 mm and 16.78 ± 1.84 mm on the non-cleft side. Notably, significant differences were detected in terms of height between the cleft and non-cleft side and cortical bone thickness by gender (P < .05). The IZ crest was found to provide sufficient support for the insertion of a miniplate, particularly in the superior and anterior regions, ensuring primary stability in growing Thai patients with UCLP.

Quantitative Measurement of Buccal Cortical Bone Thickness in Infrazygomatic Crest Area at Different Alveolar Bone Heights and Insertion Angles of Infrazygomatic Crest Screws: A CBCT Study

Introduction Skeletal anchorage devices for the efficient orthodontic treatment mechanics can be placed at various interradicular and extraradicular sites intra orally. However, their placement in the infrazygomatic crest area can broaden the horizon of orthodontic treatment. The bone thickness in the infrazygomatic crest (IZC) area can vary at different heights and insertion angles during the placement of IZC screws between maxillary second premolar and second molar region. Aims and objectives The purpose of our study was to evaluate the variation in bone thickness in the IZC area at different insertion angles along the mesiobuccal root of maxillary first molar and at different heights from the crest of the alveolar bone in the apical direction between maxillary second premolar and second molar region using cone beam computed tomography, so as to determine the best possible site where the bone thickness will be maximum that will suit to a particular size of IZC screw. Materials and Methods CBCT images of 50 subjects were analyzed by a single observer, the bone thickness in the IZC area was measured and interpreted at different heights from the alveolar crest in the apical direction, that is, 5 mm, 7 mm, 9 mm, 11 mm at six regions between maxillary second premolar and second molar. Bone thickness was also measured at different insertion angles ranging from 55º to 75º to occlusal plane of permanent maxillary first molar along its mesiobuccal root. Results The bone thickness in the IZC area was 4.5 mm–3.5 mm, when it was measured at different angles ranging from 55º to 75º to the occlusal plane of maxillary first molar along its mesiobuccal root with maximum bone thickness at 75° with a mean ± SD of 4.56 ± 1.4. Statistically significant differences in bone thickness were found between maxillary first and second molar on both right and left sides at different heights with maximum bone thickness at 11 mm apical from the alveolar crest with a mean ± SD of 2.03 ± 0.76 and 1.91 ± 0.88, respectively, and along the mesial root of maxillary second molar on right and left sides at 11 mm apical from the alveolar crest with a mean ± SD of 2.12 ± 0.80 and 1.95 ± 0.75, respectively. Conclusions The best site and safe zone for miniscrew insertion in IZC area is at 7 mm to 9 mm distance from the alveolar crest apically along the mesial root of maxillary second molar and at an angle of 55°–75º to the occlusal plane of maxillary first molar, so as to ensure the adequate stability of the miniscrew and without causing any damage to the adjacent anatomical structures.

Study on Impoundment Deformation Characteristics and Crack of High Core Rockfill Dam Based on Inversion Parameters

In the numerical simulation of earth-rock dam, accurate and reliable mechanical parameters of the dam material are the important basis for dam deformation predictions and dam safety evaluations. Based on the deformation monitoring data of Luding core wall rockfill dam, the rheological parameters of rockfill and core wall materials are inverted in this paper. Combined with the actual filling and impoundment process of the dam, the numerical simulation is carried out, and the stress deformation and differential settlement of the dam after completion and impoundment are analyzed. The results showed that the stress deformation results of the dam based on the inversion parameters were in good agreement with the actual deformation. The horizontal displacement, settlement, and principal stress of the dam during the completion period were symmetrically distributed along the core wall. The maximum horizontal displacement occurred at the main dam on both sides of the core wall and the upstream and downstream dam slopes, and the maximum settlement occurred in the middle of the core wall. During the impoundment period, under the action of reservoir water pressure and upstream rockfill wetting deformation, the deformation and stress of the dam body no longer met the symmetrical distribution law, and the maximum horizontal displacement of the dam body during the impoundment period was located at 2/3 of the upstream dam slope. The maximum settlement of the dam body was located at 1/2 of the dam height. The maximum principal stress on the upstream side of the core wall was located on the left side of the bottom of the core wall, and the minimum principal stress was also located on the left side of the bottom of the core wall. The simulation results of the deformation and stress met the general law of earth-rock dam engineering. During the completion period, the deformation inclination of the dam crest was less than 1%. During the impoundment period, the deformation inclination of the dam crest area increased due to the wetting deformation of the upstream rockfill material. At the same time, the deformation inclination of the dam crest axis was larger than that of the upstream and downstream sides, and the deformation inclination of the dam crest at the middle of the valley was the largest, but it did not exceed 3%, that is, there would be no longitudinal cracks, which is consistent with the actual situation. The research results can better predict the stress deformation and crack of the dam body, and provide important support for dam safety evaluations.

