The erythrocytes of neonates show a considerable degree of macrocytosis if they are assessed in relation to those of adults cheap asacol 400mg with mastercard. A slight degree of macrocytosis is also seen as a physiological feature of pregnancy  and in older adults  buy discount asacol on-line. Associated with reticulocytosis Ethanol intake Haemolytic anaemia Liver disease Haemorrhage Phenytoin therapy Associated with megaloblastic erythropoiesis Some cases of copper defciency  Vitamin B defciency and inactivation of vitamin B by chronic Arsenic poisoning  12 12 exposure to nitric oxide? Any of the con ditions leading to microcytosis may also cause hypochro mia order asacol cheap online, although in some subjects with α or β thalassaemia trait the blood flm shows microcytosis without appreci able hypochromia and, in rare patients with copper defciency, hypochromia is associated with macrocytosis . Since the intensity of staining of the red cell is determined by the thickness of the cell as well as by the concentration of haemoglobin, hypochromia can also be noted in cells that are thinner than normal, whether or not they have a normal volume and haemoglobin con centration; such cells are designated ‘leptocytes’. It can be applied when cells are more intensely stained than normal, but it is more useful to indicate why a cell is hyperchromic. One population of cells is normocytic and the hyperchromia is related not only to a change in normochromic while the other is microcytic and hypochromic. In practice, it usually means that there mosaicism for β thalassaemia trait associated with a con is a spectrum of staining from hypochromic to normo stitutional chromosomal abnormality  and chimaer chromic. Anisochromasia commonly indicates a chang ism post‐stem cell transplantation when either the donor ing situation, such as iron defciency developing or or the host has microcytosis with a genetic basis. The term is most often a visible reticulum, it will be seen that there is likely to applied when there is one population of hypochromic, be a relationship between reticulocytes and polychro microcytic cells and another population of normochro matic cells. Both are immature red cells newly released mic cells, the latter being either normocytic or macro from the bone marrow. Since the term is a general one, it is necessary to chromatic cells in a normal blood flm is usually less than describe the two populations. Automated counters may the reticulocyte count is about double the visual estimate confrm the visual impression of dimorphism, although of polychromatic cells . This is because only the most some instruments may be unable to distinguish between immature (grade I) reticulocytes are polychromatic. In a difference in size and a difference in haemoglobin con conditions of transient or persistent haemopoietic stress, centration. Causes of a dimorphic flm included iron when erythropoietin levels are high, immature reticu defciency anaemia (following administration of iron or locytes are released from the bone marrow. Sometimes the consequence of a reduced haemoglobin concentration, irregular shape apparent on electron microscopy can also are less dense. On scan locytes, which are the only forms present in the blood ning electron microscopy they have an irregular, multi of haematologically normal subjects, are cup‐shaped and lobated surface (Fig. High altitude ing altitude or other hypoxic stimulus and as a normal produces some degree of poikilocytosis in haematolog response to anaemia when there are no factors limiting ically normal subjects . In severely anaemic patients, a lack of poly mon, often non‐specifc abnormality in many haema chromasia is signifcant. It may result from the production sia and in aplastic anaemia, and is inconspicuous in the of abnormal cells by the bone marrow or from damage anaemia of chronic disease and often in renal failure when to normal cells after release into the blood‐stream. The absence poikilocytosis is very marked, diagnostic possibilities of polychromasia in a patient with sickle cell anaemia or include primary or secondary myelofbrosis, congeni other haemolytic anaemia is important since it may indi tal and acquired dyserythropoietic anaemias, heredi cate complicating parvovirus B19‐induced red cell aplasia. Extreme poikilocytosis with myelofbrosis and in metastatic carcinoma of the bone microcytosis was noted in a child with compound het marrow. Patients with matic cells is greater than would be expected from the Gaucher disease have been found to have an increased degree of anaemia and the polychromatic cells may be proportion of poikilocytes, 2. The presence of When the reticulocyte count is increased, auto poikilocytes of certain specifc shapes, e. The presence of cryoglobulin can lead to remarkable deformation of red cells (Fig. Because the cryo poikilocytosis globulin may be only weakly basophilic it may not be A cell of abnormal shape is a poikilocyte. The appearance of something extran sis is therefore a state in which there is an increased eous indenting red cells provides a clue. Spherocytosis object of the same volume, and thus a spherocyte may Spherocytes are cells that, rather than being disci appear smaller than a discocyte. They are cells that have lost membrane reduced volume rather than merely reduced diameter. The the presence of spherocytes it is important to examine diameter of a sphere is less than that of a disc‐shaped that part of the flm where the cells are just touch ing, since normal cells may lack central pallor near the tail of the flm. The distinction between spherocytes and irregularly contracted cells (see below) is important since the diag nostic signifcance is different. In hereditary spherocytosis there is an abnormality of the cytoskeleton