Teeth In Patients Research Articles

Qualitative computer aided evaluation of dental impressions in vivo

Clinical investigations dealing with the precision of different impression techniques are rare. Objective of the present study was to develop and evaluate a procedure for the qualitative analysis of the three-dimensional impression precision based on an established in-vitro procedure. The zero hypothesis to be tested was that the precision of impressions does not differ depending on the impression technique used (single-step, monophase and two-step-techniques) and on clinical variables. Digital surface data of patient's teeth prepared for crowns were gathered from standardized manufactured master casts after impressions with three different techniques were taken in a randomized order. Data-sets were analyzed for each patient in comparison with the one-step impression chosen as the reference. The qualitative analysis was limited to data-points within the 99.5%-range. Based on the color-coded representation areas with maximum deviations were determined (preparation margin and the mantle and occlusal surface). To qualitatively analyze the precision of the impression techniques, the hypothesis was tested in linear models for repeated measures factors (p < 0.05). For the positive 99.5% deviations no variables with significant influence were determined in the statistical analysis. In contrast, the impression technique and the position of the preparation margin significantly influenced the negative 99.5% deviations. The influence of clinical parameter on the deviations between impression techniques can be determined reliably using the 99.5 percentile of the deviations. An analysis regarding the areas with maximum deviations showed high clinical relevance. The preparation margin was pointed out as the weak spot of impression taking.

Visusrehabilitation bei schwersten Veränderungen der Augenoberfläche

Severe ocular surface diseases, such as Stevens-Johnson syndrome, ocular cicatricial pemphigoid or severe ocular burns may result in a significant loss of corneal stem cells, eventually leading to vision impairment or even corneal blindness. In case of unilateral involvement, limbal autografting, by means of transplanting limbal stem cells from the healthy fellow eye, has proved to be an effective procedure for restoring the integrity of the ocular surface. Limbal allografts may be performed in patients with bilateral disease, however, systemic immunosuppression is mandatory in these cases, with a long-term outcome that is frequently reduced compared to limbal autografts due to acute or chronic graft rejection. In recent years, amniotic membrane transplantation has been successfully employed as an additional tool in ocular surface reconstruction. The AlphaCor synthetic cornea, which is made of flexible acrylic may be considered as an alternative in patients with repeated corneal graft failures. Both limbal transplantation and the AlphaCor have been shown to be effective in eyes with an adequate tear film, but are most likely to fail in severe dry eyes or in patients with cicatrising diseases. Such conditions are the domain of keratoprostheses (KPros) with rigid optics, which certainly can be considered as the 'last resort' to restore vision in patients with profound corneal blindness not amenable to conventional corneal and limbal grafting. The osteo-odonto-keratoprosthesis according to Strampelli and modified by Falcinelli makes use of a "biological" support consisting of a longitudinal section of one of the patient's teeth that is also supported by the surrounding alveolar bone tissue. Compared to other devices favourable long-term results have been reported. In patients lacking any usable teeth, implantation of a keratoprosthesis with haptics made of Dacron (Pintucci-KPro) or tibial bone (Temprano-KPro) might be considered.

3D Computed-assisted surgery in orthodontic treatment of impacted canines in palatal position

An original method of mini-invasive oral surgery based on 3D images from computed tomography is presented. Fourteen patients referred for treatment of unerupted canine in palatal location underwent a multislice CT scan (MSCT). The patient data were analyzed with an original 3D imaging software based on «region growing» method. The 3D images were then segmented in order to separate bone teeth and mucosae. The optimal position of the expected bracket attachment was calculated and reported on the 3D images of the canine to be treated. A virtual geometric construction of this optimal point was determined using neighboring teeth and then transposed to the patient's teeth, allowing then a limited surgical incision when sticking the bracket on the impacted canine. For all treated patients, the orthodontic treatment was facilitated by this procedure which allowed a more accurate and more limited surgical incision.

