Biomedical subjects

B Prahl-Andersen

Publications and source records attributed to B Prahl-Andersen.

At least 37 records · Page 2Linked to original sources

PubMed2001

Bone volume after secondary bone grafting in unilateral and bilateral clefts determined by computed tomography scans.

OBJECTIVE: The purpose of this study was to evaluate the outcome of bone grafts in cleft palate patients, thus assessing the amount of bone necessary to facilitate eruption-especially in the buccopalatal direction-of the permanent canine into the bone graft. STUDY DESIGN: Computed tomography scans taken immediately postoperatively and 1 year postoperatively of 42 unilateral and of 8 bilateral cleft lip and palate patients who underwent surgery at the age of 9 years (early secondary bone graft) or 12 years (late secondary bone graft) were compared. Three slices from the computed tomography scans taken immediately after the surgery were selected from the center of the bone graft and were then compared with corresponding slices from the 1-year postoperative computed tomography scans. Statistical analysis was performed by using the Wilcoxon 2-sample rank sum test. RESULTS: In the unilateral cleft group, 70% of the transplanted bone remained in the cleft area after 1 year, whereas in the bilateral cleft group, only 45% of the initial bone graft remained after 1 year. CONCLUSION: No statistically significant difference was found between early secondary bone grafting and late secondary bone grafting. In most cases, a sufficient amount of bone was present in the target area to facilitate eruption of the permanent canine.

Age Factors↗

PubMed2001

Relationship in hypoplasia between the masticatory muscles and the craniofacial skeleton in hemifacial microsomia, as determined by 3-D CT imaging.

The purpose of this study, based on three-dimensional (3-D) computed tomographic (CT) reconstructions, was to evaluate the relation between underdevelopment of masticatory muscles and hypoplasia of the craniofacial skeleton in hemifacial microsomia (HFM). In 25 patients with HFM and 19 control patients the volumes of the masseter, the temporal, and the medial-pterygoid and lateral-pterygoid muscles were measured on the basis of CT scans, using three-dimensional segmentation and voxel addition. The size and shape of the craniofacial structures were classified, using three-dimensional imaging based on CT scans. Contiguous 1.5-mm computed tomography scans were made with a Philips Tomoscan 350 and processed by a Cemax 1500X 3-D workstation. Using the Pearson product moment correlation coefficient, the Pruzansky/Kaban classification system, the new Craniofacial Deformity Scoring System, Cranial Deformity Scoring System, and Mandibular Deformity Scoring System (MDS) demonstrated correlation coefficients with the "masseter muscle percentage" varying from 0.71 to 0.81 (P < 0.05), with the medial pterygoid muscle percentage correlation coefficient varying from 0.43 to 0.56 (P < 0.05), with the lateral pterygoid muscle percentage correlation coefficient varying from 0.55 to 0.61 (P < 0.05), and with the temporal muscle percentage correlation coefficient varying from 0.67 to 0.84 (P < 0.05). The normal right/left difference in volume of the masticatory muscles of the control patients, calculated as a percentage of the total, demonstrated small differences of 3.4% to 4.8%. Bony malformations are associated with underdevelopment of the masseter and the temporal muscles, and demonstrate a tendency toward a clear relationship. The degree of muscular underdevelopment of the different muscles of mastication in one patient could vary widely. The normal right/left difference of the masticatory muscles of the control patients is minimal. The volume of the masticatory muscles of the non-affected side does not demonstrate a compensatory effect in patients with HFM.

Analysis of Variance↗

PubMed2001

CT-based size and shape determination of the craniofacial skeleton: a new scoring system to assess bony deformities in hemifacial microsomia.

The purpose of this study was to design a better craniofacial classification system for bony deformities in patients with hemifacial microsomia than the existing ones. It was meant to incorporate the deformity of the craniofacial skeleton other than that of the mandible. The "Mandibular Deformity Scoring" System (MDS), the "Cranial Deformity Scoring" System (CDS), the the "Craniofacial Deformity Scoring" System (CFDS) are three newly developed classification systems, which are based on three-dimensional computed tomography (3-D CT) reconstructions. The size and shape of the craniofacial structures of 34 children, 25 with hemifacial microsomia and 9 with minimal dysplasia or trauma, were determined from CT scans, using 3-D image segmentation and rendering. Contiguous 1.5-mm CT scans were made using a Philips Tomoscan 350 and were processed using a Cemax 1500X 3-D workstation. The precision of the 3-D imaging was assessed by repeated determinations carried out by two observers (intra- and interreliability). Accuracy of the bone determination technique was assessed by comparing the interpretations of the craniofacial skeleton by 3-D CT reconstructions of laser-stereolithographic 3-D models. Correlations of the Pruzansky/Kaban classification system and the newly developed classification systems were demonstrated by the use of the Pearson product moment correlation coefficients. The new CFDS (= CDS + MDS) provides an adequate basis for assessment of bony structures using three-dimensional imaging and demonstrates a high correlation with the known Pruzansky/Kaban classification system. This new scoring system can handle the wide variety of individual variation of the deformity seen in patients with hemifacial microsomia better than the existing scoring systems.