with a secondary destabilisation and loss of membrane. In acquired conditions, spherocytosis can result from direct damage to the red cell membrane, e. Courtesy of the late Professor spherocytes, microspherocytes and red cells that appear to be Harry Smith. In Heinz body haemolytic cytes; this is the mechanism of formation of spherocytes anaemias, although most abnormal cells are irregularly in microangiopathic haemolytic anaemia, mechanical contracted cells (see below), there are usually also some haemolytic anaemia and hereditary pyropoikilocytosis. Erythrocytes stored for transfusion become spheroechi nocytes as the blood ages (see below). Rarely, marked Irregularly contracted cells spherocytosis has been described in hypophosphataemia, Irregularly contracted cells lack central pallor and appear e. Irregularly contracted cells are formed when there is oxidant damage to erythrocytes, or damage to red cell membranes by precipitation of unstable haemoglobin or free α or β chains. Blood flms showing irregularly contracted cells often also show some spherocytes; these are formed when a red cell inclusion, such as a Heinz body, has been removed by the pitting action of splenic macrophages with associated loss of red cell membrane. Keratocytes (see below) may likewise be present as a result of the removal of a Heinz body. Blood flms show ing irregularly contracted cells may also show ghost cells and also hemighosts or blister cells. Chan and col half of the cell leaving the red cell membranes in appo leagues, Hong Kong, and the British Journal of Haematology . Some causes of patient has an inherited abnormality affecting the red cell irregularly contracted cells are shown in Table 3. These terms have not been used in occasionally in inherited red cell enzyme abnormalities, any consistent manner, but it has been suggested that a cell e. In Papua New Guinea, ovalocytosis When elliptocytes or ovalocytes are numerous (Fig. Elliptocytes are biconcave and thus are Haemoglobin C/β thalassaemia capable of forming rouleaux. The compound heterozygotes also have small Moderate oxidant stress in patients without abnormalities of the numbers of pincered cells and schistocytes. Homozygotes pentose shunt and compound heterozygotes who are also heterozygous Defects in glutathione biosynthesis Neonatal glutathione peroxidase defciency (which is probably for haemoglobin E have ovalocytes comprising about two‐ secondary to transient defciency of selenium, an essential thirds of red cells. Heterozygotes for G701D are haemato co‐factor) logically normal unless they also carry haemoglobin E or Haemoglobin C trait α+ thalassaemia, in which case they also have ovalocytes. Unstable haemoglobins However, a heterozygote for A858D had 20% ovalocytes β thalassaemia trait and also had acanthocytes, echinocytes and schistocytes Haemoglobin H disease .
Post-synaptic receptor imaging agents are necessary to diferenti- ate among the various Parkinsonian syndromes (not routinely available) generic asacol 400 mg otc. Indications • Movement disorders: distinguishes Parkinson’s syndrome (PkS) from benign essential tremor cheap asacol 400mg free shipping. Results Intense discount 400 mg asacol with visa, symmetric uptake in basal ganglia receptors—striatum, caudate, and putamen (see Fig. Advantages Sensitive and specifc for PkS, diferentiating PkS from essential tremor. Symptoms of shunt obstruction may be non-specifc and do not indicate the level of obstruction. Interpretation Delayed clearance implies obstruction—level usually at reservoir/proximal shunt or due to intra-abdominal kinking. Imaging is undertaken using 99mTc-pertechnetate, which is trapped by the thyroid by the same transporter mechanism as iodine but, unlike iodine, is not organifed. Indications • Characterization of thyrotoxicosis—difuse toxic goitre (Graves’ disease), toxic multinodular goitre (Plummer’s disease). Results • Uptake refects function of the thyroid iodine trap (sodium iodide symporter). Nuclear medicine is of value in localizing parathyroid adenomas, particularly following previous surgery. Results Normal thyroid concentrates 123I, 99mTc- pertechnetate, 99mTc- sestamibi (initially), and 210Tl, whereas parathyroid only concentrates 99mTc- sestamibi and 201Tl. Computer-assisted image subtraction [(thyroid + parathyroid) − thyroid] identifes abnormal parathyroid tissue. Interpretation Parathyroid adenoma shown as hyperfunctioning nodule(s) (see Figs 14. Parathyroid adenoma at left lower lobe of the thyroid (arrow) evident on delayed image. Advantages Good when other imaging fails, particularly ectopic adenomas and after unsuccessful neck exploration. Pitfalls Multinodular thyroid prevents subtraction analysis in smaller adenomas and hyperplastic glands and thyroid nodules. Symptoms refect hormone hypersecretion, but intermittent secretory patterns can result in false −ve screening tests, e. Indications • Localization, staging, and response monitoring of neuroectodermal tumours. Image the posterior abdo- men at 5min to identify renal outlines, then whole body imaging at 18– 24h. Results Physiological uptake at 24h in the salivary glands, myocardium, liver, and normal adrenals, with gut and renal excretion. Interpretation • Intense i uptake in phaeochromocytomas, with suppressed activity in the contralateral and normal adrenal, and myocardium. Advantages Sensitive, non-invasive tumour localization preoperatively excludes multi- focal and extra-adrenal tumours. Prophylactic laxatives at time of radiopharmaceutical administration accelerate gut clearance and improve image quality. Advantages Tumour uptake predicts symptom response to somatostatin analogue ther- apy. Radioactive iodine is adminis- tered post-operatively to ablate the thyroid remnant. Tg can then be used as