Clinical and immunological evaluation of peri-implant tissues around ultra-polished and conventionally-polished zirconia abutments. A 1-year follow-up randomized clinical trial.

PURPOSE: This is a randomized clinical trial to compare the clinical and immunological performance of ultrasmooth versus conventionally-smooth zirconia abutments placed subgingivally after a period of 1 year. MATERIALS AND METHODS: Sixty-two bone level platform-switched implants (NobelParallel CC) were placed epicrestally in the mandibular molar or premolar region in 62 patients. After osseointegration, implants were restored with auto polymerizing acrylic resin crowns and subsequently randomly allocated to two groups according to the type of screw-retained zirconia crown prescribed. The control group received custom zirconia restoration with the subgingival zirconia part conventionally polished, whereas the test group implants were restored with ultra-polished zirconia abutments. Periodontal parameters (PD, PI, and BOP) and marginal bone level changes (MBLC) were recorded for each implant 2 months after insertion (T0), 1 month after final delivery of the crown (T2), and at the 1-year follow-up (T3). Immunological mediators from gingival crevicular fluid (IL-1α, IL-1ra, and TNF-α) were inspected at 1 month after provisional (T1) and accordingly at T2 and T3. Data was analyzed statistically, and significance level was set to α = 0.05. RESULTS: After 1 year, there were no significant changes in PD control-2.18 ± 0.89 mm and test-2.5 ± 0.72 mm (p = 0.073). PD between T2 and T3 dropped significantly in the test group (p = 0.037) and remained stable in the control group. PI was not different in both groups at T0 (p = 0.518) and T2 (p = 0.817). At T3, the test group (0.9 ± 1.01) had a significantly lower PI than the control group (1.55 ± 1.23) (p = 0.035). There was no difference in BOP positive cases between groups after 1 year (control-61.3%, test-51.7%, and p = 0.455). The amount of IL-1ra decreased significantly in the test group (41.75 ± 57.58) (p = 0.001) but not in the control group (59.59 ± 70.43) (p = 0.177). MBLC for the control and test groups after 1 year were 0.68 ± 0.7 and 0.94 ± 0.65 mm (p = 0.061). CONCLUSIONS: PD dynamics, PI, BOP, and IL-1ra revealed better outcomes around ultra-polished zirconia abutments than around conventionally polished zirconia abutments.

Comparison of Different Cleaning Procedures for Decontaminating Zirconium Oxide Surface After Polishing.

PURPOSE: To evaluate the efficacy of cleaning protocols for the decontamination of organic compounds from polished zirconium oxide samples. MATERIALS AND METHODS: A total of 24 rectangular plate specimens were sintered from zirconium oxide. All samples were polished with commercially available polishers (coarse, fine, and superfine) and polishing paste. During the first step of the protocol, all specimens were cleaned with steam. Samples were then randomly assigned to one of three groups (n = 8 each): A, B, or C. In group A, no additional cleaning was performed, while specimens in group B underwent ultrasonic cleaning in distilled water. Group C specimens were cleaned in an ultrasonic bath with a special detergent solution. After washing, samples were subjected to energy-dispersive x-ray spectroscopy (EDX) and scanning electron microscopy (SEM) examination. In order to detect organic materials, the level of carbon atoms was measured. RESULTS: EDX analysis revealed that samples in group A had the highest percent of carbon atoms (9.57 ± 3.67) on the surface compared to other cleaning protocols. Following the Group B cleaning protocol resulted in lower carbon levels (4.73 ± 3.56), but this difference was not significant compared to group A (P = .439). None of the specimens in group C had detectable carbon atoms (0), which implies that all wax molecules were removed (P < .05). CONCLUSION: Total decontamination of organic compounds from a polished zirconium surface can be expected only following the C cleaning protocol; therefore, it is advised to employ an ultrasonic bath with detergent solution for cleaning procedures of zirconium abutments before delivery. Int J Prosthodont 2023;36:588-594.

Effect of Ti-Base Abutment Gingival Height on Maintenance of Crestal Bone in Thick Biotype Patients: A Randomized Clinical Trial with 1-Year Follow-up.

