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Biomedical subjects

L B Lum

Publications and source records attributed to L B Lum.

9 recordsLinked to original sources
PubMed1992

Early uncovering of HA-coated cylinder implants: case report of an in vivo shear strength test.

A new approach was used to test the readiness of an HA-coated implant for commencement of prosthetic procedures after two months of bone healing in humans. A torquing device was used for clinical measurement of the shear resistance of the supporting bone. It was found that the bone was capable of resisting a shear force just slightly greater than that which was necessary to produce displacement of implants placed in dog femurs with a comparable bone-healing period and with healing to full maturity. This report suggests that it may be feasible to uncover HA-coated implants after two months of bone healing.

Dental Implants↗
PubMed1992

Load transfer from endosteal implants to supporting bone: an analysis using statics. Part one: Horizontal loading.

By use of engineering statics, the amount of force transferred to the crestal bone from a horizontal occlusal load, relative to the implant length necessary to support that load, was analyzed for hypothetical instances when the implant was embedded in a uniform mass of bone and when it was bicorticated. The analysis revealed that implants longer than 12 mm will not significantly reduce force transfer proportionately to the increased length. Also, bicortication will mitigate force transfer to the crestal bone. Finally, the amount of force transfer is directly proportional to the height of load application from the crestal bone.

Alveolar Process↗
PubMed1992

Load transfer from endosteal implants to supporting bone: an analysis using statics. Part two: Axial loading.

Engineering statics was used for the analysis of axial occlusal load transfer by a dental implant to the supporting bone. The analysis revealed that an implant can be totally supported by trabecular bone. Also, an implant of only 10 mm in length with a 4-mm diameter can transmit average maximum biting forces to the supporting bone within the physiologic strain limits of the bone.

Alveolar Process↗
PubMed1991

A biomechanical rationale for the use of short implants.

In general, the use of short implants has not been recommended by some because it is believed that occlusal forces must be dissipated over a large implant area in order for the bone to be preserved. Finite element modeling (FEM) analyses have shown that the occlusal forces are distributed primarily to the crestal bone rather than evenly throughout the entire surface area of the implant interface. Since masticatory forces are light and fleeting, these forces are normally well-tolerated by the bone. It is the bruxing forces that must be adequately attenuated, and this may be done by increasing the diameter and number of implants.

Bite Force↗
PubMed1991

Histologic evaluation of hydroxylapatite-coated versus uncoated titanium blade implants in delayed and immediately loaded applications.

It has been suggested that the long-term success of blade implants could be improved by placing the implants using a two-stage surgical protocol to allow the implant to develop a direct bony interface instead of a fibrous tissue interface. This study compared the implant interfaces of delayed and immediately loaded blade implants in nonhuman primates. A second objective was to compare the effects of hydroxylapatite coating on delayed and immediate loading applications. The delayed loaded uncoated titanium and hydroxylapatite-coated blade implants did osseointegrate. This study also suggests that hydroxylapatite-coated blade implants may form a direct bony interface even when they are loaded immediately after implantation, provided that they are splinted to a firm natural tooth.

Animals↗
PubMed1988

Osseointegration of two types of implants in nonhuman primates.

Branemark developed a dental implant that can reliably replace missing teeth. The success of this implant is attributed to a direct connection of bone with the implant (osseointegration). Several implants, including the Core-Vent implant, adhere to the requirements described by Branemark and his coworkers to achieve osseointegration, yet no studies have attempted to directly compare osseointegration of the Biotes implant with other implants. This study directly compared the response of bone to the unloaded and occlusally loaded Core-Vent and Biotes implants at the light microscopic level by using the nonhuman primate model. Histologic examination revealed that both Core-Vent and Biotes implants achieved osseointegration and maintained the direct contact with bone after 5 months of occlusal loading.

Animals↗
PubMed1986

Viability of the retained bone core in the core-vent dental implant.

The survival of dental implants has been correlated with the formation of a bone-implant interface. This study was done to determine whether the recently developed Core-Vent dental implant forms a bone-implant interface without intervening fibrous tissue. Core-Vent implants were placed in four dogs, and healing was evaluated histologically 15, 30, 60, and 120 days after insertion. Bone grew through the implant vents to join with the inner bone plug, and the implants approximated the bone without an intervening fibrous tissue layer.

Alveolar Process↗
PubMed1978

Human blood pressure and pulse rate response to racemic epinephrine retraction cord.

1. The pulse rate of patients after application of racemic epinephrine-impregnated retraction cords depends more on the level of anxiety and stress than on the level of the epinephrine. 2. Blood pressure is elevated by placement of racemic epinephrine-impregnated retraction cords upon an exposed vascular bed or lacerated tissue. 3. Four percent racemic epinephrine-impregnated retraction cords cause less elevation of blood pressure than 8% racemic epinephrine cords. 4. Although the elevations in blood pressure from 8% cord occur within a narrow range, this range may be hazardous to cardiac patients. Therefore, 4% racemic epinephrine cord should be used. 5. A desirable amount of tissue retraction is produced by 4% racemic epinephrine cord. 6. Dry cords do not provide adequate retraction of tissue and are contraindicated for tissue-retraction purposes.

Adult↗