Clinical efficacy of resin-based direct posterior restorations and glass-ionomer restorations – An updated meta-analysis of clinical outcome parameters

ObjectiveThe present review is an update of a systematic review that has been published in 2012. Meanwhile, many new clinical trials on resin composites had been published. New materials such as bulk fill resin composites and new glass-ionomer (GIC) based materials had been introduced. The focus of this review was to evaluate the longevity in relation to the material class and adhesive class, while adjusting for a possible study bias effect.Material and methodsThe database PUBMED/SCOPUS were searched for clinical trials on posterior resin composites. The inclusion criteria were: (1) studies published between 2000 and 2019, (2) prospective clinical trial with at least 2 years of observation; (2) minimal number of restorations at last recall = 20; (3) report on drop-out rate; (4) report of operative technique and used materials; (5) utilisation of Ryge, modified Ryge or FDI evaluation criteria. The bias of each study was assessed by two independent reviewers using Cochrane Collaboration’s tool for assessing risk of bias in randomised trials. For the statistical analysis, linear mixed models fitted on the individual data recorded along time have been used with random effects to account for study, patients and experiment effects. P-values smaller than 0.05 were considered significant.ResultsOf the 423 clinical trials, 62 studies (including 110 experiments) met the inclusion criteria. Material class was divided according to the composite filler in microhybrid (39 experiments/2807 restorations), nanohybrid (24 experiments/1254 restorations), and hybrid (22 experiments/1255 restorations). So-called bulk fill materials were treated as a separate category (9 experiments/506 restorations) as were the GIC (11 experiments/2121 restorations) and the compomer materials (5 experiments/238 restorations). Only one study (1.6%) had low risk of bias, 42 (67.7%) were assessed to have unclear risk of bias and 19 (30.6%) had a high risk of bias. In 52.3% of the studies Class II and Class I restorations had been placed. After 10 years, the survival rate for resin composite restorations dropped to about 85–90% with no significant difference between hybrid, microhybrid and nao-hybrid resin materials. The main reasons for restoration replacement were bulk fractures and wear, which accounted for a about 70% of replacements. Caries at the restorative margins accounted for about 20% of the replacements, and retention loss, inacceptable colour match or marginal integrity, endodontic treatment or cusp fracture for about 10% of the replacements of the resin composite restorations. For compomer and GIC restorations the mean overall survival rate was about 80% after 6 years. For GIC, the main reasons for failure were substantial loss of anatomical contour along with loss of proximal contacts and retention loss. Mainly fractures reduced the longevity of compomers restorations. Also, there was no statistically significant difference between hybrid, micro-hybrid, nano-hybrid and bulk fill resin composites with regard to colour match, surface texture, material fractures, and anatomical form.Conclusions:Posterior resin composite restorations that were placed with the enamel etch technique showed the best overall performance; the longevity was not significantly influenced by the filler type or viscosity of resin composite material. With regard to colour match, surface texture and anatomical form, nanohybrid resins were not significantly superior to hybrid or microhybrid resin composites. Compomer and GIC restorations demonstrated considerable shortcomings and had a significant shorter longevity.     

Fracture frequency and longevity of fractured resin composite, polyacid-modified resin composite, and resin-modified glass ionomer cement class IV restorations: an up to 14 years of follow-up

