Last millennium hurricane activity linked to endogenous climate variability.

Despite increased Atlantic hurricane risk, projected trends in hurricane frequency in the warming climate are still highly uncertain, mainly due to short instrumental record that limits our understanding of hurricane activity and its relationship to climate. Here we extend the record to the last millennium using two independent estimates: a reconstruction from sedimentary paleohurricane records and a statistical model of hurricane activity using sea surface temperatures (SSTs). We find statistically significant agreement between the two estimates and the late 20th century hurricane frequency is within the range seen over the past millennium. Numerical simulations using a hurricane-permitting climate model suggest that hurricane activity was likely driven by endogenous climate variability and linked to anomalous SSTs of warm Atlantic and cold Pacific. Volcanic eruptions can induce peaks in hurricane activity, but such peaks would likely be too weak to be detected in the proxy record due to large endogenous variability.

Northeast Yucatan hurricane activity during the Maya Classic and Postclassic periods.

The collapse of the Maya civilization in the late 1st/early 2nd millennium CE has been attributed to multiple internal and external causes including overpopulation, increased warfare, and environmental deterioration. Yet the role hurricanes may have played in the fracturing of Maya socio-political networks, site abandonment, and cultural reconfiguration remains unexplored. Here we present a 2200 yearlong hurricane record developed from sediment recovered from a flooded cenote on the northeastern Yucatan peninsula. The sediment archive contains fine grain autogenic carbonate interspersed with anomalous deposits of coarse carbonate material that we interpret as evidence of local hurricane activity. This interpretation is supported by the correlation between the multi-decadal distribution of recent coarse beds and the temporal distribution of modern regional landfalling storms. In total, this record allows us to reconstruct the variable hurricane conditions impacting the northern lowland Maya during the Late Preclassic, Classic, and Postclassic Periods. Strikingly, persistent above-average hurricane frequency between ~ 700 and 1450 CE encompasses the Maya Terminal Classic Phase, the declines of Chichén Itza, Cobá, and subsequent rise and fall of the Mayapán Confederacy. This suggests that hurricanes may have posed an additional environmental stressor necessary of consideration when examining the Postclassic transformation of northern Maya polities.

Revising evidence of hurricane strikes on Abaco Island (The Bahamas) over the last 700 years.

The northern Bahamas have experienced more frequent intense-hurricane impacts than almost anywhere else in the Atlantic since 1850 CE. In 2019, category 5 (Saffir-Simpson scale) Hurricane Dorian demonstrated the destructive potential of these natural hazards. Problematically, determining whether high hurricane activity levels remained constant through time is difficult given the short observational record (< 170 years). We present a 700-year long, near-annually resolved stratigraphic record of hurricane passage near Thatchpoint Blue Hole (TPBH) on Abaco Island, The Bahamas. Using longer sediment cores (888 cm) and more reliable age-control, this study revises and temporally expands a previous study from TPBH that underestimated the sedimentation rate. TPBH records at least 13 ≥ category 2 hurricanes per century between 1500 to 1670 CE, which exceeds the 9 ≥ category 2 hurricanes per century within 50 km of TPBH since 1850 CE. The eastern United States also experienced frequent hurricanes from 1500 to 1670 CE, but frequency was depressed elsewhere in the Atlantic Ocean. This suggests that spatial heterogeneity in Atlantic hurricane activity since 1850 CE could have persisted throughout the last millennium. This heterogeneity is impacted by climatic and stochastic forcing, but additional high-resolution paleo-hurricane reconstructions are required to assess the mechanisms that impact regional variability.

Climatic control of Mississippi River flood hazard amplified by river engineering.

Over the past century, many of the world's major rivers have been modified for the purposes of flood mitigation, power generation and commercial navigation. Engineering modifications to the Mississippi River system have altered the river's sediment levels and channel morphology, but the influence of these modifications on flood hazard is debated. Detecting and attributing changes in river discharge is challenging because instrumental streamflow records are often too short to evaluate the range of natural hydrological variability before the establishment of flood mitigation infrastructure. Here we show that multi-decadal trends of flood hazard on the lower Mississippi River are strongly modulated by dynamical modes of climate variability, particularly the El Niño-Southern Oscillation and the Atlantic Multidecadal Oscillation, but that the artificial channelization (confinement to a straightened channel) has greatly amplified flood magnitudes over the past century. Our results, based on a multi-proxy reconstruction of flood frequency and magnitude spanning the past 500 years, reveal that the magnitude of the 100-year flood (a flood with a 1 per cent chance of being exceeded in any year) has increased by 20 per cent over those five centuries, with about 75 per cent of this increase attributed to river engineering. We conclude that the interaction of human alterations to the Mississippi River system with dynamical modes of climate variability has elevated the current flood hazard to levels that are unprecedented within the past five centuries.

