Carious Destruction Research Articles

Silver Diamine Fluoride as Indirect Pulp Capping Agent in Primary Molars: A Case Series

According to the current recommendations of the American Academy of Pediatric Dentistry (AAPD), Indirect Pulp Capping or Indirect Pulp Treatment (IPT) is defined as a procedure that preserves the deepest cavities adjacent to the pulp to prevent pulp exposure. Preserving and protecting the vital pulp through remineralisation of hypomineralised carious dentin poses a significant challenge in restorative dentistry. Traditionally, managing deep caries often led to pulp exposure and subsequent root canal treatment. Selective or stepwise caries removal is based on the concept of halting the progression of carious destruction, allowing for biological repair of the pulp-dentin complex by promoting the formation of tertiary dentin between temporary and definitive restorations. Silver Diamine Fluoride (SDF) has gained popularity due to its unique combination of silver and fluoride, which provides antimicrobial and remineralising properties. In this case series of three cases, three-year-old preschool boy, five year old girl and five year old girl, in whom, deep carious lesions in primary molars were treated using selective caries removal techniques with SDF as an IPT agent, resulting in successful minimally invasive restorative procedures. This case series underscores the importance of employing selective caries removal techniques and the potential use of SDF as an IPT agent in such scenarios to preserve tooth vitality in a less invasive therapeutic approach suitable for the pediatric population.

Comparative evaluation of caries removal efficacy between chemomechanical agents & conventional methods regarding time consumption

Introduction: The use of minimally invasive procedures and attention to patient comfort are of great importance, especially for dental treatment in young children. This has led to the development of chemomechanical methods for caries removal. Aim: To evaluate and compare the efficacy in terms of time consumption between the chemomechanical caries removal agent Papacarie and conventional method of caries removal. Methods: Subjects for this study were chosen from the outpatients of the Dept of Pediatric & Preventive Dentistry, Karpaga Vinayaga Institute of Dental Sciences. Twenty five children (age 6 -10 years) with bilateral frank cavitated lesions were included in this study. Bilateral primary teeth with comparable degrees of carious destruction were chosen in each child for caries removal with Papacarie and rotary instruments. The time taken for caries removal was measured using stopwatch. Results The time taken for caries removal in chemomechanical caries removal method was longer than the conventional method which was assessed using the student t test. Conclusions: Papacarie can be an effective clinical alternative treatment for the removal of occlusal dentinal caries in cavitated primary molars but requires longer time as compared to conventional method.

Minimalistic Intervention of White Spot Lesions and Dental Fluorosis with Resin Infiltration Technique- A Report of Two Cases

The advances in scientific developments in dentistry have led to the emergence of innovative technologies for early diagnosis, prevention, interception, and therapeutic strategies for the preservation of tooth structure loss due to carious destruction or tooth decay arresting the carious lesions in order to preserve the tooth structure loss. Minimal intervention techniques to replace, repair, and remove as little tissue as possible is gaining significant importance over traditional techniques, as the emphasis is given on the preservation of the original tooth structure. White spot lesions are a form of enamel demineralisation which usually occurs due to dental fluorosis or postorthodontic treatment, compromising the aesthetics and self-esteem of the patient. The resin infiltration technique is a reliable treatment option advocated for the treatment of white spot lesions and non cavitated carious lesions. It is a microinvasive intervention performed without drilling or sacrificing the healthy tooth structure aiming at reinforcing the demineralised enamel by filling with visible light curing resin. The rationale for the use of resin infiltration is to allow the light-activated resin to permeate into the enamel porosities by virtue of capillary action, into the treated surface of the tooth. The infiltrated resin occludes the enamel microporosities and prevents the lesion progression further as it blocks the various pathways of ingress created by the acid penetration and dissolved materials in the enamel matrix. The first case presentation highlights the successful management of white spots visible in the maxillary anterior region of a female patient of age 25 years. The second case represents the use of the resin infiltration technique to treat and eliminate yellow-brownish stains in the maxillary anterior teeth of a female patient of age 23 years. Both the patients expressed concerns about the non uniform colour and appearance of their teeth and wanted solutions to rectify the same, without any drilling or removal of the tooth surface. This article highlights the concept of resin infiltration as a minimally invasive treatment option for the management of white spot lesions as a viable solution to suit patient specific needs.