The aim of this study was to evaluate the fracture frequency and longevity of fractured class IV resin composite (RC), polyacid-modified resin composite (compomer; PMRC), and resin-modified glass ionomer cement (RMGIC) restorations in a longitudinal long-term follow-up. Eighty-five class IV RC (43: Pekafil), PMRC (24: Dyract (D), Hytac (H)), and RMGIC (18: Fuji II LC (F), Photac Fil (P)) restorations were placed in ongoing longitudinal follow-ups in 45 patients (mean age 54.5 years). The restorations were evaluated during 14 years by slightly modified USPHS criteria at yearly recalls especially for their fracture behavior. For all restorations, 36.5% were fractured, with a Kaplan–Meier (KM) estimate of 8.8 years (standard error (SE) 0.5, confidence interval (CI) 7.9–9.8). The number of fractures per material was 11 RC (25.6%; KM 9.9 years, CI 8.7–11.0), 13 PMRC (54.2%; D 66.6%; H 50.0%; KM 7.5 years, CI 5.8–9.2), and seven RMGIC (36.5%; F 22.2%, P 71.4%; KM 6.9 years, CI 7.9–9.8). Significant differences were seen between RC and PMRC (p = 0.043). A significant higher fracture rate was observed in teeth 12 + 22 compared to teeth 11 + 21. No significant differences were observed between male and female patients. Restorations in bruxing patients (45) showed 22 fractures (KM 8 years; CI 6.9–9.3) and in non-bruxing patients (39) nine fractures (KM 9.9 years, CI 8.7–11.1; p = 0.017). With regard to the longevity of the replaced failed restorations, for RC, the mean age was 4.5 years; for PMRC, 4.3 years; and for RMGIC, 3.3 years. It can be concluded that fracture was the main reason for failure of class IV restorations. An improved longevity was observed for class IV restorations compared to those presented in earlier studies. RC restorations showed the lowest failure frequency and the highest longevity.     

Is surface roughness of direct resin composite restorations material and polisher-dependent? A systematic review

Statement of Problem

Direct resin composite bonding offers a highly esthetic, minimally invasive option for the treatment of anterior teeth however the challenge to improve their longevity remains. Direct resin composite restorations are limited by the risk of staining which may be influenced by the final surface roughness (Ra) of composite achieved.

Purpose

The purpose of this review is to investigate, using a systematic approach, whether the final surface roughness of anterior composite restorations is affected by the interaction between resin composite and polishing systems.

Materials and Methods

The review was conducted by 3 independent reviewers and included articles published up to January 21, 2021. Three electronic databases were searched: Medline, Embase, and Web of Science. Studies assessing a quantitative effect of polishing methods on the Ra of direct composite resin materials published after the year 2000 and restricted to the English language were included.

Results

The database search for the effect of polishing systems on composite materials retrieved 125 eligible studies. Twelve duplicate records were removed. The resulting records were screened using title and abstract leading to 38 reports which were sought for retrieval. Application of eligibility criteria led to 11 studies included in the review. Hand searching of these studies yielded no additional papers.

Conclusions

There is insufficient evidence to determine whether combination of composite and polisher influences final Ra. More research is required to determine if there is an optimum combination of polisher and composite.

Clinical Implications

Polishing should be completed following planned finishing procedures. The approximation to the final surface and which finishing burs to use, if any, should be considered when planning a restoration. Durafill VS predictably achieves an acceptable Ra by different polishers.     

Long-term clinical evaluation of direct resin composite restorations in vital vs. endodontically treated posterior teeth — Retrospective study up to 13 years

ObjectivesThis retrospective study evaluated and compared the survival rate of Class II posterior direct resin based composite (RBC) restorations made in vital teeth (VT) and endodontically treated teeth (ETT). The influence of risk factors on the long-term performance of restorations was also investigated.MethodsPatients (n = 245) receiving RBC posterior restorations between 2004 and 2012 were selected. A total of 597 restorations (485 in VT, 112 in ETT) with minimum 2.5–3 mm remaining cusp thickness, made with the same brand of RBC and adhesive, were evaluated using the USPHS criteria. Data were analyzed with Mann–Whitney, Chi-square and Fisher’s Exact Test, Extended Cox-regression and Kaplan–Meier analysis (p < 0.05). Relative risk ratio was estimated for each evaluated parameter.ResultsThe mean observation period was 8.6 ± 2.3 years. An annual failure rate in VT and ETT of 0.08% and 1.78%, respectively, was detected. The reasons of failures included restoration fracture, secondary caries in VT; vertical root fracture, cusp fracture, restoration fracture, secondary caries and loss of adhesion in ETT. Significantly better performance was observed in RBCs of VT for each evaluated parameter. Among the evaluated risk factors only occlusal stress affected negatively the survival of RBC in ETT (Hazard Ratio 37.1; CI_95% 8.4–163.7).SignificanceAlthough, there is significant difference in the success rate of RBCs in VT (98.97%) and ETT (76.8%), the long-term (6–13 years) durability of Class II RBCs with 2.5–3 mm cusp thickness in ETT is also clinically acceptable. The presence of occlusal stress decreases the survival of RBCs in ETT.     