DEVELOPMENT OF FIBER OPTICS SPECTROSCOPIC TOOTH COLORIMETER USING WHITE LED

Tooth colorimeter provides the determination of patient's tooth shade, and assists dentists, technicians and patients in satisfying the clinical needs for dental medicine. The traditional visual matching approaches of tooth shade tabs had some limitations that are based on subjective color perception and could be easily affected by environmental factors. In this research, we have developed a fiber optics spectroscopic tooth colorimeter with white LED, instead of the tungsten lamp to improve the size and heat problems. We have also developed a Whiteness-Yellowness index to simplify the tooth color information and have achieved an objectively and quantitatively tooth color representation.

Validation of Align Technology's Treat III digital model superimposition tool and its case application.

An assessment of the efficacy and accuracy of three-dimensional computer-based predictive orthodontic systems requires that new methods of treatment analysis be developed and validated. Invisalign is a digitally fabricated, removable orthodontic appliance that has been commercially available since 1999. It is made up of two main components: 1) computerized graphical images of a patient's teeth moving through a series of stages from initial to final position; 2) pressure formed clear plastic appliances made from stereolithography models of the images in the first component. The manufacturer of Invisalign (Align Technology, Inc.) has created a software tool that can be used to superimpose digital models to evaluate treatment outcomes in three dimensions. Using this software, research was conducted to determine if a single operator could repeatedly superimpose two identical digital models using 12 selected points from the palatal rugae over 10 trials. The tool was then applied to one subject's orthodontic treatment. EXPERIMENT VARIABLES: The output from this tool includes rotations, translations and morphological changes. For this study, translations and rotations were chosen. The results showed that the digital superimposition was reproducible, and that after multiple trials, the superimposition error decreased. The average error in x, y, z, Rx, Ry and Rz after 10 trials was determined to approach approximately 0.2 mm in translation and less than 1 degree in rotation, with a standard deviation of 0.15 mm and 0.7 mm, respectively. The treatment outcome from a single Invisalign-treated bicuspid extraction case was also evaluated tooth-by-tooth in x, y, z, Rx, Ry and Rz dimensions. Using the palate, as a stable reference seemed to work well and the evaluation of the single case showed that many, but not all, of the planned movements occurred.

Prevalence of dental caries in thalassaemic major patients

The aims of this study are to determine the prevalence of dental caries among thalassaemic major patients and compare the results with normal subjects. The study sample consisted of (35) thalassaemic patients and (35) non thalassaemic controls, all aged (14-22) years. Examination of the patient's teeth for dental caries prevalence in the two groups was performed using two methods: clinical and transillumination. There was no statistical difference in the prevalence and severity of dental carries between thalassaemic and non-thalassaemic groups. The results of this study indicate that the percentage of treated teeth in thalassaemic group was very low in comparison with non thalassaemic patients and this difference is statistically significant for all age groups except the last age group (20-22), where it is not significant.

Microbiological findings and host response in patients with peri-implantitis.

The aim of the present study was to characterise microbiota and inflammatory host response around implants and teeth in patients with peri-implantitis. We included 17 partly edentulous patients with a total of 98 implants, of which 45 showed marginal bone loss of more than three fixture threads after the first year of loading. Nineteen subjects with stable marginal tissue conditions served as controls. Oral hygiene, gingival inflammation, and probing pocket depth were evaluated clinically at teeth and implants. Microbiological and crevicular fluid samples were collected from five categories of sites: 1) implants with peri-implantitis (PI), 2) stable implants (SI) in patients with both stable and peri-implantitis implants, 3) control implants (CI) in patients with stable implants alone, 4) teeth in patients (TP) and 5) controls (TC). Crevicular fluid from teeth and implants was analysed for elastase activity, lactoferrin and IL-1 beta concentrations. Elastase activity was higher at PI than at CI in controls. Lactoferrin concentration was higher at PI than at SI in patients with peri-implantitis. Higher levels of both lactoferrin and elastase activity were found at PI than at teeth in patients. The concentrations of IL-1 beta were about the same in the various sites. Microbiological DNA-probe analysis revealed a putative periodontal microflora at teeth and implants in patients and controls. Patients with peri-implantitis harboured high levels of periodontal pathogens, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus and Treponema denticola. These findings indicate a site-specific inflammation rather than a patient-associated specific host response.

