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Biomedical subjects

E Romberg

Publications and source records attributed to E Romberg.

At least 19 recordsLinked to original sources
PubMed1998

Indentation damage and mechanical properties of human enamel and dentin.

Understanding the mechanical properties of human teeth is important to clinical tooth preparation and to the development of "tooth-like" restorative materials. Previous studies have focused on the macroscopic fracture behavior of enamel and dentin. In the present study, we performed indentation studies to understand the microfracture and deformation and the microcrack-microstructure interactions of teeth. It was hypothesized that crack propagation would be influenced by enamel rods and the dentino-enamel junction (DEJ), and the mechanical properties would be influenced by enamel rod orientation and tooth-to-tooth variation. Twenty-eight human third molars were used for the measurement of hardness, fracture toughness, elastic modulus, and energy absorbed during indentation. We examined the effect of enamel rod orientation by propagating cracks in the occlusal surface, and in the axial section in directions parallel and perpendicular to the occlusal surface. The results showed that the cracks in the enamel axial section were significantly longer in the direction perpendicular to the occlusal surface than parallel. The cracks propagating toward the DEJ were always arrested and unable to penetrate dentin. The fracture toughness of enamel was not single-valued but varied by a factor of three as a function of enamel rod orientation. The elastic modulus of enamel showed a significant difference between the occlusal surface and the axial section. It is concluded that the cracks strongly interact with the DEJ and the enamel rods, and that the mechanical properties of teeth are functions of microstructural orientations; hence, single values of properties (e.g., a single toughness value or a single modulus value) should not be used without information on microstructural orientation.

Analysis of Variance↗
PubMed1998

Clinical evaluation of a new 10% carbamide peroxide tooth-whitening agent.

NUPRO Gold Tooth Whitening System was evaluated for efficacy according to the proposed ADA guidelines for acceptance. Sixty participants with discolored anterior teeth participated in a 14-day, double-blind, clinical trial. The participants were matched for age, gender, and oral health status and were given either a placebo gel without the active agent or the NUPRO Gold active gel, which they wore in a custom-fabricated mouth guard for home use. The shade of each participant's maxillary anterior teeth was evaluated using a value-oriented Vita Lumin Vacuum Shade Guide before the study. The same shade guide was used to determine shade changes. Time of use of the agent and potential side effects, such as tooth and gingival hypersensitivity and tissue irritation, were assessed at all recall examinations and were recorded by participants in daily diaries. The average shade change for the placebo users was less than one shade. The average shade change for the NUPRO Gold users was 6.96 shades. Tooth hypersensitivity varied from none to severe. Tissue irritation was minimal. The results of these evaluations indicate that NUPRO Gold is effective as a tooth-whitening system, when administered properly under the supervision of a dentist, with commonly reported side effects of transient tooth sensitivity and minimal gingival sensitivity. Little or no change in tissue health was noted. This study was supported by Dentsply Preventive Care (York, Pennsylvania).

Adolescent↗
PubMed1997

Carbon dioxide laser for de-epithelialization of periodontal flaps.

