Biomedical subjects

D Schwartz-Arad

Publications and source records attributed to D Schwartz-Arad.

At least 19 recordsLinked to original sources

PubMed2006

[Atrophic ridge augmentation using intra-oral onlay bone grafts--expanding the limits].

Placement of an endosseous implant requires sufficient bone volume for complete bone coverage. There is a growing use of intraoral block bone grafts from intraoral sources. The use of bone from the mandibular symphysis, retromolar area, mandibular ramus, and the maxillary tuberosity can serve as a good treatment alternative for alveolar ridge augmentation with a high success rate for long span augmentation, up to complete jaw augmentation or extensive bone reconstruction. The intraoral block bone graft procedure can be combined with other surgical procedures, such as sinus lift elevation or nasal floor elevation.

Alveolar Bone Loss↗

PubMed2005

Radiological features of central haemangioma of the jaws.

OBJECTIVES: The aim of this study was to evaluate the radiological and clinical features of central haemangioma of the jaws. METHODS: A total of 86 cases (84 from the English-language literature and two new cases) were studied and critically evaluated with emphasis on the radiological features. RESULTS: Age at time of initial diagnosis ranged from 0 to 74 years (mean 23 years, median 17 years). There was approximately equal distribution between females and males. The ratio between the mandible and maxilla was 3.3:1. Of the lesions, 69% were located in the posterior region of the jaws. Lesions were radiolucent in 96% of cases. Of the lesions, 66% were multilocular, 33% unilocular, and 1% not loculated. Borders were described in 41 cases, as well defined in 32% and diffuse in 68%. Tooth resorption was described in 23% of the lesions and tooth displacement in 16%, both more common in the mandible. The inferior alveolar nerve canal was involved in 15% of the mandibular lesions and the sinus in 35% of the maxillary lesions. CONCLUSIONS: Central haemangioma has a marked variability in its radiological appearance and should be considered in the differential diagnosis of many unilocular or multilocular radiolucent lesions of the jaws, especially in the mandible. Some radiographic patterns, such as the spoke-like and sunray appearance frequently described in the literature, are actually extremely rare.

Adolescent↗

PubMed2005

[Smoking as a risk factor for dental implants and implant-related surgery].

Cigarette smoking is known to adversely affect wound healing, and thus may jeopardize the success of dental implantation and implant-related oral surgery. The present study is aimed to present the influence of cigarette smoking on the success and survival of dental implantation as well as on the complication and success of implant-related surgery. We conclude that smokers undergoing both implant-related surgical procedures and dental implantation should be encouraged by their dentists, oral and maxillofacial surgeons, or treating physicians to cease smoking, emphasizing that smoking can increase complications and reduce the success rate of these procedures.

Dental Implantation, Endosseous↗

PubMed2004

[Preservation of alveolar bone of un-restorable traumatized maxillary incisors for future].

