Biomedical subjects

J Thomas Lambrecht

Publications and source records attributed to J Thomas Lambrecht.

At least 19 recordsLinked to original sources

PubMed2006

Accuracy of treatment planning based on stereolithography in computer assisted surgery.

Three-dimensional stereolithographic models (SL models), made of solid acrylic resin derived from computed-tomography (CT) data, are an established tool for preoperative treatment planning in numerous fields of medicine. An innovative approach, combining stereolithography with computer-assisted point-to-point navigation, can support the precise surgical realization of a plan that has been defined on an SL model preoperatively. The essential prerequisites for the application of such an approach are: (1) The accuracy of the SL models (including accuracy of the CT scan and correspondence of the model with the patient's anatomy) and (2) the registration method used for the transfer of the plan from the SL model to the patient (i.e., whether the applied registration markers can be added to the SL model corresponding to the markers at the patient with an accuracy that keeps the "cumulative error" at the end of the chain of errors, in the order of the accuracy of contemporary navigation systems). In this study, we focus on these two topics: By applying image-matching techniques, we fuse the original CT data of the patient with the corresponding CT data of the scanned SL model, and measure the deviations of defined parameter (e.g., distances between anatomical points). To evaluate the registration method used for the planning transfer, we apply a point-merge algorithm, using four marker points that should be located at exactly corresponding positions at the patient and at connective bars that are added to the surface of the SL model. Again, deviations at defined anatomical structures are measured and analyzed statistically. Our results prove sufficient correspondence of the two data sets and accuracy of the registration method for routine clinical application. The evaluation of the SL model accuracy revealed an arithmetic mean of the relative deviations from 0.8% to 5.4%, with an overall mean deviation of 2.2%. Mean deviations of the investigated anatomical structures ranged from 0.8 mm to 3.2 mm. An overall mean (comprising all structures) of 2.5 mm was found. The fiducial registration error of the point-merge algorithm ranged from 1.0 mm to 1.4 mm. The evaluated chain of errors showed a mean deviation of 2.5 mm. This study verifies that preoperative planning on SL models and intraoperative transfer of this plan with computer assisted navigation is a suitable and sufficiently reliable method for clinical applications.

Algorithms↗

PubMed2006

[Periradicular surgery with endoscopy--a clinical prospective study].

Using an endoscope in periradicular surgery provides an impressive optical enlargement and may lead to better clinical diagnostics and a high rate of success. Aims of this investigation were examining this hypothesis as well as detecting influencing factors. In 2002 and 2003, 114 teeth of 91 patients were root-end resected using endoscope. Before surgery, the tooth, number of resected root-ends, content of root channels, clinical diagnosis and moment of surgery were recorded. Patients were controlled one year after surgery and success was evaluated as a summary of clinical and radiological findings. Four patients did not reappear for the control examination. Out of 110 teeth, treatment was successful in 91.8% and failed in 7.3%. 0.9% could not be classified. Statistically, more failures were noted after periradicular surgery in molars. The rate of success increased during the study by means of a learning curve. The results confirm the hypothesis that where using an endoscope periradicular surgery is highly successful.

Adolescent↗

PubMed2006

[Sinus floor elevation and implantation--a retrospective study].

A retrospective analysis of sinusfloor elevation and implantation should evaluate in a sense of quality control the clinical results and complications during or after sinusfloor elevation. In our institution we performed 98 sinusfloor elevations in 80 patients (44 women, 36 men) between August 9, 1995 and November 18, 2002. In those elevated sinuses, 201 implants were inserted till October 16, 2003. Dates were sampled from the patient medical histories. Sinusfloor elevation and implantation in posterior maxillary bone have a good prognosis. Nevertheless implant survival depended on the chosen implant system (Kaplan-Meier-analysis). Implant survival was 98% for Straumann implants and 80% for Frialit-II implants after two years. A significant correlation between Frialit-II implants and Straumann implants (p=0.0119) was identifiable. There was no difference in healing between different augmentation materials (autogenous bone, Ceros 82, Algipore), but case numbers were too small for a relevant validity. In one-stage procedures implant loss was 8%, in two-stage procedures it was 18%. Implant losses in smokers were generally higher than in non-smokers. The period of consolidation of the augmentation's material introduced in two-stage procedures was about 10.3 months, healing time of implants 9.2 months. In one-stage procedures healing time of implants was about 7.7 months. Membrane perforations during surgery occurred in 11% and were not related to the development of postoperative sinusitis as described in literature.

Adolescent↗

PubMed2006

[The "globulomaxillary cyst" a specific entity or a myth?].

The following review investigates the term and concept of the globulomaxillary cyst as a correct clinico-pathological diagnosis to describe a so-called fissural cyst said to be caused by epithelial entrapment between the nasal and maxillary process. After analyzing the available literature it has to be concluded that neither from an embryologic nor from a clinical or pathohistological standpoint the term globulomaxillary cyst represents a real entity by itself. Therefore, globulomaxillary cysts have to be diagnosed alternatively after a thorough clinical, radiological and histological examination as other odontogenic cysts like dentigerous cysts or odontogenic keratocysts, odontogenic tumors like ameloblastoma, central giant cell tumors, solitary bone cysts, etc.