MICROBIOLOGICAL ASPECTS OF APPLYING CLINICAL DIAGNOSTIC COMPLEX OF ORTHODONTIC METHODS FOR RESTORING DESTROYED CORONAL PART OF TEETH

Improving the quality of restoration of the destroyed coronal part of the teeth by orthopaedic methods has led to significant scientific and clinical interest and has been discussed in numerous reports, but the issues on reparative regeneration and restoration of the gingival margin relief in the area of ​​the anterior group of teeth after reconstructive orthodontic measures in the case of restoration of destroyed tooth crowns and deep subgingival carious destruction have not been sufficiently studied yet. The purpose of this study was to investigate the microbiological peculiarities of applying a clinical diagnostic complex of manipulations designed to restore anterior teeth with cast posts to provide the grounds for long-term favourable outcomes of further orthopaedic treatment in order to obtain aesthetic appearance, taking into account the state of the surrounding soft tissues. To carry out high-quality preparation of periodontal tissues around the abutment tooth, patients underwent gingivectomy using a scalpel with a disposable blade, diode laser electrocoagulation and coagulation. The effectiveness of each method of the preparation of the marginal gingiva was evaluated by the findings of clinical and microbiological studies. We have found out all three tested methods of forming a new gum relief in the root area of ​​a preserved tooth can significantly improve the qualitative and quantitative composition of the microflora in the stump area. A significant decrease in the frequency of biotope colonization by pathogenic and transient microorganisms and the improvement of the species composition in the local oral microbiocenosis can be achieved by cutting the hypertrophied epithelial edge of the cervical area with a microsurgical scalpel and using laser coagulation. Clinical and microbiological studies have confirmed the effectiveness of the clinical diagnostic complex of techniques for preparing the marginal gum around the root of the tooth, which is planned for orthodontic treatment with a post and an inlay. The use of a diode laser has been found to show the highest efficiency compared to other presented methods. All of the above techniques can be used in dental practice as methods of choice.

Morphological condition of the pulp of intact and affected by caries third molars

To date, there is a theory that increased resistance to caries is observed in the teeth, which for any reason underwent destructive changes in the pulp. That is why there is a need to study the impact of pulp vitality on the development of the carious process. The aim of the research was to study the microscopic structure of epoxy sections of intact and carious third molars. We studied 4 intact and 6 carious third molars. For this purpose, specimens were made taking into account the free penetration of the fixative solution into the pulp. To this end, immediately after the tooth was removed, we cut off its roots almost near the crown, preserving the integrity of the latter. The method relied on the impregnation of specimens with epoxy resin, according to the method of epoxy plastination of tooth specimens, developed at the Department of Human Anatomy of Ukrainian Medical Stomatological Academy. The epoxy blocks were cut with a disk into two halves until the hard tissues of the tooth crown were exposed together with the pulp. We found that the hard tissues (dentin and enamel coating) of intact third molars did not have any structural defects. However, their pulp chamber contained mainly an amorphous substance, devoid of any typical pulp tissue structures. That is, the pulp was in a state of complete devolution. Quite the opposite presentation was observed in specimens of carious teeth. We found that their pulp chamber contained quite noticeable tissue structures typical of the dental pulp. It is interesting that in the subodontoblastic layer, in front of the carious alteration of the enamel, there was compaction of the pulp, which may be due to infiltration of perivascular connective tissue by immunocompetent cells. It was found that on the border with carious destruction of enamel, there was a compacted spot of altered dentin, whose matrix was intensely pigmented in brown colour, due to the accumulation of melanin on the dentino-enamel junction. Its excessive formation is associated with the destruction of protein-carbohydrate complexes of organic matter in the deep layers of dentin. We found that the pulp compaction and the focus of carious alteration of the enamel are projectively connected by a radial cord of altered dentin, known in the literature as “dead tracts”. Hence, there is reason to believe that the identified changes indicate a latent form of caries, with a pulpogenic mechanism of development. Thus, it can be argued that the teeth, which for any reason underwent degenerative changes in the pulp, are not prone to carious lesions, whereas in carious teeth, the pulp is active and involved in the pathogenesis of the carious process.