Case-Control Studies↗

PubMed2000

In response:

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Journal Article↗

PubMed2000

The air-abrasion technique versus the conventional acid-etching technique: A quantification of surface enamel loss and a comparison of shear bond strength.

The purpose of this study was to quantify the surface enamel loss that results when an air-abrasive technique is used and to compare the shear bond strength of different prebonding and bonding methods. Enamel loss was determined for 2 enamel-conditioning methods: acid etching with 37% phosphoric acid; and sandblasting with 50 microm aluminum oxide particles under different conditions. A profilometer was used to determine the surface enamel loss. Forty-two bovine teeth were divided into 7 groups (N = 6). The statistical comparison of the different groups was carried out by analysis of variance. The results showed that under certain conditions the enamel loss associated with sandblasting is equal to or smaller than that resulting from acid etching. In addition, the effectiveness of different prebonding and bonding techniques used in the bonding of orthodontic brackets was evaluated by means of shear bond strength measurements. For bonding, 1 resin and 1 glass ionomer cement were evaluated; for prebonding, a sandblaster, 2 different polyacrylic acids and phosphoric acid were tested. Seventy bovine teeth were divided into 7 groups (N = 10) and then stored in water for 24 hours. An Instrom testing machine was used to determine bond strengths, and the 7 groups were compared by means of analysis of variance. The significance of post hoc tests was predetermined at P <.003. The results showed that the bond strength of the sandblasted groups was significantly lower than that of the etching groups. This indicates that sandblasting is not an alternative for the acid-etching technique currently used in orthodontic practice.

Acid Etching, Dental↗

PubMed2000

Dental treatment of predental and infant patients with clefts and craniofacial anomalies.

Children with cleft lip and/or palate differ in facial morphology and dentition from normal noncleft children. This paper reviews the current understanding of early dento-maxillary development in children with palatal clefts and the role of presurgical orthopedic treatment prior to primary palatal surgery. Finally, shortcomings of previous approaches to studying the outcome of treatment are presented, with a challenge to reevaluate how success is measured in the new millennium.

Cleft Lip↗

PubMed2000

A 'sufficient cause' model for dental caries.

BACKGROUND: It is generally believed that dental caries is an infectious disease. The occurrence of dental caries is affected by a variety of determinants. In order to estimate the precise extent of the relation between specific determinants and the outcome phenomenon (i.e. the occurrence of dental caries), a coherent disease model is required. This model should also permit multivariate analysis to control for confounders and interactions. Only with such a disease model will it be possible to investigate the relation between the occurrence of a determinant and dental caries, and to estimate the extent of this relation. The known causal models for the explanation of dental caries do not fully meet these requirements. METHOD: Rothman's 'sufficient cause' model has been used as a starting point for the development of a new coherent disease model, to explain the occurrence of dental caries and allow multivariate analysis. RESULTS: The sufficient cause for dental caries comprises three component causes: sufficient microorganisms with cariogenic potential, easily fermentable carbohydrates and teeth. Whether dental caries actually occurs also depends on the influence of independent risk factors that interact with the component causes in a protective, as well as in a risk-increasing manner. These independent risk factors are saliva, fluoride, oral hygiene and diet. CONCLUSIONS: The 'sufficient cause' model for dental caries is a biological model in which distinction between protective and risk-increasing factors has been made, and interaction between factors has been described. With this model, it will now be possible to assess the extent of the relationship between a determinant and dental caries (the outcome phenomenon) using multivariate techniques.

Confounding Factors, Epidemiologic↗

PubMed2000

[Quality management in orthodontics].

For the Dutch government efficient and effective care aimed at patient satisfaction are key words in the quality policy. Without a structural feedback from patients, the users of care, and the purchasers of care successful development of a quality system is not possible. This is the reason why the Dutch government stimulates coordination and cooperation between three parties involved in health care: providers, purchasers and patients. Three different aspects of quality deserve attention in this respect: professional, relational and organisational quality. The ultimate aim is that every patient in orthodontic treatment can count on care that is based on respect and on treatment in which the discomfort is limited to the minimum.

