Sabrina Mutinelli

Evaluation of Zirconium-Oxide-Based Ceramic Single-Unit Posterior Fixed Dental Prostheses (FDPs) Generated with Two CAD/CAM Systems Compared to Porcelain-Fused-to-Metal Single-Unit Posterior FDPs: A 5-Year Clinical Prospective Study

PURPOSE The purpose of this prospective clinical study was to determine the success rate of single-unit posterior fixed dental prostheses (FDPs) with zirconia copings generated with two CAD/CAM systems, compared to porcelain-fused-to-metal (PFM) single-unit posterior FDPs after 5 years of function. MATERIALS AND METHODS From 2005 to 2006, 60 patients who needed a single-unit FDP on a first molar in the mandibular jaw (left or right) in a private office setting were included in this study. The 60 first mandibular molars were randomly divided into three groups (n = 20): in the control group (group C), 20 PFM FDPs were included. In the other two groups CAD/CAM technology was used for the fabrication of the zirconium-oxide copings: 20 single-unit posterior FDPs with zirconia copings were generated with the Procera system (group P, Nobel Biocare); 20 single-unit posterior FDPs with zirconia copings were generated with the Lava system (group L, 3M ESPE). For the ANOVA follow-up data, the clinical life table method was applied. The statistical analysis was performed using two nonparametric tests, the log-rank test for k-groups and the Fisher exact test. RESULTS No statistically significant difference in the clinical outcome of zirconia-ceramic FDPs of both groups (P and L) evaluated together and metal-ceramic posterior single FDPs was found at 5 years of function; however, clinical data showed that technical problems, such as extended fracture of the veneering ceramic, tended to occur more frequently in the zirconia-ceramic FDP groups. The difference in the frequency of failure was statistically significant only in the comparison of groups C and P. CONCLUSIONS Even if no statistically significant difference in the clinical outcome of zirconia-ceramic FDPs of both groups (P and L) considered together and metal-ceramic posterior single FDPs was found at 5 years of function, clinical data showed that the two zirconia-ceramic FDP groups tended to have more frequent clinical problems: for this reason all the clinical and technical variables related to the use of zirconia-ceramic FDPs generated with CAD/CAM systems should be carefully considered prior to all treatment procedures.

Arch width changes with a rapid maxillary expansion appliance anchored to the primary teeth.

OBJECTIVE To examine the dimensional changes after rapid maxillary expansion (RME) carried out in the transitional dentition with the primary teeth as anchorage. MATERIALS AND METHODS Group A was composed of 31 consecutive transitional dentition patients with posterior quadrant crossbites treated with a Haas-type RME appliance anchored on the maxillary primary molars and canines. No treatment was administered after palatal expansion. Study models were made before RME (T1), at appliance removal (T2), and at least 1 year after appliance removal (T3). A control sample of 60 individuals with posterior quadrant crossbites who had had no orthodontic treatment was categorized into group B (30 individuals with an average age comparable with the treated patients at T2) and group C (30 individuals with an average age comparable with the treated patients at T3). RESULTS Permanent molar crossbites were corrected at T2, and this correction was maintained at T3 in all patients. The mean permanent maxillary intermolar width was 42.6 +/- 2.3 mm at T1, 46.7 +/- 1.9 mm at T2 (P < .01), and 46.3 +/- 1.8 mm at T3 (P < .01) in group A; 42.9 +/- 2.7 mm (P < .01) in group B; and 44.4 +/- 3.0 (P < .01) in group C. Premolar and canine widths were slightly wider than the control at T3. CONCLUSION To avoid undesirable treatment-induced effects on maxillary permanent molars, a stable transverse correction could be achieved with the RME appliance anchored on the primary teeth.

Dental arch changes following rapid maxillary expansion.