PURPOSE: To determine the effect of 0.7- and 2.4-mm transmucosal abutment height titanium bases on the crestal bone stability and peri-implant soft tissue condition of bone-level implants with platform switching in patients with vertically thick soft tissues. MATERIALS AND METHODS: Sixty bone-level platform-switched implants were placed in the molar and premolar regions of both arches in 60 patients. All epicrestally inserted nonsubmerged implants had a 4.1-mm diameter and, after osteointegration, were randomly allocated into two groups: (1) the short group, with a titanium base of 0.7-mm transmucosal abutment height, and (2) the high group with a 2.4-mm height. Monolithic zirconia restorations were fabricated for all implants. Parallel intraoral radiographs were obtained after the delivery of restorations (T1) and after 1 year (T2). Crestal bone levels and peri-implant soft tissue conditions were calculated for each implant. The significance level was set at α = .05. RESULTS: After 1 year, 55 patients were evaluated, with a mean bone loss of 0.6 ± 0.51 mm (median: 0.71, range: 0 to 2.09 mm) in the short group (23 patients) and 0.45 ± 0.59 mm (median: 0.65, range: 0 to 2.12 mm) in the high group (22 patients), showing no significant difference between groups (P = .168). A significant increase in marginal bone height was noted between the T1 and T2 time points in the short and high (P = .029 and .001, respectively) groups. The peri-implant soft tissue health parameters did not show statistically significant differences. CONCLUSION: Crestal bone stability after 1 year of follow-up around epicrestally placed platform-switched implants is not influenced by transmucosal abutment height, if the vertical soft tissue thickness is ≥ 3 mm.

The influence of new immediate tissue level abutment on crestal bone stability of subcrestally placed implants: A 1-year randomized controlled clinical trial.

BACKGROUND: The relation between implant abutment disconnection (AD) and increased crestal bone loss is still debated. PURPOSE: To compare bone changes below implant-abutment junction of subcrestally placed implants between: (1) implant level restorations, that underwent four ADs and (2) implants with immediate tissue level abutment with no AD, 1 month (T2) and 1-year (T3) after final restoration delivery. MATERIALS AND METHODS: Sixty-four patients received 64 bone level implants with platform-switching and conical connection in edentulous sites of posterior mandible and maxilla. All implants were placed 1.5 mm subcrestally and distributed among: (1) control group, that received a regular healing abutment and (2) test group with immediate tissue level (ITL) abutment, which was torqued to implants during surgery, transforming bone level implant to tissue level type. After 2-3 months of healing and a 1-month temporization, final zirconia-based screw-retained crowns were delivered to both groups. Crestal bone levels were calculated after final crown delivery (T2); after 1-year follow-up (T3) and compared using Mann-Whitney U test (p ≤ .05). RESULTS: Early bone loss of the test and control groups was 0.14 ± 0.27 mm and 0.64 ± 0.64 mm, respectively; the 0.5 mm difference was statistically significant (p = .0001). Late bone loss was 0.06 ± 0.16 mm and 0.21 ± 0.56 mm for the test and control group, respectively; the 0.15 mm difference between the groups was no more statistically significant (p = .22). Both groups displayed bone gain, 0.08 and 0.43 mm, respectively, and the overall crestal bone loss was reduced. CONCLUSIONS: Immediate tissue level abutments can significantly reduce early bone loss when measured 1 month after final prosthesis delivery, however, after 1-year follow-up, difference between the groups was no more statistically significant.

The influence of submerged healing abutment or subcrestal implant placement on soft tissue thickness and crestal bone stability. A 2-year randomized clinical trial.