Impact of Chitosan-Coated Implants on the Alveolar Ridge: Preliminary MicroCT and Radiographic Study in a Canine Model.

To compare crestal bone loss (CBL) 12 weeks after immediate implant placement in the mandible of a canine model between titanium (Ti) implants with a conventional etched surface (SLA type) and Ti implants coated with chitosan (Cht). A total of 48 Ti-Al16-V4 implants (24 experimental and 24 control) with an internally connected tapered screw design were randomly placed into six canine maxillae, 4 per hemiarch. The experimental implants were coated with Cht by immersion and sterilized with ethylene oxide. Primary stability was measured using the Osstell device, and no grafting materials were used. The 3D microCT measurements included crestal bone volume (CBV) and bone volume change in crestal area (ΔCBV), which were considered outcome measures. Parallelized periapical radiographs were also taken at the time of implant placement and after 12 weeks to assess changes in crestal bone levels. In terms of volumetric changes, it was observed that the experimental group showed better results than the control group (P = .049 and P = .303, respectively). Regarding the implant sites, no significant differences were found between the experimental implant sites and control sites. The implants placed at P4 level in the experimental group obtained the best result (P = .041). The linear data obtained from the periapical radiographs indicated greater bone loss in the control group compared to the experimental group (3.2 ± 0.45 mm and 2.75 ± 0.55 mm, respectively). Despite the better results obtained for the Cht-coated surface group, further preclinical studies are necessary to confirm these results.

Pilot Study: Periosteal Mattress Sutures as an Alternative to Pins and Screws in Guided Bone Regeneration in the Esthetic Zone.

To quantify the buccal bone thickness, area, and perimeter following guided bone regeneration (GBR) using stabilizing periosteal sutures. The loss in hard tissue volume may impair proper implant placement. GBR has been used to regenerate the lost alveolar ridge prior to or at the same time as dental implant placement. The most important factor for GBR success is graft stability. The periosteal mattress suture (PMS) stabilizing technique is an alternative to pins and screws to stabilize bone grafting material and has the advantage of not requiring the removal of the fixing devices. A CBCT was acquired before and 6 months after surgery from six patients who underwent GBR with the PMS stabilizing technique. Images were analyzed for buccal bone thickness, area, and perimeter. The mean change in buccal bone thickness was 3.42 mm (± 1.31 SD) and proved statistically significant (P = .005). The mean change in bone crest area also proved statistically significant (P = .001). No significant difference was found in bone perimeter (P = .12). The PMS technique delivered optimal results without clinical complications. This study shows the potential of this technique as an alternative to pins or screws for graft stabilization in the esthetic zone.

Comparison of tissue displacement in edentulous arches among three-dimensional files obtained through different impression-making methods: A retrospective study.

