Chemomechanical caries removal: a comprehensive review of the literature

Compared to the past, caries removal has become more efficient, however inherent fundamental drawbacks of the drilling approach have remained: unpleasantness to patients, need for local anesthesia, and potential adverse effects to the pulp due to heat and pressure. Chemomechanical caries removal, introduced almost three decades ago, was claimed to be a non-invasive alternative for the removal of carious dentine. In essence, the technique involved applying a solution onto the decayed dentinal tissue, allowing it to soften it, and, finally, scraping it off with blunt hand instruments. The partially degraded collagen in carious dentine was chlorinated by chemomechanical caries removal solutions. This chlorination affected the secondary and/or quaternary structure of collagen, by disrupting hydrogen bonding. Carious material removal was thus facilitated. The purpose of this paper is to perform a comprehensive review of the literature regarding chemomechanical caries removal, including the most recently available product, the initial reports on which warrant renewed interest in the approach.

Influence of resin cement viscosity on microleakage of ceramic inlays

OBJECTIVES

The aim of the present investigation was to evaluate the effect of the different viscosities of two resin luting cements on microleakage of ceramic inlays at dentinal margins. The effect of the width of the space between inlay and tooth, on the quality of the marginal seal was also investigated.

METHODS

Mesial and distal class V cavities were prepared in 48 extracted third molars. The incisal margins of the cavities were in enamel and the cervical margins in dentin. Subsequently, Empress inlays with different cervical margin gap dimensions were fabricated. The mean cervical gap dimensions in the respective groups were as follows: group 1 (27 microm); group 2 (232 microm); group 3 (406 microm). Half the inlays in each group (16) were cemented with a low viscous resin luting cement, and half (16) with a highly viscous resin luting cement. The teeth were subjected to occlusal loading with synchronized thermal cycling in a masticatory simulator. Then, the specimens were immersed in basic fuchsin solution, and dye penetration along the cavity walls was measured. In addition, marginal adaptation was analyzed in the SEM at baseline and after loading, using a replica technique.

RESULTS

With regard to dye penetration at dentinal margins, the highly viscous cement performed statistically significantly better at dentin/composite margins than the low viscous cement (p=0.0158). These findings are supported by SEM analysis.

SIGNIFICANCE

It is assumed that polymerization stress within the luting cement could not be completely compensated for by larger luting spaces. Highly viscous luting cements are recommended for cementing class V inlays in larger luting spaces.

Clinical evaluation of chemomechanical caries removal in primary molars and its acceptance by patients

The purpose of this study was to evaluate the clinical efficiency and patient acceptance of the chemomechanical caries removal agent Carisolvtrade mark in deciduous teeth. Contralateral primary molars of sixteen 7- to 9-year-old patients (32 teeth) were treated with the air-motor and with Carisolv, respectively. Patients replied to a pre- and a postoperative questionnaire. Complete caries removal (CCR) was accomplished in all air-motor sessions. It was not achieved within the time limit of 15 min in 6 (37.5%) Carisolv sessions. Air-motor CCR time ranged between 6 and 18 s (mean: 11.81 s ). Carisolv CCR time, where accomplished within 15 min, ranged between 6 min 46 s and 13 min 57 s (mean: 6 min 51 s). Preoperatively, the majority of the children reported disliking the drilling, and that they would visit the dentist more often and prefer sitting in the chair longer if they could avoid it. Postoperatively, the majority of the children reported disliking the taste of Carisolv, estimated Carisolv to have taken longer, would not recommend it to their friends, and preferred the air-motor. In conclusion, Carisolv, although a step forward in terms of solution volume required, is not in a position to replace rotary instruments for caries removal: it did not remove decay completely in one third of our sample; it was much slower than the air-motor; it had a chlorine taste/odor our patients disliked.