a tumour marker—Tg is undetectable in the absence of functioning thy- roid tissue. If Tg rises, a diagnostic 131I imaging study localizes the site of relapse and assesses the feasibility of further radioiodine therapy. Indications Routine diferentiated follicular thyroid cancer follow-up, after surgery and 131I thyroid remnant ablation. Advantages Detects residual tumour and identifes patients likely to beneft from 131I therapy. Lymphatic drainage can be demon- strated by radiolabelled colloid imaging, which identifes the frst or ‘sentinel’ draining node. Staging based on the excision and histological examination of this node for evidence of metastasis is as reliable as that obtained from block dissection and avoids the morbidity of extended lymph node dissection. Procedure Intradermal, subcutaneous, or intratumoural injection of 99mTc- labelled nanocolloid. Where surgery is undertaken within 24h, an intra-operative gamma probe can be used to identify the sentinel node for staging excision biopsy. Results Sentinel node usually identifable 15min to 2h post-injection, depending on the ° tumour location and injection technique used. Interpretation The sentinel node is the frst lymph node identifed on gamma imaging or the node with the highest radioactive count rate using the gamma probe (see Fig. Advantages Accurate sentinel node identifcation avoids block node dissection where this is undertaken solely for tumour staging. Pitfalls May fail if local lymphatic channels have been disrupted by previous surgery. Further reading Procedure guidelines for several types of cancer are available at: M http:// www. Indications Investigation of suspicious breast lesions, in difcult-to-interpret mammo- grams, e. Patient is imaged prone, with the breast fully dependent, with prone and lateral views of each breast, to include the axillae. Results Normal distribution of 99mTc-sestamibi is to the myocardium, the liver, and occasionally the thyroid. Interpretation Focal accumulation in the breast and/or axilla implies the presence of a tumour. Advantages Can demonstrate multi-focal, multicentric disease, and both ipsilateral and contralateral axillary spread. Pitfalls Not reliable in small (<1cm) lesions; extravasation of injection in upper limbs may result in false +ve axillary uptake. The camera and supporting software require high count rate capability, and the technique requires expertise in data analysis to ensure reliable, reproducible results. Close liaison with the referring clinician is essential to maximize the value of the investigation. Spatial resolution (75mm) is signifcantly superior to conventional nuclear medicine imaging. Other oncological tracers that are available for clinical use include 11C- methionine, measuring tumour amino acid transport and protein synthesis and H 15O water for blood fow measurements. The combination of functional and anatomical data in fused images signifcantly improves the sensitivity and specifcity of imaging.
The Lingual surface of crown layer of cementum covering the root of an actual tooth is proportionately much thinner than seen in these drawings asacol 400mg for sale. Radiographs (x-rays) showing tooth crowns covered with enamel purchase generic asacol canada, and the Enamel tooth roots embedded within the alveolar Dentin bone purchase asacol 400mg mastercard. You can distinguish the whiter outer enamel shape from the darker inner dentin, Pulp and the darkest pulp chamber in the middle of Periodontal ligament the tooth. The very thin, dark periodontal (dark line) ligament can also be seen between the root and Alveolar bone the bone, but the cementum cannot be seen. The pulp cavity has a coro- mouth or handheld) normally covered by an enamel nal portion (pulp chamber) and a root portion (pulp layer, and the anatomic root is the part of a tooth cov- canal or root canal). Like dentin, the pulp is normally not visible, except on a dental radiograph (x-ray) or sectioned tooth (Fig. This is refers to the amount of tooth that is not visible since it called secondary dentin. Clinically, the gin- • Sensory: Nerve endings relay the sense of pain caused gival margin in a 25-year-old patient with healthy gin- from heat, cold, drilling, sweet foods, decay, trauma, giva approximately follows the curvature of the cervical or infection to the brain, so we feel it. However, the line, and under these conditions, the clinical crown is nerve fibers in a dental pulp are unable to distin- essentially the same as the anatomic crown. This results in a clinical crown that is longer than the anatomic crown since the clinical crown in this mouth consists of the entire ana- Clinical tomic crown plus the part of the anatomic root that is crown exposed (Fig. In this situation, the clinical root is Anatomic crown shorter than the anatomic root. This maxillary molar has a very long clinical crown since all of the anatomic crown and much of the anatomic Examine the mouths of several persons of differ- root are exposed due to recession of the gingiva and loss of bone. As the individual grows older, the location of the margin of the gingiva mouth) that is much shorter than the anatomic crown. Of course, the tomic root plus the part of the anatomic crown covered location of the cervical line on the tooth remains with gingiva). In other words, the distinction between In contrast, the gingival margin in a 70-year-old per- the anatomic crown and root does not change son may exhibit gingival recession, especially after hav- over a lifetime. If you insert a thin probe into this sulcus, it periodontal ligament, and the outer, cementum layer of should extend only 1 to 3 mm deep in a healthy per- the tooth roots (Fig. The papilla also has a it is firmly bound to the underlying alveolar bone and hidden sulcus where