To retrospectively compare and analyze differences in tissue displacement of edentulous arches among three-dimensional (3D) files obtained using various impression-making techniques. Fourteen patients who underwent prosthodontic treatment for edentulous arches at Yonsei University Dental Hospital between June 2020 and April 2023 were included in the study. Three types of 3D files were used for the evaluation of each arch: a 3D scan file of a definitive cast (Group DEF), a preliminary cast (Group PRE), and an intraoral scan file (Group IOS). The files were superimposed on a reference 3D scan file of the definitive cast group through best-fit matching using metrology software. Seventeen measurement points (MP1-4, RC1-6, TB1-2, and PPS1-5 for the maxilla and RP1-2, RC1-7, BS1-4, and LS1-4 for the mandible) were selected for both the maxillary (n = 13) and mandibular arches (n = 6). The deviation considering the direction (DD) between the three groups and the absolute deviation (AD) between the three groups were recorded. Kruskal-Wallis and post-hoc Mann-Whitney tests were used for statistical analyses (α = 0.05 and α = 0.0167, respectively). Concerning the DD values, at the RC4 point of the maxillary arch, Group PRE exhibited significantly higher values than Groups IOS (p = 0.006) and DEF (p < 0.001), and at the RC5 point of the maxillary arch, Group IOS exhibited significantly lower values than Groups PRE (p = 0.016) and DEF (p < 0.001). Group IOS showed significantly lower DD values in the mandibular arch than Group DEF at the RP2 and RC3 points (p < 0.167). The AD values in Groups PRE and IOS significantly differed from those in Group DEF (all p < 0.001) at all measurement points but did not exhibit significant differences between each other (p > 0.05). Different impression-making methods yielded different amounts of tissue displacement. The tendency of 3D files regarding tissue displacement varied at certain residual ridge crest areas and retromolar pad areas. The absolute amount of tissue displacement observed in the intraoral scan data was comparable to that observed in the preliminary casts.

Should Cone-Beam Computed Tomography Be Performed Prior to Orthodontic Miniscrew Placement in the Infrazygomatic Crest Area?-A Systematic Review.

There is no unequivocal scientific consensus for the temporary anchorage device (TAD) positioning in the infrazygomatic crest area (IZC). The two principal aims of this systematic review were to assess bone availability in the IZC and to establish both the target site and the need for cone-beam computed tomography (CBCT) prior to miniscrew placement. The study was performed following PRISMA guidelines (PROSPERO: CRD42023411650). The inclusion criteria were: at least 10 patients, three-dimensional radiological examination, and IZC assessment for the TAD placement. ROBINS-I tool and Newcastle-Ottawa Scale were used for quality evaluation. No funding was obtained. The study was based on the information coming from: PubMed, Google Scholar, Web of Science Core Collection, MDPI, Wiley, and Cochrane Libraries. The last search was carried out on 1 August 2023. Fourteen studies were identified for analysis. A narrative synthesis was performed to synthesize the findings of the different studies. Unfortunately, it is not possible to establish the generally recommended target site for IZC TAD placement. The reasons for this are the following: heterogeneity of available studies, inconsistent results, and significant risk of bias. The high variability of bone measurements and the lack of reliable predictors of bone availability justify the use of CBCT for TAD trajectory planning. There is a need for more high-quality studies aiming three-dimensional bone analysis of the IZC.

Sexual Dimorphism in the Limb Bones of Asiatic Toad (Bufo gargarizans) in Relation to Sexual Selection.

Sexual dimorphism is often considered to be the result of differences in the intensity of sexual selection between sexes. From this point of view, the sexual dimorphism of the limb bones of the Bufo gargarizans in southwest China was studied. Results showed that the fore- and hindlimb skeletons of this species were sexually dimorphic in anatomy. The humerus, radioulna, and total lengths of the forelimb skeleton of males were substantially longer than those of females, but the hand length of males was smaller than that of females. Several other features of males, such as deltoid and medial crest areas and humerus and radioulnar weights, were also significantly larger than those of females. The femoris, tibiofibula, talus-calcaneus, and foot lengths; total hindlimb skeleton length; and femoral upper crest areas of males were significantly greater than those of females. However, no significant intersexual difference in femoris and tibiofibular weights was observed. These findings suggested that robust forelimb bones and long hindlimb bones could contribute to the mating success of males; if so, sexual selection promotes the evolution of sexual size and shape dimorphism in the limb bones of the B. gargarizans.