The purpose of this research was to evaluate changes in upper arch dimension and form following rapid maxillary expansion (RME) using a modified Haas appliance in the primary dentition. The sample comprised 49 children [17 males, 32 females, mean age 7 years 5 months, standard deviation (SD) 1 year 1 month] with a crossbite or maxillary crowding. Twenty patients had a normal SN-GoGn angle (7 males, 13 females, mean 33.25 degrees, SD 2.10), three were low angle (1 male, 2 females, mean 27.67 degrees, SD 2.31), and 22 were high angle (8 males, 14 females, mean 39.95 degrees, SD 3.15). The vertical dimensions of four patients could not be measured, due to the unavailability of radiographs. Expansion was undertaken to either correct a crossbite or treat maxillary crowding. The upper dental casts were analysed using a computerized system: before treatment (T1), at appliance removal (T2), and 2 years 4 months after appliance removal (T3). Using bootstrap statistical analysis applied to distance ratio values [Euclidean distance matrix analysis (EDMA)], it was found that 48 patients showed a change in arch form. In 40.82 per cent (n = 20, group A), the arch form changed from T1 to T2, T1 to T3, and T2 to T3. In 32.65 per cent (n = 16, group B), it varied from T1 to T2 but relapsed at T3 to the form of T1. For 24.5 per cent (n = 12, group C), it changed from T1 to T2 but maintained the same form at T3. The favourable characteristics for obtaining expansion, identified by logistic regression analysis, were being male, of an immature stage of dental development (lateral incisor not fully erupted) and the presence of a lateral crossbite. Intercanine and intermolar widths, arch length, and the distance between the interincisive point and the line joining the canines (depth of the intercanine arch) at the different time points were analysed using a two-tailed t-test (P < 0.05). For the whole group, the increase in intercanine and intermolar width and in the depth of the intercanine arch was significant. Comparison between groups A, B, and C was undertaken using an analysis of variance, but there was no significant difference between the groups. This modified type of Haas appliance was able to increase the transverse dimension of the maxillary dental arch in the mixed dentition. The most appropriate timing for treatment appears to be before the eruption of the permanent lateral incisors.

Clinical evaluation of marginal bone level change around multiple adjacent implants restored with splinted and nonsplinted restorations: a 10-year randomized controlled trial.

PURPOSE The management of occlusal forces on implant restorations may influence their long-term prosthetic success. The purpose of this randomized controlled trial was to compare marginal bone level changes around adjacent splinted and nonsplinted implants, functionally loaded with cemented restorations, up to 10 years in maxillae. MATERIALS AND METHODS During 2002 and 2003, all patients who received three adjacent implants in a private office and a university setting were included in this study. All implants featured an external-hexagon design and were placed in the posterior maxilla. Implants in the left maxilla were randomly selected to be restored with splinted cemented restorations; maxillary right implants were restored with nonsplinted cemented restorations. Marginal bone resorption was measured with intraoral radiographs yearly over a period of at least 10 years after placement of abutments and restorations. The amount of bone loss in each group was analyzed with the two-sample Wilcoxon rank-sum (Mann-Whitney) test because variable bone loss was normally distributed at the fifth year only. RESULTS One hundred thirty-two implants were placed in 44 patients. Three implants failed at stage-two surgery. Five years after initial loading, two patients moved away and were lost to follow-up (6 implants in total); three additional patients did not complete the study (9 implants in total). Of the remaining 114 implants, 60 left implants were restored with splinted cemented restorations and 54 right implants were restored with nonsplinted cemented restorations. At 10 years, the splinted group showed a mean of 1.2 mm (interquartile range: 0.2 mm) of bone loss; the nonsplinted group showed 1.3 mm (interquartile range: 0.2 mm). CONCLUSION A significant difference in bone loss was seen between the two groups. However, the difference of 0.1 mm was not considered clinically meaningful.

Comparison of Maxillary Molar Distalization with an Implant-Supported Distal Jet and a Traditional Tooth-Supported Distal Jet Appliance

Aim. To investigate and compare the efficiency of two appliances for molar distalization: the bone-anchored distal screw (DS) and the traditional tooth-supported distal jet (DJ) for molar distalization and anchorage loss. Methods. Tests (18 subjects) were treated with a DS and controls (18 subjects) were treated with a DJ. Lateral cephalograms were obtained before and at the end of molar distalization and were analysed. Shapiro Wilk test, unpaired t-test, and Wilcoxon rank-sum test were applied according to values distribution. The α level was fixed at 0.05. Results. Maxillary first molars were successfully distalized into a Class I relationship in all patients. The mean molar distalization and treatment time were similar in both groups. The DS group exhibited a spontaneous distalization (2.1 ± 0.9 mm) of the first premolar with control of anchorage loss, distal tipping, extrusion, and skeletal changes. Conclusions. The DS is an adequate compliance-free distalizing appliance that can be used safely for the correction of Class II malocclusions. In comparison to the traditional DJ, the DS enables not only a good rate of molar distalization, but also a spontaneous distalization of the first premolars.

