1,721,037 research outputs found
Fatigue Resistance of Monolithic Ceramic Crowns: In Vitro Comparison with Teeth.
No full textPurpose: To compare the tooth fatigue resistance to lithium disilicate, UTML (ultra-translucent-multi-layered zirconia), and Y-TZP (yttrium-stabilized tetragonal zirconia) monolithic crowns, tested using a new, simplified fatigue testing machine (Ball-mill) and digital wear analysis. Materials and Methods: Twenty extracted human molars were used. In addition, 60 monolithic crowns were produced and subdivided into 3 groups (n = 20) according to material (lithium disilicate 1.5 mm, IPS e-max CAD LT, IvoclarVivadent; UTML 1.5 mm, Katana STML, Kuraray Noritake; Y-TZP 1.0 mm, Katana, Kuraray Noritake). Teeth were subjected to three 10-min cycles of Ball-mill and to one 30-min cycle. For monolithic crowns, twelve 60-min cycles were performed (since in a preliminary pilot study no significant volumetric losses were observed before 60 min). At T0 and after each cycle, an analysis was carried out using a stereomicroscope (Wild M3C, Heerbrugg) to evaluate the wear morphology, an intraoral scanner (CS 3500, Carestream Dental), and software (Rhinoceros, McNeel) to calculate the volumetric loss of the samples caused by the wear. Results: The lithium disilicate and Y-TZP crowns showed a 100% survival rate and high wear resistance; UTML had 95% survival. Lithium disilicate and UTML showed many parting-cleavage fractures (>90%). The wear generated on teeth at T60 was statistically greater (p < 0.05) than the one of crowns, Y-TZP in particular (p < 0.0001); all couples of compared materials differed significantly (p = 0.0008), except for lithium disilicate and UTML crowns. From comparison with the anthropometric classification of Miles, it was estimated that 60 min of Ball-mill testing correspond approximately to an average clinical wear time of 18 years. Conclusion: The Y-TZP crowns showed the best results in terms of wear resistance. The lithium disilicate presented excellent resistance, but with uniform 1.5-mm thickness over the entire crown (marginal and occlusal area). The Ball-mill testing machine provided good results in reproducing the clinical conditions: its in vitro outcomes demonstrated the same mechanical characteristics of the 3 ceramics as shown by other fatigue testing machines. The investigation methodology was effective when using digital technology to compare materials and calculate the volumetric dental loss over time
Retrospective study of tooth loss in 92 treated periodontal patients
No full textBackground/Aims: In this retrospective study, the efficacy of periodontal therapy and maintenance in preventing tooth loss was evaluated. Methods: The study included 92 patients with 2310 teeth diagnosed with chronic adult periodontitis and observed over a mean period of 6.7 years, with each patient receiving surgical therapy in two or more quadrants. The group was divided into two subgroups: those who complied with the recommended maintenance schedule and those whose compliance was erratic. Individual tooth prognosis was assigned according to radiographic parameters. Results: At the completion of active periodontal therapy, 2184 teeth were present. During the maintenance period, 44 teeth were lost due to periodontal reasons. Tooth mortality revealed a mean annual adjusted tooth loss rate of 0.07/year. Molars were the teeth most frequently lost; canines the least. The number of teeth lost in the three prognostic categories was: one (0.07%) for teeth with good prognoses, 21 (3.63%) for questionable prognoses and 22 (11.34%) for hopeless prognoses. Patients complying erratically with supportive periodontal therapy were at a 5.6 times greater risk for tooth loss following active therapy than regularly compliant patients. Conclusions: The results demonstrated a low tooth mortality rate in periodontal patients following active treatment combined with a strict maintenance program. © Blackwell Munksgaard 2002
Maxillary first premolar inclination in 8- to 11-year-old children: An observational cross-sectional study on panoramic radiographs
No full textIntroduction: In this study, we examined first premolar inclination in a large sample. Methods: First premolar
inclination, canine inclination, and mesiodistal location were measured on 797 panoramic radiographs of orthodontically
untreated children (ages, 8-11 years; 381 boys, 416 girls). The sample comprised 1496 premolars and
1496 canines. A linear mixed-effects model was used to determine the contribution of age, sex, canine
inclination, canine sector location, second molar maturational stage (D-G), and dental arch side on premolar
inclination. Results: First premolar inclination values (medians and interquartile ranges) were 12.76 (8.12-
19.05) at 8 years, 11.82 (7.87-16.04) at 9 years, 10.40 (6.38-15.46) at 10 years, and 9.03 (5.42-
12.81) at 11 years; 13.86 (8.60-18.78) at stage D, 10.56 (7.39-14.77) at stage E, 10.43 (6.08-15.09)
at stage F, and 8.00 (4.62-10.74) at stage G. The following equation was selected (Akaike information
Q1 criteria 5 424.99): first premolar inclination 5 –2.211 1 2.240 (8 years) 1 1.363 (9 years) 1 0.955
(10 years) 10.387 (canine inclination) 1 0.902 (right side) 1 2.320 (stage D) 1 6.320 (sector 1)1 5.446 (sector
2) 1 3.803 (sector 3). There was no difference between percentiles constructed by age and maturational stage.
