In Vitro Investigation into the Effect of Cryopreservation on the Mechanical Characteristics of Dental Hard Tissues.

Previous research has reported on hidden damage within the dentin introduced by cryopreservation, but the effect on the mechanical properties of the hard tissues at tooth level remains unclear. The main objective of this study is to investigate the effect of cryopreservation on the mechanical properties of teeth. A matched sample of 234 premolars of 117 children (9 ≤ age ≤ 16 years), bilaterally extracted for orthodontic reasons, were included. For each child, one tooth was randomly allocated to the cryopreservation group and the contralateral tooth was assigned to the control group. Static compression tests were performed to determine load to failure, stiffness, and toughness. In a subgroup of 20 teeth, a cyclic preloading or chewing simulation was performed. Additionally, the fracture mode was determined, and the microstructure of the fractured surfaces was examined using a scanning electron microscope (SEM). Linear mixed model analyses could not detect a statistical difference in the mean load to failure (p = 0.549), mean toughness (p = 0.968), or mean stiffness (p = 0.150) between cryopreserved and non-cryopreserved teeth. No significant difference in load to failure after cyclic preloading was detected between groups (p = 0.734). SEM analysis revealed comparable fracture characteristics between groups. It is concluded that cryopreservation does not affect the mean load to failure, stiffness, or toughness of teeth, indicating that hidden damage in the dentin is not critical at tooth level.

Combined orthodontic-orthognathic management of a patient with generalized short root anomaly and anterior open bite.

Short root anomaly is a rare dental disorder affecting tooth root development. It is characterized by reduced root-to-crown ratios (1:1 or less) and rounded apices. The short roots introduce a potential complication during orthodontic treatment. This case report describes managing a girl with generalized short root anomaly, an open bite, impacted maxillary canines, and a bilateral crossbite. In the first phase of treatment, the maxillary canines were extracted, and the transverse discrepancy was corrected with a bone-borne transpalatal distractor. In the second phase of treatment, a mandibular lateral incisor was removed, fixed appliances were placed in the mandibular arch, and bimaxillary orthognathic surgery was performed. A satisfactory result was obtained without further root shortening, adequate smile esthetics, and 2.5-year posttreatment stability.

Reliability of the novel cleft lip and palate smile esthetic index (CLP-SEI).

BACKGROUND/OBJECTIVES: The aim of this research was to determine the reliability of a novel index for the assessment of smile esthetics in patients with cleft lip and/or palate (CL ± P) at the end of their multidisciplinary treatment, for use in clinical and academic settings. MATERIALS AND METHODS: Five orthodontists, five periodontologists, five general practitioners, five dental students, and five laypeople rated the smiles of 10 patients with CL ± P twice at a 2 weeks interval. The rating scale consisted of four main categories: 1. nasolabial esthetics, 2. gingival esthetics, 3. dental esthetics, and 4. overall esthetics. A total of 15 parameters were rated. Intra- and inter-rater agreements were calculated using SPSS. RESULTS: The inter-rater agreement varied between good and excellent whereby the orthodontists, periodontists, general practitioners, dental students, and laypeople obtained agreement scores of 0.86, 0.92, 0.84, 0.90, and 0.89, respectively. The intra-rater agreement was good with agreement scores of 0.78, 0.84, 0.84, 0.80, and 0.79, respectively. LIMITATIONS: Smile esthetics were rated on static pictures, not in real life or by video recordings in a young adult population. CONCLUSIONS/IMPLICATIONS: The cleft lip and palate smile esthetic index is a reliable tool for the assessment of smile esthetics in patients with CL ± P.

Rapid maxillary expansion vs slow maxillary expansion in patients with cleft lip and/or palate: a systematic review and meta-analysis.