Health Policy↗

PubMed2000

[Therapeutic strategies for impacted maxillary canines].

A disturbance in the normal eruption pattern of one or both of the maxillary canines is found in 1% to 2% of the teenagers aged ten to thirteen years. Frequently, dentists refer these patients to orthodontists who, in turn, seek the assistance of an oral and maxillofacial surgeon to retrieve the impacted canine, either by exposure alone or by exposure and attachment of a bracket and ligature for orthodontic extrusion. A common request in this procedure is the extraction of the persistent upper deciduous canine and/or, in case of an Angle Class II molar relationship, extraction of the upper first premolar. It has been shown, however, that on average 15% of these exposed or ligated maxillary canines fail to erupt. Therefore, one should be reluctant to extract the deciduous canine or the permanent first premolar before it is clear that the impacted maxillary canine will indeed erupt after surgical exposure and/or placing of a bracket and ligature for orthodontic extrusion.

Adult↗

PubMed1999

A systematic review of the relationship between overjet size and traumatic dental injuries.

The aim of this study was to aggregate the risk of traumatic dental injury due to overjet using several published papers and performing a meta-analysis on the results. The 11 articles involved in this investigation were identified by a literature search of Medline (1966-1996) and Exerpta Medica (1985-1996) databases using predetermined keywords, and inclusion and exclusion criteria. In order to assess the quality of each paper, a methodological checklist for observational studies was developed resulting in a score between 0 and 100. The relative risk of overjet, compared with a reference, was expressed as an Odds Ratio (OR). For each study, the OR was computed using the data presented and, subsequently, these ORs were pooled across studies. The effect of confounders (i.e. age, gender), which could bias the relationship between overjet and dental injury was taken into account. Furthermore, the influence of quality of the study on the pooled OR was addressed. The average methodological score was 41. From the results, it can be concluded that children with an overjet larger than 3 mm are approximately twice as much at risk of injury to anterior teeth than children with an overjet smaller than 3 mm. The effect of overjet on the risk of dental injury is less for boys than for girls in the same overjet group. In addition, risk of injury of anterior teeth tends to increase with increasing overjet size. Furthermore, the pooled OR does not seem to be affected by the quality of the studies.

Adolescent↗

PubMed1999

Contribution of jaw muscle size and craniofacial morphology to human bite force magnitude.

The existence of an interaction among bite force magnitude, jaw muscle size (e.g., cross-sectional area, thickness), and craniofacial morphology is widely accepted. Bite force magnitude depends on the size of the jaw muscles and the lever arm lengths of bite force and muscle forces, which in turn are dictated by craniofacial morphology. In this study, the relative contributions of craniofacial morphology and jaw muscle thickness to the bite force magnitude were studied. In 121 adult individuals, both magnitude and direction of the maximal voluntary bite force were registered. Craniofacial dimensions were measured by anthropometrics and from lateral radiographs. The thicknesses of the masseter, temporal, and digastric muscles were registered by ultrasonography. After a factor analysis was applied to the anthropometric and cephalometric dimensions, the correlation between bite force magnitude, on the one hand, and the "craniofacial factors" and jaw muscle thicknesses, on the other, was assessed by stepwise multiple regression. Fifty-eight percent of the bite force variance could be explained. From the jaw muscles, only the thickness of the masseter muscle correlated significantly with bite force magnitude. Bite force magnitude also correlated significantly positively with vertical and transverse facial dimensions and the inclination of the midface, and significantly negatively with mandibular inclination and occlusal plane inclination. The contribution of the masseter muscle to the variation in bite force magnitude was higher than that of the craniofacial factors.

Adolescent↗

PubMed1999

Symmetry and morbidity assessment of unilateral complete cleft lip nose corrected with or without primary nasal correction.