Can phenyl-propanedione influence Knoop hardness, rate of polymerization and bond strength of resin composite restorations?

Objectives

The aim of this study was to evaluate the degree of conversion (DC), rate of polymerization (R_p^max), Knoop hardness (KHN) and bond strength between tooth/restoration of composite resins containing different photo-initiators photo-activated by different light-curing units (LCUs).

Materials and methods

A mixture of BisGMA, UDMA, BisEMA and TEGDMA was prepared along with the following photo-initiators: camphorquinone (CQ), phenyl-propanedione (PPD) or the association (CQ/PPD) and 65 wt% of silanated filler particles. The LCUs included a halogen lamp XL 2500 and two LEDs: UltraBlueIS and UltraLume5. The conversion profiles during photo-polymerization were investigated using middle-infrared spectroscopy (mid-IR). Bond strength was evaluated using push-out test in ninety teeth with prepared cavities. Before the push-out test, Knoop hardness (KH) was verified in the top and at the base of the restorations.

Results

PPD obtained lower R_p^max values, regardless of the LCU used. It also provided a greater bond strength than CQ when the LEDs LCUs were used. The degree of conversion after 40 s of irradiation was the same for all composite resins, except PPD photo-activated for XL 2500, which showed lower DC values than CQ and CQ/PPD. In the top and at the base of the restorations, PPD showed the lowest KH values when photo-activated with XL 2500. XL 2500 produced higher KH values than UltraBlueIS when used with CQ or CQ/PPD photo-initiators.

Conclusion

Because it increased the bond strength without compromising the properties of composite resins when photo-activated by an LED, PPD can be used as an alternative photo-initiator.     

Correction to: Class II resin composite restorations—tunnel vs. box-only in vitro and in vivo

Clinical Oral Investigations -     

Is the clinical performance of composite resin restorations in posterior teeth similar if restored with incremental or bulk-filling techniques? A systematic review and meta-analysis

Clinical Oral Investigations - A systematic review was performed to analyze the clinical performance of class I and II restorations in posterior teeth placed with the incremental or the...     

Factors affecting wear of composite resin denture teeth—24-month results from a clinical study

The objectives of this study were to measure the occlusal wear of composite resin denture teeth in patients wearing a complete denture and to evaluate factors affecting wear. Fifty participants provided with complete dentures in at least one jaw were included. Gypsum casts were made from preliminary vinyl polysiloxane impressions 4 weeks after insertion, then after 6 (t ₁), 12 (t ₂), and 24 months (t ₃). Three-hundred and three posterior denture teeth were evaluated after 24 months. Wear was measured indirectly, from the casts, by means of a three-dimensional laser scanner device. Sequential images of the occlusal surfaces were digitized and superimposed (occlusal matching). Statistical analysis was performed by the use of mixed regression models, with the patient being a random effect. Mean wear (median, interquartile range; micrometer) of the entire occlusal surface was 8 (19) at t ₁, 18 (34) at t ₂, and 40 (61) at t ₃. Maximum vertical loss (median, interquartile range; micrometer) was 92 (112) at t ₁, 146 (148) at t ₂, and 226 (184) at t ₃. The dental status of the opposing jaw and the nature of the opposing material significantly affected the wear of denture teeth at t ₃. Gender, daily wearing time, jaw, and type of tooth had no significant effects on the extent of wear. Clinically relevant vertical loss of composite resin denture teeth occurs after 24 months. Considering the limitations of this study, wear of denture teeth was affected by dental status and opposing material. The results suggest that wear of composite resin denture teeth exceeds that of enamel.     