Osteo-odonto-keratoprosthesis. A summary of 6 years surgical experience

In patients with severe corneal scarring and vascularisation, corneal grafts have a high risk of failure. In those patients an osteo-odonto-keratoprosthesis (OOKP) can be performed. We performed OOKP in eight patients in all with ocular pemphigoid, severe alkali burns, or repulsion of a corneal graft. Each of the patients had finger-counting visual acuity or less. The OOKP consisted of a PMMA cylinder 8 mm long, with a diameter of 3-4 mm, and from a root of the patient's tooth. This was implanted in the cornea and covered with buccal mucosa. The medium follow-up was 3 years. The implants are now well incorporated. The best visual acuity was between 0.6 and 0.9 in four patients with intact retinas. In the remaining patients, visual acuity was dependent on the posterior segment findings. The visual field was centred. Five of the eight patients had vitreous bleeding after the operation that was spontaneously absorbed. Revision of the mucous coverage was necessary in four patients, and one of them had a severe inflammation with partial absorption of the bone and tooth implant. One patient developed a secondary angle-closure glaucoma and was treated successfully by implantation of an Ahmed valve. Two patients developed membranes behind the cylinder that were successfully removed. There was no loss of any prosthesis during follow-up. In impasse in severe corneal scars, the osteo-odonto-keratoprosthesis is still indicated and shows good results in visual rehabilitation of patients.

The quantification of dental plaque using an image analysis system: reliability and validation

Established clinical indices used to measure dental plaque have limitations. The aim of this study was to develop and evaluate a new method of quantitative plaque measurement, with increased sensitivity and reproducibility, using a purpose designed image analysis system. After plaque disclosure, the patient was positioned in a cephalometric head holder mounted in a custom-built frame with standard lighting and camera position. A 32-bit Digital Camera grabbed the image of the patient's teeth, which was analysed using Adobe Photoshop (V5.02, Adobe Systems Ltd, Europe) and Image Pro Plus software (V4.0, Media Cybernetics, USA). Measurements were made on 120 incisors in 15 patients and reproducibility was assessed using Fliess' Coefficient of Reliability. Sensitivity was assessed by comparison of results of treatment effects from a clinical trial involving 30 patients. Analysis of covariance was used to compare the image analysis system with the Turesky modification of the Quigley and Hein plaque index and the Addy plaque area index. The results were within the 'Excellent Reliability' category, for inter-operator reproducibility and intra-operator repeatability. This new system provided accurate quantitative measurements of dental plaque and labial tooth surfaces and was shown to have increased sensitivity when compared with the Turesky modification of the Quigley and Hein plaque index and the Addy plaque area index. The stored images can be re-measured for reliability and comparability between studies.

Simulated shape design: Helping patients decide their esthetic ideal

Esthetic care is changing dentistry from a need-based to a want-based practice. Patients are asking for esthetic treatment, and clinicians are retooling their practices to satisfy this need. One important part of providing esthetic dentistry is ensuring that the patient is as well-informed as possible about treatment outcomes. This article describes a tool dentists can use to show patients potential tooth sizes, shapes and arrangements before carrying out treatment. Simulated shape design, or SSD, is a reversible method of demonstrating potential esthetic outcomes that involves creating trial restoration shapes and placing them over a patient's teeth. SSD is a simple technique that any dentist can perform. In essence, the technician makes new tooth shapes in wax, the dentist places these in the patient's mouth and the patient evaluates them. The dentist then makes modifications in the SSD, which he or she reports to the technician. With the decisions of shape, arrangement and size made at chairside, the whole flow of esthetic treatment can be handled smoothly. Preparations can be cut more accurately to better support the restorative material; decisions can be made to open or not open the contacts; and shapes can be agreed on in the earliest stage of evaluation, then duplicated faithfully in the provisional and final restorations. There are no surprises for the patient, the dentist or the technician. Both the esthetic (smile design) and functional elements (anterior guidance) of the restoration can be checked with SSD. SSD could become the standard in determining whether or not to proceed with esthetic treatment.