Regeneration of mineralized and soft connective tissue components of the attachment apparatus is the main goal in the treatment of periodontal diseases. Often, apical migration of epithelium (long junctional epithelium) effectively prevents the formation of bone and connective tissue attachment after periodontal surgery. The purpose of the present study was to compare conventional periodontal surgery combined with carbon dioxide laser and conventional periodontal surgery alone with respect to epithelial elimination and degree of necrosis of mucoperiosteal flaps. After signing a consent form, five patients with at least two comparable bilateral periodontal defects needing pocket elimination surgery participated in this study. The investigators randomly divided each side into test and control sites. Each patient received oral hygiene instruction and initial therapy prior to surgery. At surgery, the test site received a sulcular incision and carbon dioxide laser de-epithelialization of the outer and inner aspects of the flap. The control group received reverse bevel incision only. The surgeon performed open flap debridement on all teeth. At the time of surgery, the surgeon did a biopsy of each site and submitted specimens for histologic evaluation. A matched pairs t-test was used to analyze the data. The results show significant differences between the carbon dioxide laser and reverse bevel incision with respect to sulcular (P < or = 0.025) and gingival (external) (P < or = 0.01) flap surface epithelial elimination and tissue necrosis (P < or = 0.005). These results should be replicated with a larger number of subjects. The carbon dioxide laser eliminated sulcular and gingival (external) epithelium without disturbing underlying connective tissue. This finding supports the concept that the carbon dioxide wavelength has little or no effect on tissues beyond the target. However, neither laser nor blade eliminated all the epithelium. Researchers observed chronic inflammation in the control and test sites, with a predominance of plasma cells. Lining the sulcular and gingival (external) lased areas, investigators found coagulation necrosis covered by fibrin and coagulated blood. The laser appears to effectively remove epithelium at the time of surgery; however, future long-term, well-controlled quantitative histologic studies are needed to evaluate the effect of repeated carbon dioxide laser de-epithelialization of the gingival (external) surface of mucoperiosteal flaps at intervals during the healing period.

Biopsy↗
PubMed1996

Resin-bonded fixed partial dentures. I. Proposed standardized criteria for evaluation.

Since etched cast resin-bonded prostheses were introduced in 1980, many articles have been written about them. Most state that the reported clinical success of these bonded restorations has been based primarily on the longevity of the bonding. For a comprehensive evaluation, however, it is important not only to examine the bonding but also to evaluate the periodontal response. The proposed standard method provides a consistent and comprehensive evaluation of resin-bonded prostheses that is applicable for researchers and clinicians alike.

Dental Plaque Index↗
PubMed1996

Resin-bonded fixed partial dentures. II. Clinical findings related to prosthodontic characteristics after approximately 10 years.

A clinical study was conducted for patients who were functioning with resin-bonded fixed partial dentures for approximately 10 years. The purpose of this study was to evaluate the periodontal health and determine the prosthodontic characteristics of the fixed partial dentures. Results indicated that plaque indexes, probing, recession, and loss of attachment were greater for abutments than for control teeth. The differences were statistically significant but clinically small. The bonded restorations were generally well adapted and contoured for case of cleaning.

Chi-Square Distribution↗
PubMed1996

Ten-year clinical and microscopic evaluation of resin-bonded restorations.

A clinical recall was conducted for 103 patients who were functioning with resin-bonded restorations for approximately 10 years. The purpose of this study was to evaluate marginal adaptation of the cast metal retainers. Following clinical evaluations, replicas of incisal and occlusal margins were examined in the scanning electron microscope to determine marginal separation and microscopic patterns of the resin composite interface between metal and tooth. Anterior abutments exhibited better clinical adaptation and fewer voids and debonds than did posterior abutments. Larger microscopic marginal separations were associated with those retainers that had clinically detectable voids or defects.

Chi-Square Distribution↗
PubMed1995

10-year periodontal response to resin bonded bridges.

The purpose of this study was to evaluate the long-term (10 years +/- 15 months) periodontal response to resin bonded bridges (RBRs). A total of 103 patients who had RBRs bonded between 1980 and 1984 were recalled. Periodontal evaluations were made by two clinicians for all abutment teeth and for selected control teeth with intact, non-restored lingual surfaces. Periodontal indices consisted of: plaque index (PI), gingival index (GI), gingival recession, probing depth, and loss of attachment. Paired t tests indicated no significant difference in overall GI between experimental and control sites, but a significant difference in PI and probing depth with experimental sites (abutment teeth) showing higher PI and greater probing depths. Significant differences were found in overall recession and attachment loss, again with more recession and attachment loss observed on the abutment teeth as compared to the controls. Site specific analyses for PI, probing, and loss of attachment showed small but significant differences between experimental and control teeth in 15 of 21 sites. Although these findings may be statistically significant, the clinical impact for resin bonded restorations functioning for over 10 years is minimal and is comparable to periodontal response to other types of restorations.

Analysis of Variance↗
PubMed1994

Evaluation and use of a low nutrient medium and reduced incubation temperature to study bacterial contamination in the water supply of dental units.