PURPOSE: Aims of the study were: (a) to register crestal bone loss around 1.5 mm subcrestally placed implants and epicrestally placed implants with soft tissue tenting technique, (b) to record bone remodeling in subcrestal group, and (c) to determine the increase of vertical soft tissues after tenting. MATERIALS AND METHODS: Thirty-two patients with vertically thin tissues of 2 mm or less received 40 submerged bone level platform-switched implants, divided into two groups-(a) 1.5 mm subcrestally placed implants and (b) epicrestally placed implants with soft tissue tenting over 2 mm healing abutments. At the second stage surgery, implants received 4 mm healing abutments, soft tissue thickness was measured in epicrestal group, and later implants were restored with zirconia-based screw-retained single restorations. Radiological images were taken at the second stage surgery, restoration delivery and after 2 years of follow-up. Bone loss was calculated as a distance between implant neck and first radiographically visible bone-to-implant contact. Bone remodeling was calculated as a distance between the bone crest and implant neck. Mann-Whitney U test was used for statistical analysis, significance set to 0.05. RESULTS: After 2 years of follow-up, Group 1 (subcrestal) had 0.18 ± 0.32 mm of bone loss, Group 2 (epicrestal with 2 mm healing abutment) had 0.51 ± 0.4 mm of bone loss, with statistically significant difference (P = .001). Bone remodeling in Group 1 (subcrestal) was 1.17 ± 0.51 mm. Vertical tissue thickness in epicrestal group before the intervention was 1.85 ± 0.26 and 3.65 ± 0.41 mm after the use of 2 mm healing abutment, with a statistical difference (P = .005). CONCLUSION: Subcrestal implant placement can significantly reduce crestal bone loss, compared to vertical soft tissue thickening by tenting of epicrestally placed implants, although soft tissue tenting can significantly increase soft tissue thickness.

The Effect of a Polishing Protocol on the Surface Roughness of Zirconium Oxide.

PURPOSE: To evaluate the surface roughness values of zirconium oxide samples that were gradually polished using a commercially available polishing system and polishing paste. MATERIALS AND METHODS: A total of 50 rectangular specimens of predetermined size (10 × 10 × 3 mm) were sintered from zirconium oxide. Samples were randomly assigned to one of five groups (n = 10 each): control, coarse (Co), fine (F), super fine (SF), or polishing paste (PP). In the control group, no polishing was done; in the Co group, a coarse polisher was used; and the specimens in the remaining three groups underwent additional processing with a fine rubber abrasive. For SF and PP samples, subsequent treatment with a super fine polisher was applied. Finally, for the PP group, a goat-hair brush with diamond polishing paste was used. An optical profilometer was used to evaluate roughness average (Ra) in micrometers (µm). ANOVA and Games-Howell post hoc tests were utilized to detect differences between groups. The significance level was set to α = .05. RESULTS: Surface roughness gradually decreased with further polishing throughout the groups: control Ra = 0.525 ± 0.099 µm; Co Ra = 0.252 ± 0.038 µm; F Ra = 0.196 ± 0.035 µm; SF Ra = 0.114 ± 0.031 µm; and PP Ra = 0.054 ± 0.020 µm. Statistically significant differences were detected among all groups (P < .05). CONCLUSION: A surface roughness of 0.054 µm can be achieved if a full zirconia polishing protocol is used. Zirconium oxide can be polished to various surface roughnesses using commercially available polishing products.

Clinical and Histologic Evaluations of Porcine-Derived Collagen Matrix Membrane Used for Vertical Soft Tissue Augmentation: A Case Series.

This case series aimed to clinically and histologically evaluate porcine-derived membrane used for vertical thickening of thin soft tissues. Twenty porcine-derived collagen membranes and bone-level implants were placed in 20 patients. After 2 months, thickened soft tissues were measured and biopsy samples were harvested. All xenografts healed successfully. The average thickness of thin soft tissue before vertical thickening was 1.65 ± 0.36 mm, while tissue thickness increased to 3.45 ± 0.52 mm after the procedure (P < .001); the mean thickness increase was 1.8 ± 0.13 mm. Histologic analysis showed complete integration of the graft and no differences (P = .4578) in vascularization between the host (39.74 ± 17.15 vessels/mm2) and graft (30.43 ± 11.26 vessels/mm2). It can be concluded that porcine-derived membrane can be used for vertical soft tissue thickening with substantial gain in tissue height.

Retention of zirconia copings over smooth and airborne-particle-abraded titanium bases with different resin cements.

