Transverse drag of slow light in moving atomic vapor.

The Fresnel-Fizeau effect of transverse drag, in which the trajectory of a light beam changes due to the transverse motion of the optical medium, is usually extremely small and hard to detect. We observe transverse drag in a moving hot-vapor cell, utilizing slow light due to electromagnetically induced transparency (EIT). The drag effect is enhanced by a factor 3.6×105, corresponding to the ratio between the light speed in vacuum and the group velocity under EIT conditions. We study the contribution of the thermal atomic motion, which is much faster than the mean medium velocity, and identify the regime where its effect on the transverse drag is negligible.

Inter-abutment and peri-abutment mucosal enlargement with mandibular implant overdentures.

A variety of terms have been used to describe changes in the oral mucosa around abutments underneath fixed and removable implant prostheses such as mucosal inflammation, peri-implant mucosal hyperplasia, gingival hyperplasia, hyperplastic tissue, mucosal proliferation, proliferative gingivitis and peri-implant mucositis. Although such terms have become part of the evidence-based literature, there is no histological evidence to support the descriptive terminology used by authors. The use of the alternative term mucosal enlargement for clinical observations underneath mandibular implant overdentures is proposed. Prospective and retrospective reports have failed to use similar criteria to measure periodontal parameters in relation to these mucosal changes, both in keratinized or non-keratinized tissues. Therapeutic remedies for mucosal enlargement are dictated by authors' opinions on the possible aetiology. This literature review, coupled with clinical observations during a 5-year prospective study, prompts this proposal of the term mucosal enlargement underneath splinted and unsplinted mandibular implant overdentures.

The outcome of implant overdentures from a prosthodontic perspective: proposal for a classification protocol.

PURPOSE: This article proposes a classification protocol for reporting the outcome of implant overdentures. MATERIALS AND METHODS: Review of the literature pertaining to postinsertion prosthodontic procedures for maxillary and mandibular implant overdentures revealed a wide range in the terminology used and methods of reporting outcome, usually as a result of the use of varying designs among different implant systems. A need for comparative evaluation of the prosthodontic success of implant overdentures was identified. RESULTS: An existing classification protocol for implant-fixed prostheses containing six objectively defined fields was modified for implant overdentures. This new protocol, which also uses the descriptive fields of success, survival, unknown, dead, and retreatment (repair or failure), provides a method whereby postinsertion prosthodontic procedures and subsequent time to retreatment can be quantified regardless of design, method of attachment, or implant system. A ratio method for identifying prosthodontic treatment cost effectiveness of implant overdentures is included. CONCLUSION: This protocol could assist clinicians in their choices of implant overdenture therapy by providing accurate comparisons of varying implant overdenture systems and designs, and by identifying prosthodontic treatment cost effectiveness.

The prosthodontic maintenance requirements of mandibular mucosa- and implant-supported overdentures: a review of the literature.

PURPOSE: This article presents a critical review of the literature on the prosthodontic maintenance requirements of mandibular mucosa- and implant-supported overdentures. MATERIALS AND METHODS: A search of the literature produced 35 papers pertaining to prospective and retrospective studies. The relationship of these prosthodontic maintenance requirements to the axis of rotation treatment concept was examined. RESULTS: More often than not, 2 anterior mandibular implants either splinted (round or ovoid bars) or unsplinted (balls or magnets) have been used to evaluate this prosthodontic follow-up. Wide variation existed in the categories used for prosthodontic complications. Although principally related to alterations of overdenture contour and aspects of patrix and matrix maintenance, they also provide subjective information on relines and the rationale for avoiding overdenture fractures. These prosthodontic maintenance requirements undoubtedly have a direct impact on the time to retreatment of mandibular mucosa- and implant-supported overdentures. CONCLUSION: There appears to be a need for a more uniform, standardized categorization with criteria for determining prosthodontic success, in terms of maintenance requirements and complications, for mandibular mucosa- and implant-supported overdentures. Controlled prospective evaluations of exact prosthodontic maintenance requirements of mandibular overdentures using different systems are lacking and encouraged. There is also an absence of prospective studies on such maintenance requirements of mandibular overdentures using multiple round bars on 3 or 4 implants.

Mandibular implant-supported overdentures: a prospective evaluation of the burden of prosthodontic maintenance with 3 different attachment systems.

PURPOSE: A prospective study on mandibular implant-supported overdentures using more than 2 Brånemark implants splinted with multiple round bars evaluated a hypothesis that unnecessary prosthodontic maintenance would result from the contravention of accepted biomechanical principles. MATERIALS AND METHODS: A randomized prospective trial on 59 edentulous patients details prosthodontic maintenance and complications of 52 mandibular overdentures (11 unsplinted, 41 splinted) over a 3-year period. RESULTS: Prosthodontic maintenance was greater in the first year than in subsequent years, regardless of design. Comparison between the splinted designs with round bars revealed no statistically significant difference with either retentive clip activation or fractures. More than 70% of the retention clips in the 2-implant (single round bar) design needed activation, as compared to 44% of those with the 3-implant (double round bar) or 4-implant (triple round bar) design. Retention clip fracture occurred in 30% of patients with 3 or 4 implants and 16% of those with 2 implants. Relining the overdentures, regardless of design, revealed an excessive maintenance burden in 40% of overdentures. Remaking of overdentures was necessary in 21% of patients. CONCLUSION: Multiple round bars splinting 3 or 4 implants can still be a treatment concept in mandibular overdenture treatment. Results from prospective evaluation of this design indicate less prosthodontic maintenance of clip activation but more clip fractures than with 2 implants splinted with single round bars, although not at statistically significant levels.

Standardization of radiographs for mandibular implant-supported overdentures: review and innovation.

Radiographic monitoring of marginal peri-fixture bone is mandatory during prospective evaluation of different dental implant systems. Unyielding, uni-directional focus towards identifying the credibility of implant-supported overdenture therapy for the management of the edentulous predicament, has often neglected correct standardization of follow-up radiographs. Techniques for truly accurate location of film-holding devices have often not been applied to both unicentre and multicentre reports on mandibular implant-supported overdentures using Brånemark implants. An innovative improvement on existing methods using conventional and custom-made components, shows a procedure to accurately and simply standardize follow-up radiographs, for both free-standing and bar designs for mandibular implant-supported overdentures.

Experience with the Brånemark implant system: 1985-1995.

The osseo-integrated dental implant programme started at the University of the Witwatersrand, Johannesburg in 1985. This retrospective study describes the experience gained in the Division of Maxillofacial and Oral Surgery and the Department of Prosthetic Dentistry with the Brånemark implant system. The numbers of fixtures placed, the types of prostheses prescribed and the surgical and prosthodontic successes and problems are described. The results of implant treatment have improved, and follow a marked learning curve.