The LMP1 gene isolated from Russian nasopharyngeal carcinoma has no 30-bp deletion

The Epstein-Barr virus (EBV) is tightly linked to the induction of undifferentiated nasopharyngeal carcinoma (NPC), a tumour endemic in certain areas of southeast Asia. The LMP1 gene encoded by EBV is a classical oncogene due to its ability to transform rodent fibroblasts. LMP1 is absolutely essential for transformation of B cells by the virus and is one of the few EBV genes found to be expressed in NPC. It was originally shown that the LMP1 gene from NPC harbours a deletion of 30 bp in the 3' part of the gene. However, this deletion is also present in the virus spread in healthy people of the areas endemic for NPC and also in other EBV-positive tumours as well as in healthy carriers. We isolated and sequenced the LMP1 gene obtained from tissue of 7 Russian patients with NPC and 1 German patient with an NPC-like tumour of the parotid gland (PG) and compared them with the LMP1 gene isolated from peripheral blood lymphocytes (PBLs) of 6 Russian and 4 German healthy EBV-positive carriers. Neither the Russian NPC cases nor the German NPC-like tumour harboured an LMP1 gene with the 30-bp deletion, while 1 Russian and 2 German carriers contained the LMP1 gene with the 30-bp deletion. In addition, the LMP1 gene isolated from PBLs of the German patient was virtually identical to the gene isolated from the primary tumour. Functional analysis showed no correlation between the presence or absence of the 30-bp deletion and the level of induction of the transcription factors NFkappaB and jun/AP-1 caused by LMP1. These data indicate that the 30-bp deletion is not a factor predisposing for NPC. Comparison of the DNA sequences revealed that the LMP1 genes present in the NPCs most likely represent the "strain" persisting in the general population.

Dynamic T1-weighted ferumoxides enhanced MRI for imaging liver hemangiomas: preliminary observations

The T1-based signal-enhancing effects of ferumoxides was studied in five liver hemangiomas on short echo-time gradient-recalled echo dynamic magnetic resonance imaging to assess the utility of this technique to image perfusion patterns in liver hemangiomas. We observed peripheral nodular enhancement with centripetal fill in all hemangiomas. Our results suggest that this imaging technique, after rapid injection of ferumoxides, can be used for lesion characterization.

Nonlinear dynamic properties of low calcium-induced epileptiform activity

The analysis of the dynamic properties of epileptiform activity in vitro has led to a better understanding of the time course of neural synchronization and seizure states. Nonlinear analysis is thus potentially useful for the prediction of seizure onset. We have used nonlinear analysis methods to investigate the development of activity in the low calcium model of epilepsy in brain slices. This model is particularly interesting since neurons synchronize in the absence of synaptic transmission. The dynamic properties calculated from extracellular recordings of activity were used to analyze the transition to synchronous firing and their relation to neuronal excitability. The global embedding dimension, local dimension and the Lyapunov exponent were calculated from time segments corresponding to the onset, transition and fully developed stages of activity. The analysis was repeated for recordings made in the presence of various levels of DC electric fields to modulate neuronal excitability. The global and local dimensions did not change once activity was first initiated, even in the presence of the electric field. The maximum Lyapunov exponents increased during the onset of activity but decreased when the applied hyperpolarizing electric field was large enough to partially suppress the activity. These findings establish a relationship between neuronal excitability and the maximum Lyapunov exponent, and suggest that the Lyapunov exponent may be used to distinguish between various states of the neural network and might be important in seizure prediction and control.

[Stener lesion yes or no? Diagnosis by ultrasound]

25 patients with clinical signs for ulnar collateral ligament injury to the metacarpophalangeal joint of the thumb were examined by ultrasonography before operation to verify Stener's lesion. The results were compared with intraoperative findings. In 18 patients (74%), ultrasound and surgical exploration yielded equivalent results. Seven patients showed signs of Stener's lesion in ultrasound that could not be verified during surgery. No Stener's lesion was missed.