UNLABELLED: Anterior maxillary implantation is a challenging treatment for both the surgeon and prosthodontist due to high esthetic demands in this area. However, it is the most traumatized and most exposed region to habits. Prompt and appropriate management can significantly improve prognosis of many dentoalveolar injuries, especially in young patients. Unfortunately, many traumatized teeth are overtreated or left untreated, which lead to a much more complicated treatment at the time of permanent restoration at adulthood. The facial cortical plate over the roots of the maxillary teeth is thin and porous. Periapical infections, as well as prolonged and stubborn surgical treatments (repeated root end surgeries) can cause resorption of the labial plate, migrate to a more palatal position, and may later require an augmentation procedure prior to implant placement. The treatment-options of traumatized, anterior maxillary, un-restorable fractured root and ankylosed infraocluded teeth, in relation to preservation of the adjacent alveolar bone for future use of dental implantation will be discussed. The recommended treatment of crown-root fracture of permanent incisor includes removal of the coronal fragment and supragingival restoration of the fractured root. In severe cases in which the fracture line positions deeply under the gingival margin, this treatment may be supplemented by gingivectomy and/or osteotomy, as well as surgical or orthodontic extrusion of the root. In young patients, use of these treatment options as temporary treatment to preserve the facial cortical plate is important. Preservation of alveolar dimension will enable implantation after the completion of growth and development. Dento-alveolar ankylosis accompanied by replacement resorption is a serious complication following severe injury to the periodontal membrane. This complication develops mainly following avulsion and intrusion but also following lateral luxation and root fracture. Replacement resorption develops after severe damage to the periodontal ligament cells that cover the root surface. As a result of this damage, the periodontal ligament is replaced by bone tissue, causing ankylosis between bone and tooth. Following ankylosis, resorption of cementum and root dentin occurs. These processes eventually result in replacement of the entire root by bone. In young children it could arrest the growth of the alveolar process and create an infra-occluded tooth, resulting in a severe bony defect that is difficult to correct. In addition, loss of the maxillary incisor leads to serious esthetic and restorative problems, particularly when the trauma occurs at a young age. Therefore, ankylosed teeth should be treated as soon as diagnosed. Alternative treatments include intentional extraction and immediate replantation of the ankylosed tooth to its socket after embedding the tooth and the socket in Emdogain. This treatment is indicated only when the ankylosis or the replacement resorption is diagnosed at an early stage or has affected only a small area of the root. When the resorption is diagnosed at a later stage, auto transplantation of first lower pre-molar to the anterior region or decoronation of the ankylosed tooth may be considered. Decoronation is a simple and safe surgical procedure for preservation of alveolar bone prior to implant placement. It should be considered as a treatment option for teeth affected by replacement resorption. The alternative treatment of surgical extraction of an ankylosed tooth often leads to considerable bone loss and reduced bone volume in the oro-facial dimension. This may later necessitate an augmentation procedure. CONCLUSION: Scrupulous diagnosis of teeth and the alveolar bone after a traumatic injury is necessary. Treatment is multidisciplinary, requiring endodontic, surgical, orthodontic, operative and prosthetic compliance. An individual treatment plan for each patient is necessary. General rule do not apply. Periodic check-up is essential.

Adult↗

PubMed2002

[Intraoral autogenous onlay block bone grafting for implant dentistry].

The use of autogenous bone graft with endosseous implant for the reconstruction of alveolar ridge deficiencies has been reported with increasing frequency in the past two decades. These bone grafts were harvested mainly from extra oral sites. Various donor sites have been described in the literature including the calvarium, tibia and iliac crest, the latter being most common. Due to the need for hospitalization, general anesthesia and the great morbidity of surgery associated with these donor sites, alternative intra oral sources for graft harvest have been suggested. The most common sites for, being the mandibular symphysis and the mandibular ramus. For the repair of localized alveolar bone defects these donor sites are advantageous. In addition to the ease of donor site access and minimal morbidity, membranous bone grafts show less resorption, good incorporation and shorter healing times. The use of these bone grafts allow us to correct the alveolar ridge height, width and trajectory prior to implant placement thus not only enable a better surgical success, but also should enhance a better prosthetic results as well.

Alveolar Ridge Augmentation↗

PubMed2000

The clinical effectiveness of implants placed immediately into fresh extraction sites of molar teeth.