GENERAL FEATURES OF CARIES PATHOGENESIS IN THIRD MOLARS AND AUTOIMMUNE DISEASES

This article presents a literature review, the results of the analysis of random samples of third molars removed for various clinical indications (11 samples). The teeth samples were analyzed visually, then their coronal parts were treated with epoxy plastination technique and prepared polished sections were studied microscopically. The analyzed data demonstrate the pathogenesis of fissure caries in our samples studied can be explained in terms of the direct virulent effect of pathogenic bacteria on the organic matter in the superficial dentin and basal enamel with the formation of auto antigens, which, as a result of sensitization of the local immune system, become the initial source of the carious process spreading to other teeth. This gives grounds to identify it with the pathogenesis of autoimmune pathology. It has been established that carious damage to hard tissues on the smooth surfaces of the dental crown begins with the pulp, when it is vital, and stops as a result of its tissue degeneration. It has been shown that a single latent damage to the hard dental tissues is the initial manifestation of the latent stage of the carious process, while multiple defects indicate its further progression. As for the generally accepted classification of caries, according to which superficial, medium and deep caries are distinguished, then, in our opinion, they should be considered as stages of the further process of carious destruction of hard dental tissues. We can suggest the study of the pathogenesis of carious lesions of third molars is necessary in order to prevent the occurrence of autoimmune diseases and increase the effectiveness of their treatment.

The Use of Walnut Tree Bark Powder as a Teeth Whitener

The chemical changes that may occur with carious destruction of enamel lead to unacceptable appearance of teeth. For males and females the appearance of teeth is of most importance, therefore they should take care with their teeth. The cleaning and whitening processes are expensive and may be harmful for enamel of teeth, so this research includes the whitening of teeth by using natural product containing toothpaste. The powdered bark of walnut tree has been used as whitening material in four forms and these are tested on 40 volunteers with stained teeth in dentist clinic. The four products were powder only. Powder mixed with toothpaste, condensed aqueous extract and granules of the product. The percentage of the powder in the paste was 5%, the mixture is homogenized by using mortar and pistil and the pH is tested and calibrated by pH meter to 6.5 which is the acceptable medium for mouth and is included the normal range of saliva pH. The product is examined by brushing gently for two minutes after the brushing for same period by toothpaste without the powder. Walnut bark contains high quantities of minerals particularly manganese, and contains important subgroup of polyphenolic compound called ellagitannins which have antibacterial effects and antioxidant properties. The differences before and after brushing with powder were highly significant.

A Comparative study of Biodentine and Calcium Hydroxide as Pulpotomy Material in Primary Teeth.