Evaluation of robot-based registration for subtraction radiography

Digital subtraction of (plane film) radiographs of an area of interest taken over time is a powerful diagnostic tool. In dentistry for example, this is used to detect and treat periodontal disease (i.e. the sequence of diseases that leads to the loss of bone supporting the teeth). A precondition of subtraction radiography is correct three-dimensional registration of the film and X-ray source, without which the subtraction images are meaningless. A small misalignment can be compensated for by post-processing of the digitized films (by correspondence and rectification) to remove artifacts due to positioning errors. This paper presents a novel approach to subtraction radiography which replaces customary mechanical alignment methods (such as a stent or cephalostat) with a robot. A mechanical stent is a short rod attached at one end to the X-ray source and at the other to a mechanical appliance protruding from the patient's mouth. An experimental system was constructed which creates a ‘sensorized stent’ by integrating a plastic mouth appliance (with the impression of the patient's teeth), a robot carrying an X-ray source and a host computer. Results showed that the robotic system was superior to the mechanical alignment approach, due to its excellent accuracy and repeatability. This resulted in much less variation in the non-registered X-ray images, and in a smaller standard deviation in the intensities of subtracted images overall. The results suggest that in the future, diagnostic studies including subtraction radiography will not need either mechanical alignment (which is imprecise) or post-processing registration (which is time consuming).

Lip prosthesis retained with resin-bonded retentive elements as an option for the restoration of labial defects: A clinical report

J Prosthet Dent 1998;80:143-7

NdYAG laser treatment of dentinal hypersensitivity

Eighteen per cent of all patients have some degree of sensitivity and a range of therapies has been devised to alleviate this condition. An electronic monitoring machine was constructed which allowed for air stream, directed at a patient's tooth, to be started by the clinician and halted by the patient when the sensation of pain in the tooth became too unpleasant to tolerate. The time for which the patient could tolerate the air flow was electronically measured in units of 1/50th second. By measuring the patient's reaction time on each visit and correcting the readings obtained for 'tooth pain time' using these figures, a quantitative measure of sensitivity change is achieved. Using this system, a clinical trial has been conducted to test the efficacy of the NdYAG dental laser. The 30 patients treated had an average tooth pain time initially of 1.2 seconds. Following laser treatment patients were recalled at 3, 7 and 14 days. At the 2-week review, this figure had increased to 7.8 seconds, which was found to be statistically significant. Control (unlased) teeth demonstrated an average improvement of only 1.7 seconds (not statistically significant). Patients' subjective assessment of sensitivity pain on a 0-10 scale averaged 8.0 before treatment. This reduced to 3.7 after treatment. Treatment of this condition can thus be performed easily and painlessly with a predictable response and considerable patient satisfaction.

Head Holder for PET, CT, and MR Studies

A new head holder for the fixation and repositioning of the patient head in PET, CT, and MR scanners has been designed and tested. With this device, a bidimensional correlation between functional and anatomical brain images can also be obtained. Head fixation and repositioning are achieved using the patient's dental morphology as an anatomical reference. With a dentistic material, a mold of the patient's teeth is obtained in a few minutes. The molding substance rests on a plastic support, fixed to the head holder. Each time the patient undergoes a new study, his/her personal mold is used, ensuring accurate head repositioning. External markers fixed on the head holder (made visible in lateral PET and CT projection images, midsaggital MR images, and also on the axial images) make it possible to record and recognize the angular orientation and the position of the brain in the three-dimensional space, to correlate images of the same patient obtained with different neuroimaging modalities, and to accurately reposition patients for follow-up studies. The head holder was tested on several subjects. Fixation and repositioning accuracy of within 2.5 mm were achieved in the three-dimensional space. Orientation accuracy was 1 degree.

Comparison of Enamel Microabrasion Techniques: Prema Compound versus a 12‐Fluted Finishing Bur

This clinical study was done to compare the effectiveness of microabrasion with Prema Compound versus a high speed 12-fluted bur with water spray in removing incisor hypomineralized defects. Twenty-one patients had two incisors with enamel surface defects. It was randomly decided to use Prema Compound on one of the incisors and a 12-fluted bur on the contralateral incisor. One operator did all the procedures, but the tooth's color changes were rated by three observers who rated color photographs pre- and postoperatively, and one of the three rated each patient's teeth in person. The data revealed that there was no significant difference between Prema Compound and the 12-fluted bur in removing incisor hypomineralized defects. Both microabrasion techniques significantly improved the tooth's color, but the Prema method took over 9 minutes longer. The 12-fluted bur caused no clinically identifiable marks on the enamel surface. Both techniques were very reliable in removing the brown hypomineralized enamel defects, but were far less reliable in removing the white mineralization defects. The 12-fluted bur appeared to be an easier and equally effective alternative to Prema Compound for mineralization defects in incisors.

