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Biomedical subjects

L A Weinberg

Publications and source records attributed to L A Weinberg.

At least 19 recordsLinked to original sources
PubMed2001

Therapeutic biomechanics concepts and clinical procedures to reduce implant loading. Part I.

A new approach called therapeutic biomechanics that uses 5 possible corrective procedures that can be used in conjunction with each other to reduce implant loading has been suggested. These procedures are the following: (1) a cross-occlusion (to reduce horizontal implant offset); (2) the head (hex) of the implant should be placed as close to the midline of the restoration as possible; (3) angled or custom reangulated abutment; (4) shallow cusp inclines; and (5) modified centric occlusal anatomy. On maxillary anterior restorations, a horizontal lingual stop redirects the resultant line of force in a vertical direction much closer to the implant and supporting bone. Part II of this paper will focus on laboratory and clinical procedures to implement the concept of therapeutic biomechanics.

Alveolar Bone Loss↗
PubMed2001

Therapeutic biomechanics concepts and clinical procedures to reduce implant loading. Part II: therapeutic differential loading.

Practical laboratory procedures were suggested in order to provide a modified occlusal anatomy to reduce implant loading. The concept of differential mobility caused by the flexion between a natural tooth/periodontal ligament interface with its supporting bone, compared with the stiffness of the implant/bone interface, was described. When individual tooth-supported and implant-supported prostheses coexist in the same arch, this differential mobility can shift the loading disproportionately from the natural teeth to the implants. A new concept of therapeutic differential loading is introduced and a clinical technique of differential occlusal adjustment is described to bring about a more favorable distribution of loading to all the supporting bone. Long-term natural tooth intrusion can cause implant overload. Therefore, it is suggested that periodic differential occlusal adjustment procedures be used to re-establish a long-term balance of loading between individual implant- and tooth-supported prostheses within the same arch.

Biomechanical Phenomena↗
PubMed1999

Three-dimensional guidance system for implant insertion: Part II. Dual axes table--problem solving.

The three-dimensional guidance system for implant insertion is a technique for placing a radiopaque vertical orientation pin over the crest of the alveolar ridge on the stone cast during fabrication of the radiographic guide. The cross-sectional and panoramic reformatted images were reproduced on a Polaroid or 35-mm print. The true vertical orientation pin facilitates (1) identification and the exact planned location of each implant in the reformatted images of the CT scan, (2) establishment of the internal starting point for the osteotomy on a photographic print, (3) optimum implant orientation, and (4) measurement of the angulation between the true vertical orientation line and optimum implant orientation. With the aid of a newly developed dual-axes base and transfer of the internal starting point of each implant to the stone cast, the buccolingual and mesiodistal implant inclinations for each implant were transferred to a surgical guide in the form of surgical steel drill guide tubes. The resulting pilot osteotomy transfers to the alveolar bone the exact starting point and the buccolingual and mesiodistal inclination for each implant. The technique provides a three-dimensional guidance system for implant insertion that is extremely accurate and yet practical.

Anatomy, Cross-Sectional↗
PubMed1998

Three-dimensional guidance system for implant insertion: Part I.

A technique is presented, with two sets of newly designed drills, that facilitates three-dimensional guided insertion of implants. A radiographic guide has been fabricated with titanium markers that are transferred into the CT scan reformatted images. The resulting cross-sectional and panoramic reformatted images provide the precise location for each implant. The buccolingual and mesiodistal inclinations of each implant are measured and transferred to a surgical guide that contains steel drill guide tubes. The starting point and three-dimensional orientation of each implant is then transferred to a pilot osteotomy. The widening of an osteotomy, with end-cutting drills of the usual design, can lead to the loss of orientation because a wider drill cannot be effectively guided by a smaller diameter osteotomy. A newly designed set of drills has been developed that maintains tracking of the original orientation as the incremental increase in width proceeds. The three-dimensional guidance system for implant insertion was first accomplished in vitro and then on patients.

Anatomy, Cross-Sectional↗
PubMed1998

Reduction of implant loading with therapeutic biomechanics.

