Biomedical subjects

S Jivraj

Publications and source records attributed to S Jivraj.

17 recordsLinked to original sources

PubMed2007

An interdisciplinary approach to treatment planning in implant dentistry.

The practice of implant dentistry requires an interdisciplinary approach that integrates the knowledge, skills and experience of all the disciplines of dentistry into a comprehensive treatment plan. This article outlines a comprehensive interdisciplinary treatment philosophy designed for developing the foundation of optimal aesthetics in implant dentistry. Cases are presented to illustrate the utility of interdisciplinary treatment in which specialists are recruited to enhance and improve a patient's dental function and aesthetics.

Adult↗

PubMed2006

The role of orthodontics in implant dentistry.

Orthodontic treatment of partially edentulous patients is difficult, especially if a significant number of teeth are missing. With loss of teeth, adjacent or opposing teeth usually tip, drift or over-erupt leaving spaces that are not optimal for replacement of missing teeth. Orthodontic correction of these spatial relationships will aid prosthetic replacement of the missing teeth, function, hygiene and aesthetics. Orthodontists rely on teeth to provide the anchorage to correct malocclusions. With patients with an intact dentition dental anchorage is usually adequate to facilitate tooth movement. In some partially edentulous patients however, insufficient anchorage may present to correct the malocclusion. In these patients implants can provide additional anchorage. At times, osseointegrated implants can also be used to support restorations after completion of orthodontic therapy if treatment planning is precise. The use of implants for orthodontic anchorage requires an interdisciplinary approach and precise planning to achieve optimal results.

Alveolar Bone Loss↗

PubMed2006

Transitioning patients from teeth to implants.

One major obstacle to treatment with implants is the transitional phase between a tooth supported occlusion and an implant supported occlusion. This is of particular concern when a patient with a failing dentition has not worn a removable prosthesis before and is planning to have a reconstruction supported by implants.

Dental Abutments↗

PubMed2006

Connecting implants to teeth.

Osseointegrated implants have proven to have a high degree of success in the edentulous arches. This success has been replicated in partially edentulous arches. When natural teeth are present, it can be tempting to fabricate restorations using support from both implants and natural teeth. The mechanism of attachment and the perceived problem of the differential support provided by the implant and the tooth have been discussed by many authors.

Dental Implantation, Endosseous↗

PubMed2006

Designing abutments for cement retained implant supported restorations.

In another article in this series the authors' preference for screw retained implant supported restorations was presented together with a literature review and rationale.(1) There remain situations when screw retention is not possible due to implant position, implant trajectory, aesthetics or function.

Animals↗

PubMed2006

Screw versus cemented implant supported restorations.

Implant supported restorations can be attached to implants with screws or can be cemented to abutments which are secured to implants with screws. Screw retained implant restorations are the authors' preferred method of securing restorations to implants. This article will be written from this perspective and the advantages and disadvantages of each method of retention will be discussed under the following headings: Aesthetics, Retrievability, Retention, Implant placement, Passivity, Provisionals, Occlusion, Immediate loading, Impression procedures, Long term treatment planning.

Cementation↗

PubMed2006

Impression techniques for implant dentistry.

The object of making an impression in implant dentistry is to accurately relate an analogue of the implant or implant abutment to the other structures in the dental arch. This is affected by use of an impression coping which is attached to the implant or implant abutment. This impression coping is incorporated in an impression - much as a metal framework is 'picked up' in a remount impression for fixed prosthodontics. With implant copings the coping is usually attached to the implant or abutment with screws. The impression material used is usually an elastomeric impression material; the two types most widely used and shown to be the most appropriate are polyether and polyvinyl siloxane impression materials.

Dental Abutments↗

PubMed2006

Treatment planning of the edentulous mandible.

Edentulism can be a debilitating handicap. Zarb described endentulous individuals who could not function as 'denture cripples'.(1) Most difficulty with complete denture prostheses arises from the inability to function with the mandibular prostheses. Factors that adversely affect successful use of a complete denture on the mandible include: 1) the mobility of the floor of the mouth, 2) thin mucosa lining the alveolar ridge, 3) reduced support area and 4) the motion of the mandible (Figs 1,2). These factors alone can explain the difficulty of wearing a denture on the mandibular arch compared to the maxillary arch. The maxilla exhibits much less mobility on the borders of the denture than the mandible, moreover having a stable palate with thick fibrous tissues available to support the prostheses and resist occlusal forces. These differences explain most of the reasons why patients experience difficulty with using a complete denture on the mandibular arch compared to the maxillary arch.

Dental Prosthesis, Implant-Supported↗

PubMed2006

Treatment planning of the edentulous maxilla.