Phenotypic characteristics of human monocytes undergoing transendothelial migration

In our study we characterised the immunophenotype of monocytes that migrated through an endothelial cell (EC) monolayer in vitro. We found that monocyte migration led to an enhanced expression of CD11a, CD33, CD45RO, CD54 [intercellular cell-adhesion molecule (ICAM)-1] and human leucocyte antigen-DR. The most striking increase was observed for ICAM-1 when ECs were activated with tumour necrosis factor-alpha and interleukin-1alpha. The results of our study indicate the following: (1) there is a characteristic immunophenotype on the surface of monocytes after transendothelial migration; (2) this phenotype seems to be induced by interactions between monocytes and ECs; and (3) this change is enhanced by the pretreatment of ECs with cytokines. Taken together, the results suggest that local cytokine production activating ECs is sufficient to enhance monocyte migration and that this, in turn, can induce changes consistent with an activated phenotype known to be interactive between antigen-presenting cells and T cells. These results have implications for our pathogenetic insights into rheumatoid arthritis.

An in vitro assessment of the strength of porcelain veneers dependent on tooth preparation

The treatment of teeth using veneer restorations combines aesthetic and functional improvements with a low destructive technique. Different kinds of tooth preparation techniques are described in the literature for this kind of restoration. This in vitro study aimed to examine the influence of the incisal preparation on the loadability of teeth restored with porcelain laminate veneers. Thirty-six selected mandibular incisors were randomly assigned to three groups with 12 teeth per group. In the first group, only the facial surface was prepared. In the second group, the preparation included a rounded incisal edge and a distinct chamfer lingually. The third group served as an unprepared control. Empress(R) veneers were then fabricated and cemented with a low viscous luting composite material. After 120 days storage in Ringer's solution, the specimens were loaded incisally to the point of failure. Statistical analysis of the results showed significant differences between the series (P=0.0103). Group 2 (with preparation of the incisal edge) exhibited the lowest fracture resistance (466+/-99 N) (N, mean forces). When prepared only facially, the teeth restored with Empress veneers reached the strength of unprepared teeth. Compared with the biting force described for incisors in the literature, the in vitro loadability reached in this investigation seems to jusitify the clinical use of both preparation designs tested.

[Strategy for defect coverage in extensive degloving and crush injuries of 4 fingers]

Severe crush injuries with avulsion require specific treatment strategies. Usually we find complete loss of soft tissue, nerves and vessels, where only tendons and parts of the phalanges are preserved. Primary reconstructive procedures are usually not possible due to the complexity of the injury with severely destroyed structures. Bone shortening should be avoided in order to maintain finger length and motion. Therefore, emergency soft-tissue coverage represents the first step. Later, sensibility and mechanical stability of the skin should be restored. In our clinic, seven patients with this injury pattern were treated. Three cases involved four finger crush-avulsion injuries. In all cases, we performed a primary soft-tissue coverage with a pedicled flap. In a second session, the skin areas of the first web space of both feet were transplanted as neurovascular flaps. With this strategy, a useful hand function could be restored. The functional results are described and advantages and disadvantages of various techniques discussed.

[Bursitis of the ulnar recess]

We investigated 20 patients suffering from wrist pain accompanied by local swelling of the recessus ulnaris. Pain could be produced by direct pressure to the recessus ulnaris or by rotation of the forearm during prehension grip. One group (n = 14) had no previous operation or trauma. A second group (n = 6) had undergone previous surgery or suffered from trauma. All patients were treated by injection of cortisone and lidocaine into the recessus ulnaris. In the first group, ten (71%) remained pain-free during a period of 19 (9 to 40) months. In the second group, no improvement could be achieved. Based on anatomy and evolution of the recessus ulnaris, we try to establish a theory of the pathology.

Immunology and aging

Aging is accompanied by numerous functional and phenotypic changes in T cells, B cells and monocytes/macrophages; moreover, increases in autoimmunity, infections and occurrence of cancer have been reported in aged people. Healthy elderly persons, defined according to the criteria of the SENIEUR protocol, show various alterations in immunocompetent cells. Recent data have shown that the distribution of the subsets of peripheral blood, T-cell subtypes, is influenced by age. With increasing age, CD45RA(+) naive cells are replaced by CD45RA(-) memory CD4(+) T cells. In the CD8(+) T-cell subset, we found an increased proportion of cells co-expressing CD57. In monocytes also, some alterations of the immunophenotype, for example the expression of the adhesion molecule CD54, were observed. A relative deficit of transendothelial migration with aging was found in T cells, whereas this function was not impaired in monocytes. The immunophenotype and the function of dendritic cells do no t appear to be affected by aging. Due to their capacity to present antigens to T cells and to induce T-cell proliferation, dendritic cells may provide a useful tool for immunotherapy. In conclusion, investigations of immune functions in aging people reveal that there is an alteration of the immunophenotype of T cells and monocytes. Several functions of T-cell accompanying mechanisms, for example cytokine production and cell migration, are also affected by aging. In contrast, dendritic cells do not seem to be influenced by the aging process.