Terminal Posterior Tilted Implants Planned as a Sinus Graft Alternative for Fixed Full-Arch Implant-Supported Maxillary Restoration: A Case Series with 10- to 19-Year Results on 44 Consecutive Patients Presenting for Routine Maintenance.

PURPOSE: Posterior maxillary tilted implants are gaining prevalence as an alternative to sinus grafts supporting fixed maxillary restorations. This paper reports long-term results after loading using this technique. MATERIALS AND METHODS: Consecutive patients presenting for either routine hygiene maintenance or unplanned emergency care who had received tilted implants as a sinus graft alternative to support fixed fully implant-supported restoration of an edentulous maxilla and were followed for a minimum of 10 years from initial implant placement were included in this evaluation. RESULTS: Forty-four patients were identified: 40 with bilateral tilted implants and 4 with one tilted and one axial posterior implant. Eight patients received one-piece fixed porcelain-to-gold screw-retained restorations, and thirty-six patients received a fully implant-supported patient-removable Marius Bridge. Seventy-nine out of 84 originally loaded posterior tilted implants survived a minimum of 10 years loading; one tilted implant was lost at 10 years. Eight additional posterior implants were placed for either these lost tilted posterior implants or as proactive supplemental support; one of these replacement tilted implants survived for at least 10 years and is included in the data. All patients have maintained continuous fixed function throughout the follow-up period. Forty-one out of 44 patients continue with the original restoration, 33 without modification or removal of the fixed restoration or implant-connecting bar. One porcelain-to-gold and seven Marius Bridges had framework modifications to accommodate additional implants; 3 Marius Bridge restorations were replaced with a newer generation. CONCLUSION: Within the limits of this retrospective study, the results show that continuous fixed function of fully implant-supported maxillary restorations using posterior tilted implants in terminal positions of support as a sinus graft alternative combined with axial anterior implants is possible over a prolonged period. Loss of a posterior tilted implant after loading is treatable with another tilted, zygomatic or axial implant, typically requiring only modification of the fixed restoration.

How unique was Hurricane Sandy? Sedimentary reconstructions of extreme flooding from New York Harbor.

The magnitude of flooding in New York City by Hurricane Sandy is commonly believed to be extremely rare, with estimated return periods near or greater than 1000 years. However, the brevity of tide gauge records result in significant uncertainties when estimating the uniqueness of such an event. Here we compare resultant deposition by Hurricane Sandy to earlier storm-induced flood layers in order to extend records of flooding to the city beyond the instrumental dataset. Inversely modeled storm conditions from grain size trends show that a more compact yet more intense hurricane in 1821 CE probably resulted in a similar storm tide and a significantly larger storm surge. Our results indicate the occurrence of additional flood events like Hurricane Sandy in recent centuries, and highlight the inadequacies of the instrumental record in estimating current flood risk by such extreme events.

Lifelong craniofacial growth and the implications for osseointegrated implants.

PURPOSE: The sequence of observations presented is intended to alert the dental profession to complications that may occur when teeth and implants co-exist and subtle adult craniofacial growth occurs. MATERIALS AND METHODS: The authors' observations of partially edentulous implant restorations with more than 20 years of follow-up included some observed changes relative to patients' remaining teeth and jaw structures. These changes, which were not easily explained and appeared to be random deviations from expected implant-restorative stability, conformed with research findings of craniofacial growth continuing into adulthood. The authors identified several distinct areas in which such adult craniofacial growth could potentially influence the relationship of implant restorations to the remaining teeth and jaw structure. RESULTS: Potential esthetic, occlusal, and periodontal ramifications of continued adult craniofacial growth were found to include changes in occlusion, opened contact as a result of teeth migration, and changes in anterior esthetic results. The latter may include labialization of the anterior implant restoration and a progressive discrepancy of the cervical gingival margin of the implant restoration relative to the adjacent teeth. Cases are presented showing poor sequellae of treatment due to growth occurring after the assumption was made that a stable jaw dimension had been reached. While continued adult craniofacial growth sufficient to cause clinical problems is not common, it is also presently not predictable. CONCLUSION: When changes in tooth position relative to implant restorations secondary to long-term adult growth occur, they can cause problems that are difficult or even impossible to correct. Future research will ideally enable identification of patients at risk for developing such problems.