BACKGROUND: Studies concerning immediate implantation describe its use in the anterior and premolar regions. However, its clinical effectiveness in immediately replacing molar teeth has rarely been challenged. The purpose of this study was to evaluate the survival rate of implants placed immediately after extraction of molar teeth to support a fixed ceramo-metal prosthesis. METHODS: From 1989 to 1996, 56 immediate implants were placed in 43 patients following extraction of 51 molars; 46 molars were replaced by 1 implant and 5 molars replaced by 2 implants. All implants were restored with fixed prostheses (4 single crowns and 52 splinted). Mean follow-up period was 15 months (range, 4 to 60 months). The influence of the following parameters on implant failure was evaluated: gender, arch, smoking, pre-extraction vertical bone loss, implant length, and severity of complications between the two stages of surgery. RESULTS: The 5-year cumulative survival rate (5-year CSR) was 89%. The 5-year CSR among men was 84% compared to 93.5% among women. The maxillary 5-year CSR was 82% and the mandibular 92%. Among non-smokers (50 implants), the 5-year CSR was 90% compared to 83% among smokers (6 implants). Complications were evident in 8 (6 minor, 2 major) out of 50 non-failing implants compared to 2 (minor) of the 6 failing implants. No differences were evident in the other study variables. CONCLUSIONS: Immediate implantation in the molar region is an alternative, predictable surgical treatment. Immediate implantation in the posterior mandible has a better prognosis than in the posterior maxilla.

Adolescent↗

PubMed2000

Immediate versus non-immediate implantation for full-arch fixed reconstruction following extraction of all residual teeth: a retrospective comparative study.

BACKGROUND: Immediate implants placed into fresh extraction sites are considered a predictable and acceptable procedure. The main biological advantage is the preservation of bone height and width. However, there is no direct proof of the clinical and surgical importance of this. The purpose of this study was to evaluate the correlation between implant dimensions, anatomic factors, and survival rates of immediate versus non-immediate implants. METHODS: From 1989 to 1996, 380 implants (117 immediate and 263 non-immediate) were placed in 43 patients (50 jaws) following extraction of all residual teeth. A total of 253 implants were placed in the maxilla and 127 in the mandible, with a mean of 7.65 and 7.9 per jaw, respectively. Of the implants, 31% were placed immediately into fresh extraction sites. RESULTS: Total 5-year cumulative survival rate (CSR) was 92%, mandibular 96% and maxillary 90%. Immediate implants had a better 5-year CSR (96%) versus non-immediate implants (89.4%). The maxilla mainly contributed to this difference (95% versus 88%). The mean potential contact surface area (PCSA) was 230 mm2. Implants with significantly higher values yielded a higher 5-year CSR in the maxilla (96.6% versus 82.9%). Immediate implants in the posterior maxilla had a 100% 5-year CSR versus 72% with the non-immediate implants. CONCLUSIONS: 1) Implant-supported fixed ceramo-metal prosthesis is a predictable treatment modality for edentulous patients; 2) factors favorably affecting the survival of implants placed to support full-arch ceramo-metal prosthesis include immediate implantation, higher PCSA values, and implant location; 3) immediate implantation exerts its effect through higher PCSA values and by a compensatory effect to bone quality; 4) immediate implantation does not carry additional morbidity; and 5) potential contact surface area (PCSA) is a reliable mean that accurately represents implant dimensions and may replace length and diameter in future studies.

Adult↗

PubMed1999

Odontogenic cysts related to pulpotomized deciduous molars: clinical features and treatment outcome.

OBJECTIVE: The purpose of this study was to assess the morbidity and outcomes associated with large cysts that developed in conjunction with pulpotomized deciduous molars. STUDY DESIGN: This retrospective study was based on the files of 18 patients who were referred to 2 oral surgery departments during a 10-year period (1986-1996). The inclusion criteria were large cyst lesions (>1 cm in diameter) and complete documentation. Data regarding symptoms at presentation, histologic and radiologic features, treatment modalities, morbidity, and outcomes were analyzed. RESULTS: An equal gender distribution of patients was found, as were a later development in males (12+/-2 years in boys, 9+/-2 years in girls) and a 5:1 ratio favoring the mandible over the maxilla. Treatment included enucleation (12 patients) and marsupialization (6 patients). The morbidity was high and included loss of permanent teeth (3 patients), extensive loss of alveolar bone (3 patients), use of flaps (2 patients), and adjuvant orthodontic treatment (9 patients). CONCLUSION: Failure of early detection and treatment of cysts that develop in conjunction with pulpotomized deciduous molars can cause considerable morbidity. Therefore, periodic clinical and radiologic follow-up until the eruption of succedaneous teeth is recommended.