dental floss can fit once it passes is called attached gingiva. The groups of fibers of the periodontal ligament gingival margin) is the edge of the gingiva closest to the represented in Figure 1-9 are greatly enlarged. The healthy periodontium is made up of alveolar bone which surrounds the anatomic root, gingiva (gum tissue) which covers the bone, cementum which covers the tooth root, and the periodontal ligament which connects the bone to the cementum of the tooth. Gingiva surrounds each tooth forming a characteristic scalloped shape gingival margin. The potential space between the free gingiva and the tooth can be accessed with a thin periodontal probe. The attached gingiva is the gingiva which is firmly attached to the underlying bone. Refer to should not be used when referring to the premolars or Figure 1-11 when studying the terms to denote tooth the molars. In the face, that is, the surface of a tooth in the mouth rest- maxillary arch, this surface can also be called the pala- ing against or next to the cheeks or lips. Facial may tal surface due to its proximity with the palate (labeled be used to designate this surface of any tooth, ante- on tooth No. Remember that the labial surface of an anterior tooth and the buccal surface of a posterior tooth are both referred to as facial surfaces. Also, the mesial and distal sides or surfaces are both correctly called proximal surfaces. Anterior teeth (incisors and canines) do not Examples of external line angles of a molar crown have an occlusal surface but do have a cutting incisal include mesio-occlusal, mesiolingual, mesiofacial, disto- edge or ridge (labeled on tooth No. Note that the mesial surface of a tooth could be described as its cervicoapical dimension. Proximal surfaces are not naturally cleaned by the action of the A tooth can be divided into thirds in order to define cheeks, lips and tongue when compared to most of the more precisely the location of its specific landmarks facial or lingual surfaces which are more self-cleansing. When viewing a tooth from the facial, lin- gual, mesial, or distal surface, horizontal lines can divide the tooth crown into the following thirds: cervical, mid- E. To name a line angle, combine the When viewing a tooth from the facial (or lingual) names of the two surfaces, but change the “al” ending of surface, vertical lines can be used to divide the crown or the first surface to an “o. Use the ing a tooth from the proximal (mesial or distal) sur- following order: mesial is used first, then distal, facial, face, vertical lines can be used to divide the crown or lingual, and lastly occlusal or incisal. When view- line, it is better to say mesio-occlusal than occlusome- ing a tooth from the occlusal (or incisal) surface, lines sial, and it is better to say distolingual than linguodistal. Diagrammatic representation of an incisor and molar crown shows some external tooth line angles and point angles. Diagrams of a maxillary canine and mandibular molars to show how a crown or root may be divided into thirds from each view for purposes of describing the location of anatomic landmarks, contact areas, and so forth. Since the roots of teeth are normally longer than their crowns, the root-to-crown ratios for teeth are normally >1. When this number is close to 1, it indicates that the root is not much longer than the crown. The obvious difference between maxillary central incisor where the root is not much longer than the root-to-crown ratio on these two teeth is apparent in the crown (and the ratio is only 13 divided by 11. The ratio can be clinically significant, since maxillary canine where the root is considerably longer than the a tooth with a small root-to-crown ratio (closer to 1) crown (and the ratio is much larger: 16. Specific tooth structures that are named after the adjacent line angles: mesiobuccal, occur with some frequency on teeth within a class have distobuccal, mesiolingual, and distolingual. To identify the following Figure 1-15 for examples of cusp names on teeth with anatomic structures, reference will be made to rep- two, three, and four cusps. On this example, three of the ridges are and premolars, and on the incisal edges of canines. Cusp names on teeth having two, three, and four cusps, viewed from the occlusal and buccal views. Notice that the distobuccal cusps are named after the adjacent surface or line angle. Chapter 1 | Basic Terminology for Understanding Tooth Morphology 19 All cusps are basically a gothic pyramid: tal borders of the occlusal surface. Each triangular ridge extends from a 4 cusp tip toward the depression (sulcus) in the middle of the occlusal surface faciolingually (Fig. When a triangular ridge from a facial cusp joins with a triangular ridge from an adjacent lingual cusp, the two The cuspal gothic pyramid produces 4 ridges: ridges together form a longer ridge called a transverse 1. Buccal cusp ridge (labial ridge on canines) of posterior teeth in a more or less buccolingual direc- 4. Triangular ridge on posterior teeth (lingual ridge on canines) tion, running between the buccal and lingual cusps on a premolar (Fig. Buccal cusp of a two-cusped premolar showing lingual cusps that are lined up across from one another the pyramidal design (actually, the pyramid with rounded sides is on a molar (seen on the two-cusped premolar and on called a gothic pyramid) formed by the four cusp ridges that make a mandibular molar in Fig.