Diagnosis, Differential↗

PubMed2006

[Proliferative verrucous leukoplakia].

Proliferative verrucous leukoplakia (PVL) is a seldom form of oral leukoplakia (OL) with high transformation tendency. It starts as a bold hyperkeratosis changing into an exophytic verrucous form spreading in the oral cavity. The clinical diagnosis therefore is a retrospective one.

Aged↗

PubMed2006

[Diagnostic possibilities of digital volume tomography].

Cone beam computed tomography allows high quality 3D images of cranio-facial structures. Although detail resolution is increased, x-ray exposition is reduced compared to classic computer tomography. The volume is analysed in three orthogonal plains, which can be rotated independently without quality loss. Cone beam computed tomography seems to be a less expensive and less x-ray exposing alternative to classic computer tomography.

Adult↗

PubMed2005

[Vertical distraction osteogenesis of the alveolar process for implant treatment].

The rehabilitation of the chewing function of a patient is ultimately dependent on the quality and volume of the available jawbone. The vertical augmentation of the jawbone is often a challenge for the implanting dentist. Various methods, from transplanting autogenous bone through to the employment of bone substitute materials have been described and often controversially discussed. Vertical distraction offers an alternative to the pre-implantological augmentation of the vertically reduced bone. A technique which shows certain advantages over conventional augmentative methods.

Adolescent↗

PubMed2005

[The odontogenic keratocyst--odontogenic cyst or benign tumor?].

The odontogenic keratocyst is the third most common cyst of the jaws, after the follicular and radicular cyst. Keratocysts most commonly occur as single lesions in the jaw of otherwise healthy persons. Multiple odontogenic keratocysts are a well-recognized feature of the nevoid basal cell carcinoma syndrome. The mandible, especially the third molar region, the angle of the mandible and the ascending ramus are involved far more frequently than the maxilla. Clinically, the cysts often remain asymptomatic and there are two specific histological entities: the orthokeratinized and the parakeratinized odontogenic keratocyst. Different surgical treatment options like marsupialization, enucleation with curettage or peripheral ostectomy, and osseous resection (marginal or segmental) have been discussed in the literature with variable rates of recurrence. Besides a predilection for recurrence, the keratocysts, in contrast to other odontogenic cysts, show a more aggressive clinical behavior and demonstrate a high mitotic count and higher turnover rate of the epithelium. This led to the tentative suggestion that the keratocyst might be a benign cystic neoplasm rather than simply an odontogenic cyst.

Basal Cell Nevus Syndrome↗

PubMed2005

[Cardiovascular monitoring and its consequences in oral surgery].

The increasing number of high-risk patients in oral surgery makes it necessary to monitor the patient's general condition while operating. The surgeon needs a simple technical procedure to detect an impending clinical incident in time. From June 2002 to June 2004, 3012 patients underwent surgery in local anesthesia and were monitored with Colin BP 306 compact monitor. Heart rate, blood pressure, and oxygen saturation were checked non invasively during surgery. 17 times the operation was cancelled due to blood pressure problems. The treatment was cancelled twice due to cardiac arrhythmia. The average of the 19 patients' age was 63.5. Monitoring patients during surgery enables the surgeon to recognize high-risk situations immediately before the operation, to detect problem situations early and to avoid them, to work more calmly because of the enhanced security factor.

Adult↗

PubMed2005

[Controlled orthodontic extrusion with subsequent implantation].

Controlled orthodontic extrusion constitutes a non-surgical technique to increase alveolar bone material. Prosthetic reconstruction alone frequently does not achieve sufficient long-term aesthetics. An adequate implantation bed is indispensable to meet aesthetic demands. Controlled orthodontic extrusion represents an alternative to pre-implantological augmentation of the vertically reduced alveolar process and its soft tissue.

Adult↗

PubMed2005

[Knowledge and re-evaluation of the prevention of endocarditis in dentistry].

Physicians, dentists and patients were questioned as to their knowledge of endocarditis prophylaxis. about three quarters of the physicians and about half of the dentists were able to judge the risk of endocarditis correctly. Removal of calculus was underestimated as a risk for bacteriemia by physicians and patients alike. dentists overestimated the risk for endocarditis in the group of "non-risk-patients" (bypass), a fact resulting in an overdose/overuse of antibiotics. patients with lower education had less knowledge about the relation between their own personal risk and the necessary dental treatment.

Antibiotic Prophylaxis↗

PubMed2004

[Intraoral piezo-surgery].