Surface markers and transendothelial migration of dendritic cells from elderly subjects

Age-related changes of immune functions have been extensively investigated in both humans and animal models; nevertheless, the literature on potential alterations of dendritic cells, potent antigen presenting cells responsible for initiating immune responses, with aging is very scarce. We studied the immuno-phenotype of peripheral blood dendritic cells of elderly and young subjects by three-color flow cytometry. In addition, the capacity of transendothelial migration, an important step in inflammatory reactions, of peripheral blood dendritic cells of elderly subjects was investigated in an in vitro model. The expression of HLA-DR in the peripheral blood dendritic cells of the elderly subjects was significantly decreased when compared to the young control subjects. The expression of various other surface markers was similar in the young and elderly subjects. The ability of transendothelial migration of dendritic cells was found to be unimpaired in the elderly subjects. Both in the young and elderly subjects a significantly higher expression of CD29, CD86, HLA-DR, and HLA-DQ in the dendritic cells that had migrated through the endothelium in comparison to nonadherent, nonmigrating cells was found. In the migrating dendritic cells of the elderly subjects a significantly increased expression of CD11c was observed, whereas the expression of CD54 was significantly enhanced in the migrating dendritic cells of the young subjects only. In conclusion, our results demonstrate intact functions and a normal immunophenotype of dendritic cells derived from elderly subjects. Dendritic cells thus seem to be functional and therefore are not responsible for the well-known decline of T cell functions with aging.

[Bone growth after finger replantation in childhood]

Following replantation in childhood, growth disorders of the affected epiphysis can influence function and aesthetic appearance of the hand. In a retrospective study long-term results of replantation in the upper limb in childhood were analysed with respect to factors influencing further growth. 22 patients with 29 replanted fingers were reviewed clinically and radiologically after an average interval of ten years. An average bone growth of 93% compared to the contralateral non-injured side was found. With the epiphysis affected, bone growth was reduced to 86% of the contralateral side. Analysis of single phalanges showed a growth rate of 71 to 100% in phalanges distal to the amputation and also in phalanges initially severed. Potential factors influencing bone growth were assessed separately. Best results were achieved in straight injuries without epiphyseal affection. An influence of anoxia time or number of anastomosed vessels could not be found. Even though replantation in childhood affects growing bone, almost normal bone growth can be expected afterwards.

Effect of different luting procedures on the seating of ceramic inlays

This in vitro study evaluated the effect of different luting procedures on the proper seating of ceramic inlays and on the marginal seal through microleakage testing. Sixty mesial-, occlusal-, distal- (MOD) cavities were prepared in third molars, and distributed among four groups. In the control group 1, the cavity surface was treated with dentin and enamel bonding agents; ceramic inlays were placed into the cavity and light cured. In group 2, the dentin and enamel bonding agents were cured prior to the placing of the inlays, and following the insertion. In group 3, the inlays were luted without enamel bonding. In group 4, the inlays were cemented using a one-bottle bonding and two times light curing. The groups with only one time light curing at the end of the luting process exhibited the smallest luting space following cementation. The smallest dye penetration values were obtained for the two groups with separate light curing of the dentin bonding agent. Reducing the film thickness of polymerized dentin bonding agents, i.e. by changing the composition of the bonding agents, could facilitate proper seating of ceramic inlays together with a better marginal seal.