OBJECTIVE: Unilateral complete cleft lip patients treated with or without a primary nasal correction at the time of cleft lip repair were compared to evaluate the relevance of early surgical correction of the nose by using two assessments: nasal symmetry and morbidity. DESIGN, SETTING, PATIENTS: The no nasal correction group (NNC, n = 19) was operated by surgeon A using the Millard technique. The primary nasal correction group (PNC, n = 9) was operated by surgeon B combining the modified Millard technique with a columellar lift and alar mobilization. Symmetry was assessed on two sets of standardized photographs at 9 years of age using a computer-assisted analysis. Both cleft groups were compared with normal controls (NC, n = 20). The computer method included area and angular measurements. Morbidity was assessed by the number of procedures on the vermilion, the lip, and/ or nose for revisional surgery up to the age of 9 (NNC, n = 26; PNC, n = 12). RESULTS: No significant differences in symmetry were found between the NNC and PNC groups regarding the area and angular measurements. With regard to the area measurements, both cleft groups produced a significant asymmetry when compared to the NC group. Concerning the angular measurements, however, the NNC group differed significantly from the NC group, whereas such a difference could not be noted between the PNC group and NC group. With respect to morbidity, no revisional procedures were performed in the PNC group. The number of revisional procedures in the NNC group was 16 in 10 patients. CONCLUSION: Results are presented that favor, up to the age of 9 years, a primary nasal correction at the time of cleft lip repair.

Child↗

PubMed1998

Alveolar and skeletal dimensions associated with lower face height.

In this study, the relationships between the lower face height and the structure of the frontal alveolar and basal bone were investigated. The areas and the dimensions of the anterior alveolar and basal midsagittal cross-sectional bone from the maxilla and the mandible were recorded on lateral cephalograms from 460 untreated adults. An index was calculated dividing the sagittal by the vertical dimension of the midsagittal cross-sectional area. The subjects with a normal overbite between 0.5 and 4 mm (N=165) were divided into three groups according to the lower face height. A larger lower face height coincided with a larger maxillary alveolar and basal area and with a smaller mandibular alveolar index. Correlations between the lower face height and the maxillary alveolar index and the mandibular alveolar and basal area were low. It is concluded that long-faced subjects have a large mandibular alveolar height, which is more associated with a narrowed shape than with a large volume of the symphysis.

Adolescent↗

PubMed1998

Effects of early treatment on maxillary arch development in BCLP. A study on dental casts between 0 and 4 years of age.

The present investigation analyses longitudinally the effects of early orthopaedic and/or surgical treatment on maxillary alveolar arch development in 30 children with a complete bilateral cleft lip and palate (BCLP). Palatal arch dimensions were measured on dental casts and their growth velocities during different treatment periods were calculated. Differences in growth velocities between consecutive treatment periods were examined and tested statistically. Furthermore, growth velocities were compared with those of 80 non-cleft children. Before lip closure, growth of the intercanine width of children with a BCLP and non-cleft children was comparable. Only for arch length significantly was less growth observed in BCLP patients in comparison with the control group. After lip closure, intercanine width, arch length and segmental angle diminished. During the intersurgical period, arch form seemed to adapt to a new muscular balance. Immediately after soft palate surgery, growth of the intercanine width and intertuberosity width was restricted. This negative growth was compensated in the postsurgical period, where a catch-up growth of intertuberosity width was even observed.

Alveolar Process↗

PubMed1998

Incidence of mutans streptococci and lactobacilli in oral cleft children wearing acrylic plates from shortly after birth.

Children with a palatal cleft can be treated with preoperative infant orthopedics including an acrylic plate that is applied shortly after birth to obturate the cleft. It is advised to wear these plates until the 18th month of age. Such a plate, being a hard non-shedding surface, may be expected to facilitate early colonization of mutans streptococci. The first aim of the present investigation was to assess the incidence of mutans streptococci and lactobacilli in children with cleft lip and/or palate during the first 2 years of life. The second aim was to study whether preoperative orthopedics, that is, the wearing of an acrylic plate, had facilitated the establishment of mutans streptococci and lactobacilli. The third aim was to determine other factors associated with colonization of these organisms in these children. Sixty-two Caucasian Dutch children with cleft lip and/or palate participated in this study. Twenty-four of these children were treated with preoperative infant orthopedics and had been wearing an acrylic plate from within a few days after birth. At regular control visits plaque and saliva samples and samples from the surface of the acrylic plate were taken, while a dental examination was performed to document the emergence of the primary teeth, caries status, gingival condition and oral hygiene procedures. Saliva samples were also taken from the accompanying parents. At the visit at the age of 18 months, the parents were interviewed using a structured questionnaire. At this age, the prevalence of mutans streptococci and lactobacilli was compared to that in a control group of non-cleft children. The oral cleft children wearing an acrylic plate from shortly after birth were colonized earlier with mutans streptococci and lactobacilli than the non-plate oral cleft children. In the children wearing acrylic plates, the prevalence of lactobacilli decreased with age, while the prevalence of mutans streptococci increased. At the age of 18 months the prevalence of mutans streptococci was comparable in both groups of oral cleft children and in the control children. There was no relation between the numbers of mutans streptococci in the saliva of the mothers and their children. The presence of mutans streptococci in the saliva of the oral cleft children was significantly associated with between-meal snacking and with the presence of lactobacilli.