Effects of a fluoride etchant and a phosphate primer on bonding of veneering composite to Ti–6Al–4V alloy for CAD/CAM restorations

PurposeTitanium abutments and superstructures are commonly veneered or covered with esthetic materials. The present investigation was carried out to evaluate the effects of an experimental surface treatment using etchant and primer on bond strength between a resin composite and Ti–6Al–4V alloy.MethodsDisk-shaped Ti–6Al–4V alloy was machine milled, the surface was air abraded with alumina, and the alloy was chemically etched with 5wt% ammonium hydrogen fluoride (F-etch) for 30 s. A phosphate primer (MDP-primer) was applied to the bonding area, and then a resin composite, with or without milled-fiber resin composite (FRC), was veneered on the specimen. Shear bond strengths were determined after thermocycling for 20,000 cycles. Bond strength data were analyzed by means of ANOVA and a multiple comparison test (α = 0.05). The surface of Ti–6Al–4V alloy was observed using a scanning electron microscope before and after the etching procedure.ResultsNo-FRC/F-etch/MDP-primer exhibited the highest bond strength (28.2 MPa), followed by No-FRC/No-etching/MDP-primer (24.2 MPa), FRC/F-etch/MDP-primer (19.9 MPa), FRC/No-etching/MDP-primer (17.8 MPa), No-FRC/No-etching/No-primer (13.6 MPa), while FRC/No-etching/No-primer (2.5 MPa) resulted in the lowest value. Microphotographs showed that numerous micro and nano pits were created on the Ti–6Al–4V alloy surface modified with F-etch.ConclusionsThe bond strength between Ti–6Al–4V alloy and the veneering resin composite was the highest when the alloy surface was modified with alumina blasting, fluoride etchant, and phosphate primer successively.     

Attitudes and behavioural factors relating to toothbrushing and the use of fluoride toothpaste among caries-active Swedish adolescents – a questionnaire study

Objective: The aim of this study was to identify attitudes and behaviour relating to fluoride toothpaste and toothbrushing habits among caries-active Swedish adolescents.

Materials and methods: This cross-sectional study is based on an earlier clinical, two-year toothpaste intervention study. At the last appointment, 206 adolescents (of 211) answered a questionnaire comprising nine semi-closed questions.

Results: The majority (93%) brushed their teeth every day, while 7% did so only occasionally. Most participants (77%) brushed twice a day, while 12% brushed just once a day. About half of those brushing just once a day forgot to brush in the evening. Similarly, more than half of the adolescents (53%) used 1?cm of toothpaste or less on their toothbrush. Moreover, 49% brushed for less than 2?min, 41% brushed for 2?min and 10% for more than 2?min. The majority (73%) rinsed with water after toothbrushing. A difference between boys and girls was also observed; 87% of the girls brushed twice a day, whereas only 67% of the boys did so and boys more frequently forgot in the evening.

Conclusions: Attitudes and behaviour relating to fluoride toothpaste and toothbrushing habits among caries-active Swedish adolescents are still inadequate after two years of toothpaste intervention. There are several areas where improvements can be made, such as frequency of brushing, brushing time, amount of toothpaste and post-brushing procedures. The majority (81%) included ‘fresh breath’ as a reason for performing oral hygiene and this aspect can be used by dental staff in health promotion.     

Delayed diagnosis of displaced and impacted canines – a prospective longitudinal study

Abstract

Objectives: To assess the frequency and reasons for delayed diagnoses of displaced/impacted canines and to determine to what extent this causes complications. In addition, to assess whether any preventive measures were taken.