All physiologic biomechanical processes are interrelated and, therefore, reactive, which produces an accumulative effect that can cause implant overload. A new approach called "therapeutic biomechanics" suggests using corrective procedures to reduce implant loading. The head of the implant is positioned as close to the midline of the restoration as possible. Implant inclination may be required, but it produces less torque (moment) than horizontal implant offset. Posterior cross occlusion should be used where possible to decrease horizontal implant offset. Angulated, or reangulated abutments provide access or parallelism as needed. The posterior cusp inclination should be markedly reduced. When a vertical overlap is present anteriorly, a horizontal stop on the maxillary lingual surface redirects harmful lateral force to be vertical toward the implant and supporting bone. Because of physiologic variability, creating a modified centric occlusion that contains a 1.5-mm fossa will produce vertical resultant force within this range of motion rather than lateral force.

Alveolar Bone Loss↗
PubMed1997

Problems in educating abused and neglected children with disabilities.

OBJECTIVE: This study considers whether Goerge and colleagues' (1992) thesis is correct--that the reason the special education needs of abused or neglected children in foster care are not being met appropriately is that the services provided to them revolve around their need for protection. METHOD: A case study was done of 12 children with disabilities who were removed from the homes of their parents because of abuse or neglect. The primary data were the legal interventions made on the children's behalf with various agencies serving them by a legal services office. Data were collected through semi-structured interviews and a review of the children's case files. RESULTS: The number of dysfunctions identified in the various agencies serving the children that negatively affected the children's ability to receive an appropriate education were in the following categories: search and serve (3); eligibility (1); timeline violation (8); IEP violation (11); inappropriate program (17); inadequate resources (4); lack of knowledge (3); parent advocacy problem (3); lack of coordination (7); dependent status (8); mobility delay (9). CONCLUSIONS: In those instances where the child welfare agency did not take into account a child's educational needs when placing that child, but simply considered the appropriateness of the living situation to protect and care for the child, then the thesis appears to be borne out. However, some-dysfunctions appear to be part of routine lack of compliance with certain areas of special education law, and would seem to affect any child with similar disabilities and educational needs in the offending school districts.

Adolescent↗
PubMed1996

An evaluation of torque (moment) on implant/prosthesis with staggered buccal and lingual offset.

The supposition that staggered buccal and lingual implant offset is biomechanically advantageous was examined mathematically. The method of evaluation utilized a standard hypothetical geometric configuration from which implants could be staggered buccally and/or lingually in both arches. Torque (moment) values were calculated at the gold screw, abutment screw, and 3.5 mm apical to the head of the implant. Comparisons were made in percentages of change from the hypothetical standard to the buccal and/or lingual implant offset. In the maxillary arch, buccal offset decreased the torque (moment) while lingual offset increased it. If more lingually offset implants were present in the maxillary restoration, the total torque would be greater than if they were all in a straight line. Staggered buccolingual implant alignment often requires abutment reangulation. The resultant line of force produced by occlusal anatomy usually results in buccal inclination in the maxillary arch and lingual inclination in the mandibular arch. As a result, mandibular implant/prostheses are greatly favored over similar maxillary configurations because the mandibular resultant line of force usually passes lingually, closer to the components and supporting bone and considerably less torque is produced. Therefore, the concept of staggered offset for multiple implant-supported prostheses can be utilized on the mandible but is not recommended for the maxilla where maximum uniform buccal implant orientation is advised.

Algorithms↗
PubMed1994

Biomechanical considerations when combining tooth-supported and implant-supported prostheses.

The force distribution of multiple tooth-supported and implant-supported prostheses is completely different. A direct correlation exists between the degree of flexion at the site of loading and the amount of force distribution to other members of the prosthesis. Micromovement produced by the periodontal fibers facilitates force distribution to all the root surfaces of the natural tooth abutments. The rigidity of the implant/abutment/prosthesis configuration concentrates the force at the crestal bone at the site of loading with limited distribution to the remaining implants. Differential mobility concentrates the force distribution to the bone support of the most rigid members of splinted natural teeth or to the implants when they are united with natural teeth in a combined prosthesis. Implants always support the natural teeth and never the other way around. Therefore a nonrigid attachment is recommended between a tooth-supported prosthesis and an implant-supported prosthesis when they are combined. However, when implants are interspersed with natural teeth in the same prosthesis, the restoration will be implant borne. This requires special force distribution analysis to prevent implant overload.