Acrylic Resins↗

PubMed1998

Short-term cost-effectiveness analysis of presurgical orthopedic treatment in children with complete unilateral cleft lip and palate.

OBJECTIVE: The aim of this article was to investigate cost-effectiveness in cleft palate treatment using cost-effectiveness of presurgical orthopedic treatment (PSOT) as an example. DESIGN: A three-center randomized clinical trial compared PSOT with non-PSOT for children with unilateral cleft lip and palate (UCLP, n=52). PATIENTS: The inclusion criteria for the trial were: complete UCLP, no other malformations, born at term, both parents Caucasian, trial entrance preferably within 2 weeks after birth, and informed consent by the parents. INTERVENTIONS: PSOT was performed by means of a passive plate according to Hotz and Gnoinski. MAIN OUTCOME MEASURE: The short-term cost-effectiveness of PSOT was based on the time taken for the surgical lip closure procedure. Medical and nonmedical costs until surgical lip closure at 18 weeks of age were analyzed. RESULTS: The durations of the surgical lip closure procedures did not differ significantly (57.2 minutes for PSOT and 56.4 minutes for non-PSOT). The mean medical cost for PSOT treatment was US$852. The non-PSOT treatment group had a significantly different mean medical cost (US$304). Mean travel costs and indirect nonmedical costs were US$128 and US$231 for PSOT and US$79 and US$130 for non-PSOT, respectively. CONCLUSIONS: The combination of a clinical trial and an economic evaluation makes it possible to relate effects to costs involved in treatment alternatives. Longer-term costs and effects will be incorporated into an extended cost-effectiveness analysis to determine the cost-effectiveness of PSOT.

Analysis of Variance↗

PubMed1998

Maxillary arch dimensions in bilateral cleft lip and palate from birth until four years of age in boys.

OBJECTIVE: To describe the development of maxillary arch dimensions in children with bilateral cleft lip and palate (BCLP) during the first 4 years of life and to compare it with that in noncleft children. DESIGN: This was a retrospective, mixed-longitudinal study. SETTING: The study was conducted at the Cleft Palate Center of the University Hospital of Nijmegen. SUBJECTS: The sample consisted of 26 boys with BCLP who were born between 1976 and 1990 and treated at the University Hospital of Nijmegen. Data for a control group of 34 noncleft boys were collected at the University Hospital of Amsterdam. METHOD: Palatal arch dimensions were digitized on dental casts. A comparison between BCLP and noncleft dimensions was made at fixed time intervals. RESULTS: At birth, anterior and posterior arch widths as well as arch depths were significantly larger in children with BCLP. After 7 months (lip closure), anterior arch width and arch depth diminished considerably in the cleft group. After 12 months (palatoplasty), a slight decrease in posterior arch width was observed, and arch depths showed slight catch-up growth. At 4 years of age, anterior arch width was significantly narrower and anterior arch depth was shorter in children with BCLP than in control subjects. Posterior arch width was significantly wider. CONCLUSIONS: During the first 4 years of life, maxillary arch dimensions in children with BCLP show a unique development that is significantly different from that in noncleft children.

Cephalometry↗

PubMed1998

Transmission of mutans streptococci between mothers and children with cleft lip and/or palate.

OBJECTIVE: The aim of this study was to investigate the transmission of Streptococcus mutans between children with cleft lip and/or palate and their mothers. DESIGN: Saliva samples of 21 mother-child pairs were collected and cultured on plates containing a selective growth medium for mutans streptocci. At least five separate colonies of each colony morphotype were isolated. A polymerase chain reaction (PCR) with randomly chosen primers was used to type the isolates. RESULTS: The number of morphotypes and PCR types was significantly lower in the children than in the mothers. Significant correlations were found between the number of morphotypes and PCR types, in the children as well as in the mothers. In only 38% of the mother-child pairs were the same PCR types found in mother and child. CONCLUSIONS: This suggests that S. mutans had been transmitted from mother to child in one-third of the population studied. No correlations were found among the number of colony-forming units, the number of colony-colony-morphotypes, and the number of PCR types of the mothers and transmission. Similar PCR types in mother and child were found significantly more often in children who had more than one PCR type. The results indicate that transmission of S. mutans from mother to child is not frequent in children with oral cleft. This may have consequences for preventive treatment of cleft lip and/or palate children and their mothers.

Chi-Square Distribution↗