Materials and methods: Patients with displaced/impacted canines that were diagnosed late; i.e. at an age ≥12 years, were consecutively collected during September 2015 to September 2018 in the County Region of Halland, Sweden. Additionally, patients who had undergone surgical exposure or extraction of an impacted canine during the same time period were identified.

Results: Eighty-four individuals (58% girls, 42% boys, mean age: 13.75?±?1.53?years) with 114 impacted canines were detected among 33,488 adolescents aged 12–20?years, resulting in a low-frequency rate: 84 cases per 100,000 persons. Eighty-six percent of the delayed canines were in the maxilla, the rest in the mandible. Deciduous canines were present in 80% of the cases. Most patients had a dental examination at 9–11 years of age but the position of the canine was not documented in many cases. Root resorption of adjacent teeth was noticed in 13% of the patients. No new clinical procedures or guidelines were developed.

Conclusions: The frequency of delayed diagnoses of displaced/impacted canines was low. To minimize the frequency even more, documentation of the canine position during the dental examination should not be forgotten at ages 9–11. Presence of the deciduous canine can be used as a clinical indicator that the position of the permanent canine needs to be investigated.     

Clinical longevity of ceramic laminate veneers bonded to teeth with and without existing composite restorations up to 40 months

Objectives

This study evaluated the survival rate of ceramic laminate veneers bonded to teeth with and without existing composite restorations (ECR).

Materials and methods

Twenty patients (mean age: 49.7 years) received 92 feldspathic ceramic laminate veneers (Shofu Vintage AL) on the maxillary teeth (intact teeth: n?=?26; teeth with ECR: n?=?66). Preparations with incisal overlap were made, and ECR of good quality were not removed but conditioned using silica coating (CoJet) and silanization (ESPE-Sil). Enamel and dentin were etched with 38 % H₃PO₄ for 15–30 s and rinsed 30 s; adhesive resin (Excite) was applied, and laminate veneers were then cemented (Variolink Veneer). Restorations were evaluated at baseline and thereafter every 6 months using modified United States Public Health Service criteria.

Results

Mean observation period was 21.6 months. Overall, five absolute failures were encountered (fractures: n?=?3; chipping: n?=?1; debonding: n?=?1), resulting in a survival rate of 94.6 % (Kaplan–Meier). Survival rates of the laminates bonded to teeth without (96 %) and with ECR (93.5 %) did not show significant differences (p?>?0.05). Slight marginal defects (16 of 87 laminates) and slight marginal discoloration at the margins were noted (12 of 87 laminates) until the final recall. Secondary caries and endodontic complications were not detected in any of the teeth.

Conclusion

The clinical survival of ceramic laminate veneers up to 40 months was not significantly influenced when they were bonded onto intact teeth or onto teeth with ECR.

Clinical relevance

When no caries is present, it may not be necessary to replace existing composite restorations prior to cementation of ceramic laminate veneers.     

Long term clinical performance of ‘open sandwich’ and ‘total-etch’ Class II composite resin restorations showing proximal deterioration of glass-ionomer cement

ObjectivesTo compare clinical performance of resin composite posterior Class-II restorations placed with etch-and-rinse adhesive or open sandwich technique using glass-ionomer cement.MethodsData on Class II restorations placed by one dentist between 1990 and 2016 were collected from patient files, including caries risk, tooth related variables, applied materials and dates of last check-up visit and restoration placement.Open sandwich restorations were placed before 2001, while after 2001, a total-etch technique using etch-and-rinse 3-step adhesive was used when placing a Class II composite restoration. For statistical analysis, Kaplan-Meier statistics and a multilevel Cox-Regression was conducted (p < 0.05). Annual Failures Rates (AFR) were calculated.Results675 Class II restorations were placed in 91 patients, 491 total-etch restorations (observation time 2–18 y), and 184 open sandwich restorations (observation time 19–29 y) showing AFRs at 15 years as 2.9 % for total-etch and 9.7 % for open sandwich restorations.Secondary caries as failure was equally distributed among the 2 groups and 27 % of the failures in the open sandwich group were due to proximal deterioration of glass-ionomer cement. The Cox-regression showed a significant higher risk for failure for the open sandwich technique compared to total-etch class-II composite restorations (HR = 2.9; p < 0.001).SignificanceApplication of glass-ionomer cement using the open sandwich technique cannot be recommended for class-II restorations as being more complex and showing poorer clinical performance.     