OBJECTIVES: To compare the dentoalveolar outcomes of slow maxillary expansion (SME) and rapid maxillary expansion (RME) used for maxillary expansion before secondary alveolar bone grafting in patients with cleft lip and/or palate (CL/P). Secondarily, the advantages and disadvantages of SME vs RME were reviewed. MATERIALS AND METHODS: A systematic search was conducted up to November 2021, including Medline (via PubMed), Embase (via Ovid), Web of Science, Cochrane Central, and Google Scholar. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. Risk-of-bias assessment was performed using the Risk of Bias (RoB 2.0) and Risk Of Bias In Non-randomized Studies of Interventions (ROBINS I) tool. Overall quality was assessed using the Grading of Recommendations Assessment, Development, and Evaluation tool. RESULTS: Of 4007 records, five studies met the inclusion criteria. The randomized control trial (RCT) had a low risk of bias, the non-RCTs presented with a moderate risk of bias. Arch width and perimeter increased significantly with both SME and RME treatments. No difference in the increase in palatal depth was found. The meta-analysis showed a greater anterior-to-posterior expansion ratio for the Quad Helix (QH) appliance. The results for dental tipping were not conclusive. CONCLUSIONS: SME and RME promote equal posterior expansion in cleft patients. The anterior differential expansion is greater with SME (QH appliance). No clear evidence exists concerning the amount of dental adverse effects of SME and RME in cleft patients.

A non-cephalometric three-dimensional appraisal of soft tissue changes by functional appliances in orthodontics: a systematic review and meta-analysis.

BACKGROUND: Patients with dental and skeletal Class II growth patterns present typical facial characteristics. Functional appliance (FA) therapy is one of the conventional orthodontic treatment modalities used to harmonize these facial imbalances. OBJECTIVES: The aim of this systematic review was to investigate and summarize the effects of FAs on the facial soft tissues captured in three dimensions. SEARCH METHODS: A systematic search was conducted up to December 2020. Databases Medline (via PubMed), Embase (via Ovid), Web of Science, and Cochrane Central were searched without language restrictions. SELECTION CRITERIA: Randomized clinical trial (RCT)'s investigating the influence of FA therapy on the facial soft tissues in a non-cephalometric and three-dimensional (3D) manner, were included. DATA COLLECTION AND ANALYSIS: Data extraction was independently undertaken by two authors. In case of conflict, a third author was consulted. RoB 2.0 tool was used to assess the risk of bias. A meta-analysis was performed for total facial height, upper lip length, lower lip length, commissural width, and facial depth. The single-step activation versus incremental approach was compared using a random effects model. RESULTS: Five studies were included in the qualitative synthesis of the systematic review. Facial height increased after FA therapy. Three studies met the criteria for the meta-analysis. The mean facial depth increased significantly (P < 0.003) with 1.39 mm (0.46 to 2.32). CONCLUSIONS: Current evidence suggests a positive influence of the FA therapy on the soft tissues in Class II patients. However, conclusions were drawn based on a two-dimensional analysis of 3D images, suggesting that more controlled studies using a comprehensive 3D analysis are necessary to confirm these results. REGISTRATION: PROSPERO registration (CRD 42021224016).

A non-cephalometric two-dimensional appraisal of soft tissue changes by functional therapy in Class II patients: a systematic review and meta-analysis.

BACKGROUND: Facial attractiveness has social, psychological, and economic repercussions. Class II malocclusions are associated with a retroposition of the mandible, facial convexity, protruded upper lip, retruded lower lip, and pronounced mentolabial fold. Functional appliances (FA) try to increase mandibular length and normalize lip position, thereby decreasing the facial profile convexity and aesthetics. OBJECTIVES: The aim of this review and meta-analysis is to investigate the effects of FA on the soft tissues in a non-cephalometric two-dimensional manner. SEARCH METHODS: Medline (via PubMed), Embase (via Ovid), Web of Science, and Cochrane Central were used to identify studies describing the soft tissue results of FA in a non-cephalometric way. The search was conducted up to July 2021. SELECTION CRITERIA: Prospective and retrospective studies investigating the effects of FA appliances on the soft tissues, with non-ionizing, two-dimensional imaging, including an attractiveness assessment based on Visual Analogue Scale or Likert scale, were considered eligible. DATA COLLECTION AND ANALYSIS: Data extraction was performed separately by two authors. Risk of bias was assessed using the ROBINS-I tool. RESULTS: From the eight eligible studies, four were included in the meta-analysis to investigate the influence of assessors on facial attractiveness scores. Age range of the included studies varied from 8 to 21 years old including 313 Caucasian patients whereof 64% females. Six out of eight studies used growing patients as treatment group and only two studies reported follow-up after the end of treatment. Overall facial attractiveness increased after treatment with FA, resulting from a decrease in facial convexity and a normalization of the lip relationship. Orthodontists score higher aesthetic improvements after FA treatment as compared to laypeople. CONCLUSIONS: Current evidence suggests the positive effects of FA on the facial attractiveness in growing and non-growing patients. FA normalize the lip relationship. Furthermore, they tend to decrease facial convexity and advance the chin point. More pleasing results can be expected in growing patients. Orthodontists are more generous when assessing treatment changes as compared to laypeople. REGISTRATION: PROSPERO registration (CRD42021254835).