Colocação de implantes Mk IV em áreas ósseas comprometidas e com enxerto: resultados radiográficos em 61 sítios de 27 pacientes com acompanhamento longitudinal entre três e sete anos / Placement of brånemark mk IV implants in compromised and grafted bone: radiographic outcome of 61 sites in 27 patients with 3- to 7-year follow-ups

Objetivo: sítios onde osso é reduzido em altura ou qualidade criam desafios na reconstrução estética e no suporte para carregamento, gerando maior risco de falha. O sistema Mk IV com superfície TiUnite foi especialmente desenhado para colocação em osso macio. Este artigo descreve os resultados pós-carregamento de 103 implantes Mk IV, com ênfase na preservação óssea em sítios ósseos comprometidos durante remodelamento precoce, estabilidade e conexão do pilar, após três e sete anos de colocação dos implantes. Material e Métodos: uma série de 103 implantes Mk IV (4 mm de diâmetro, 10 mm de comprimento) foi colocada na maxila de 25 mulheres e 14 homens; 23 pacientes também receberam enxertos ósseos em etapas e dois passaram pelo aumento do alvéolo e enxertos. Áreas com infecções prévias foram preparadas mecanicamente e quimicamente. Para garantir estabilidade inicial primária, o tamanho da osteotomia e o número de entradas foi minimizado. Após um protocolo de carregamento tardio, todos os pacientes receberam próteses parciais fixas. Para análise da estabilidade óssea, os níveis ósseos marginais nos aspectos mesiais e distais foram mensurados com sete vezes de aumento por um radiologista envolvido no tratamento. Resultados: três implantes foram perdidos, um implante nunca foi carregado embora tivesse osseointegrado, 14 implantes não estavam disponíveis para acompanhamento após a conexão do pilar e cinco possuíam qualidade radiográfica inadequada. A perda óssea marginal entre a inserção do implante e o carregamento foi 1,21 ± 0,86 mm (n = 80). As diferenças nos níveis de remodelamento ósseo em sítios enxertados e não enxertados não foi significativa. Os dados foram relatados em 103 implantes em 39 pacientes consecutivos até a conexão do pilar, com acompanhamento radiográfico entre três e sete anos pós-colocação para 27 pacientes...

Planned labial plate advancement with simultaneous single implant placement for narrow anterior ridges followed by reentry confirmation.

This article reports on the efficacy of a technique involving expansion of edentulous ridges of less than 3 mm in width by means of a planned green stick fracture of the labial plate and simultaneous implant placement without the need for membranes. This retrospective case series includes long-term results from 21 patients with 36 sites and 37 implants with a mean follow-up of 4 years, 5 months from the date of restoration. Freeze-dried bone allograft was used in 22 sites (61%) to augment the ridge. Reentry at stage-two surgery confirmed the preservation of the displaced labial plate after implant integration. Three implants were removed prior to the planned uncovering because of incomplete healing of the overlying gingival tissue; therefore, the survival rate of the labial advancement was 92%. No implants failed after definitive prosthetic loading; therefore, the cumulative survival rate of loaded implants was 100%. No significant bone loss was detected at the final follow-up visit. Follow-up after loading ranged from 9 to 148 months. Advancement of the labial plate with simultaneous implant placement to gain horizontal ridge width dimension was shown to be a reliable and practical procedure for single-tooth sites where other grafting methods are often difficult.

Placement of Brånemark Mk IV implants in compromised and grafted bone: radiographic outcome of 61 sites in 27 patients with 3- to 7-year follow-ups.