Multiple Keratoacanthomas and Junctional Epidermolysis Bullosa

REPORT OF A CASE Since a few months after birth, this 43-year-old man has reportedly suffered from sporadic blistering that occurs both spontaneously and in response to trauma. The blistering generally heals without scar formation. The patient has a younger brother with the same disease; their parents are first cousins. When first seen in our department in March 1986, the proband was noted to have multiple blisters, erosions, and crusts located primarily on the lower legs. Numerous atrophic scars, diffusely distributed over the entire body, were also observed, although milia were absent. The nails of both the fingers and the toes were either dystrophic or missing. The teeth were normal; however, many of the patient's teeth were extracted because of early caries. The scalp and hair were found to be normal, and no lesions were found on the oral mucosa. Histologic examination of a fresh lesion showed a subepidermal blister

Methods

Dental caries is a significant public health problem especially amongst children from low-income backgrounds. This longitudinal study examined the development of new occlusal caries in 227 Newark, NJ children ages 10–18. The role of previous caries experience and the presence of occlusal white and dark lesions in predicting the development of new lesions were examined.At each visit, the patient's teeth were given a visual-tactile examination and the subject's decayed, missing and filled (DMFS) score was determined. Next, molars lacking probeable caries or restorations were examined using transillumination for occlusal white and dark spots. This examination was repeated periodically. A Cox proportional hazard was used to analyse data concerning the development of new occusal caries in molars.The longitudinal data indicates that patients who were caries free at visit-1 developed significantly fewer occlusal caries during the longitudinal study. The hazard ratio for subjects who had first-visit caries was 2.27 compared to caries free subjects. Intact molars with occlusal white or dark lesions had caries hazard ratios of 0.78 and 1.49 respectively, compared to molars lacking initial colour changes.Having a prior caries history places the subject at increased risk of developing future caries. Teeth with dark lesions but not white lesions are at significantly increased risk for developing decay. White lesions may represent remineralizing or slowly progressing lesions. The results of this study can help identify patients and tooth surfaces at risk for future occlusal decay.

Dental extractions in relation to radiation therapy of 224 patients

The case histories of 224 patients treated with radiation therapy for head and neck malignancies at the Radiotherapy Clinic of the University Central Hospital in Turku during the years 1974–77 are reviewed. Of the 92 patients surviving for 5 years, 90 were available for re-examination. The median radiation dosage was 61 Gy in 6 to 8 weeks in patients with squamous cell carcinoma and other solid tumours and 43 Gy in 5 weeks in patients with lymphoma. The oral status of the patients was examined clinically and radiographically. From these patients, 45 teeth had been extracted before irradiation and 94 after irradiation. In no case had this resulted in osteoradionecrosis of the jaws. It is evident that the repairing of patient's teeth before radiation treatment, coupled with continuous preventive care of caries, will prevent serious complications from arising.

An intraoral single-tray impression system to protect the craniomandibular articulation.

AbstractProtection of the craniomandibular articulation is critical during lengthy prosthetic procedures. The system described in this article can make accurate recordings of anatomic detail by providing an impression of the dentition while the patient's teeth are in a fully occluded position. The procedure is accurate and easily accomplished, and it is not traumatic to the tissues within the temporomandibular joint.

Rationale for Treatment and Management of Avulsed Teeth

Fifteen hours after the patient's tooth was avulsed in a bicycle accident, replantation procedures began. This case presents a process of replantation and its success. An avulsed tooth is a traumatic experience. Replantation is often of psychological value. Although the possibility of the eventual loss of the tooth should be explained to the patient, replantation reduces the traumatic effect of the accident. It also has clinical value. Successful replantation results in prolonged retention which will improve esthetic appearance, arch form, chewing, enunciation, and integrity of the arch. Use of calcium hydroxide in avulsed teeth has allowed the rate of replantation success to increase greatly. It is a practical technique that is scientifically sound, has many positive indications, and has provided an invaluable service to patients.