Stefano Bonetti

Dental status of three Egyptian mummies: radiological investigation by multislice computerized tomography

OBJECTIVE The aim of the study was to provide a paleopathologic and radiologic overview of the jaws and teeth of 3 Egyptian mummies preserved in the Civic Museum of History and Art in Trieste. Computerized tomography (CT) imaging and postprocessing techniques were used to examine the oral structures. STUDY DESIGN A 16-slice CT scanner was used (Aquilion 16; Toshiba Medical Systems Europe, Zoetermeer, The Netherlands). Scans were obtained at high resolution. Orthogonal-plane and 3-dimensional (3D) reconstructions were created along with curved reconstructions of the lower and upper jaws. Determination of decayed/missing teeth (DMT) and decayed/missing/tooth surfaces (DMTs) were made with 3D images. RESULTS Analyses revealed differences in the embalming techniques and state of preservation of the bodies. Marked wear of the occlusal surfaces was a characteristic finding in all of the mummies. The DMT and DMTs were low compared with values for contemporary populations. Two mummies had fully erupted third molars. All mummies exhibited bone changes consistent with periodontitis. CONCLUSION The CT evaluations of the oral structures of the mummies provided insight into the dental status and oral diseases of these ancient Egyptians. The low DMT and DMTs values and indications of periodontitis may be associated with the lifestyle of these Egyptians. The fully erupted and well aligned third molars may represent a morphologic adaptation of the arches to the muscular activity associated with grinding tough foods.

Effectiveness of an indirect bonding technique in reducing plaque accumulation around braces

OBJECTIVE To evaluate if the use of an indirect braces bonding protocol for localized enamel etching and adhesive application could help reduce plaque accumulation and demineralization around the brackets compared with a conventional direct-bonding technique. MATERIALS AND METHODS Thirty patients were bonded with a split-mouth approach: two randomly selected opposite quadrants were used as the test sides and the other two as control sides. During the first 6 months, the plaque presence around the braces was recorded monthly according to a plaque accumulation index (PAI), as was the presence of demineralization. PAI values were measured at each of the four bracket sides for every bonded tooth. Analysis of variance was used to identify significant differences between different bracket margins and between test and control sides. RESULTS Test and control sides differed significantly for PAI measurements from t(1) (1 month after bonding) to t(4) (4 months after bonding), with the highest value of significance (P < .001) at t(1) but with no significant differences from t(5) to t(7) (treatment end). Considering whole-mouth results, different bracket margin PAI scores did not differ significantly. PAI scores were higher at t(1) and progressively decreased during the treatment. At debonding, the onset of 21 new white spots was recorded overall for the control sides and eight new white spots for the test sides. CONCLUSION Especially during the first 4 months after brackets placement, this indirect bonding protocol allowed for significant reduction in plaque accumulation around the braces and reduced onset of white spots during the orthodontic treatment.

In vitro evaluation of the effects of a fluoride-releasing composite on enamel demineralization around brackets

OBJECTIVES The aim of this in vitro study was to evaluate the effectiveness of a fluoride-releasing bonding agent in inhibiting enamel demineralization around orthodontic brackets after the exposure to a demineralizing solution. MATERIALS AND METHODS Twenty-six extracted upper molars were bonded with two different composites: Transbond XT (TXT) and Transbond Plus (TPlus), fluoride-releasing (both 3M Unitek, Monrovia, CA, USA). The samples were exposed to an acid lactic solution for three days and then subjected to Metallographic Optical Microscope (MOM) and Scanning Electron Microscope/Energy Dispersive X-Ray (SEM/EDX) analyses. Enamel surface was examined in different areas: un-treated, etched and primer-painted, un-treated area with no acid exposure, central area with bracket bonded. The maximum demineralization depths and the fluoride content at 100, 200 and 300 μm depth were evaluated. RESULTS MOM analysis showed statistically significant (p<0.001) differences in demineralization depth for TPlus group compared to TXT group with lower values for the first one. EDX analysis confirmed the presence of fluoride in TPlus group. CONCLUSIONS The fluoride content of TPlus appeared able to weakly reduce the enamel demineralization.

Mixed dentition space analysis for a northern italian population: new regression equations for unerupted teeth.