Internal- vs external-connection single implants: A retrospective study in an italian population treated by certified prosthodontists

PURPOSE The design of an implant connection that allows prosthetic suprastructures to be attached to implants has long been debated in the dental literature. The goal of this retrospective study was to evaluate the 5-year clinical results for a large number of single implants restored by certified prosthodontists in an attempt to establish whether different clinical outcomes could be detected for external- or internal-connection implants. MATERIALS AND METHODS All single implants with internal or external connections inserted in 27 private dental practices from January 1, 2003 to December 31, 2007 were evaluated. An initial statistical analysis was performed to describe the sample population at baseline and then to compare the two types of implant-abutment connection configurations and their clinical outcomes. All data were statistically analyzed with STATA12 (StataCorp). RESULTS Twenty-eight of the 85 active members of the Italian Academy of Prosthetic Dentistry (AIOP) participated in this study. The sample included 1,159 patients and 2,010 implants. Of the implants, 75 were dropped because there was no information about follow-up. Of the remaining implants, 1,431 (74.0%) were followed for at least 5 years, and 332 implants (17.2%) were followed for more than 8 years. Nearly 99% (98.9%) of the implants survived. The difference between the survival frequencies of the two types of implant-abutment connection configurations was not significant for each negative event (log-rank test, P > .05). There was no difference between the two types of implants regarding restoration fracture, implant screw loosening, and peri-implant disease. CONCLUSION Within the limitations of this study, it can be suggested that there is no difference in clinical outcomes of single restorations joined to internal- or external-connection implants.

An in vitro evaluation of impression techniques for multiple internal- and external-connection implant prostheses.

PURPOSE This in vitro study evaluated the accuracy of three different impression techniques, using polyether impression material, to obtain a precise definitive cast for a multiple-unit implant restoration with internal- or external-connection implants. MATERIALS AND METHODS Two reference resin models, one with four internal-connection implants (RRMI) and one with four external-connection implants (RRME), were fabricated. The longitudinal axes of all implants diverged by 15 to 20 degrees from the midline toward the labial/buccal. Six groups of 15 specimens each (45 RRMI, 45 RRME) were made with medium-consistency polyether: nonmodified square impression copings (NMIC and NMEC groups), square impression copings joined together with autopolymerizing acrylic resin before the impression procedure (RIC and REC groups), and square impression copings that were airborne particle-abraded and coated with impression adhesive (MIC and MEC groups). A single calibrated examiner evaluated the positional accuracy of the implant replica heads with a profile projector. These measurements were compared to the measurements calculated on the RRMI and RRME, which served as controls. All differences between the distances measured on the RRMI and on the RRME and those measured on the definitive casts of the six groups were transformed into the differences in microns each 1,000 μm of length (per mil difference) and statistically analyzed. RESULTS Considering anterior and posterior per mil median differences together, the highest precision of the definitive casts was in the groups MEC, REC, and RIC. CONCLUSION Within the limitations of this study, splinted square impression copings (RIC and REC) and airborne particle-abraded and coated (MIC and MEC) impression techniques showed greater accuracy in replicating the control models (RRMI and RRME) than the nonmodified technique (NMIC and NMEC). The definitive casts of the model with internal-connection implants achieved the highest precision with splinted square impression copings (RIC).

Comparison between an Acrylic Splint Herbst and an Acrylic Splint Miniscrew-Herbst for Mandibular Incisors Proclination Control.