Adolescent↗

PubMed1999

Full-arch restoration of the jaw with fixed ceramo-metal prosthesis: late implant placement.

BACKGROUND: The completely edentulous patient has few treatment options in conventional dentistry. When implants are considered, treatment plans range from a 2-implant overdenture to a completely implant-supported prosthesis. Fixed prosthesis is often the preferred selection of the edentulous patient. This study assesses the 5-year cumulative survival rate of implants placed to support full-arch fixed restoration. METHODS: During 1990 to 1995, 171 implants were placed in 22 completely edentulous jaws of 20 patients. All patients were discharged wearing immediate dentures. The implants were analyzed as to the number of implants per jaw, implant location, length, and diameter. RESULTS: The 5-year cumulative survival rate was 89.9%. The mean number of implants per jaw was 7.7 for the maxilla and 8 for the mandible. In the maxilla, the preferred implant locations were the canines, centrals, laterals, and first premolars; in the mandible, they were the canines, laterals, and first molars. The mean implant length was 14.2 mm for the mandible and 13.2 mm for the maxilla. The mean implant diameter was 3.6 mm for the maxilla and 3.8 for the mandible. CONCLUSIONS: The results of the present study indicate that fixed full-arch ceramo-metal restorations can be a predictable implant treatment modality for the edentulous patient.

Adult↗

PubMed1999

Single tooth replacement of missing molars: a retrospective study of 78 implants.

As experience with osseointegrated implants has grown, greater use has been made of placement in the posterior jaw. The aim of this study is to present the survival rate of 78 osseointegrated single implants, inserted in the molar area and to evaluate the prosthetic rehabilitation on these teeth. This retrospective study presents findings of 55 consecutive patients with 78 restored single osseointegrated implants in the molar area. The patients went through a clinical and radiological evaluation. The same maxillofacial surgeon inserted all implants. Three of the implants were inserted into the maxilla and 75 into the mandible; 4 of the 78 implants were immediate implants. The cumulative survival rate after one year was 93.6%. Follow-up was up to 80 months, with an average of 27 months. Out of all the implants, 6 failed (7. 7%): 5 failed in the surgical stage, and 1 after prosthetic loading. The main implant failures were among the titanium screw implants. Prosthetic complications occurred in 11 cases (14%), which included loosening of the abutment and/or the crown (9 cases), fracture of the abutment (1 case), and porcelain fracture (1 case). No incident of implant fracture occurred. Within the limits of this study, replacement of a single molar by a single implant is a valid and successful surgical treatment modality, with a high survival rate.

Adult↗

PubMed1998

Immediate implant placement: a procedure without incisions.

Primary socket closure in immediate implantation may be difficult, due to the opening left by the extracted tooth. The absolute need for bone augmentation and primary flap closure for implants placed into fresh extraction sites has never been proven. The hypothesis of the present study was that immediate implants can succeed without primary flap closure. A technique that does not require any incisions during immediate implant placement is described. No barrier membranes were used and the sole grafting material used were autogenous bone chips. Full soft tissue coverage was achieved 1 week to 2 months postimplantation. Clinical osseointegration was achieved with minimal gingival recession and papillae preservation. Immediate implant placement in the anterior maxilla can be successful for replacing a single tooth even without primary closure.

Adult↗

PubMed1997

The ways and wherefores of immediate placement of implants into fresh extraction sites: a literature review.

A waiting period of 12 months or longer to allow total socket healing used to be accepted protocol for placing dental implants. More than 15 years of research and clinical practice were needed for the concept of immediate endossceous implantation into fresh extraction sites to be accepted. Today the dilemma is no longer when, but which, protocol to follow. The diverse recommendations found in the literature leave the practitioner confused as to the methodology of choice. The conclusions drawn after reviewing the relevant literature on immediate dental implantation are: 1) implants placed into fresh extraction sockets have a high rate of survival, ranging between 93.9% to 100%; 2) implants must be placed 3 to 5 mm beyond the apex in order to gain a maximal degree of stability; 3) implants should be placed as close as possible to the alveolar crest level (0 to 3 mm); 4) there is no consensus regarding the need for gap filling and the best grafting material; 5) the use of membrane does not imply better results-on the contrary, membrane exposure may carry complications in its wake; and 6) the absolute need for primary closure remains to be established.