Role of periosteum during healing of alveolar critical size bone defects in the mandible: a pilot study.

Minipigs present advantages for studying oral bone regeneration; however, standardized critical size defects (CSD) for alveolar bone have not been validated yet. The objectives of this study are to develop a CSD in the mandibular alveolar bone in Aachen minipigs and to further investigate the specific role of periosteum. Three female Aachen minipigs aged 17, 24, and 84months were used. For each minipig, a split-mouth design was performed: an osteotomy (2cm height × 2.5cm length) was performed; the periosteum was preserved on the left side and removed on the right side. Macroscopic, cone beam computed tomography (CBCT), microcomputed tomography (µCT), and histological analyses were performed to evaluate the bone defects and bone healing. In both groups, spontaneous healing was insufficient to restore initial bone volume. The macroscopic pictures and the CBCT results showed a larger bone defect without periosteum. µCT results revealed that BMD, BV/TV, and Tb.Th were significantly lower without periosteum. The histological analyses showed (i) an increased osteoid apposition in the crestal area when periosteum was removed and (ii) an ossification process in the mandibular canal area in response to the surgical that seemed to increase when periosteum was removed. A robust model of CSD model was developed in the alveolar bone of minipigs that mimics human mandibular bone defects. This model allows to further investigate the bone healing process and potential factors impacting healing such as periosteum. This model may be relevant for testing different bone reconstruction strategies for preclinical investigations.

HISTOLOGICAL AND MORPHOMETRIC STUDIES OF BONE TISSUE AUTOGRAFTS FROM INTRAORAL AND EXTRAORAL DONOR ZONES

Major research carried out in modern dentistry and maxillofacial surgery is commonly focused on long-term and stable results for implant rehabilitation of jaw defects and deformities in patients with bone and soft tissue losses at the site of planned implantation. Various osteoplastic materials, donor or the patient’s own bone, tissue-engineering and cellular products are common in clinical medicine, since guided regeneration can help not only recover the volume of bone tissue once lost, yet also ensure an outcome acceptable from both functional and aesthetic view. Guided bone regeneration employs methods of regenerative medicine and tissue engineering, with transplantation of native bone tissue and cell transplants, as well as various osteoplastic materials with osteoinductive and osteoconductive properties. In order to compare the structure of intact bone tissue obtained from intraoral and extraoral donor zones, histological and morphometric studies of bone autografts in 4 certified male cadavers with intact dentition were carried out. The results of histological studies in bone tissue autografts from intraoral and extraoral donor zones revealed that the highest density of bone rods could be observed in biopsies taken from the mandible outer oblique line area and chin symphysis. Whereas the lowest rate of the said factor we observed in the biopsies obtained from the iliac crest area. The highest rate of the inter-rod girder space was found in the area of the iliac crest, and the minimal – in biopsies from the parietal bone. The highest bone vascularization level was identified at the iliac crest and the parietal bone, while its lowest levels were seen in biopsies taken from the area of the mandible outer oblique line. The density of cellular elements was found to be highest at the iliac crest. The lowest density level was registered in biopsies from the area of the mandible outer oblique line. The high rates of cellular elements in autografts from the iliac crest area can be accounted for by the predominance of spongy substance over cortical, while in bone biopsies taken from the mandible outer oblique line, chin symphysis, maxillary tuberosity and parietal bone, the share of cellular elements failed to exceed 27% within the total data set. This points at the predominance of cortical rather than spongy substance. In reconstructive bone plastic surgery for augmentation of the maxillary alveolar process and the mandible alveolar part with significant atrophy, it is reasonable to use autogenous transplants taken from intraoral donor zones. The autogenous transplants have cortical morphology and embryological origin similar to the jaw bones. Bone blocks from the donor zones of the mandible outer oblique line, the chin symphysis and the maxillary tuberosity have the highest density of the bone cortical substance and the duly sufficient amount of spongy substance.