Fracture resistance of endodontically treated teeth restored with indirect composite inlay and onlay restorations – An in vitro study

Objective

The purpose of this in vitro study was to evaluate and compare the fracture resistance and fracture mode of extensive indirect inlay and onlay composite resin restorations performed for endodontically treated premolars.

Materials and methods

A total of 55 extracted maxillary premolars were randomly divided into four groups. The first group (n = 15) remained untreated to serve as a positive control; the second group (n = 15) was endodontically treated with inlay cavities prepared and restored with indirect composite inlay restorations; the third group (n = 15) was also endodontically treated with onlay cavities prepared and restored with indirect composite onlay restorations; and the fourth group (n = 10) was endodontically treated with mesio-occlusodistal (MOD) cavities prepared and left unrestored to serve as negative controls. Dual cure indirect composite resin was used to fabricate the inlay and onlay restorations performed for the second and third groups, respectively. All teeth were subjected to compressive axial loading test using a metal ball (6 mm in diameter) in a universal testing machine (Instron 1195) with a cross-head speed of 0.5 mm/min until a fracture occurred. Statistical analysis of fracture resistance and fracture mode were performed with analysis of variance (ANOVA) (α = 0.05) and Kruskal–Wallis (α = 0.05) tests, respectively.

Results

For the four treatment groups, the mean fracture resistance values were 1326.9 N, 1500.1 N, 1006.1 N, and 702.7 N, respectively. Statistical analyses showed no significant differences between the mean fracture resistance of the intact tooth group and the inlay restoration group (p > 0.05), while significant differences were observed between the mean fracture resistance of all the other groups (p < 0.05). The Kruskal–Wallis test showed statistically significant differences between the fracture modes of the four groups.

Conclusion

Within the limitations of this study, endodontically treated teeth were successfully restored with indirect composite inlay and onlay restorations. However, the fractures that accompanied the inlay restorations were more severe and were unable to be restored.     

Incidence and patterns of maxillofacial trauma—a retrospective analysis of 3611 patients—an update

Background

Maxillofacial fractures occur in a significant proportion worldwide and can occur as an isolated injury or in combination with other severe injuries including cranial, spinal, and upper and lower body injuries requiring prompt diagnosis with possible emergency interventions. The epidemiology of facial fractures varies with regard to injury type, severity, and cause and depends on the population studied. Hence, understanding of these factors can aid in establishing clinical and research priorities for effective treatment and prevention of these injuries.

Materials and methods

In this present retrospective study, we provide a comprehensive overview regarding cranio-maxillofacial trauma on 3611 patients to assist the clinician in assessment and management of this unique highly specialized area of traumatology. A preformed pro forma was used to analyze the medical records of patients treated for facial trauma in The Department of Oral and Maxillofacial Surgery, Meenakshi Ammal Dental College and Hospital, Chennai. The distribution according to age, gender, etiology, type of injury, time interval between accident and treatment, loss of consciousness, facial bones involved, pattern of fracture lines, treatment offered, and postoperative complications were recorded and evaluated.

Results

We inferred male patients sustained more injuries mostly in the third decade of age. Road traffic accidents were the most common cause of injury. Mandible was the most commonly fractured bone in the facial skeleton. Soft tissue injuries occurred more in road traffic accidents and upper lip was the commonest site of injury.