A low nutrient medium, dilute peptone, and reduced incubation temperatures (25 or 30 degrees C) were used to recover bacteria from dental unit water supply. Significantly greater numbers of bacterial colony-forming units were recovered on the dilute peptone medium than on the enriched media, blood agar or trypticase soy agar. Lower incubation temperatures yielded greater numbers of colony-forming units on all media. The bacterial population in dental unit water supply following stagnation in the supply lines and flushing of the lines was studied using dilute peptone incubated at 25 degrees C. No significant differences in the numbers of colony-forming units were found in stagnant water versus fresh water. Flushing the water lines for 10 min did not significantly reduce the numbers of colony-forming units.

Agar↗
PubMed1991

Histologic comparison of regeneration in human intrabony defects when osteogenin is combined with demineralized freeze-dried bone allograft and with purified bovine collagen.

A bone-inductive protein, osteogenin, has been isolated from long bones of humans and offers promise as a grafting material. Studies, however, suggest that osteogenin must be combined with a bone-derived matrix in order to initiate bone differentiation. The purpose of this study was to determine if osteogenin combined with demineralized freeze dried bone allograft (DFDBA), a bone-derived matrix, and with a bovine tendon-derived matrix will enhanced regeneration of intrabony defects in humans. The tendon-derived matrix and DFDBA used alone served as controls. The ability of each material to form a new attachment apparatus was evaluated independently in submerged and nonsubmerged environments in 2 patient populations. Lymphocyte testing was performed to assess development of an immune reaction to osteogenin. The most apical level of calculus on the root served as the histologic reference point to measure regeneration. Biopsies were obtained at 6 months and regeneration was measured histomorphometrically by 2 blinded evaluators. Serial sections from 36 submerged defects in 8 patients and 50 nonsubmerged defects in 6 patients were submitted for statistical analysis. Mean results indicate that osteogenin combined with DFDBA significantly enhanced regeneration of a new attachment apparatus and component tissues in a submerged environment. DFDBA plus osteogenin and DFDBA alone formed significantly more new attachment apparatus and component tissues than either the tendon-derived matrix plus osteogenin or the tendon-derived matrix alone in both submerged and nonsubmerged environments. There were no significant differences between the tendon-derived matrix plus osteogenin and the tendon-derived matrix alone in either the submerged or nonsubmerged environment. Osteogenin does not impair normal lymphocyte blastogenesis at 6 months postsurgical challenge.

Alveolar Bone Loss↗
PubMed1989

Histologic evaluation of new attachment apparatus formation in humans. Part I.

Part I of this three-part human study evaluated the formation of a new attachment apparatus (bone, cementum, and periodontal ligament) on pathologically exposed root surfaces in an open and closed environment. The most apical level of calculus on the root served as a histologic reference point to measure regeneration on root surfaces exposed to the oral environment. Attempts were made to initiate the formation of a new attachment apparatus by flap curettage, root planing, coronectomy, and submersion of vital roots beneath the mucosa. Nonsubmerged defects were treated by the same surgical technique and served as controls. Biopsies were obtained at 6 months and regeneration was evaluated histometrically by two investigators who were unaware of the treatment performed. Data from 9 patients with 25 submerged and 22 nonsubmerged defects were submitted for statistical analysis. Results indicate that a new attachment apparatus did not form in any of the 22 nonsubmerged teeth; a new attachment apparatus did form in a submerged environment (0.75 mm); significantly more new attachment apparatus (P less than 0.05), new cementum (P less than 0.01), new connective tissue (P less than 0.05), and new bone (P less than 0.02) formed in submerged defects; new cementum was cellular in nature and formed equally well on old cementum and dentin. Greater percent positive regeneration of the attachment apparatus and all component tissues occurred in submerged defects and no extensive root resorption, ankylosis, or pulp death was observed on submerged or nonsubmerged roots.

Analysis of Variance↗
PubMed1989

Histologic evaluation of new attachment apparatus formation in humans. Part II.