Mean follow-up was 7 years for patients that still had their grafts in place and all clinical outcomes scores saw improvement cheap asacol 400mg with mastercard. The authors reported their results on 39 patients who received osteochondral allografts who were followed for an average of 3 purchase 400 mg asacol with amex. In patients with traumatic unicompartmental arthritis safe asacol 400mg, the success rate was only 30%. Osteochondral allografts were used to treat 43 pediatric and adolescent knees (mean age of 16. Graft survivorship was 90% at 10 years, with fve knees experiencing failed grafts at an average of 2. Sixty-three patients who received an osteochondral allograft were followed for an average of 22 years. Sixty-fve patients with failed tibial plateau fractures were treated with fresh osteochondral allografts. Kaplan-Meier survivorship analysis showed the rate to be 95% at 5 years, 80% at 10 years, 65% at 15 years, and 46% at 20 years. Weight- bearing pain in the involved region with or without loose body symptoms may be present. As the knee is slowly extended, catching symptoms are felt at about 30° of fexion as the tibial spine abuts the lateral aspect of the medial femoral condyle. If the patient only has symptoms with higher-level activities, then they can be allowed to walk on the lesion if not symptomatic with these activities. Portals/Exposure • Standard arthroscopic anteromedial and anterolateral portals are used for the initial diagnostic arthroscopy. This method is typically recommend- ed due to the ease of obtaining a perpendicular approach compared with perform- ing arthroscopically. Step 2: Decision Making • If the lesion has subchondral bone and can be fxed: • If the lesion is stable (stage I), perform retrograde or antegrade drilling (see Proce- dure 15) or fx the lesion in situ. If this occurs, it can cially after initial treatment is rendered (see Procedures 12 and 13). The small at the time of defnitive cartilage management such as osteochondral allograft place- arthrotomy can be used to perform defnitive ment. Be aware that the patient commonly will have bone loss deep to the lateral femoral condyle (i. If K-wires are used, be sure they do • Bone grafting can be performed when not interfere with the desired screw location unless they are part of the cannulated necessary as previously described. Although bioabsorable screws are used broadly by other authors and offer the convenience of being left in place, we prefer metallic headless compression standard or miniscrews. Using a perpendicular angle, the wire is drilled into the center of the lesion and advanced about 3 cm to 4 cm (Fig. If the guidewire is within 2 mm of the posterior cortex, we recommend using a screw that is at least 2 mm shorter than the measured depth. If resistance is met, the screw should be removed and the hole should be re-drilled further into the bone. A dedicated tapered drill is pushed until the shoulder of the drill contacts the cannula (Fig. The headless tip of the screw is separated by 3 mm from the smooth shaft of the driver (Fig. Twenty-four patients (30 knees) were treated with a total of 61 bio-absorbable screws. Four patients required revision surgery for implant failure with pain and clinical locking symptoms. Seventy-fve percent of lesions were completely healed radiographically at 12 months and 98% were healed at 36 months. At a minimum of 2 years’ follow-up, 88% of the patients were rated as good or excellent. Graft survivorship was 90% at 10 years and, among those with retained grafts, 88% were rated good or excellent. Peterson L, Minas T, Brittberg M, Nilsson A, Sjogren-Jansson E, Lindahl A: Two- to 9-year outcome after autologous chondrocyte transplantation of the knee, Clin Ortho Rel Res 374:212–234, 2000. When combined with a tibial tubercle osteotomy, the results improved to 85% good and excellent. A retrospective review of 16 knees with focal articular defects treated with osteochondral auto- grafts. Careful evaluation of the previously menisectomized knee should be performed to interpret new injury versus postmenisectomized appearance. These scans can also help evaluate osseous overgrowth in the setting of a failed prior cartilage restoration procedure. As a guideline, the osteotomy is possibly not necessary in this setting if correcting less than 5°. A radiolucent extension is ap- • Fluoroscan plied to enable fuoroscopic examination. Alternatively, the patient can be placed • Allograft cortical wedges on the ipsilateral edge of the table to enable fuoroscopic access by abducting the leg. Any necessary concomitant procedures are done prior posterior cortex, as this is often an area of incomplete osteotomy. As a fuoroscopic guideline, the pin should traverse the superomedial tibial tuberosity at the junction of the patellar tendon insertion and end at the tip of the fbular head. Step 3: Performing the Osteotomy Cut • The cutting guide is placed over the two pins. An oscillating saw is used to cut the tibia anteriorly, medially, and posteriorly to within 1 cm of the lateral cortex (Fig. Fluoroscopy is used to make sure the oste- otomes do not violate the lateral cortex (Fig. Step 4: Plate Fixation • An anterior-to-posterior sloped plate of the opening size is placed in the space be- tween the two wedges. It is important to use fuoroscopy to make sure the screws do not pen- etrate the articular surface. Step 5: Bone Graft the Osteotomy Site • Allograft or autograft bone is inserted in the osteotomy site on both sides of the plate (Fig. Step 6: Closure • The tourniquet is defated, the knee is irrigated with saline, and hemostasis is achieved. The authors reported improve- ment in dynamic knee joint load and patient-reported measures of pain, function, and quality of life 2 years postoperatively. Nineteen patients were placed in a cast for 3 days and precast and postcast gait analysis was performed. There was a correlation between the reduction of pain and adduction moment (r = 0. Franco V, Cerullo G, Cipolla M, Gianni E, Puddu G: Open wedge tibial osteotomy, Tech Knee Surg 1:43–53, 2002.