The Piezo "effect"describes a physical interaction, which is used in different fields of clinical medicine. An ultrasound technology results in the power of a surgical cut technique, which is able to distinguish between hard and soft tissue. With the presented instruments it is possible to treat bone mechanically in a piezo-surgical manner without hurting the surrounding soft tissues when touching them. Four examples: Tooth extraction before implantation under minimal grinding of bone, Gaining bone for peri-implant transplantation, Preparation of Sinus Lift, Exposing the inferior alveolar nerve demonstrate the use of Piezo-Surgery in the intraoral area. This method shows a remarkable addition to the intraoral operation techniques.

Bone Transplantation↗

PubMed2004

[Bacterial contamination of bony particles from the bone collection trap].

Intraoral bony defects can be filled with bony particles that are collected in a titanium filter while drilling. The rinsing liquid is contaminated with blood and saliva which implies that the bony particles are also contaminated with bacteria. The aim of this study was to determine quantitatively and qualitatively the degree of this contamination. Over a period of three months bony particles were collected from 50 patients undergoing surgery. The bony particles were scraped off the filter, resuspended and incubated aerobically and anaerobically on human blood agar media. Colony forming units (CFU) were determined as well as the most common species of bacteria. All samples showed anaerobic and aerobic growth. After anaerobic incubation in 44 samples the number of bacteria was higher (38) or equal (six) to that after aerobic incubation. On average 435,000 CFU (aerobic) and 1,013,000 CFU (anaerobic) per sample were found. The most frequently identified bacteria belonged to Veillonella spp. in the anaerobic and to Streptococcus oralis in the aerobic cultures. In 43 samples black pigmented colonies were detected. There were only bacteria identified which are common in the oral cavity.

Adolescent↗

PubMed2004

[Treatment of intraoral hemangiomas with the CO2 laser].

Intra-oral haemangiomas can lead to intra-operative bleeding while being excised conventionally with a scalpel. Therefore excision with CO2-Laser using coagulating effects and vaporisation of soft-tissues has been introduced. 52 intra-oral haemangiomas were excised minimal invasively and without relapse. With CO2-Laser no complications were seen postoperatively but the healing period was prolonged.

Adult↗

PubMed2004

[Antibiotic prophylaxis and therapy in dental surgery].

Antibiotics are used for prophylactic and therapeutic indications. Since the conditions caused by bacteria resistance are in constant modification the regime has to be verified at regular intervals and adapted to the new conditions. The prescription of antibiotics in oral surgery and medicine should be administrated with reservation. The use of antibiotic prophylaxis is imperatively required during treatment of high-risk patients, especially in cases of endocarditis. An antibiotic therapy is absolutely indicated in acute osteomyelitis as well as in spreading and multispacial abscesses.

Abscess↗

PubMed2004

[Dose exposure from analog and digital full mouth radiography and panoramic radiography].

The present study investigated the dose exposition in the head and neck region by use of analog and digital radiographic dental systems. Four radiographic devices were tested: panoramic radiography (analog and digital) and 14-image full-mouth-survey (FMS, analog and digital). Organ doses were measured on a Rando-phantom by use of CaF2-dosimeters according to the IRCP-guidelines and the effective doses calculated. The results were the following: the value of E was lowest in digital FMS (41 microSv) and highest in analog FMS (78 microSv), i.e. dose was reduced by 47% by using a digital device. In panoramic radiography, doses were 17% lower using digital technique (digital 45 microSv vs. analog 54 pSv). Thus, FMS is no longer associated with higher doses than orthopantomography when conventional films are replaced by digital techniques.

Humans↗

PubMed2004

[Guided bone regeneration beneath titanium foils].

The aim of this study was to examine the clinical and histological bony healing process beneath titanium foils used for guided tissue regeneration as well as of the Frios Algipore graft which was applied with autologous bone. 66 sinus floor elevations were carried out and examined over a period of three years and eight months. A success rate of 64% was recorded with foil incorporation. Complications occurred in form of primary and secondary disturbances in the healing process caused by exposure of the foil. 12 of the 66 foils had to be removed early. In all but one case, the augmented bone material was macroscopically well integrated despite the loss of the foil. Primary stability of the inserted dental implants into the ossified augmented site after operations of the sinus maxillaris was reached in all cases with absence of post-operative complications, and in 94% when there was postoperative exposure of the membrane. Histologically, a thin layer of connective tissue poor in cells but rich in collagen fibers appeared underneath the titanium foil. This was followed by newly-formed bony tissue transforming into osseous lamella parallel to the membrane underneath the new periost. In 65 out of 66 cases a sufficient amount of stable bone was built up locally suggesting good bio-compatibility and barrier function. Further, the foil also provided mechanical rest and supporting function for the space underneath. However, the occurrence of healing complications in 36% of the cases showed a need to improve on the titanium foils.

Bone Regeneration↗

PubMed2004

[Cleft lip and palate surgery in India].

10 cleft lip and palate temporary facilities were set up 1994-2003 in a Christian Hospital in Central India. 725 patients were operated upon. An analysis of the operations in regard to lip closure, closure of the soft and the hard palate, secondary cleft operations and cleft-related surgery is given. Differing therapy concepts in developed countries are discussed and compared to experiences of other third world volunteer medical groups.

Adolescent↗