There is conflicting evidence regarding the value of graft materials in enhancing the formation of new bone, cementum, and periodontal ligament (new attachment apparatus). Part II of this study compared the healing of intrabony defects with and without the placement of decalcified freeze-dried bone allograft (DFDBA) in a submerged environment. The most apical level of calculus on the root served as a histologic reference point to measure regeneration on root surfaces exposed to the oral environment. Biopsies were obtained at 6-months and evaluated histometrically by two investigators unaware of the treatment performed. Data from 9 patients with 30 grafted defects and 13 nongrafted defects were submitted for statistical analysis. Results indicate that in a submerged environment significantly more new attachment apparatus (P less than .05) and new bone (P less than .05) formed in grafted than nongrafted sites. Significantly greater loss of alveolar crest height occurred in nongrafted than grafted defects (P less than .05); regeneration of new attachment apparatus, new bone, and new cementum occurred more frequently in grafted than nongrafted defects. There was a greater chance for the regeneration of a connective tissue attachment in nongrafted intrabony defects than in grafted defects; new cellular cementum formed equally well on old cementum, dentin, or both old cementum and dentin in the same defect. The periodontal ligament was oriented parallel, perpendicular, or both parallel and perpendicular in the same defect; and, no extensive root resorption, ankylosis, or pulp death was observed in grafted or nongrafted defects.

Alveolar Process↗
PubMed1989

Histologic evaluation of new attachment apparatus formation in humans. Part III.

There is still controversy as to the role of bone grafting materials in the formation of a new attachment apparatus and component tissues (bone, cementum, and periodontal ligament). The purpose of this study was to compare the healing of intrabony defects with and without the placement of decalcified freeze-dried bone allograft (DFDBA) in a nonsubmerged environment in humans. The most apical level of calculus on the root served as a histologic reference point to delineate root surfaces exposed to the oral environment and to measure new attachment apparatus and new component tissue formation. Free gingival grafts were placed over grafted and nongrafted defects to retard epithelial migration. Biopsies were obtained at 6 months and regeneration was evaluated histometrically. Data from 12 patients with 32 grafted and 25 nongrafted defects were submitted for statistical analysis. Results indicate that in nongrafted defects, a long junctional epithelium formed along the entire length of exposed root surfaces and often extended apical to the calculus reference notch. Free gingival grafts did not enhance regeneration of a new attachment apparatus, new cementum, new connective tissue, or new bone in nongrafted defects. The formation of a new attachment apparatus was observed when intrabony defects were grafted with DFDBA (x1.21 mm); significantly more new attachment apparatus (P less than .005), new cementum (P less than .005), new connective tissue (P less than .05), and new bone (P less than .0001) formed in intrabony defects grafted with DFDBA than in nongrafted defects. There was a greater chance for regeneration of a new attachment apparatus and component tissues in grafted defects than in nongrafted defects. New cellular cementum formed on old cementum and dentin but more often formed over both in the same defect). The periodontal ligament was more frequently oriented perpendicular to the root; there was greater loss in alveolar crest height in nongrafted than grafted defects (P less than .05); and extensive root resorption, ankylosis, and pulp death were not observed in grafted or nongrafted defects.

Analysis of Variance↗
PubMed1988

The use of pit and fissure sealants in private practice: a national survey.

The slowness in the adoption of sealant use has been caused by many interrelated professional, scientific, social, and economic factors. To study these factors, data were collected by the use of mail questionnaires sent to a representative sample of 3,504 private practice general dentists. The average percent of patients 18 years of age and younger receiving sealants was 18.7. Nearly one-third of the respondents indicated that none of their patients received sealants. Data describing the following factors were obtained: demographic background, sealant awareness, attitudes and knowledge about sealants, and decision-making factors. We concluded that professional organizations should take a more active role in promoting sealants to dentists, professional organizations and governmental agencies should increase efforts to inform patients/consumers of the benefits of sealants, guidelines for sealant use should be developed, state boards should permit the delegation of sealants to trained auxiliaries, and sealant manufacturers should make more effort to advertise and promote sealants.

Adolescent↗