OBJECTIVE: Sites in which bone is reduced in quality or height create challenges in esthetic reconstruction and loading support, which leads to a higher risk of failure. The Mk IV system with a TiUnite surface was designed specifically for placement in soft bone. This paper describes postloading outcomes of 103 Mk IV implants, with a focus on bone preservation in compromised bone sites during early remodeling, stability after abutment connection, and a 3- to 7-year follow-up from implant placement. METHOD AND MATERIALS: A series of 103 4-mm (diameter), ≤ 10-mm (length) Mk IV implants were placed in the maxillae of 25 females and 14 males. Twenty-three patients also received staged bone grafts, and two underwent socket augmentation as well as grafts. Areas of previous infection were prepared mechanically and chemically. To ensure primary implant stability, the size of the osteotomy and the number of entries were minimized. Following a delayed loading protocol, all patients were restored with fixed partial dentures. For analysis of bone stability, the marginal levels on the mesial and distal aspects of the implants were measured at 7x magnification by a radiologist not involved in the treatment. RESULTS: Three implants were lost, 1 implant was never loaded although it integrated, 14 implants were not available for follow-up after abutment correction, and 5 had poor-quality radiographs. The mean marginal bone loss between implant insertion and loading was 1.21 ± 0.86 mm (n = 80). The differences in bone-remodeling levels in grafted and nongrafted sites were not significant. Data are reported on 103 implants in 39 consecutive patients through abutment connection, with radiographic follow-up from 3 to 7 years postimplant placement on 27 patients. CONCLUSION: It is critical to ensure optimal three-dimensional orientation and minimize site preparation, particularly when placing implants in compromised bone. With bone of poor preoperative density using a customized site preparation technique, excellent short-term implant survival and long-term bone stability have been demonstrated. Further follow-up will determine whether the Mk IV implant is the optimal design for compromised bone, including associated soft tissue stability.

Parameters for successful implant integration revisited part I: immediate loading considered in light of the original prerequisites for osseointegration.

PURPOSE: With the increasing popularity and publication of loading implants at the time of placement, including at time of dental extraction and simultaneous with reconstructive procedures, the objective was to evaluate known variables identified for a traditional unloaded healing period and determine the applicability of these variables to immediate loading. MATERIALS: A total of 124 published reports available as of January 2008 that contained information about loading from the time of surgery up to 3 months postsurgically were examined in light of published variables affecting osseointegration based on a 2 stage surgical approach. METHODS: The articles were examined to differentiate between immediate loading (within the initial 48 hours) and early/delayed loading of implants. Success or survival criteria were noted, and where reasons for failure were available, categorized according to six variables considered as determinants for maintaining a long-term bone-to-implant contact. RESULTS: Approximately 60 of the 124 reports described immediately loading implants within 48 with single-tooth, partial, and full-arch restorations, as well as implant overdentures. The implant success or survival rates ranged from 70.8% to 100%. Most studies considered implant survival to be the only criterion for success. CONCLUSIONS: Of six parameters identified in 1981 as influencing osseointegration, two parameters (the status of the bone/implant site and implant loading conditions) appear to have diagnostic implications, whereas three (implant design, surgical technique, and implant finish) may affect immediate loading positively or adversely.

Parameters for successful implant integration revisited part II: algorithm for immediate loading diagnostic factors.

Immediate loading of dental implants has become a widely reported practice with success rates ranging from 70.8% to 100%. Although most studies have considered implant survival to be the only measure of success, a better definition includes the long-term stability of the hard and soft tissues around the implant(s) and other adjacent structures, as well as the long-term stability of all the restorative components. The parameters identified in 1981 by Albrektsson and colleagues as influencing the establishment and maintenance of osseointegration have been reconsidered in relation to immediate loading to improve the chances of achieving such success. Two of the six parameters (status of the bone/implant site and implant loading conditions) have preoperative diagnostic implications, whereas three (implant design, surgical technique, and implant finish) may compensate for less-than-ideal site and loading conditions. Factors affecting the outcome of immediate loading are reviewed to assist clinicians attempting to assess its risks and benefits.

Vertical ridge augmentation procedure using guided bone regeneration, demineralized freeze-dried bone allograft, and miniscrews: 4- to 13-year observations on loaded implants.

This retrospective case series presents results from eight patients treated with demineralized freeze-dried bone allograft particles and barrier membranes using either miniscrews or implants to support the membrane in seven patients. In all patients, the amount of vertical bone regeneration enabled placement of one or more implants in the graft sites, followed by loading with definitive prostheses at least 5.5 months after implant placement. Marginal bone heights around the implants have remained stable throughout 4 to 13 years of follow-up.