On closer examination buy asacol 400mg line, Erosion is the loss of tooth structure from chemical (not the first and second mandibular premolars and first buy asacol 400mg with amex, mechanical) means and affects smooth and occlusal second buy cheap asacol 400mg line, and third mandibular molars on both sides also surfaces. A close-up of the mandibu- lar dentition of a 23-year-old man who has premolars and molars with crown morphol- ogy more similar to maxillary premolars and molars, particularly on the left side. Both denti- tions are seen from the occlusal aspect, maxillary in the top photo and mandibular in the bottom photo. Lower premolar crowns do not resemble mandibular premo- lars in any fashion but are more similar to maxillary premolars. The mandibular right first molar has three buccal cusps but otherwise seems to be a mixture of both maxillary and man- dibular first molars: oblong mesiodistally like a lower, but with a much larger mesio- lingual cusp and a Carabelli-like cusp similar to upper first molars. The mandibular left three molars seem to have only morphologic characteristics of maxillary molars. It is most interesting to note that the lower left posterior teeth (particularly the premolars) have the morphology of maxillary right-side teeth. Likewise, the lower right teeth appear similar to those found in an upper left quadrant. Chapter 11 | Dental Anomalies 343 posterior teeth The mandibular six anterior teeth unquestionably belonged to the mandibular dentition. The occlusion of the young man’s teeth was remarkably good considering the fact that maxillary posterior teeth were occluding against practically identical maxillary teeth on both sides! Another most unusual dentition of a foreign exchange student from Africa is seen in Figure 11-49. There appear to be 4 incisors, 1 canine, 6 premolars, and 13 molars (5 of which somewhat resemble mandibular molars). Which three of the following locations are most likely to have supernumerary teeth form? Amelogenesis imperfecta mally single rooted are most likely to have a bifur- cated root? Hypoplasia 344 Part 2 | Application of Tooth Anatomy in Dental Practice Critical Thinking List and describe as many anomalies you can that you are likely to see in the maxillary incisor area of the mouth. Upper canine in position of upper tical twins in relation to three dental anomalies. Forensic engineering investigates events such as uses autopsy techniques and the analysis of tissues airplane and other vehicular accidents, as well as in the investigation of a crime or suspicious death structural collapse as part of the legal process. This duty is legally study and provide legal testimony about printing, the responsibility of a coroner or medical examiner handwriting, typewriting, ink, paper, and other with specialized training in pathology and forensic features of documents. General forensics involves other specialists mine matters such as the cause and manner of who are qualified to analyze specific evidence death (for example, a gunshot wound to the chest such as designers, photographers, and techni- resulting in laceration of the left ventricle, which cal experts. They might report, for example, in a resulted in cardiac arrest as a result of a homicide). Toxicology uses chemistry, photography, and areas: (a) human dental identification, (b) mass biology to identify harmful substances in the victim disaster human dental identification, (c) bite such as medications, poisons, and illegal drugs. Forensic psychiatry and behavioral sciences issues such as the standard of care considerations examine and provide legal opinions regarding in personal injury cases. Situations involving decomposition and skeletal dental radiographs, photographs, impressions and remains may yield no recognizable facial features or casts, antemortem and postmortem charting, and the fingerprints. Points of comparison prostheses, and appliances can yield a positive identifi- (specific features) include (a) the number, class, and cation, given the existence and accuracy of antemortem type of teeth; (b) tooth rotation, spacing, and malposi- (before death) records. This information is derived tions include high costs and lengthy processing times. Comparison of antemortem and postmortem photographs looking for similarities in general morphology. Similar dental arch form is observed as is the overall morphology of the dental coronal structure. Postmortem radiographs show consistency in some using consistent and standardized methods that are restorations when compared to the antemortem radiographs, easily understood by other professionals and defen- but note that several teeth have had restorations placed after sible in a legal action. These radiographs show antemortem (top) and postmortem (bottom) radiographs of a homicide victim with orthodontic appliances in place, which are identical to actual postmortem findings (seen in B and C) and served to confirm the identity. This postmortem photograph shows the orthodontic retainer in the mandibular arch as evident in the antemortem radiographs. This postmortem photograph shows the orthodontic retainer B in the maxillary arch as evident in the antemortem radiographs. Some dentists mount radiographs as viewed from the front of the patient (with the film bump facing toward the viewer), which is the standard in forensic dentistry, while others still prefer mounting them as viewed from the lingual (film bump facing away from the viewer). Charting tooth identification in dental offices (the antemor- tem record) is not always done using the Universal system. However, 20 of the 33 to obtain swabbings of bite marks or other human tissues for known victims were identified through their dental comparison to antemortem records. Due to the focus of this text (the relevance of dental anat- omy), only brief comments