STATEMENT OF PROBLEM: How cement type and the surface treatment of a titanium base affect the retention of zirconia copings on titanium bases is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the dislodging forces of zirconium oxide copings cemented on implant-supported titanium bases with different luting agents and to examine the influence of airborne-particle abrasion on titanium surfaces. MATERIAL AND METHODS: Thirty implant laboratory analogs (BioHorizons) were fixed in metal blocks, and 30 prosthetic titanium bases (BioHorizons) were tightened with 35 Ncm of torque. Zirconium oxide copings with a luting-gap size of 30 µm were produced by using the Lava (3M ESPE) technology. The specimens were bonded to the titanium bases with 3 different resin cements (G-CEM LinkAce, RelyX U200, and Ceka Site). The specimens were kept in artificial saliva at 37°C for 24 hours and then subjected to a dynamic loading of 5000 cycles with a mastication simulator (SD Mechatronic) with thermocycling between 5°C and 55°C. The tensile force was measured by using a universal testing machine (Zwick/Roell) at a crosshead speed of 5 mm/min. After the measurement, the cement was cleaned from the titanium bases and zirconia copings. The titanium bases were airborne-particle abraded with 50-µm aluminum oxide (Al2O3) particles, and the bonding process was repeated. The statistical analysis included descriptive analysis, 2-way ANOVA, the Tukey post hoc, and simple main effect tests (α=.05). RESULTS: Bond strengths were significantly different according to the cement type used and before and after airborne-particle abrasion (P<.05). The cement retentiveness before airborne-particle abrasion was as follows: G-CEM LinkAce (1338 ±69 N)>RelyX U200 (665 ±36 N)>Ceka Site (469 ±22 N). The differences among all the cement types before airborne-particle abrasion were statistically significant (P<.05). After airborne-particle abrasion, retention decreased in all the groups, and the ranking of the cements' retentiveness remained the same: G-CEM LinkAce (662 ±65 N)>RelyX U200 (352 ±21 N)>Ceka Site (122 ±17 N). After airborne-particle abrasion, the differences among all the cements remained statistically significant (P<.05). The comparison within the groups before and after airborne-particle abrasion revealed that abrading the titanium bases with 50-µm Al2O3 decreased the bond strength for all the tested cements. CONCLUSIONS: The cement type had a significant influence on the retention of the zirconia copings, and abrading the titanium bases with 50-µm Al2O3 significantly decreased the dislodging force of the coping from the titanium base.

Influence of titanium base, lithium disilicate restoration and vertical soft tissue thickness on bone stability around triangular-shaped implants: A prospective clinical trial.

OBJECTIVE: To evaluate how vertical mucosal tissue thickness affects crestal bone stability around triangular-shaped bone-level implants, restored with low profile titanium bases and monolithic lithium disilicate restorations. MATERIAL AND METHODS: Fifty-five bone-level implants of 4.3 mm diameter were evaluated in 55 patients (22 males and 34 females, mean age 48.3 ± 3.4 years) in prospective cohort study. According to vertical mucosal thickness, patients were assigned into three groups: 1 (thin, 2 mm or less), 2 (medium, 2.5 mm) and 3 (thick, 3 mm and more). Implants were placed in posterior mandible and maxilla in one-stage approach and, after integration, were restored with single screw-retained monolithic lithium disilicate crowns, using low gingival profile titanium bases. Radiographic examination was performed after implant placement and after 1-year follow-up. Crestal bone loss was registered mesially and distally, and mean value was calculated. One-way ANOVA and Tukey's HSD tests were applied; significance was set to 0.05. RESULTS: Mean vertical tissue thickness in 1 group was 1.76 ± 0.26 mm, 2 group-2.5 mm and 3.91 ± 0.59 mm in group 3, with statistically significant difference between all groups (p < 0.001). After 1-year follow-up, implants in group 1 (thin) had 1.25 ± 0.8 mm bone loss. Implants in group 2 (medium) had 0.98 ± 0.06, while implants in group 3 (thick) lost 0.43 ± 0.37 mm of crestal bone. Tukey's HSD test showed that differences between 1/3 and 2/3 were statistically significant (p < 0.001 and p = 0.0014, respectively), while between 1 and 2 was not significant (p = 0.310). CONCLUSIONS: Significantly less bone loss occurs around triangular-shaped bone-level implants in thick mucosal tissues (≥3 mm), compared to medium or thin tissue biotype. Crestal bone loss did not differ between medium and thin tissues.

Enamel microcracks in the form of tooth damage during orthodontic debonding: a systematic review and meta-analysis of in vitro studies.