The predictability of successful osseointegrated implant rehabilitation of the edentulous jaw as described by Branemark et al., introduced a new era of management for the edentulous predicament. Implant rehabilitation of the edentulous maxilla remains one of the most complex restorative challenges because of the number of variables that affect both the aesthetic and functional aspect of the prosthesis. Among the prosthesis designs used to treat the edentulous maxilla are fixed or removable implant-supported restorations. Since the aesthetic requirements and preoperative situation of each patient varies, considerable time must be spent on accurate diagnosis to ensure patient desires are satisfied and predictable outcomes are achieved. The purpose of this article is to compare the treatment options and prosthesis designs for the edentulous maxilla. Emphasis will be placed on diagnosis and treatment planning. Criteria will be given to guide the practitioner in deciding whether a fixed or removable restoration should be placed. This objective will be accomplished through the review of cases with regard to varying design considerations and factors that influence the decision-making process.

Aged↗

PubMed2006

Treatment planning of implants in the aesthetic zone.

Aesthetic restoration of anterior teeth with implant supported restorations is one of the most difficult procedures to execute. Bone resorption following anterior tooth extraction often compromises gingival tissue levels for the implant restoration. In the last 10 years the focus has shifted from osseointegration, to creation of an implant borne restoration which is in harmony with the surrounding hard and soft tissue. Complete reconstruction of tooth and gingival related aesthetics remains the primary objective and in some instances can be very difficult to achieve.

Alveolar Ridge Augmentation↗

PubMed2006

Treatment planning of implants in posterior quadrants.

Differences in anatomy and biomechanics make treatment of posterior quadrants with dental implants substantially different to that of anterior areas. Without implants, when posterior teeth were lost, treatment options included a long span fixed partial denture or a removable prosthesis, especially when no terminal abutment was available. Today, with the use of implants, options are available that allow preservation of unrestored teeth.(1) When teeth are missing, implant supported restorations can be considered the treatment of choice from the perspective of occlusal support, preservation of adjacent teeth and avoidance of a removable partial denture.

Bicuspid↗

PubMed2006

Rationale for dental implants.

The clinical replacement of lost natural teeth by osseointegrated implants has represented one of the most significant advances in restorative dentistry. Two decades ago, a majority of dentists were sceptical about implants and rejected them entirely. Today it is rare to find a practitioner who does not work with dental implants or who is not actively participating in one of the many seminars or courses offered by universities, professional societies and implant manufacturers.

Alveolar Bone Loss↗

PubMed2006

Genetic thrombophilic mutations among couples with recurrent miscarriage.

BACKGROUND: Some cases of recurrent first trimester miscarriage (RM)-the loss of three or more consecutive pregnancies at <12 weeks' gestation-have a thrombotic aetiology. METHODS: We determined (i) the prevalence of three thrombophilic mutations [factor V Leiden (FVL), prothrombin G20210A (PTG) and methylenetetrahydrofolate reductase (MTHFR) C677T] amongst 357 Caucasian couples with RM and 68 parous Caucasian couples with no history of miscarriage and (ii) the prospective outcome of untreated pregnancies amongst couples with RM in which either partner carried a thrombophilic mutation. RESULTS: The allele frequencies of FVL (2%), PTG (2%) and MTHFR C677T (31%) were similar between cases and controls. The prevalence of multiple thrombophilic mutations (greater than one mutation) was also similar between cases and controls. Amongst couples in whom either partner carried greater than one thrombophilic allele, the relative risk of miscarriage in a future untreated pregnancy was 1.9 (95% confidence interval, 1.3-2.8) compared with those couples who carried no thrombophilic mutation. CONCLUSION: The prevalence of thrombophilic mutations is similar in couples with RM and parous controls. In couples with RM, multiple genetic thrombophilic mutations in either partner significantly increases the risk of miscarriage in a subsequent pregnancy.

Abortion, Habitual↗

PubMed2003

Thromboelastography, whole-blood haemostasis and recurrent miscarriage.

BACKGROUND: Some cases of recurrent miscarriage have a thrombotic basis. Thromboelastography is a rapid, reproducible test of whole-blood haemostasis. METHODS: Thromboelastography was performed in 494 consecutive, non-pregnant women (median age 35 years; range 21-48) with a history of miscarriages at <12 weeks gestation (median 4; range 3-12) and 55 parous women (median age 33 years; range 20-41) with no history of pregnancy loss. The prospective outcome of untreated pregnancies amongst 108 women with recurrent miscarriage was studied. RESULTS: The maximum clot amplitude (MA) (median 66.0 mm; range 48.0-76.0) was significantly higher and the rate of clot lysis (LY30) (median 2.5%; range 0.5-7.8) significantly lower amongst women with recurrent miscarriage compared with controls (MA 61.5 mm; range 50.0-67.0; P = 0.01; LY30 4.9%; range 2.9-9.7; P = 0.01). The pre-pregnancy MA was significantly higher amongst women who subsequently miscarried (median 66.0 mm; range 54.0-73.0) compared with those whose had a live birth (median 61.7 mm; 48.0-71.5; P < 0.01). A pre-pregnancy MA >or=64 mm has a sensitivity of 68% and specificity of 82% to predict miscarriage. CONCLUSIONS: Thromboelastography identifies a subgroup of women with recurrent miscarriage to be in a prothrombotic state outside of pregnancy. Women in such a state are at increased risk of miscarriage in future untreated pregnancies.