Alveolar Process↗
PubMed1993

CT scan as a radiologic data base for optimum implant orientation.

There are many factors directly related to the longevity of implant osseointegration. Overload has been considered an etiologic factor in implant failure after a prosthesis has been constructed. Optimum implant orientation can be aided by the three-dimensional radiographic data base provided by a CT scan. The reformatted sectional images, when related to each other, facilitate a thorough visualization of the bone topography, sinus and nerve location, and bone density. The fundamentals of the CT imaging and the interrelationship of the cross-sectional, panoramic, and three-dimensional reformatted images are described.

Calibration↗
PubMed1993

The biomechanics of force distribution in implant-supported prostheses.

Force distribution with natural teeth depends on micromovement induced by the periodontal ligament. The location and cusp inclination of the tooth qualitatively alter the force pattern. Osseointegrated implants do not have micromovement associated with force distribution. Force distribution to the osseointegrated implant interface is completely different than with natural teeth. Alterations in tooth location and cusp inclination are suggested to limit implant overload. Force distribution in splinted natural teeth and osseointegrated prostheses are compared. The mechanism of interface force distribution and the consequences of poor interface fit are interrelated. The differential mobility of splinted natural teeth affects diagnosis and treatment. However, combining natural teeth with an osseointegrated prosthesis requires new design principles.

Alveolar Process↗
PubMed1992

Alternate methods of teaching: use of self-learning packets.

Self-directed learning takes multiple forms, all of which allow a person to study at an individual pace and direction. By applying principles of adult learning and various other styles of learning, self-directed learning can be used as an alternative method of education. The focus of this article is one type of self-directed learning, self-learning packets. The step-by-step process of designing a self-learning packet is covered. Various methods of topic selection and the key components of self-learning packet design are included. Finally, the usefulness of alternative methods of education such as self-learning packets is examined by cost analysis.

Costs and Cost Analysis↗
PubMed1991

The role of muscle deconditioning for occlusal corrective procedures.

Research has indicated that the suspension mechanism of the condyle in the fossae is muscular rather than ligamentous. Therefore, in a normal condyle-disk-fossa relationship, variations in muscle tone influence condylar position and function. The proprioception of the muscles, tendons, periodontal membrane, and temporomandibular joints influence the muscle programming of centric occlusion. In many patients the usual chairside muscle deconditioning procedures are too weak and inefficient to overcome habitual closure. The role of long-term and short-term muscle deconditioning for the occlusal correction of centric relation deflective contacts has been discussed.

Centric Relation↗
PubMed1990

New TMJ clinical data and the implication on diagnosis and treatment.

A review of the literature and the presentation of 220 patients with acute temporomandibular disorders and a control group are presented. Condylar position in the fossae is related to clinical symptoms. Ten important clinical factors were recorded and the data compared without reference to specific condylar position in the fossae and then in relation to condylar displacement groups. The significantly high incidence of posterior condylar displacement and joint pain in the patients described in this report indicates that elimination of the term joint in our definition of this disorder may be premature.

Acute Disease↗
PubMed1989

Tooth preparation for porcelain laminates.

A simple controlled technique is suggested for porcelain laminate tooth preparation that promotes exact tooth reduction and length which insures the maximum esthetic results.

Dental Cavity Preparation↗
PubMed1989

A new material and technique for appliance therapy.

A new material (thermoplastic) and clinical technique has been presented which can be utilized for appliance therapy. The major occlusal problems caused by distortion of acrylic appliances after traditional heat curing has been eliminated by this material. As a result, a clinical technique has been suggested that utilizes a relieved duplicate master cast that is mounted on the articulator for wax up and processing purposes. The inordinate accuracy of the material permits the finished appliance to be reseated on the master cast with great precision. The occlusion is refined and the appliance inserted with insignificant occlusal adjustment.

Dental Occlusion↗