will be made about these topics. In civil litigation cases, a person might claim that improper dental care was rendered (malpractice) as illustrated in the radiographs in Figure 12-6; damage was sustained at the hands of another person (criminal assault and battery); damage was sustained due to food contaminated with a foreign body (glass, shell, etc. One can see marginal discrepancies between tooth contours and restoration contours (especially on the forensic dentist. This is a Panorex (panoramic) radiograph of a 14-year-old girl showing rampant caries that progressed over many years resulting in a treatment recommendation to extract all teeth. This evidence of parental neglect was reason for the dentist to contact legal authorities for suspected child abuse/ neglect. This is a photograph of this same 14-year-old girl B showing rampant dental caries. All of the techniques and careful comparisons situation was reported immediately to the appropriate described previously are useful. The dentist’s suspicions had Dentists and other health caregivers have a respon- been aroused sufficiently regarding the incongruity of sibility to report suspected abuse and neglect of their the story and the injuries sustained. This includes recognition and dif- treatment, the police arrived, and the man was arrested. One abuse scenario is observe include fractured bones and teeth, bruises, lac- described here. As often seen by this woman was silent while the man related an accident author, children may not be taken to a dentist for treat- as the cause of the injuries. This can result in pain and infec- present during the treatment and was evasive about tion and, in some cases, may result in the loss of all answering questions. Color and black-and-white film photography is buckles, and other blunt objects such as a hammer or still the standard, but digital photography has become pipe. The use of infrared photography solved by bite mark identification, analysis, and com- can be used to identify subcutaneous evidence of dam- parison.
Therefore as the prevalence of disease in a population approaches zero order asacol 400 mg free shipping, the positive predictive value of a test also approaches zero order asacol now. Conversely discount asacol online american express, if everyone in a population tested has the disease, all negative results will be false negative even for a sensitive test. Post-test likelihood of not having the target disorder following a negative test Posterior probability of not having the target disorder following a negative test Post-test probability of not having the target disorder following a negative test Definition: The “predictive value of negative test” indicates the probability that a patient with a negative test result does not, in fact, have the disease in question or this is the proportion of patients with negative test results who do not have the target disorder. Nearly 88 percent of patients with negative test results (clinical diagnosis of strep throat – negative) did not have the disease (throat culture negative for group A b-hemolytic streptococcus) Features • It reflects the diagnostic power of a test. Likelihood Ratio As the prevalence of disease in a population approaches zero, the positive predictive value of a test also approaches zero and if the prevalence of disease in a population approaches 100 percent, the positive predictive value of a test also approaches 100 percent. However, as prevalence approaches 100 percent, negative predictive value approaches zero and if prevalence approaches zero, negative predictive Research on Diagnostic Tests 79 value approaches 100 percent. But, sensitivity and specificity are usually not affected by varying prevalence rates, Even if they are affected, much less so than the predictive values. However, predictive values are far more relevant to clinical and laboratory decision making, as they are patient oriented and focus attention on the probability of disease in a given patient rather than the probabilities of different test results. A clinician is, therefore, more likely to use predictive values and hence should be clear about the manner in which the prevalence of the disease in different clinical settings alters them. Likelihood ratios are also patient-oriented but are even more stable than sensitivity and specificity and are therefore likely to become more popular as diagnostic test evaluation statistics. Likelihood Ratio of a Positive Test Result Definition: This is the ratio of the proportion with a positive test result in those with disease to the proportion with a positive test result in those without disease, i. Estimation a/a+c Sensitivity Likelihood ratio of a positive test result = = b/b+d 1 − Specificity True positives = False positives Calculation and Interpretation (Table 7. Likelihood Ratio of Negative Test Result Definition: This is the ratio of proportion with a negative test result in those with disease to the proportion with a negative test result in those without disease, i. Estimation: c/a + c 1 – sensitivity Likelihood ratio of a negative test result = = d/b+ d Specificity False negatives = True negatives Calculation and Interpretation (Table 7. Because the proportions that make up the likelihood ratio are calculated “vertically” like sensitivity and specificity, likelihood ratios need not change with changes in the prevalence (or pretest probability) of the target disorder. Likelihood ratios can be calculated for several levels of the sign, symptom, or laboratory test result. It can be used in a very powerful way to shorten a list diagnostic hypotheses, because: The pretest odds for the target disorder × the likelihood ratio for the diagnostic test result = the post-test odds for the target disorder. As a result, if you start