Objectives: To evaluate and compare the enamel microcracks (EMCs) characteristics (qualitative and quantitative) in the form of tooth damage before and after debonding from human teeth of in vitro studies. Eligibility criteria: Laboratorial studies evaluating EMCs characteristics before and after debonding metal and ceramic brackets from human teeth with intact buccal enamel. Information sources: An electronic search of four databases (all databases of the Cochrane Library, CA Web of Science, MEDLINE via PubMed, and Google Scholar) and additional manual searches were carried out, without language restrictions. Studies published between 2000 and 2017 years were selected. Reference lists of the included articles were screened, and authors were contacted when necessary. Risk of bias: The following six parameters were analyzed: blinding of examiner and outcome assessment, incomplete outcome data before bonding and after debonding, selective outcome reporting, and incomplete reporting of EMCs assessment. Included studies: Out of 430 potentially eligible studies, 259 were screened by title and abstract, 180 were selected for full-text analysis, 14 were included in the systematic review. Seven studies were selected for the meta-analysis. Synthesis of results: The results for EMCs characteristics were expressed as mean differences (MDs) with their 95 per cent confidence intervals (CIs), and calculated from random-effects meta-analyses. Debonding was associated with the increase in number (three studies, MD = 3.50, 95% CI, 2.13 to 4.87, P < 0.00001), length (seven studies, MD = 3.09 mm, 95% CI, 0.75-5.43, P < 0.00001), and width (three studies, MD = 0.39 µm, 95% CI, -0.01 to 0.79, P = 0.06) of EMCs. Considerable statistical heterogeneity was found for two forest plots evaluating the changes of number and length characteristics during debonding. Conclusions: There is weak evidence indicating length and width of EMCs increase following bracket removal and the scientific evidence concerning quantitative evaluation of the number parameter before and after debonding is insufficient. However, there is a strong evidence that after debonding the number of EMCs is likely to increase. Registration: No registration was performed.

Enamel microcracks in terms of orthodontic treatment: A novel method for their detection and evaluation.

The study aimed at introducing current available techniques for enamel microcracks (EMCs) detection, and presenting a method for direct quantitative analysis of an individual EMC. Measurements of the detailed EMCs characteristics (location, length, and width) were taken from the reconstructed images of the buccal tooth surface (teeth extracted from two age groups of patients) employing a scanning electron microscopy (SEM) and our derived formulas before and after ceramic brackets removal. Measured parameters of EMCs for younger age group were 2.41 µm (width), 3.68 mm (length) before and 2.73 µm, 3.90 mm after debonding; for older -4.03 µm, 4.35 mm before and 4.80 µm, 4.37 mm after brackets removal. Following debonding EMCs increased for both groups, however the changes in width and length were statistically insignificant. Regardless of the age group, proposed method enabled precise detection of the same EMC before and after debonding, and quantitative examination of its characteristics.

Does orthodontic debonding lead to tooth sensitivity? Comparison of teeth with and without visible enamel microcracks.

INTRODUCTION: Our aim was to assess the possible changes in sensitivity of teeth with and without visible enamel microcracks (EMCs) up to 1 week after the removal of metal brackets. METHODS: After debonding, 15 patients possessing teeth with visible EMCs and 15 subjects whose teeth were free of EMCs were enrolled in the study. For each experimental group, a control group was formed. The assessments of tooth sensitivity elicited by compressed air and cold testing were performed 5 times: just before debonding, immediately after debonding, and at 1, 3, and 7 days after debonding. Tooth sensitivity was recorded on a 100-mm visual analog scale. RESULTS: For the patients without visible EMCs, discomfort peaked immediately after debonding and started to decrease on day 1; at 1 week after debonding, the visual analog scale scores were lower than just before debonding and immediately after debonding. For the subjects possessing teeth with visible EMCs, the pattern of sensitivity dynamic was inherently the same. However, the patients with visible EMCs showed higher visual analog scale values at each time interval. CONCLUSIONS: Debonding leads to a short-term increase in tooth sensitivity. EMCs, a form of enamel damage, do not predispose to greater sensitivity perception in relation to bracket removal.

The prognostic value of visually assessing enamel microcracks: Do debonding and adhesive removal contribute to their increase?

