Straight and tilted implants for supporting screw-retained full-arch dental prostheses in atrophic maxillae: A 2-year prospective study.

BACKGROUND: To evaluate, over a 2-year period, the treatment outcomes for maxillary full-arch fixed dental prostheses (FDPs) supported by a combination of both tilted and axially-placed implants and to compare the marginal bone loss (MBL) and implant survival rates (SR) between tilted and axial implants. MATERIAL AND METHODS: A retrospective study has been carried out. Thirty-two patients (16 males and 16 females) treated with maxillary full-arch FDPs were included in this retrospective study. A total of 187 implants were inserted to rehabilitate the fully edentulous maxillary arches: 36% of them were tilted (T group, n = 68) and the remaining 64% were axially placed (A group, n = 119). From the total, 28% of the implants (n=53) were immediately loaded with screw-retained provisional acrylic restorations, whereas 72% underwent conventional delayed prosthetic loading 6 months post-operatively. Definitive restorations were hybrid implant prostheses (metal framework covered with high-density acrylic resin) and metal-ceramic screw-retained implant prostheses, and were placed 6 months after surgery. Such definitive restorations were checked for proper function and aesthetics every three months for two years. Peri-implant marginal bone levels were assessed by digital radiographs immediately after surgery and MBL was assessed at definitive implant loading (baseline) and 2 years afterwards. RESULTS: The 2-year implant SR were 100% for axially placed implants and 98.5% for tilted implants. No significant differences were found amongst the A and T implant groups. Marginal bone loss measured at 2 years after definitive prosthetic loading was of -0.73 ± 0.72 mm (maximum MBL of 1.43 mm) for axially positioned implants vs. -0.51 ± 0.92 mm for tilted implants (maximum bone 1.45 mm). Differences in MBL were statistically significant when comparing immediately and delayed loaded implants. CONCLUSIONS: Based on the results of this retrospective clinical study, full-arch fixed prostheses supported by a combination of both tilted and axially placed implants may be considered a predictable and viable treatment modality for the prosthetic rehabilitation of the completely edentulous maxilla.

Evolution of oral neoplasm in an andalusian population (Spain).

BACKGROUND: Head and neck cancer are one of the most common neoplasm pathologies in humans. The aim of this study was to analyze the type, characteristics, treatment and evolution of oral neoplasm or precancerous lesion in a sample of Andalusian population (Spain) derived from the Oncology Rehabilitation Hospital Unit during a period of 20 years. MATERIAL AND METHODS: A retrospective descriptive study was carried out during the years 1991 and 2011 analyzing the type, characteristics, treatment and follow-up of oral neoplasm in the Oral and Maxillofacial Surgery Unit of the Universitary Hospital Virgen del Rocio. The inclusion criteria were patients whose underlying pathology was any type of benign or malignant neoplasm or presence of precancerous lesion that, after treatment, had been referred to the Prosthetic Rehabilitation Unit. RESULTS: Of the initial analyzed sample of 60 patients, only 45 patients met the inclusion criteria. Of the final sample analyzed, 31 subjects were men (68.9%) and 14 women (31.1%) (p = 0.0169). The mean age of the sample was 57 years ± 13.83, been more frequently in older people with more than 50 years (73.3%) (p = 0.0169). The most common type of neoplasm was epidermoid carcinoma (64.4%). The site most frequently found in squamous cell carcinoma was the floor of the mouth (31%). The most frequent treatment modality was surgery with postoperative radiotherapy (42.2%). All patients had a minimum follow-up of 5 years, and a recurrence in this period was identified in 11.1% of the sample. Multivariate logistic regression showed a statistically significant association for the variables age (p = 0.0063) and smoking (p = 0.0434). CONCLUSIONS: Epidermoid carcinoma is the most frequent tumor in the oral cavity, where increase age and smoking are confirmed as associated risk factors.

Reduction rate by decompression as a treatment of odontogenic cysts.

BACKGROUND: Odontogenic cysts are defined as those cysts that arise from odontogenic epithelium and occur in the tooth-bearing regions of the jaws. Cystectomy, marsupialization or decompression of odontogenic cyst are treatment approach to this pathology. The aim of this study was to evaluate the effectiveness of the decompression as the primary treatment of the cystic lesions of the jaws and them reduction rates involving different factors. MATERIAL AND METHODS: 23 patients with odontogenic cysts of the jaws, previously diagnosed by anatomical histopathology (follicular cysts (7) and radicular cysts (16)) underwent decompression as an initial treatment. Clinical examination and pre and post panoramic radiograph were measured and analyzed. In addition, data as gender, age, time reduction and location of the lesion were collected. RESULTS: Significant results were obtained in relation to the location of lesions and the reduction rate (p<0.01). In a higher initial lesion, a greater reduction rate was observed (p<0.05). CONCLUSIONS: Decompression as an initial treatment of cystic lesions of the jaws was effective; it reduces the size of the lesions avoiding a possible damage to adjacent structures. Cystic lesions in the mandible, regardless of the area where they occur will have a higher reduction rate if it is compared with the maxilla. Similar behavior was identified in large lesions compared to smaller.