Socket Shield Technique and Immediate Implant Placement – A Systematic Review

&lt;p&gt;Purpose: A novel method, socket shield technique (SST), preserving the peri-implant tissue dimensions by retaining the buccal aspect of root was published by Hurzeler et al in 2010. Our study aims to compare the clinical and radiographic outcomes between conventional immediate implantation and socket shield technique (SST) based on prospective clinical trials. Also, we will discuss the different protocols and modifications of the socket shield technique. Material and methods: A PubMed, Cochrane Library, Embase database search was conducted to identify relevant publication up to March 2022. Result: 7 articles were included in our systemic review. The follow-up periods of the included literature ranged from 6 months to 4 years and contained 106 cases of socket shield technique (Test group) and 112 cases of conventional immediate implantation technique (Control group). None of the implants failed to have osseointegration. The horizontal bone loss at the crestal area in test group and control group ranged from 0.12~0.29mm and 0.29~1.45mm half a year post-operatively on CBCT, respectively. On the other hand, the vertical bone loss in test group and control group ranged from 0.28~0.36mm and 0.77~1.71mm half a year after operation on CBCT. All the results showed the socket shield techniques had less tissue alterations compared to the conventional immediate implantation with statistical significance. The overall Pink Esthetic Score (PES) of the test group (Socket shield technique) in the included studies ranged from 12.0 to 13.25 postoperatively, comparing to those ranging from 8.85 to 12.60 for the control group. Conclusion: All the included clinical trials showed promising results of socket shield technique in respect of less bone and soft tissue volume changes than the conventional immediate implantation. However, it is still unclear whether the socket shield technique will provide a stable long-term outcome in this stage.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Study Details Strategy of Bottom-Up Water injection in a Heavy Oil Reservoir

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 203783, “Challenges, Opportunities, and Threats of Deep Bottom-Up Water Injection in a Heavy Oil Reservoir: Lessons Learned From the G Field, South Oman,” by Chaitanya Behera, SPE, Sandip Mahajan, and Carlos Annia, Petroleum Development Oman, et al. The paper has not been peer reviewed. _ The complete paper presents the results of a comprehensive study aimed at improving the understanding of deep bottom-up water injection, which enabled optimizing recovery in a heavy oil field in south Oman. The work concludes that the well-reservoir-management (WRM) strategy for a heavy oil field is not the same as one for a classic light oil waterflood. Nevertheless, the reservoir heterogeneity, oil-column thickness, and saturation history also are important factors for variable water-injection response in a heavy oil field. Field Background The G field is on the eastern flank of the South Oman Salt Basin 700 km south of Muscat. The main producing reservoir, the Mahwis sand of the Haima group, culminates in two accumulations (G Main and G East). The Mahwis formation is composed of clastic sediments interlayered with several cemented zones, which often act as baffles in some areas (Fig. 1). However, all stratigraphic units are hydrodynamically connected. No major pressure shift along repeat-formation-tester (RFT) pressure profiles was observed, except at few locations across a major baffle in an oil leg in the crestal area. The reservoir quality is good, with porosity averaging 28% and permeability in the range of 200–2000 md. The maximum oil column thickness is approximately 70 m. Oil viscosity ranges from 250 to 1500 cp across the field both laterally and vertically. The viscosity in the northeast crestal area is relatively low compared with the thee southeastern part of the field. The compositional grading, multiple charging, and biodegradation of oil close to the oil/water contact (OWC) contribute to such a widespread variance in oil viscosity across the G field. The field, initially delineated by five vertical wells in 1990–91, was developed in multiple phases by horizontal producers placed at the top of the reservoir. The field produced under primary depletion until deep bottom-up water injection began in 2015. Water-Injection Development A secondary recovery scheme with infill wells and bottom-up water injection was proposed in 2009 as reservoir pressure dropped by 40%. The water-injection development consisted of injecting untreated produced water at a depth of 100 m below the original OWC under fracture conditions through 35 vertical water injectors. One hundred and thirty-three infill horizontal producers (86 single laterals and 47 dual laterals) were proposed to drill at a denser spacing. The infill campaign began in 2010, while water injection was initiated in December of 2014. The plan was to ramp up the water-injection rate to 70 000 m3/d in 3 years and double the field liquid production. After 3 years of water injection, however, only 33% of the predicted incremental rate was achieved. Approximately 40% of the incremental reserves of the redevelopment scheme was estimated to be at risk.