OBJECTIVE: To find a correlation between the severity of enamel microcracks (EMCs) and their increase during debonding and residual adhesive removal (RAR). MATERIALS AND METHODS: Following their examination with scanning electron microscopy (SEM), 90 extracted human premolars were divided into three groups of 30: group 1, teeth having pronounced EMCs (visible with the naked eye under normal room illumination); group 2, teeth showing weak EMCs (not apparent under normal room illumination but visible by SEM); and group 3, a control group. EMCs have been classified into weak and pronounced, based on their visibility. Metal brackets (MB) and ceramic brackets (CB), 15 of each type, were bonded to all the teeth from groups 1 and 2. Debonding was performed with pliers, followed by RAR. The location, length, and width of the longest EMCs were measured using SEM before and after debonding. RESULTS: The mean overall width (Woverall) was higher for pronounced EMCs before and after debonding CB (P < .05), and after the removal of MB. Pronounced EMCs showed greater length values using both types of brackets. After debonding, the increase in Woverall of pronounced EMCs was 0.57 µm with MB (P < .05) and 0.30 µm with CB; for weak EMCs, - 0.32 µm with MB and 0.30 µm with CB. CONCLUSIONS: Although the teeth having pronounced EMCs showed higher width and length values, this did not predispose to greater EMCs increase after debonding MB and CB followed by RAR.

Enamel cracks evaluation - A method to predict tooth surface damage during the debonding.

The objective of this in vitro study was to evaluate the effect of the enamel cracks on the tooth damage during the debonding. Measurements of the cracks characteristics (visibility, direction, length, and location) were performed utilizing a scanning electron microscopy (SEM) technique and mathematically derived formulas (x=h/30, l=n*x) before and following the removal of mechanically retained metal and ceramic brackets. The likelihood of having greater extent enamel defects was higher for the teeth with pronounced cracks (odds vatios, OR=3.728), increased when the crack was located in more than one zone of the tooth (OR=1.998), and the inclination did not exceed 30-45° (OR=0.505). Using ceramic brackets the risk of greater amount tooth structure defects raised 1.45 times (OR=1.450). Enamel crack showing all these characteristics at the beginning of the orthodontic treatment and the use of ceramic brackets might predispose to higher risk of greater extent tooth surface damage after the debonding by 20.4%.

Radiological comparison of laser-microtextured and platform-switched implants in thin mucosal biotype.

OBJECTIVE: To compare how laser-microtextured implants and implants with platform switching maintain crestal bone stability in thin peri-implant tissues. MATERIAL AND METHODS: Thirty laser-microtextured implants of 4.6 mm diameter (Tapered Internal Laser-Lok, BioHorizons, Birmingham, AL, USA; Group 1) and 30 implants with platform switching of 5/4 mm diameter (Certain Prevail; Biomet/3i, Palm Beach Gardens, FL, USA; Group 2) were placed in 30 patients (12 males and 18 females, mean age 42.3 ± 2.4) with thin mucosal tissues (≤2 mm). Implants were placed in posterior mandible in one-stage approach and after integration were restored with screw-retained metal-ceramic restorations. Radiographic examination was performed after implant placement, 2 months after healing, at prosthetic restoration delivery and after 1-year follow-up. Mean crestal bone loss was calculated, Mann-Whitney U-test was applied, and significance was set to 0.05. RESULTS: After 2 months of healing, the crestal bone loss was 0.71 ± 0.25 mm SD (range, 0.25-1.6 mm) and 1.02 ± 0.25 mm SD (range, 0.6-1.55 mm) in groups 1 and 2, respectively (P = 0.001). At restorations' delivery, the crestal bone loss was 1.10 ± 0.30 mm SD (range, 0.65-1.85 mm) and 1.37 ± 0.27 mm SD (range, 0.90-1.80 mm) in groups 1 and 2, respectively (P = 0.001). After 1-year follow-up, the crestal bone loss was 1.41 ± 0.42 mm SD (range, +0.1-2.30 mm) and 1.43 ± 0.23 mm SD (range, 1-1.80 mm) in groups 1 and 2, respectively (P = 0.976). CONCLUSIONS: Laser-microtexturing of implant collar or platform-switched implant/abutment connection did not eliminate crestal bone loss, if at the time of implant placement vertical soft tissue thickness was ≤2 mm. However, laser-microtextured implants may present less proximal bone loss than platform-switching implants in the period before implant loading.

Influence of Vertical Soft Tissue Thickness on Crestal Bone Changes Around Implants with Platform Switching: A Comparative Clinical Study.