Background: Pulpotomy is measured as one of the most worldwide accepted favourable clinical procedure for the treatment of deciduous tooth with reversible pulpitis with carious destruction of tooth tissue.
 Objectives: To evaluate the clinical and radio-graphical findings of primary tooth with reversible pulpitis by Biodentine and Calcium Hydroxide as pulpotomy material.
 Study Design: Randomized comparative study.
 Study place and period: Conservative Dentistry & endodontics department of Bangabandhu Sheikh Mujib Medical University, Dhaka, September 2013 to September 2014.
 Study Population: The study population comprised of patients having primary tooth with reversible pulpitis irrespective of sex.
 Methods/Procedure: According to inclusion and exclusion criteria, out of 100 primary teeth 50 teeth were treated with Biodentine (Group-A) and the remaining 50 teeth were treated with Ca(OH)2 (Group-B). Clinical and radiographic follow up examination were done at 3months,6 months and 12 months’ interval to evaluate the rate of postoperative pain, swelling and periapical radiolucency. Statistical package for Social Science (SPSS) version 17 was used to analyze the collected data
 Main outcomes measures (s): 01. Pain 02. Dentinal bridge 03. Root resorption
 Results: At 3 months observation period, Biodentine and Ca(OH)2 pulptomy of primary teeth showed 100% success rate in treating teeth with reversible pulpitis; neither pain nor swelling or radiographic sign of resorption was observed. At 6 and 12 months following the completion of treatment except in two case in group A and four case in group B in observation period, there results were similar to that of 3 months. Two Biodentine (4%) and four Ca(OH)2 (8%) therapy reported pain, swelling. There was no statistical difference between the two group (p>0.05).
 Conclusion: So, we can say that clinical and radiographic end result of Biodentine is better than Ca(OH)2 as a pulpotomy material in mature primary tooth with reversible pulpitis.
 Update Dent. Coll. j: 2019; 9 (1): 37-41

The epidemiological pattern of oroantral communication – a retrospective study

Introduction. Oroantral communication (OAC) between the maxillary sinus and the oral cavity is an infrequent post-surgical complication occurring most commonly after extraction of posterior maxillary teeth. Aim. To present the characteristics of OAC and predisposing factors as well as evaluate postoperative pharmacological therapy and complications in patients with an OAC. Material and methods. In this retrospective study, medical records of 63 patients with diagnosed OAC between 2011 and 2018 were analyzed. Results. The most frequent causes for tooth extraction leading to an OAC were periodontitis (n=34; 54%), carious destruction of the tooth (n=14; 22.2%), and tooth impaction (n=10; 16%). First molars (n=28; 44.4%), second molars (n=14; 22.2%) and third molars (n= 13; 20.6%) were the most frequently related teeth to OACs. The majority of OACs appeared in the fourth (n=22; 35%) and third (n=20; 31.7%) decades of life. Conclusion. OACs are rarely seen on an everyday basis by general practitioners; however, if left untreated, they may lead to further serious complications. Proper postoperative precautions must be taken in order to prevent further complications, and thus the evaluation of predisposing factors is of great importance.

Investigation of the interrelation between plaque level and tooth decay in children with nephrotic syndrome in the period of mixed dentition

The early onset of carious destruction of hard teeth tissues definitely increases the risk of caries at older age. The insufficient level of oral hygiene around a tooth affected by caries induces the corresponding effect of gingival inflammation. Primary teeth affected by caries carry the potential risk of developmental and structural disturbances of their permanent successors. The aim of this study is characterization of the interrelation between dental plaque levels and tooth decay in children with nephrotic syndrome in the period of mixed dentition. In the investigation are included children with diagnosed nephrotic syndrome and a control group of healthy participants. Implemented clinical methods, epidemiological research and graphics design have been used. In 16.85% of the children with mixed dentition and diagnosed renal disorders the epidemiological index of dft varies in the range between 86% to 100%, at the expense of afflicted by caries and complicated carious lesions primary teeth, as well as, already treated deciduous teeth. Among children suffering from nephrotic syndrome from 6 to 12 years old established a minimum value of PLI=1.32 and maximum level of PLI= 2.68 are established. We have registered a minimum level of the gingival index GI equal to 0.91 and a maximum value of GI=2.05. Concerning children without common health disorders a minimum rate of PLI=0.14 and maximum level of PLI=2.14 are registered. These participants are characterized with fluctuations of the index of GI in the range between 0.00 and 1.68. Optimization of oral hygiene procedures in domestic conditions is related to intensive, thorough and profound training of parents and children by dental medicine doctors. There is a great necessity of performance of motivation programs in the context of oral health promotion.