Conclusion

Our study provides insights into the epidemiology of facial injuries and associated factors and can be useful not only in developing prevention strategies but also for grading the existing legal regulations and also for framing a more effective treatment protocol.

     

Curing depths of a universal hybrid and a flowable resin composite cured with quartz tungsten halogen and light‐emitting diode units

This in vitro study evaluated curing depths of a universal hybrid resin composite with two viscosities (Tetric Ceram and Tetric Flow) after curing with 6 different quartz tungsten halogen and light‐emitting diode curing units. Irradiance (light intensity) of the curing units varied between 200 and 700?mW/cm ² . The curing units were used for standard, soft‐start, or pulse curing. Curing times were 20 and 40?s for standard curing, 3?+?10?s and 3?+?30?s for pulse curing, and 40?s for soft‐start. Resin composite specimens, 5 in each group, with a diameter of 4?mm and a height of 6?mm, were made in brass molds and cured from one side at a distance of 6?mm. After 2 weeks, the specimens were ground longitudinally half through the specimen. Curing depth was then determined by measurement of Wallace hardness for each half millimeter starting at 0.5?mm from the top surface. For all curing units and for both resin composites an increased curing time led to statistically significantly higher depth of cure (P?P?r?=?0.89, P?r?=?0.91, P?相似文献   

Two-stage distalization of the mental foramen to manage posterior mandibular vertical bone deficiency—a prospective observational study

Inferior alveolar nerve (IAN) transpositioning is a modality utilized to manage posterior mandibular vertical deficiency. Several complications have been reported including improper implant positioning, mandibular body fracture, and neurosensory disturbance. The aim of this prospective observational study was to introduce a two-stage mental foramen distalization technique to minimize the complications associated with IAN transpositioning. Ten patients with severely atrophied mandibular ridges were included. Cone beam computed tomography was ordered to accurately locate the position of the IAN and its incisive terminal branch before designing the outline of two cortical osteotomies anterior and posterior to the mental foramen. The osteotomies were created using a piezoelectric device, followed by separation and identification of the nerve. The incisive branch was severed to freely transpose the IAN. A new foramen was created far distally and the cortical windows were repositioned and fixed with two screws. Healing was uneventful for all patients. Neurosensory recovery was assessed by MRC scale. All cases showed full recovery within 6 weeks, except for two patients who showed complete recovery after 16 weeks. Four months postoperative, all patients showed complete consolidation of the cortical windows without any signs of failure implants were placed at the pre-planned surgical sites. Histomorphometric analysis of core biopsies from seven surgical sites showed bone area percentages ranging from 46% to 63%. The two-stage mental foramen distalization technique is a predictable and safer technique for IAN transpositioning specifically in cases of vertical bone deficiency associated with limited inter-arch space.     

Curing characteristics of a composite – Part 1: Cure depth relationship to conversion,hardness and radiant exposure

Objective

As the first part of a larger study on curing characteristics of a resin-based composite (RBC), the major objectives were to create an energy-hardness relationship (EHR) that relates Knoop hardness (KHN) with radiant exposure (H), and to do the same for degree of conversion (DC) in the form of an energy-conversion relationship (ECR). Both of these are meant to be universal relationships that satisfy reciprocity between irradiance and time for a given H value.

Methods

RBC specimens were made by curing the material in 6 mm diameter, stainless steel molds for 10–40 s and allowing the material to cure for 24 h. Cure depths were determined by a scrape-back method. KHN and DC values were determined along the central axis of the specimens, and these values were related to the internal H values using a measured transmission relationship, T(d), for the RBC.

Results

Suitable EHR and ECR relationships were developed for the RBC material that can be used to describe the curing characteristics under various curing conditions. However, predictive accuracy is affected for incident radiant exposures below about 12 J/cm² to some extent. A relationship between KHN and DC was established.

Significance

For the RBC examined, KHN measurements can be used as an alternate method or in conjunction with DC for describing the curing characteristics.