Alveolar Process↗

PubMed1997

Placement of implants into fresh extraction sites: 4 to 7 years retrospective evaluation of 95 immediate implants.

A 7-year follow-up of implants placed immediately after tooth extraction into fresh extraction sites is reported. Small autogenous bone chips (from bone adjacent to implant sites) were grafted into the defect between the implant and the socket walls when needed. Closure of the wound was obtained by coronal repositioning of the flap, and no membranes were used. Care was taken to minimize hematoma formation under the flap during healing by part-time use of removable prosthesis with thick soft linings after implant surgery. At second stage surgery, mucoperiosteal flaps were apically repositioned for maximum attached gingival width and to reconstruct the vestibule. Minor complications such as exposure occurred in 16% of cases. Implant mean 5-year cumulative survival rate was 95%. There was no implant loss after loading. The results indicated that implants placed into fresh extraction sites grafted with autogenous bone chips will heal predictably.

Adult↗

PubMed1991

Streaming liver. VIII: Cell production rates following partial hepatectomy.

Twenty-four young, female, random-bred rats weighing 250 g were partially hepatectomized and killed in groups of four animals at the following times: 1 h and 1, 2, 3, 7 and 14 days. One hour before killing, each rat was injected i.p. with 0.5 microCi [3H]-thymidine, specific activity 5 Ci/mmol/g body weight. Livers were processed histologically and dipped into liquid emulsion for autoradiography. Twenty-four hours after partial hepatectomy, hepatocyte and littoral labelling indices rose, reaching on the third day respective peak values of 3.7%, and 15.4%, whereupon they declined, remaining slightly above pre-treatment level. Labelling indices served for cell production estimates. On day 3 the hepatocyte labelling index rose 26-fold. At the same time hepatocytes doubled their ploidy, indicating that half of the observed L.I. increase was directed to DNA accumulation and not to cell division. The hepatocyte production rate therefore increased 13-fold (or 1300%). The acinus diameter increased 15%, and cell density declined 5%, so that the acinus capacity to retain cells increased only 5%. Since the acinus did not enlarge proportionally to cell production, it is concluded that 95% of newly formed cells were eliminated. Partial hepatectomy thus triggers two processes: an acute process lasting about a week marked by massive and rapid cell turnover during which most newly formed cells are eliminated; and a second, more protracted process which serves for liver mass restoration. It is proposed that partial hepatectomy induces an acute shortage of a hitherto unknown metabolite that is produced by newly formed cells immediately after hepatectomy.

Animals↗

PubMed1991

Compensatory hyperplasia of the rat submandibular gland following unilateral extirpation.

This study investigated the morphological changes in rat submandibular glands undergoing compensatory hyperplasia. Fifteen adult male rats underwent left submandibulectomy, after which they were killed in groups of five (at days 3, 7, and 14), and their right submandibular glands (SMG) were excised. Fifteen control rats were killed in groups of five (at days 0, 7, and 14), and their right SMG were removed. Sections of 3 microns were cut, and the parenchymal and stromal cells were counted in 50 microscopic fields and sorted according to their morphological features and "class". Class is equivalent to the number of nuclei in an acinar or tubular cross-section. No change in glandular weight was noted post-surgery. Total cell count/field rose to 138.5 +/- 7.1% of control values on day 3 after gland extirpation, remaining almost constant thereafter until the end of the experiment. Acinar cell count and class showed a 154.1% peak on day 3, followed by a 30% drop in cell count by day 7 and an equivalent decline in class by day 14. Tubular cell count increased gradually to 146.5% by day 14, without a change in class. In the first week, the increase in tubular cells was mainly due to intercalated duct (ID) cells, while in the second week, there was a sharp rise in granular duct (GD) cells. This diverging cellular behavior indicates that the GD cell stems from the ID cell. The cellular changes in the hyperplastic SMG indicate death of newly generated acinar cells and expansion of the glandular progenitor compartment, as expressed in elongation of the ID.