BACKGROUND: Numerous studies have shown the superiority of platform-switched implants in preserving crestal bone as compared with platform-matched implants. However, the influence of initial soft tissue thickness on development of crestal bone loss has not been addressed in previous studies; thus, further research is needed. PURPOSE: To evaluate crestal bone levels around platform-switched implants placed in thin and thick mucosal tissue. MATERIALS AND METHODS: Eighty patients (38 male and 42 female, mean age 44 ± 3.34 years) received 80 bone-level implants of 4.1 mm in diameter with platform switching (Institut Straumann AG, Basel, Switzerland). Tissue thickness was measured, and cases were distributed to Group 1, with thin soft tissue (2 mm or less, n = 40), and Group 2, with thick tissue (more than 2 mm, n = 40). Implants were placed with a one-stage approach and restored with screw-retained restorations. Radiographic examination was performed after implant placement, 2 months after healing, after restoration, and at 1-year follow-up post-reconstruction. Crestal bone loss was calculated. The Mann-Whitney U-test was applied, and significance was set to p ≤ .05. RESULTS: Implants in Group 1 (thin tissue) showed 0.79 mm of bone loss after 2 months. After 1-year follow-up, bone loss was 1.17 mm. Implants in Group 2 (thick tissue) showed bone loss of 0.17 mm after 2 months of implant placement and 0.21 mm after 1-year follow-up. The differences between groups were significant (p < .001) at both time points. CONCLUSIONS: It can be concluded that platform switching does not prevent crestal bone loss if, at the time of implant placement, mucosal tissue is thin. In thick soft tissue, use of platform-switched implants maintained crestal bone level with minimal remodeling.

Crestal Bone Stability around Implants with Horizontally Matching Connection after Soft Tissue Thickening: A Prospective Clinical Trial.

BACKGROUND: It has been shown that thin mucosal tissues may be an important factor in crestal bone loss etiology. Thus, it is possible that mucosal tissue thickening with allogenic membrane might reduce crestal bone loss. PURPOSE: The purpose of this study was to evaluate how implants with traditional connection maintain crestal bone level after soft tissue thickening with allogenic membrane. MATERIALS AND METHODS: One hundred three patients received 103 internal hex implants of 4.6 mm diameter with regular connection. According to gingiva thickness, patients were assigned into A (thin tissues, n = 34), B (thin, thickened with allogenic membrane, n = 35), and C group (thick tissues, n = 34). Groups A and C had one-stage approach, and in group B, implants were placed in two stages. Radiographic examination was performed after implant placement, 2 months after healing, after restoration, and after 1-year follow-up. Crestal bone loss was calculated medially and distally. Significance was set to 0.05. RESULTS: After 1-year follow-up, implants in group A had 1.65 ± 0.08-mm bone loss mesially and 1.81 ± 0.06 mm distally. Group B had 0.31 ± 0.05 mm mesially and 0.34 ± 0.05 mm distally. C group implants experienced bone loss of 0.44 ± 0.06 mm mesially and 0.47 ± 0.07 mm distally. Differences between A and B, and A and C were significant (p = .000) both mesially and distally, whereas differences between B and C were not significant mesially (p = .166) and distally (p = .255). CONCLUSIONS: It can be concluded that thin mucosal tissues may cause early crestal bone loss, but their thickening with allogenic membrane may significantly reduce bone resorption. Implants in naturally thick soft tissues experienced minor bone remodeling.

Clinical Factors Influencing Removal of the Cement Excess in Implant-Supported Restorations.