Abortion, Habitual↗

PubMed2002

Circulating levels of inhibin A, activin A and follistatin in missed and recurrent miscarriages.

BACKGROUND: The aim of this study was to investigate the changes in circulating levels and the clinical use of inhibin A, activin A and follistatin as endocrine markers of early pregnancy loss. METHODS: Blood samples were collected from women presenting with a sporadic missed miscarriage (n = 10), and controls having pregnancy termination at 8-12 weeks (n = 15) and from women with a history of unexplained recurrent miscarriages (n = 12) at 6-12 weeks gestation. All samples were assayed for inhibin A, inhibin B, activin A, follistatin, hCG, estradiol and progesterone. RESULTS: Serum inhibin A, hCG, estradiol and progesterone levels were significantly ( approximately 2-3 fold) decreased in sporadic miscarriages compared with controls. In the recurrent miscarriage group, time dependent changes in plasma inhibin A and hCG levels were significantly (P < 0.05) altered in the group that had a subsequent miscarriage compared with those who had a live birth. At 6-7 weeks gestation, plasma inhibin A ( approximately 4 fold, P < 0.01), hCG ( approximately 4 fold, P < 0.01) and estradiol ( approximately 2 fold, P < 0.001) levels were significantly lower in women who went on to have another miscarriage than those with a live birth. Inhibin B levels were near the detection limit of the assay. CONCLUSIONS: Our findings suggest that inhibin A is a specific marker of early pregnancy loss before the onset of the clinical symptoms of recurrent miscarriage. There is a high degree of association between levels of inhibin A and hCG in cases of miscarriage, indicating that these two proteins could be used in combination to predict future pregnancy outcome.

Abortion, Habitual↗

PubMed2001

Obstetric and neonatal outcome in women with a history of recurrent miscarriage: a cohort study.

Obstetric and neonatal outcomes of women who had a history of recurrent miscarriage were compared with a control population from 1 January 1992 to 30 June 1998. Amongst a total of 162 pregnancies which progressed beyond 24 weeks gestation in women with a history of recurrent miscarriage, there were four perinatal deaths and 16 babies were admitted to the special care baby unit. The rates of preterm delivery (13%), small-for-gestational-age (13%), perinatal loss (2.5%) and Caesarean section (36%) were significantly (P < 0.05) higher than those of the control group (3.9, 2.1, 1 and 16.7% respectively). The ratio of male to female babies was equal. There was no significant difference in the incidence of hypertension or diabetes between the two groups. Patients with recurrent miscarriage represent a population at high risk of obstetric problems and close surveillance in the antenatal period is therefore required.

Abortion, Habitual↗

PubMed1998

Insulin regulation of glucose-6-phosphate dehydrogenase gene expression is rapamycin-sensitive and requires phosphatidylinositol 3-kinase.

Glucose-6-phosphate dehydrogenase (G6PDH) controls the flow of carbon through the pentose phosphate pathway and also produces NADPH needed for maintenance of reduced glutathione and reductive biosynthesis. Hepatic expression of G6PDH is known to respond to several dietary and hormonal factors, but the mechanism behind regulation of this expression has not been characterized. We show that insulin similarly induces expression of endogenous hepatic G6PDH and a reporter construct containing 935 base pairs of the G6PDH promoter linked to luciferase in transient transfection assays. Using well tested and structurally distinct inhibitors of Ras farnesylation, lovastatin and B581, and a specific inhibitor of mitogen-activated protein kinase kinase activation, PD 98059, we show that the Ras/Raf/mitogen-activated protein kinase pathway is not utilized for the insulin-induced stimulation of G6PDH gene expression in primary rat hepatocytes. Similarly, using well characterized inhibitors of phosphatidylinositol 3-kinase, wortmannin and LY 294002, we show that PI 3-kinase activity is necessary for the induction of G6PDH expression by insulin. Rapamycin, an inhibitor of FRAP protein, which is involved in the activation of pp70 S6 kinase, blocks the insulin induction of G6PDH, suggesting that S6 kinase is also necessary for the insulin induction of G6PDH expression.

Androstadienes↗