Conclusions: First premolar inclination decreases during the mixed dentition and is moderately correlated with
canine inclination
A Laboratory Based Investigation of a New Elastic Toothbrush Head
Full text linkPurpose. To demonstrate the noninferiority of a new toothbrush head with retractile bristles compared to traditional toothbrush heads on dental models. Methods. The new toothbrush head, mounted on manual and electrical handles, presents retractile bristle groups that can singularly retract over its entire length and offer calibrated resistance. Fourteen gypsum models of dental arches, twelve with and two without anatomical impairments, were spread with a “plaque simulator.” Each arch was brushed twice with each of the four toothbrushes, one minute by the same operator, blinded to the study. The plaque index (PI) was recorded at the end of each brushing session. GLM for repeated measures analysed the data. Results. On all the casts, the manual prototype and the electric prototype, removed 11% and 14% more “plaque simulator” compared to the standard toothbrush. In presence of dental anomalies, the prototypes removed 13% and 16% more plaque, respectively, compared to standard toothbrushes (P=0.04). In both situations, the 95% confidence intervals of PI did not include −10% (the minimal margin of clinical relevance). Conclusions. The prototype is more effective in removing plaque from the casts with anomalies. The noninferiority of the prototype with respect to the standard toothbrushes was demonstrated
Retrospective study of tooth loss in 92 treated periodontal patients
No full textBackground/Aims: In this retrospective study, the efficacy of periodontal therapy and maintenance in preventing tooth loss was evaluated.
Methods: The study included 92 patients with 2310 teeth diagnosed with chronic adult periodontitis and observed over a mean period of 6.7years, with each patient receiving surgical therapy in two or more quadrants. The group was divided into two subgroups: those who complied with the recommended maintenance schedule and those whose compliance was erratic. Individual tooth prognosis was assigned according to radiographic parameters.
Results: At the completion of active periodontal therapy, 2184 teeth were present. During the maintenance period, 44 teeth were lost due to periodontal reasons. Tooth mortality revealed a mean annual adjusted tooth loss rate of 0.07/year. Molars were the teeth most frequently lost; canines the least. The number of teeth lost in the three prognostic categories was: one (0.07%) for teeth with good prognoses, 21 (3.63%) for questionable prognoses and 22 (11.34%) for hopeless prognoses. Patients complying erratically with supportive periodontal therapy were at a 5.6 times greater risk for tooth loss following active therapy than regularly compliant patients.
Conclusions: The results demonstrated a low tooth mortality rate in periodontal patients following active treatment combined with a strict maintenance program
Outcome of secondary root canal treatment filled with Thermafil: a 5-year follow-up of retrospective cohort study
No full textObjectives: The aim of the present retrospective cohort study was to assess the 5-year outcome and survival of secondary root canal treatments (2°RCT), exploring the influence of pre-, intra-, and post-operative variables. Materials and methods: One hundred thirty-two endodontically retreated teeth were radiographically and clinically re-examined after 5 years. 2°RCT had been performed during a Masters program following standardized protocols and filled with AH Plus/Thermafil (TF). Pre-, intra-, and post-operative data were collected. The 5-year outcome was blindly evaluated and categorized as healed/diseased on the basis of the periapical index. Bivariate analysis and chi-square test evaluated the association between outcome and 31 demographic/clinical parameters. Multilevel analysis was performed at both patient and tooth level. Statistical significance was calculated at 5% level. Results: At 5-year evaluation, survival rate was 80% with 7.5% lost for endodontic reasons. Eighty-three percent of the teeth were classified as healed. Multilevel analysis identified significant predictors of increased survival: female gender (p = 0.012), absence of a pre-operative metal post (p = 0.017), conservative apical preparation (diameter size < #35) (p = 0.039), teeth restored with a crown (p = 0.009), and final PAI (after 5 years) ⤠2 (p = 0.001). Multilevel analysis identified as predictor healing: not being a smoker (p = 0.048) and conservative apical preparation < size #35 (p = 0.037). Conclusions: Outcome of 2°RCT filled with Thermafil was successful at 5 years, showing a high rate of survived and healed teeth comparable to that reported previously for other obturation techniques. Clinical relevance: Present findings confirm 2°RCT as a valid therapeutic option to retain natural teeth
The influence of root surface distance to alveolar bone and periodontal ligament on periodontal wound healing
No full textPurpose: The purpose of this animal study was to perform a 3-dimensional micro-computed
tomography (micro-CT) analysis in order to investigate the influence of root surface distance
to the alveolar bone and the periodontal ligament on periodontal wound healing after a
guided tissue regeneration (GTR) procedure.
Methods: Three adult Sus scrofa domesticus specimens were used. The study sample included
6 teeth, corresponding to 2 third mandibular incisors from each animal. After coronectomy,
a circumferential bone defect was created in each tooth by means of calibrated piezoelectric
inserts. The experimental defects had depths of 3 mm, 5 mm, 7 mm, 9 mm, and 11 mm, with
a constant width of 2 mm. One tooth with no defect was used as a control. The defects were
covered with a bioresorbable membrane and protected with a flap. After 6 months, the animals
were euthanised and tissue blocks were harvested and preserved for micro-CT analysis.