BACKGROUND: The depth of the cementation margin has an influence on the amount of cement remnants around implants. However, the role of other clinical factors is still not clarified. PURPOSE: The aim of the study was to evaluate the correlation between undetected cement and (i) location of the implant, (ii) implant diameter, and (iii) undercut. MATERIALS AND METHODS: Sixty-five patients were treated with single metal-ceramic restorations on implants. The undercut between the restoration and the tissue was measured. After cementation, the restoration-abutment unit was unscrewed. All quadrants of the specimens were photographed and analyzed. The ratio between total restoration area/peri-implant tissue area and area of cement remnants was calculated in pixels. Significance was set to 0.05. RESULTS: Sixty-five metal-ceramic restorations were placed on 65 implants (39 molars, 22 premolars, 4 anteriors; 21 implants had a diameter of 3.5 mm, 34 of 4.0 mm, 10 of 5.0 mm). An undercut of 1 mm was found in 118 sites, 2 mm in 96 sites, and 3 mm in 46. The percentages of soft tissue and restoration, respectively, covered by cement were as follows: molars 4% and 7%; premolars 3.8% and 7.3%; anteriors 3% and 3.4%; 3.5 mm diameter 3.3% and 7.4%; 4.0 mm 7.7% and 7.7%; 5.0 mm 3.9% and 2.1%; 1-mm undercut 3.5% and 5.4%; 2-mm 4% and 8.1%; 3-mm 4.8% and 8.4%. The relationship between amount of cement remnants and implant location was insignificant (p > 0.05) for both soft tissue and the specimen, but significant relationships with amount of cement remnants were found for diameter (p = 0.026 for soft tissue, p = 0.600 for specimen) and undercut (p = 0.004 for soft tissue, p = 0.046 for specimen). CONCLUSION: If cemented crown restoration is desired, undercuts should be reduced to a minimum for better removal of cement excess, irrespective of the diameter and location of the implants in the mouth.

Relationship between breastfeeding, bottle-feeding and development of malocclusion.

The importance of breastfeeding to the child's psychological and physical development is evidence-based. However, scientific literature contains controversial opinions on its influence to the development of maxillofacial system. This article aims at reviewing the effects of breastfeeding and bottle-feeding to the development of malocclusion and non-nutritive sucking habits. Thirty-four articles analyzing the above mentioned associations were selected from Pubmed database. Breastfeeding and bottle-feeding may have different impact on the development of maxillofacial system due to unequal functional load of certain facial muscles involved in the feeding processes. Shortage of scientific research prevents from relating bottle-feeding with the development of skeletal malocclusions. Prolonged breastfeeding may have protective effect on developing posterior crossbite and anterior openbite. However, conflicting opinions have been observed. It has been stated that longer duration of breastfeeding diminishes the risk of acquiring non - nutritive sucking habits.

Heterogeneity of oral clefts in relation to associated congenital anomalies.

BACKGROUND AND OBJECTIVE: The first step in the search for the genetic basis of oral clefts should be the well-accepted classification and clinical data protocols, which are important in distinguishing separate phenotypic groups. The aim of this study was to compare the frequency of congenital malformations associated with oral clefts between the different groups of oral clefts. MATERIAL AND METHODS: The study population comprised 238 patients with oral clefts and one or more major congenital anomalies. All cases of oral clefts were subdivided into 2 groups: patients with the recognized conditions (n=97, 40.8%) and patients with the multiple congenital anomalies of unknown origin (n=141, 59.2%). The frequency of associated congenital anomalies was compared between the cleft palate (CP) and cleft lip and/or palate (CL/P) groups as well as between the cleft lip only (CL) and cleft lip with cleft palate (CLP) subgroups. RESULTS: A total of 420 anomalies associated with oral clefts were diagnosed in 141 patients with multiple congenital anomalies (2.98 anomalies per proband) with the highest incidence being in the CP group (3.5 anomalies per proband). Comparison of the CP and CL/P groups showed that some of associated congenital anomalies such as atresia and stenosis of the small intestine and micrognathia occurred significantly more often in the CP than CL/P group (2.1% vs. 0% and 3.5% vs. 1.1%; P<0.05). Meanwhile, comparison of the CL and CLP subgroups revealed accessory auricle, other specified anomalies of the ear, congenital anomalies of the circulatory system, and certain congenital musculoskeletal deformities of the spine to be more common in the CL than CLP group (5.1% and 0.5%, 11.9% and 5.1%, 3.4% and 0%, 3.4% and 0%, respectively; P<0.05). CONCLUSIONS: The highest incidence of associated congenital anomalies was in the CP group followed by the CL, CL/P, and CLP groups. Generally, the anomalies of the musculoskeletal system, cardiovascular system, and face including eye, ear, and neck were most common. The careful analysis of associated anomalies and cases of oral cleft subgroups with multiple congenital anomalies is helpful in identifying the etiologic entities and underscores the need for thorough evaluation and competent distinction of various types of oral clefts.