Frequency and causes of premature extractions of deciduous molar teeth – a retrospective study

Summary Introduction. Premature loss of deciduous molar teeth is a common cause of dysfunction of the masticatory system. Analysis of the causes of premature extractions of these teeth will allow the appropriate targeting of preventive and therapeutic interventions. Aim. To determine the frequency and causes of premature extraction of deciduous molar teeth. Material and methods. Analysis of randomly selected 1880 medical records of the patients of the Department of Pediatric Dentistry (Medical University of Warsaw) concerned the necessity and causes of premature extractions of deciduous molar teeth in children under the age of 6 and the course of previous dental treatment. Data was analyzed statistically using the Mann-Whitney U-test, Spearman's rank correlation and a chi-square test; significance level - p ≤ 0.05. Results. 228 deciduous molar teeth were extracted in 139 children, most commonly due to inflammation of the pulp and its complications (abscesses, fistulas) - 84.7%, and carious destruction - 7.9%. The incidence of acute purulent inflammation decreased with age, whereas the occurrence of chronic pulpitis increased. 87.3% of the extracted teeth had not been previously treated, 7.5% had fillings and 5.2% had been pulpotomized. 54.7% of the patients had a single tooth removed and the rest - more than one. Maxillary first molars were most frequently extracted. There was no statistically significant difference in terms of gender. No relationship between age and the number of the removed tooth was found. There was a positive correlation between chronic inflammation of the pulp and age; negative correlation was found between age and acute inflammatory process of the pulp or periapical tissue as causes of extraction (Spearman's rank correlation, p < 0.05). A statistically significant difference in the average amount of premature extractions performed per one patient was found - more than one tooth was more often extracted in boys (Mann-Whitney U-test, P = 0.034).

Treatment option for deficient maxilla by bone expansion using D-shaped bone expander for implant restorations

Background: Researchers are continuously developing various implant site development techniques to improve the predictability of implant restoration. The bone expansion from osteotome is a simple technique to improve the bone width, and is mainly applied to maxillary bone. It enables the dentist to select the optimum implant location and orientation for better functional and aesthetic rehabilitation. Case Presentation: A male patient of 30 years of age with history of tooth extraction nine weeks before due to non-restorable carious tooth destruction, reported to our department of Prosthodontics wanting to replace missing 11 and 16. Clinical examination of the extracted site with digital palpation, bone mapping showed the deficient bone width in both the region for the adequate implant size and buccal soft tissue concavity in the lateral incisor region. Bone mapping revealed the underlying bone was deficient in width by 1-1.5 mm for 3.4-3.8 mm diameter implant placement. Following conventional Panoramic, peri-apical radiographs, initial clinical examinations dental implants were advised with bone expansion by osteotomes. Conclusion: The osteotome techniques are a predictable, simple alternative to complex augmentation techniques to place an implant in case of bone atrophy. The bone expansion technique is limited to maxillary the bone, with bone width deficient less than 3 mm. Since it is a single stage surgical procedure, it is advantageous for the patient for early prosthetic replacement.

Esthetic restoration of severely mutilated primary anterior teeth: a case report

Early childhood caries mainly affects maxillary primary anterior teeth and it can lead to early pulpal involvement and destruction of coronal tooth structure. In early childhood caries, there is early carious involvement and gross destruction of the teeth. This leads to problems like reduced vertical habits like tongue thrusting and psychological problems. These teeth are always difficult to restore. This case report deals with the successful use of wire loops and composite resin to restore maxillary primary teeth affected by early childhood caries.