Results: New alveolar bone was consistently present in all experimental defects. Signs of root
resorption were observed in all samples, with the extent of resorption directly correlated to
the vertical extent of the defect; the medial third of the root was the most commonly affected
area. Signs of ankylosis were recorded in the defects that were 3 mm and 7 mm in depth.
Density and other indicators of bone quality decreased with increasing defect depth.
Conclusions: After a GTR procedure, the periodontal ligament and the alveolar bone
appeared to compete in periodontal wound healing. Moreover, the observed decrease
in bone quality indicators suggests that intrabony defects beyond a critical size cannot
be regenerated. This finding may be relevant for the clinical application of periodontal
regeneration, since it implies that GTR has a dimensional limit
DISTRIBUZIONE DI SEI MICRORGANISMI PARODONTO-PATOGENI TRA PAZIENTI ITALIANI ED OLANDESI AFFETTI DA PARODONTITE CRONICA
No full textI microrganismi subgengivali correlati alla malattia parodontale sembrano differire significativamente tra localizzazioni geografiche. L’obiettivo di tale ricerca è confrontare la prevalenza e la carica microbica di sei principali specie batteriche parodonto-patogene tra pazienti italiani ed olandesi affetti da parodontite cronica. Sono stati analizzati e confrontati dati ottenuti da campioni di placca subgengivale prelevata da 352 pazienti italiani e 115 olandesi. Durante la visita iniziale sono stati registrati i seguenti dati: sanguinamento al sondaggio, suppurazione, profondità di sondaggio, livello di attacco clinico, età, genere ed abitudine al fumo. La presenza e la carica batterica delle specie patogene è stata determinata seguendo un identico protocollo microbiologico mediante real-time Polymerase Chain Reaction. I test χ2 e Mann-Whitney U test sono stati usati per i confronti univariati. La regressione logistica lineare non condizionata (metodo backward) è stata utilizzata per individuare i fattori di rischio collegati alla presenza dei singoli microrganismi. Relativamente alla prevalenza microbica tra le due popolazioni il campione italiano ha mostrato valori significativamente più elevati sia per il Treponema denticola che per il Porphyromonas gingivalis (p=0.0001). La carica batterica dei microrganismi considerati, eccetto Tannerella forsythia, ha differito significativamente tra i pazienti: Treponema denticola (p=0.0001) e Prevotella intermedia (p=0.001) maggiori negli italiani; Porphyromonas gingivalis (p=0.001), Fusobacterium nucleatum (p=0.03) ed Aggregatibacter actinomycetemcomitans (p=0.001) maggiori negli olandesi. L’aumentare di profondità di tasca accresce significativamente la probabilità di rilevare tutte le specie batteriche nei pazienti italiani. Il fumo aumenta la probabilità di rilevare Fusobacterium nucleatum (O.R.=5.29) nei pazienti olandesi, mentre negli italiani di Tannerella forsythia (O.R.=4.64) e Treponema denticola (O.R.=2.44). Dai dati ottenuti emergono differenze tra le due popolazioni sia nel profilo microbiologico che nei fattori di rischio ad esso collegati. Una maggiore comprensione di tali aspetti può portare ad una strategia più mirata sia in ambito prevenzione che terapeutico
Periodontal Healing Distally to Second Mandibular Molar After Third Molar Coronectomy
No full textPurpose Coronectomy of mandibular third molars is a procedure that still raises a number of questions. The aim of the present study was to answer one unsolved question: the periodontal healing distal to the mandibular second molar after third molar coronectomy. Materials and Methods A prospective cohort study was performed of 30 patients treated at the Unit of Oral and Maxillofacial Surgery of the Department of Biomedical and Neuromotor Science of the University of Bologna. The predictor variables were the probing pocket depth (PPD), the distance between the marginal crest (MC) and the bottom of the osseous defect (BOD), and the distance between the cementum enamel junction (CEJ) and the BOD. These clinical indexes were recorded on 3 points of the distal surface of second molar: the distobuccal (DB), distomedial (DM), and distolingual (DL) sites. The other variables evaluated included root migration and postoperative complications. The Wilcoxon test for paired data and Kendall's tau-b correlation coefficient was used to evaluate all variables. The significance level was set at P = .05. Results The cohort was composed of 30 patients with 34 high-risk mandibular third molars (9 men and 21 women), with a mean age of 28 ± 7 years. At 9 months, a statistically significant reduction in the PPD of 2 ± 3, 1 ± 2, and 2 ± 2 mm and a statistically significant reduction in the MC-BOD distance of 4 ± 4, 4 ± 4, and 4 ± 5 mm for the DB, DM, and DL sites, respectively, was observed (P = .001). Also, the intraoperative CEJ-BOD distance showed a statistically significant reduction for the DB, DM, and DL sites. Conclusions After coronectomy, restoration of a clinical healthy periodontium distal to the second molar was observed. However, further studies are necessary to confirm these preliminary clinical results and to compare periodontal healing between coronectomy and complete extraction
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