OBJECTIVE The aim of this study was to determine linear regression equations for a Northern Italian population to predict mandibular permanent premolars and canines widths, and particularly, second premolar widths, using the sum of the widths of the four mandibular incisors, canines and first premolars. MATERIALS AND METHODS Mesiodistal tooth widths were measured from 230 dental casts obtained from Northern Italian patients (130 females and 100 males). Students t-test or Wilcoxon test for independent and paired samples were used to determine right/left side and male/female differences. Correlation coefficients and linear regression equations were constructed to evaluate the relationship between 1) the combined mesiodistal widths of the permanent mandibular incisors (independent variable) and the combined mesiodistal widths of the canine and premolars (dependent variable); 2) the combined mesiodistal widths of the incisors, canines and first premolars (independent variable) and the widths of the second premolars (dependent variable). Significance value was set a priori at 0.05. RESULTS A linear regression equation was found, y=0.585x+7.927 (r=0.734) considering right and left sides of mandibular arch together, to predict canines and premolars widths. For second premolar width, the linear regression equation was y=0.201x+2.149 (r=0.641), even when considering the right and left sides of the mandibular arch together. CONCLUSIONS New regression equations were derived for a Northern Italian population.

Incisal Apical Root Resorption Evaluation after Low-Friction Orthodontic Treatment Using Two-Dimensional Radiographic Imaging and Trigonometric Correction.

BACKGROUND Root resorption shall be taken into consideration during every orthodontic treatment, and it can be effected by the use of different techniques, such as the application of low friction mechanics. However, its routinely assessment on orthopantomography has limitations related to distortions and changes in dental inclination. AIM The aim of this investigation was to evaluate the severity of apical root resorption of maxillary and mandibular incisors after low-friction orthodontic treatment, using the combination of panoramic and lateral radiographs, and applying a trigonometric correction. SETTINGS AND DESIGN A hospital based Retrospective study at the orthodontic Department (Dental School, University of Brescia, Spedali Civili di Brescia, Brescia, Italy). MATERIALS AND METHODS Ninety-three subjects (53 females and 40 males; mean age, 14 years) with mild teeth crowding were treated without extractions by the same operator using a low-friction fixed appliance following an integrated straight wire (ISW) protocol. The pre- and post-treatment tooth lengths of the maxillary and mandibular incisors were measured on panoramic radiographs. A trigonometric factor of correction for the pre-treatment length was calculated based on the difference between the pre and post-treatment incisal inclination on lateral cephalograms. STATISTICAL ANALYSIS The changes in lengths were investigated using the Students t-test for paired values (p<0.05). RESULTS Maxillary central incisors showed no changes (0.3%, 0.6%), maxillary lateral incisors showed a small increase (1.4%, 1.8%) that was attributed to the completion of root development in younger patients, mandibular central and lateral incisors underwent slight resorption (-3.1%, -3.4%). A statistically significant difference was found for the mandibular incisors but not for the maxillary ones. CONCLUSION In patients with mild crowding and consequent low amount of root movement, a low-friction orthodontic treatment can lead to slight apical root resorption, mainly involving lower incisors. The use of a trigonometric correction in the panoramic radiograph analysis may reduce the limitations of this 2D evaluation.

Manufacturing lead time shortening and stabilisation by means of workload control: an action research and a new method

Abstract This paper stems from an improvement project carried out at a men’s outwear manufacturer, aimed at reducing and stabilising the production lead time (LT). A method has been developed that builds on three well-established operations management theories: Little’s law, the workload control method and the logistic operating curves. In the action research study, by setting the system’s work in process to a level more consistent with its operating curves, the average system LT was reduced by 34% while its coefficient of variation was reduced to one-third. On the grounds of these encouraging results, and given the good fit between empirical results and theoretical expectations, the method is standardised and proposed for general use in the analysis and improvement of manufacturing systems.

Resistance to sliding in orthodontics: misconception or method error? A systematic review and a proposal of a test protocol

Resistance to sliding (RS) between the bracket, wire, and ligature has been largely debated in orthodontics. Despite the extensive number of published studies, the lack of discussion of the methods used has led to little understanding of this phenomenon. The aim of this study was to discuss variables affecting RS in orthodontics and to suggest an operative protocol. The search included PubMed©, Medline©, and the Cochrane Library©. References of full-text articles were manually analyzed. English-language articles published between January 2007 and January 2017 that performed an in vitro analysis of RS between the bracket, wire, and ligature were included. Study methods were analyzed based on the study design, description of materials, and experimental setup, and a protocol to standardize the testing methods was proposed. From 404 articles identified from the database search and 242 records selected from published references, 101 were eligible for the qualitative analysis, and six for the quantitative synthesis. One or more experimental parameters were incompatible and a meta-analysis was not performed. Major factors regarding the study design, materials, and experimental setup were not clearly described by most studies. The normal force, that is the force perpendicular to the sliding of the wire and one of the most relevant variable in RS, was not considered by most studies. Different variables were introduced, often acting as confounding factors. A protocol was suggested to standardize testing procedures and enhance the understanding of in vitro findings.