In-vitro performance of CAD/CAM-fabricated implant-supported temporary crowns.

OBJECTIVES: The aim of this study was to investigate the in-vitro performance and fracture resistance of a temporary computer-aided designed and computer-aided manufactured polymethylmethacrylate (CAD/CAM-PMMA) material as implant or tooth-supported single crown with respect to the clinical procedure (permanently bonded/temporarily cemented). MATERIALS AND METHODS: Sixty-four crowns were fabricated on implants or human molar teeth simulating (a) labside procedure on prefabricated titanium-bonding base ([TiBase] implant crown bonded in laboratory, screwed chairside), (b) labside procedure ([LAB] standard abutment and implant crown bonded in laboratory, screwed chairside), (c) chairside procedure ([CHAIR] implant crown bonded to abutment), and (d) reference ([TOOTH] crowns luted on prepared human teeth). Crowns were made of a CAD/CAM-PMMA temporary material (TelioCAD, Ivoclar-Vivadent). For investigating the influence of fixation, half of the crowns were permanently (P) or temporarily (T) bonded. Combined thermal cycling and mechanical loading (TCML) was performed simulating a 5-year clinical situation. Fracture force was determined. Data were statistically analyzed (Kolmogorov-Smirnov test, one-way ANOVA; post hoc Bonferroni, α = 0.05). RESULTS: All restorations survived TCML without visible failures. Fracture results varied between 3034.3 (Tooth-P) and 1602.9 N (Tooth-T) [TOOTH], 1510.5 (TiBase-P) and 963.6 N (TiBase-T) [TiBase], 2691.1 (LAB-P) and 2064.5 N (LAB-T) [LAB], and 1609.4 (Chair-P) and 1253.0 N (Chair-T) [CHAIR]. Tested groups showed significantly (p < 0.001) different fracture values. Failure pattern was characterized by fractures in mesial-distal, buccal-oral, or mixed (mesial-distal/buccal-oral) directions, with differences for the individual groups. CONCLUSIONS: Temporary CAD/CAM crowns showed no different in-vitro performance but provided different fracture results that depended on cementation, screw channel, and type of abutment. CLINICAL RELEVANCE: All bonded and screwed PMMA crowns were in a range where clinical application seems not restricted.

The morphological variations of the lateral pterygoid muscle: A systematic review.

BACKGROUND: The lateral pterygoid muscle (LPM) has been described in many anatomical and functional studies. The morphology of the LPM is still under debate because of its deep location in the infratemporal fossa and the difficulties to approach this area with different anatomical methods. Although it has been generally accepted that this muscle is mainly composed of two separate parts, other forms have been described in the past. OBJECTIVES: To conduct a systematic literature review regarding the anatomy and variations of the LPM. METHODS: We included studies published in English, German or French employing anatomical and imaging methods or a combination of the two methods. The cadavers used in the dissections had to be human and without any pathological alterations. Studies were only included when focusing on the anatomy of the LPM or its morphological variations or when taking the frequency of variations into account. We searched 26 biomedical databases including MEDLINE, EMBASE, BIOSIS Previews and Science Citation Index Expanded (part of Web of Science) through October 2014. The review was followed by the dissection of a hemisected head in two different planes. RESULTS: We identified 4279 records (2200 after deduplication) in the databases searches plus 17 articles from manual searches. 81 studies out of these articles were included in this review. 69 articles used anatomical methods, 5 imaging methods and 7 studies a combination of the two methods. 11 studies took into account that the LPM may have variations and also considered the relative frequency of each variation. The frequency of one-headed LPMs ranged between 7.7% and 26.7%, of two-headed LPMs between 61.4% and 91.1% and of three-headed LPMs between 4.0% and 35.0%. Our own dissection showed a three-headed version of the LPM. DISCUSSION: In anatomical studies, different preparation techniques seem to be the main reason for diverging results.

Investigation of Clinical and Laboratory Wear in Locator-Supported, Implant-Retained Overdentures.

PURPOSE: To investigate the mechanical properties and wear of nylon inserts and abutments in Locator-retained, implant-supported overdentures (L-IODs). MATERIALS AND METHODS: Clinical wear of inserts and abutments was qualitatively rated in a group of 16 patients with L-IODs. The inserts were also subjected to microscopic analysis, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). RESULTS: Wear was identified in almost all inserts and abutments. These results were corroborated by DSC and TGA analyses, which showed significant mechanical deterioration of the inserts. CONCLUSION: Nylon inserts and Locator abutments show relevant signs of deterioration in clinical use, indicating that regular maintenance is an issue that should be addressed with the patients prior to treatment.

Synthesis and NMR studies of cyclopeptides containing a sugar amino Acid.

[structure: see text] Cyclopeptides containing Glucuronic acid methylamine (Gum) alternating with Gly, L-Ala, D-Ala, L-Phe, D-Phe, L-Lys, or D-Lys were synthesized by a combination of solid-phase synthesis and solution chemistry. A more effective pathway to synthesize the sugar amino acid Gum in higher yields and in a shorter period of time was developed. Gum is employed in the benzylated and deprotected form. The cyclopeptides were characterized by NMR and the structure of one deprotected cyclic peptide solved.

Design, synthesis, and NMR structure of linear and cyclic oligomers containing novel furanoid sugar amino acids.

Sugar Amino Acids (SAAs) are sugar moieties containing at least one amino and one carboxyl group. The straightforward synthesis of two furanoid SAAs, 3-amino-3-deoxy-1,2-isopropylidene-alpha-D-ribofuranoic acid (f-SAA1) and 3-amino-3-deoxy-1,2-isopropylidene-alpha-D-allofuranoic acid (f-SAA2) starting from diacetone glucose, is described. These SAAs were used as structural templates aiming at new structures for peptidomimetic drug design. f-SAA1 resembles a beta-amino acid, whereas f-SAA2 is a gamma-amino acid mimetic. Thus, for the synthesis of the mixed, linear and cyclic oligomers of f-SAA1, beta-homo-glycine (beta-hGly, also called beta-alanine) was chosen as an amino acid counterpart, while for the oligomer of f-SAA2 gamma-amino butyric acid (GABA) was chosen. Fmoc-[f-SAA1-beta-hGly](3)-OH (3) and cyclo[f-SAA1-beta-hGly](3) (5) resemble linear and cyclic beta-peptides with a very different substitution pattern, compared with the beta-peptides known so far in the literature, whereas Fmoc-[f-SAA2-GABA](3)-OH (4) resembles a gamma-peptide. The linear f-SAA oligomers 3 and 4 were synthesized on the solid-phase using Fmoc strategy. 23 unambiguous interresidue NOE contacts (from a total of 76 NOE values), obtained from extensive NMR studies in C(3)CN, were used in subsequent simulated annealing and MD calculations, to elucidate the 12/10/12-helical structure of oligomer 3 in CH(3)CN. The results indicate that f-SAA1 strongly induces a secondary structure. A characteristic CD curve for the linear oligomer 3 is observed up to 75 degrees C in both CH(3)CN and CH(3)CN/H(2)O, even though 3 contains beta-hGly, which is known to destabilize helices. By contrast, 4 does not seem to form a stable conformation in solution. The cyclic SAA containing oligomer cyclo [f-SAA1-beta-hGly](3) (5) exhibits a C(3) symmetric conformation on the NMR chemical shift time scale.