from your clinical estimate of the odds that your patient has a certain target disorder, and then carry out a diagnostic test and apply the likelihood ratio that corresponds to your patient’s test result, you can calculate new, post-test odds for the target disorder. With likelihood ratios, it is possible to summarize the information contained in a test result at different levels. One can define likelihood ratios for any number of test results, over the entire range of possible values. In this way, information represented by the degree of abnormality, rather than the crude presence or absence of it is not discarded. In computing likelihood ratios across a range of test result, sensitivity refers to the ability of that particular test result to identify people with the disease, not individuals with that result or worse. Thus likelihood ratios can accommodate the common and reasonable clinical practice of putting more weight on extremely high (or low) test result than on borderline ones when estimating the probability (or odds) that a particular disease is present. The choice of cut-off points usually depends on the relative merits of sensitivity and specificity for the diagnosis of the disease in question. The ideal cut-off values are those with the greatest net benefits of making a diagnosis and instituting therapy. However, generally there is a trade-off between the sensitivity and specificity of a diagnostic test. It is obviously desirable to have a test, which is both highly sensitive and highly specific. In comparing two or more different tests for the same disease, the areas under the respective curves should be compared for assessing relative diagnostic accuracy. Agreement: When a diagnostic test is being compared with a Gold standard, establishment of agreement between two is important. How much is the agreement between positive and negative results of two tests, has to be answered. It is also essential to evaluate the reproducibility of test interpretation by many different observers. If there is a wide disagreement between observers in interpreting the same set of test results, it renders the test useless for widespread clinical application. Two or more observers should independently evaluate the test results without having access to the clinical data. If the results are dichotomous, a chance-corrected index of agreement like Kappa should be calculated (Refer Tables 7. Observed agreement = a + d/N % As, agreement (observed) in part may be true agreement and in part it could be because of chance. Observed agreement = Chance agreement + actual (true) agreement = Agreement expected on the basis of chance + Actual agreement beyond chance. Agreement expected on the basis of chance = A + D / N Where, A = (a+c) (a+b) / N, D = (b+d) (c+d) /N Actual agreement beyond chance = Observed agreement – agreement expected on the basis of chance. Potential agreement beyond chance = 100% agreement expected on the basis of chance Kappa = Actual agreement beyond chance/Potential agreement be- yond chance tAble 7. Following are some questions to help to choose appropriate study design to solve research question. How often do test results af- Diagnostic yield stud- Proportion abnormal, proportion fect clinical decisions? Pro- post-test clinical decision portion of the tests leading to making change in the clinical decision. Cost per abnormal result or de- cision change What are the costs, risks Prospective and Mean costs, proportions, expe- and acceptability of the retrospective studies riencing adverse effects, pro- tests? Sample size requirements for statistical comparisons of two performance characteristics • Comparing two variable proportions • Comparing two variable proportions, one with a fixed sample size • Comparing a variable and a fixed proportion 2. Sample size requirements for controlling confidence intervals to set confidence intervals to a desired size 3. Agreement and sample size: • Percent agreement • Kappa statistic sample size considerations Specifications: Test Performance Characteristics: • Type I Error: Error of falsely stating that two proportions are significantly different when they are actually equivalent. To determine the optimal sample size for comparing test A with test B, we need information on following parameters: • An estimate of the expected value of the performance characteristic of interest for the reference test • The smallest proportionate difference between the reference and the new tests considered to be medically important • The level of significance required to accept two proportions as different, which is a (type I error), and • The level of certainty desired to detect the medically important difference (statistical power). What happens when these Gold Standards are not available or What if the ‘Gold Standard’ is not gold after all? There are various methods to deal with the absence of a gold standard: 86 Research Methodology for Health Professionals 1. Latent class modeling (Walter, Cook, Irwig) Bias Index: What if the test itself commits a certain type of error more commonly than the other? Bias is directly proportional to the association between selection for verification and the result of the test under study. A study by Borrow et al (Am Heart J, 1983) on patients who were referred for valve surgery on the basis of echocardiography assessment reported excellent diagnostic agreement between the findings at echocardiography and at surgery (Table 7. Prevalence (Pretest Predictive value of Predictive (Posterior prob- likelihood or prior a positive test (Pos- value of a ability of disease probability of disease) terior probability of negative test following a negative disease following a (Posterior test result) positive test result) probability of no disease test result) 99 % 99.