Aim. The aim of this study is to compare dental and skeletal effects produced by an acrylic splint Herbst with and without skeletal anchorage for correction of dental class II malocclusion. Methods. The test group was formed by 14 patients that were treated with an acrylic splint miniscrew-Herbst; miniscrews were placed between mandibular second premolars and first molars; controls also consisted of 14 subjects that were treated with an acrylic splint Herbst and no miniscrews. Cephalometric measurements before and after Herbst treatment were compared. The value of α for significance was set at 0.05. Results. All subjects from both groups were successfully treated to a bilateral Class I relationship; mean treatment time was 8,1 months in the test group and 7.8 in the controls. Several variables did not have a statistical significant difference between the two groups. Some of the variables, instead, presented a significant difference such as incisor flaring, mandibular bone base position, and skeletal discrepancy. Conclusions. This study showed that the Herbst appliance associated to miniscrews allowed a better control of the incisor flaring with a greater mandibular skeletal effect.

An In Vivo Evaluation of the Fit of Zirconium‐Oxide Based, Ceramic Single Crowns with Vertical and Horizontal Finish Line Preparations

PURPOSE Different types of tooth preparations influence the marginal precision of zirconium-oxide based ceramic single crowns. In this in vivo study, the marginal fits of zirconium-oxide based ceramic single crowns with vertical and horizontal finish lines were compared. MATERIALS AND METHODS Forty-six teeth were chosen in eight patients indicated for extraction for implant placement. CAD/CAM technology was used for the production of 46 zirconium-oxide-based ceramic single crowns: 23 teeth were prepared with vertical finishing lines, 23 with horizontal finishing lines. One operator accomplished all clinical procedures. The zirconia crowns were cemented with glass ionomer cement. The teeth were extracted 1 month later. Marginal gaps along vertical planes were measured for each crown, using a total of four landmarks for each tooth by means of a microscope at 50× magnification. On conclusion of microscopic assessment, ESEM evaluation was completed on all specimens. The comparison of the gap between the two types of preparation was performed with a nonparametric test (two-sample Wilcoxon rank-sum test) with a level of significance fixed at p < 0.05. All data were analyzed with STATA12. RESULTS In the group with horizontal finish line preparations, the median value of the gap was 35.45 μm (Iqr, 0.33); for the vertical finish line group, the median value of the gap was 35.44 μm (Iqr, 0.40). The difference between the two groups was not statistically significant (two-sample Wilcoxon rank-sum test, p = 0.0872). CONCLUSIONS Within the limitations of this study, the gaps of the zirconium-oxide-based ceramic CAD/CAM crowns with vertical and horizontal finish line preparations were not different.

Acrylic splint Herbst and Hanks telescoping Herbst: A retrospective study of emergencies, retreatments, treatment times and failures

INTRODUCTION The Herbst appliance has been reported to be one of the most efficient for the correction of class II malocclusions. However, there are many complications that make its use difficult for clinicians and patients (splint loosening, telescope breakage, splint breakage, low comfort). The aim of this study was to evaluate and compare emergencies, retreatments, failures and overall treatment time of two types of Herbst appliances: the HT Herbst and the acrylic splint Herbst. MATERIALS AND METHODS Two hundred and eight patients with Class II malocclusion were selected consecutively in a private practice. They were treated either with an acrylic splint Herbst (155 pt, mean age 10.3 ± 3.7) or with a HT Herbst (53 pt, mean age 11.3 ± 4.2 years). Tables were used for each patient to record the following complications, if present: detached Herbst, broken and repaired Herbst, broken and rebuilt Herbst (emergencies), Herbst that had to be re-made for lack of patient cooperation (retreatments) and appliances that had to be removed (failed treatment). RESULTS Results showed that the HT Herbst and the acrylic splint Herbst have the same retreatment probability and the same treatment time. Moreover, the HTH has a lower risk of functional impairment: the acrylic splint Herbst has an emergency probability that is twice as high as the HTH. On the other hand, the HTH has a failure frequency that is nearly 6 times higher than the traditional Herbst although the statistical analysis could not provide any certain conclusion about it. CONCLUSION In cases where a higher relative risk of failure for the traditional Herbst was confirmed, the HTH proved to be a better appliance than the traditional Herbst.