Analysis of morphometric changes in the anterior alveolar bone in bimaxillary protrusion adult patients after retraction with cone-beam CT

Objective: To measure and analyze the morphometric changes in the anterior alveolar bone during treatment and retention stage after retraction in bimaxillary adults using cone-beam CT(CBCT). Methods: Fifteen adult patients, four males and 11 females, aged 19 to 28 years[(22.2±3.1) years], who have completed orthodontic treatment and extracted four first premolar teeth for retraction in the Department of Orthodontics, The Affiliated Stomatological Hospital of Nanchang University from January 2016 to December 2018 were selected. CBCT was taken to assess the labial and palatal vertical bone level, total bone thickness at crest area, middle root area and apical area in pre-treatment (T1), post-treatment (T2) and at follow-up (maintained for more than two years) (T3). The differences in alveolar bone morphology at different stages were compared by single factor repeated measure ANOVA, and Pearson correlation analysis was performed on the amount of alveolar bone change in treatment stage and retention stage. Results: There were statistically significant differences in the alveolar bone height of the palatal side of maxillary anterior teeth, the labial side of maxillary lateral incisors and canine among three time points (P<0.05). The height difference of palatal alveolar bone of anterior teeth in T1-T2 stage was statistically significant (P<0.05). Palatal alveolar bone of upper and lower central incisors decreased by (1.52±0.32) and (4.96±0.46) mm, respectively. The height difference of anterior palatal alveolar bone was statistically significant in T2-T3 stage(P<0.05), the palatal alveolar bone height of central incisors increased by (1.20±0.27) and (3.14±0.35) mm respectively. The height difference of palatal alveolar bone in the anterior teeth of T1-T3 stage was statistically significant (P<0.05), and the height of palatal alveolar bone of central incisors was decreased (0.33±0.11) and (1.82±0.39) mm, respectively. There were statistically significant differences in the thickness of the cervical and middle root alveolar bone of anterior teeth among three time points (P<0.05). The difference of alveolar bone thickness of the cervical and middle root of anterior teeth at T1-T2 was statistically significant (P<0.05). decreased by (0.63±0.10) and (0.67±0.09) mm in lateral incisors, respectively. In the T2-T3 stage, the alveolar bone thickness of the crest area of the lower anterior teeth was significantly different (P<0.05), the alveolar bone thickness of mandibular central incisor crest area increased (0.09±0.03) mm. There were statistically significant differences in alveolar bone thickness in crest area and middle root of the incisors during T1-T3 stage (P<0.05), among which the middle root decreased by (0.38±0.16) mm and (0.63±0.13) mm, respectively. There was no statistically significant difference in other areas (P>0.05). The change of alveolar bone height in palatal side of upper anterior teeth at T2-T3 was very strongly negatively correlated with the change in T1-T2. The change of alveolar bone height in labial side of upper anterior teeth and lingual side of lower anterior teeth and the thickness of incisor root and neck were moderately strongly negatively correlated (r≤-0.8, P<0.001), the change of alveolar bone height in labial side of upper anterior teeth and lingual side of lower anterior teeth and the thickness of incisor crest area were moderately strongly negatively correlated (-0.8<r≤-0.4, P<0.05). Conclusions: For adult patients after retraction, anterior alveolar bone decreased significantly. In the retention stage, the same degree of bone apposition will occur, but still have alveolar bone loss compared with pre-treatment. The amount of alveolar bone change in the retention stage correlated with the amount of alveolar bone change in the treatment stage.