Production of bone mineral material and BMP-2 in osteoblasts cultured on double acid-etched titanium.

BACKGROUND: The study of osteoblasts and their osteogenic functions is essential in order to understand them and their applications in implantology. In this sense, this study try to study BMP-2 production and bone matrix deposition, in addition to other biological variables, in osteoblasts cultured on a rough double acid-etched titanium surface (Osseotite®, Biomet 3i, Palm Beach Garden, Florida, USA) in comparison to a smooth titanium surface (machined) and a control Petri dish. MATERIALS AND METHODS: An in vitro prospective study. NHOst human osteoblasts from the femur were cultured on three different surfaces: Control group: 25-mm methacrylate dish (n = 6); Machined group: titanium discs with machined surface (n = 6) and Experimental group: titanium discs with a double acid-etched nitric and hydrofluoric Osseotite® acid surface (n = 6). A quantification of the mitochondrial membrane potential, and studies of apoptosis, mobility and adhesion, bone productivity (BMP-2) and cellular bone synthesis were carried out after culturing the three groups for forty-eight hours. RESULTS: A statistically significant difference was observed in the production of BMP-2 between the experimental group and the other two groups (22.33% ± 11.06 vs. 13.10% ± 5.51 in the machined group and 3.88% ± 3.43 in the control group). Differences in cellular bone synthesis were also observed between the groups (28.34% ± 14.4% in the experimental group vs. 20.03% ± 6.79 in the machined group and 19.34% ± 15.93% in the control group). CONCLUSIONS: In comparison with machined surfaces, Osseotite® surfaces favor BMP-2 production and bone synthesis as a result of the osteoblasts in contact with it.

Reliability of new poly (lactic-co-glycolic acid) membranes treated with oxygen plasma plus silicon dioxide layers for pre-prosthetic guided bone regeneration processes.

BACKGROUND: The use of cold plasmas may improve the surface roughness of poly(lactic-co-glycolic) acid (PLGA) membranes, which may stimulate the adhesion of osteogenic mediators and cells, thus accelerating the biodegradation of the barriers. Moreover, the incorporation of metallic-oxide particles to the surface of these membranes may enhance their osteoinductive capacity. Therefore, the aim of this paper was to evaluate the reliability of a new PLGA membrane after being treated with oxygen plasma (PO2) plus silicon dioxide (SiO2) layers for guided bone regeneration (GBR) processes. MATERIAL AND METHODS: Circumferential bone defects (diameter: 11 mm; depth: 3 mm) were created on the top of eight experimentation rabbits' skulls and were randomly covered with: (1) PLGA membranes (control), or (2) PLGA/PO2/SiO2 barriers. The animals were euthanized two months afterwards. A micromorphologic study was then performed using ROI (region of interest) colour analysis. Percentage of new bone formation, length of mineralised bone, concentration of osteoclasts, and intensity of ostheosynthetic activity were assessed and compared with those of the original bone tissue. The Kruskal-Wallis test was applied for between-group com Asignificance level of a=0.05 was considered. RESULTS: The PLGA/PO2/SiO2 membranes achieved the significantly highest new bone formation, length of mineralised bone, concentration of osteoclasts, and ostheosynthetic activity. The percentage of regenerated bone supplied by the new membranes was similar to that of the original bone tissue. Unlike what happened in the control group, PLGA/PO2/SiO2 membranes predominantly showed bone layers in advanced stages of formation. CONCLUSIONS: The addition of SiO2 layers to PLGA membranes pre-treated with PO2 improves their bone-regeneration potential. Although further research is necessary to corroborate these conclusions in humans, this could be a promising strategy to rebuild the bone architecture prior to rehabilitate edentulous areas.

In vitro analysis of femtosecond laser as an alternative to acid etching for achieving suitable bond strength of brackets to human enamel.

This study aims to evaluate the effect of laser irradiation and orthophosphoric acid etching on the shear bond strength (SBS) of orthodontic brackets to enamel. Three groups (n = 20) of extracted premolar teeth were randomly established depending on the laser treatment performed on the buccal surfaces: (1) no laser (control); (2) Er:YAG laser (2,940 nm, 0.8 W, 100 µs/pulse, 10 Hz) and; (3) Ti:Sapphire laser (795 nm, 1 W, 120 fs/pulse, 1 kHz). Each group was divided into two subgroups according to whether 37%-orthophosphoric acid etching was made after laser irradiation or not. Brackets were randomly luted with Transbond(TM) XT adhesive resin. After 72 h, a SBS test was developed in a universal testing machine (crosshead speed, 0.5 mm/min). Representative specimens from each experimental subgroup were examined by means of scanning electron microscopy. Cement residuals remaining on the premolar surfaces were assessed using the adhesive remnant index. ANOVA, post-hoc tests for intergroup comparisons, chi-square test and linear regression were run for data analyses (α = 0.05). After acid etching, SBS values did not differ regardless the laser treatment. When phosphoric acid was not applied, the SBS values of the femtosecond laser group were significantly higher than for the other groups. Femtosecond laser without acid seems to be the most suitable method to improve bond strengths at the bracket/enamel interface, thus avoiding the disadvantages inherent to acid etching.