Root lesions in a group of 50-60 year-old Germans related to clinical and social factors

From a preventive point of view collection of data concerning carious and non-carious cervical tooth defects is definitely important. Consequently, the prevalence and distribution of different root lesions were studied and correlated with behavioral and biological factors in 50- to 60-year-old German individuals (n = 298). Additionally, the data were correlated with characteristics concerning oral health and known risk factors such as gender, educational level, and presence of plaque. An interview included questions on sociodemographic and socioeconomic characteristics, dental and general health status, and various behavioral parameters. During clinical examination data concerning coronal and root lesions, restorations, probing depth, gingival bleeding, and dental plaque were obtained. The participants represented a social middle class population with a high awareness of dental health. Obviously, for the participants, known risk factors for root decay such as gender, educational level and plaque index were of minor importance. Factors correlating with root caries were: (a) number of missing teeth, (b) probing depth, (c) smoking habit, (d) regular dental attendance and (e) the reason for the last dental treatment. Additionally, the prevalence of non cariogenic lesions, primarily resulting from increased but wrongly performed oral self care, seems gradually to relieve carious root destruction.

Influence of two dentin bonding systems on the demineralization of the root surface

It has been assumed that dentin adhesives can prevent root surface caries. The aim of this study was to determine the caries-protective effect of two different dentin bonding systems on the demineralization of root surfaces in vitro. The root surfaces of 60 freshly extracted caries-free human molars were thoroughly cleaned and polished, thereby removing the cementum. The teeth were then coated with acid-resistant nail varnish, exposing two rectangular windows of 6 mm2 each. One window served as an untreated control, while the other window was treated with a dentin bonding system. The specimens were distributed among the following experimental groups--Group 1: Syntac, Heliobond (no air thinning); Group 2: Syntac, Heliobond (as recommended); Group 3: Syntac, without Heliobond; Group 4: Prime & Bond 2.0 (no air drying); Group 5: Prime & Bond 2.0 (as recommended); Group 6: Prime & Bond 2.0 (dentin pretreated with 36% phosphoric acid). Subsequently, all specimens were demineralized for 6 days with acidified gel (HEC, pH 4.8, 37 degrees C). From each tooth, three dentinal slabs were cut perpendicular to the polished surface of the windows. The slabs were ground to a thickness of 80 microns and imbibed with water. The depth of the respective demineralized areas was determined using a polarized light microscope. All control specimens exhibited lesions with a mean depth of 67 microns. In Groups 2, 3, and 5 the lesion depth was reduced significantly, while in Groups 1, 4, and 6 no lesions could be detected. It was concluded that the demineralization of the root surface can be impeded by application of the dentin adhesives tested.

[Scapholunate dissociation. Results of ligament suture and ligament-plasty]

The diagnosis of scapholunate ligament rupture is frequently missed. Untreated, it will lead to carpal collapse and arthrosis of the wrist, and ultimately to scapholunate advanced collapse (SLAC-wrist). We report the results of 20 patients treated either by direct suture or reconstruction of the ligament with a follow-up of three to five years after surgery. The operation was performed between 0.5 and 120 months (suture 2.6 months, reconstruction 28 months) after the original trauma. The results of direct repair were superior to ligament reconstruction. In our experience, direct ligament repair was only possible up to four to six months after trauma, this study emphasizes the importance of early diagnosis and treatment by anatomical reposition of scapholunate ligament rupture.

[Proximal scaphoid pseudarthrosis--reconstruction by dorsal bone screw and spongiosa transplantation]

Stable fixation of small proximal pole nonunions of the scaphoid by conventional techniques of bone grafting remains difficult. Because of this, long-lasting immobilisation is necessary. Treatment by retrograde Herbert-screw fixation offers the possibility of stable osteosynthesis resulting in shorter immobilisation. Even in case of avascular proximal fragments, it allows healing of the nonunion. We report on the 29 months follow-up of 23 patients treated in this manner showing bony consolidation in 17 cases (74%). Four patients demonstrated fibrous nonunion with minor symptoms, and in two patients persistent nonunion with slight impairment was seen. Evaluation with the DASH-questionnaire revealed slight disability with an average score of ten points. The availability of the mini-Herbert-screw has improved this treatment concept.