Comparative clinical evaluation of chemomechanical caries removal agent Papacarie® with conventional method among rural population in India: in vivo study

The use of minimally invasive procedures and attention to patient comfort are of great importance, especially for dental treatment in young children. This has led to the development of chemomechanical methods for caries removal. Aim: To evaluate and compare the antimicrobial efficacy, efficacy in terms of time consumption and pain perception of chemomechanical caries removal agent Papacarie® and conventional method of caries removal. Methods: Subjects for this study were chosen from children admitted to dental clinic for restorative procedures. Forty children (age 4-8 years) with early childhood caries were included in this study. Two primary teeth with comparable degrees of carious destruction were chosen in each child for caries removal with either Papacarie® or rotary instruments. The time taken for caries removal was measured using stopwatch. Pain response during caries removal was evaluated using the Wong Baker Face Pain Scale. Dentin samples of both groups were taken prior to, and after caries removal for microbiological analysis. Results The time taken for caries removal in chemomechanical caries removal method was three times longer than the conventional method. Pain score during chemomechanical method of caries removal was 1.525 as compared with 6.65 when conventional method was used. The antimicrobial efficacy of chemomechanical caries removal was significantly similar to conventional method. Conclusions: Papacarie® can be an effective clinical alternative treatment for the removal of occlusal dentinal caries in cavitated primary molars.

Analysis of factors related to extraction of endodontically treated teeth

Endodontic therapy is a predictable treatment, resulting in up to 97% retention rate for the treated teeth. However, about 3% of endodontically treated teeth require further treatment, including extraction of the tooth. This retrospective study analyzed all endodontically treated permanent teeth that were extracted in a multidisciplinary clinic in 2006-2007 (n = 547). Associations among the extractions' indications and the patients' gender, education, and smoking status, as well as tooth type and coronal restoration, were investigated. Of the 547 endodontically treated teeth that were subjected to extraction, mandibular (44.6%) and maxillary (20.5%) first molars were the most common. Fifteen percent of the extracted teeth were restored with a crown, whereas 57.4% of the extracted teeth did not have a permanent coronal restoration. The reasons for extraction were nonrestorable caries (61.4%), endodontic failure (12.1%), vertical root fracture (8.8%), iatrogenic perforation (8.8%), periodontal disease (4.6%), unrestorable cusp fracture (2.4%), orthodontic (1.3%), and prosthetic (0.2%) considerations and dental trauma (0.5%). Periodontitis was more prevalent among current smokers than among nonsmokers (P < .05). Gender and education had no influence on the extraction of the tooth. Vertical root fracture was more prevalent in mandibular than in maxillary first molars (P < .05). Caries was more prevalent in unrestored teeth than coronally restored or crowned teeth (P = .001). Endodontic failure and VRF were more prevalent in restored than in unrestored teeth (P < .05). The most common extracted tooth profile was the mandibular first molar without permanent coronal restoration, which was lost due to caries destruction. Endodontically treated teeth were prone to extraction mainly due to nonrestorable carious destruction and to a lesser extent to endodontic-related reasons such as endodontic failure, VRF, or iatrogenic perforation.

The chemistry of enamel caries.

The chemical changes which occur during the process of carious destruction of enamel are complex due to a number of factors. First, substituted hydroxyapatite, the main component of dental enamel, can behave in a very complex manner during dissolution. This is due not only to its ability to accept substituent ions but also to the wide range of calcium phosphate species which can form following dissolution. In addition, the composition, i.e., the extent of substitution, changes throughout enamel in the direction of carious attack, i.e., from surface to interior. Both surface and positively birefringent zones of the lesion clearly illustrate that carious destruction is not simple dissolution. Selective dissolution of soluble minerals occurs, and there is the probability of reprecipitation. The role of fluoride here is crucial in that not only does it protect enamel per se but also its presence in solution means that rather insoluble fluoridated species can form very easily, encouraging redeposition. The role of organic material clearly needs further investigation, but there is the real possibility of both inhibition of repair and facilitation of redeposition. For the future, delivering fluoride deep into the lesion would appear to offer the prospect of improved repair. This would entail a delivery vehicle which solved the problem of fluoride uptake by apatite at the tooth surface. Elucidation of the role of organic material may also reveal putative mechanisms for encouraging repair and/or protecting the enamel mineral.