Operative management of distal tibialis anterior tendinopathy.

BACKGROUND: The results of operative management for distal tibialis anterior tendinopathy (DTAT) without rupture have not previously been described in the literature. We present the results of 12 operative procedures. MATERIALS AND METHODS: Of 40 patients diagnosed clinically and radiographically with DTAT, we reviewed 11 patients who underwent surgery for failure of nonoperative management. Assessment included pre and postoperative AOFAS midfoot scores, clinical examination and postoperative VAS pain scoring, at a mean followup of 29 months. RESULTS: Ten women (ten feet) and one man (2 feet) underwent surgery. The mean age at surgery was 59 years. The mean duration of symptoms prior to surgery was 1 year. The mean preoperative AOFAS score was 52. Preoperative MRI showed tendinosis in two tendons and tendinosis with longitudinal split tears in ten tendons. Six of the twelve cases showed some associated degenerative changes of the midfoot. Six tendons were simply debrided and the insertion reinforced with a suture anchor. Six tendons were augmented with an extensor hallucis longus (EHL) transfer into the medial cuneiform. All patients improved postoperatively, with a mean improvement in AOFAS score of 33 and the mean postoperative pain VAS of 0.9 out of 10. Two patients underwent concomitant procedures on the same foot. Three of the six treated with EHL transfer have some symptomatic hallux interphalangeal joint extensor lag. In six cases the patient was completely satisfied. Three were satisfied with minor reservations. Of the three that were dissatisfied, two underwent subsequent surgery improving their symptoms. The third, though pain-free, was troubled by her toe-catching when walking barefoot. No patient regretted having had the surgery. CONCLUSION: Debridement and repair of DTAT, with EHL augmentation for greater than 50% tendon involvement, provided a high level of patient satisfaction after nonoperative management failed in this series.

The Marius implant bridge: surgical and prosthetic rehabilitation for the completely edentulous upper jaw with moderate to severe resorption: a 5-year retrospective clinical study.

BACKGROUND: Patients seeking replacement of their upper denture with an implant-supported restoration are most interested in a fixed restoration. Accompanying the loss of supporting alveolar structure due to resorption is the necessity for lip support, often provided by a denture flange. Attempts to provide a fixed restoration can result in compromises to oral hygiene based on designs with ridge laps. An alternative has been an overdenture prosthesis, which provides lip support but has extensions on to the palate and considerations of patient acceptance. The Marius bridge was developed as a fixed bridge alternative offering lip support that is removable by the patient for hygiene purposes, with no palatal extension beyond normal crown-alveolar contours. PURPOSE: Implant-supported restorative treatment of completely edentulous upper jaws, as an alternative to a complete denture, is frequently an elective preference, and it requires significant patient acceptance beyond the functional improvement of chewing. Patients with moderate to severe bone resorption and thin ridges present additional challenges for adequate bone volume and soft-tissue contours. The purpose of this investigation was to develop a surgical and prosthetic implant treatment protocol for completely edentulous maxillae in which optimal lip support and phonetics is achieved in combination with substantial implant anchorage without bone grafting. MATERIALS AND METHODS: The Marius bridge is a complete-arch, double-structure prosthesis for maxillae that is removable by the patient for oral hygiene. The first 45 consecutive patients treated by one person (YF) in one center with this concept are reported, with 245 implants followed for up to 5 years after prostheses connection. RESULTS: The cumulative fixture survival rate for this 5-year retrospective clinical study was 97%. Five fixtures failed before loading, in five different patients, and two fixtures in the same patient failed at the 3-year follow-up visit. None of the bridges failed, giving a prostheses survival rate of 100%. The complications were few and mainly prosthetic: nine incidences of attachment component complications, one mesobar fracture, and three reports of gingivitis. All complications were solved or repaired immediately, with minimal or no interruption of prostheses use. CONCLUSIONS: Satisfactory medium-term results of survival and patient satisfaction show that the Marius bridge can be recommended for implant dentistry. The technique may reduce the need for grafting, because it allows for longer implants to be placed with improved bone anchorage and prostheses support. key words: clinical follow-up, complete arch, double structure, esthetics, maxilla, phonetics, tilted implants