Adaptation, Physiological↗

PubMed1990

Squamous odontogenic tumor. Review of the literature and case report.

Squamous odontogenic tumor (SOT) is a rare, benign odontogenic tumor affecting both jaws in all age groups. The tumor is composed of squamous epithelial islands surrounded by a mature connective tissue stroma. This tumor may occasionally be misdiagnosed as ameloblastoma, squamous cell carcinoma, verrucous carcinoma and keratoacanthoma. A conservative surgical approach is the recommended treatment. An additional case is reported and the literature reviewed.

Child↗

PubMed1990

Streaming liver. VII: DNA turnover in acinus zone-3.

Livers of four young, male, random-bred rats weighing 250 g were fixed in formalin and stained with Feulgen. In each section, 50 hepatocytes were randomly selected and their distance from the nearest terminal hepatic vein was measured with an eye-piece micrometer. Distance was expressed in two units: 1. micrometer and, 2. cell location, or the cell number separating a sampled cell from the terminal hepatic rim. The sections were scanned with an image cytometer. The tissue was magnified x 400 and digitized into 512 x 512 pixels. The software determined the nuclear boundary and estimated its area and optical absorbance, which was expressed in relative DNA units. One unit equals the absorbance of a diploid lymphocyte. Nuclear area and optical absorbance measurements were made up to 220 microns distance from the terminal hepatic vein which roughly covers zones 2 and 3. Previously we have shown that in zones 1 and 2 hepatocyte nucleus enlarges and becomes polyploid. The present study demonstrates that in zone-3 this trend is reversed, nuclear area and DNA absorbance decline. The average hepatocyte advances 2 microns daily. In zone-1 it accumulates daily 0.005 DNA absorbance units and in zone-3 it loses daily 0.24 DNA absorbance units. It is proposed that in zone-3 DNA leaves the intact cell in a physiological way. DNA accumulation and polyploid are regarded here as forms of gene amplification which may be reversed, so that under these circumstances amplified DNA may be "deamplified" and the excess DNA leaves the cell.

Animals↗

PubMed1990

Streaming pancreas: islet cell kinetics.

Thirty male young adult rats aged 7 weeks, weighing 200 g, were injected with 0.5 microCi/g body weight tritiated thymidine (specific activity 5.0 Ci/mM). The rats were then killed in groups of five, at the following times: 1 hour, and 14, 28, 42, 56, 90, and 120 days. The pancreata were dissected, embedded in paraffin, and cut into 5 microns thick sections which were then dipped into liquid emulsion. The labelling index of acini and islet cells was estimated in each autoradiogram, and their distance from intercalated duct was measured. Acini and islet cells streamed away from the intercalated duct at a daily velocity of 0.52 microns. Acinus labelling index which was initially 0.78% declined with time. Islet cell labelling index was initially 0.38%. In the following days it climbed upward reaching on the 42nd day its peak value of 0.78%. From then onward it declined to a low of 0.38%. Since cells were labelled only once, and labelling was instantaneous, it is concluded that labelled acinus cells entered the islet, and that acinus cells are actually islet cell precursors. The pancreas is structured kinetically like other exocrine glands, being a two compartment cell renewal system which continuously renews its cells. The pancreocyte is a descendant of an intercalated duct progenitor. After leaving the duct it turns into an acinus cell, gradually approaching the Langerhans islet. After crossing its border it becomes an islet cell, and proceeds toward the islet center. Its population size dwindles exponentially until at islet center all cells are eliminated.

Animals↗