A 3-year study of hemisectioned molars.

Over a period of 1-7 (average 2.9) years, 34 hemisectioned molars were examined clinically and radiographically. All patients were kept on a 3-6 month recall system. The indications for hemisectioning were periodontal in 9 cases and endodontic in 20 cases. In 4 cases extensive carious destruction, and in 1 case an external granuloma led to hemisectioning. Mainly mandibular molars were treated (27). Root resectioning was carried out on only 7 maxillary molars, 22 of the treated teeth were used as distal abutments for small fixed bridges. For a further 3 the same was planned. The remaining treated teeth were singly crowned. Of the 34 treated molars, 7 were considered failures, 6 for endodontic reasons (apical periodontitis) and only 1 for periodontal reasons. No correlation between failure and the length of the follow-up period was found. With 17 of the 34 molars a significant reduction in periodontal pocket depths was recorded between commencement of treatment and the final examination. No difference in periodontal pocket depth or in the height of the alveolar crest was found between hemisectioned and non-hemisectioned surfaces. The mobility of hemisectioned molars was difficult to judge because 22 of the 31 crowned teeth were used as abutments for bridges. 17 of the 22 bridges were firm, 4 showed mobility of 1 degree, and 1 mobility of 11 degrees. Of the singly crowned teeth, only 1 exhibited mobility of 111 degrees. This study indicates that the prognosis for hemisectioned teeth is favourable. Failures were primarily endodontic in origin rather than periodontal. Periodontal damage can be kept to a minimum by regularly reviewing oral hygiene standards. Treated teeth may be used as abutments for small bridges if attention is paid to achieving optimal articulation.

«Zuckertee - Karies» - Küçük Çocuklarda Görülen Süt Dişi Çürüklerinin Yeni Bir Şekli (*)

Ozet s 14 - 43 aylik on kucuk cocuktan dokuzunda ust on dislerden baslayan sut dislerinin yaygin curugu ile hazir tatli caylarin her gun icilmesi arasinda bir iliski oldugu bildirildi. Bu caylar butun vak'alarda gunde bir cok kez yemekler arasinda veya yatmadan once emzikli siselerden iciliyordu. Summary ; A correlation was established in 9 of 10 toddlers (age, 14-43 months) with rampant carious destruction of the deciduous teeth between daily consumption of so-called prepared tea» and the incidence of particular form of caries. In all cases, the tea was given to the child several times a day in a feeding bottle as a betweenmeal pacifier and help put the child to sleep.

Stages in the dissolution of human enamel crystals in dental caries.

Various stages in monocrystal dissolution occurring during human enamel were studied by high resolution transmission electron microscopy. After the development of a central core lesion, two mechanisms by which the dissolution spread laterally to the (100) faces of the crystal could be demonstrated on the basis of the systematic orientation of the crystallographic axes. In the first case, the destruction was developing parallel to (120) planes and the borders were limited by (100) planes. In the second type, the development of the lateral side lesion was observed parallel to (100) planes. The carious destruction of the enamel monocrystal occurred as a result of the development of several lateral side dissolutions of the two types described, proceeding along the entire central core lesion.

Direct effect of radiation on the solubility of human teeth in vitro.

Defects in human tooth enamel following high-dose irradiation to the head and neck have been reported for many years, but the mechanism by which these defects are produced remains controversial. Two alternative explanations are favored. One is that radiation directly alters the susceptibility of teeth to carious destruction; the other is that radiation causes salivary gland dysfunction, which in turn produces xerostomia, a condition associated with increased carious activity. In this study, we tested the first possibility by measuring the direct effect of radiation on the solubility of enamel and dentin in lactic acid, a primary factor in tooth decay in vivo.