Assessment of craniofacial maturation in preadolescents with cleft lip and/or palate using the cervical vertebral maturation method.

OBJECTIVES: Aberrant growth of the maxillomandibular complex in patients with cleft lip and/or palate (CL/P) can be managed with dentofacial orthopaedics. However, no consensus has been reached regarding timing and evolution of the maturational stages. Therefore, the aim of this study is to determine if patients with CL/P have an increased risk for delayed craniofacial maturation. MATERIALS AND METHODS: A sample of 246 cleft patients and 210 non-affected individuals was retrospectively compiled. Cephalometric radiographs taken between the ages of 10 and 14 years (girls) and 12 and 16 years (boys) were collected and assessed with the cervical vertebral maturation (CVM) method. RESULTS: In boys, no significant association between the presence of CL/P and a CVM score of CS3 or higher was observed in any age subsample. This was similar for a CVM score of CS5 or higher. Girls in the CL/P group had a significant lower probability of having a CVM score of at least CS3 in the subsample with age 11 to 12 (p = 0.001) and a borderline non-significant lower probability of having a CVM score of at least CS5 in the subsample with age 12 to 13 (p = 0.055). CONCLUSIONS: The current study demonstrated a discrete delay in skeletal maturation before the pubertal growth spurt of (pre)adolescents with CL/P, especially girls. This delay was less apparent at the end of the pubertal growth spurt. CLINICAL RELEVANCE: This research suggests that the craniofacial maturational stages relevant for dentofacial orthopaedic treatment in cleft patients, especially girls, occur at higher chronological age. Further research must quantify this delay, investigate its clinical significance, and determine its effect on the timing of dentofacial orthopaedic treatment.

The effect of manual lymphatic drainage on patient recovery after orthognathic surgery-A qualitative and 3-dimensional facial analysis.

OBJECTIVE: The aim of this study was to investigate the effect of manual lymphatic drainage (MLD) on postoperative facial swelling and pain. STUDY DESIGN: A randomized, single-center, prospective, 2-arm clinical trial with blinded endpoint assessment was set up. Patients were enrolled from the Maxillofacial Department of the Ghent University Hospital (Belgium) between January 2015 and March 2018. Both the intervention group (n = 13) and the control group (n = 13) received the same postoperative care; in addition, the intervention group underwent 6 sessions of MLD after orthognathic surgery. Three-dimensional facial scans were performed and questionnaires administered on postoperative days 3, 7, 14, 30, 90, and 180. A linear mixed model was performed, and statistical significance was assumed at the 5% level. RESULTS: In total, 26 patients (mean age 29 years; range 16-57 years) were included for statistical analysis. A faster decrease in swelling in the intervention group was observed on 3-dimensional scans. Furthermore, patients receiving MLD reported reduction in swelling and pain within the first month after surgery. However, no statistically significant difference could be detected in these observations (P > .05). CONCLUSIONS: Within the limitations of this study, no statistically significant difference could be found between patients treated with or without MLD after orthognathic surgery with regard to swelling and pain.

The Effect of Autologous Alveolar Bone Grafting on Nasolabial Asymmetry in Unilateral Cleft Lip and Palate.

The objective of this study was to examine whether an autologous alveolar bone graft has an effect on the nasolabial asymmetry in unilateral cleft lip, alveolus, and palate. Fifteen children (mean age 7.5 ±â€Š2.4 years) with non-syndromic unilateral cleft lip and palate (CLP) were included. Non-ionizing three-dimensional images were acquired prior to and three months after the alveolar bone grafting procedure. A 2D and a landmark-independent 3D asymmetry assessment were used to detect changes of asymmetry in the nasolabial area. For the 2D assessment, a cleft and non-cleft side ratio for 4 linear nasal and 2 linear labial distances was expressed as a Coefficient of Asymmetry (CA). The 3D asymmetry assessment comprised a robust superimposition of the face with its mirror image, expressed as a root-mean-square-error (RSME) in mm. A significant decrease in the CA for the labial distance from the facial midline to the labial commissure was observed (P = 0.036). Also, the CA for the labial distance from the facial midline to the highest point of Cupid's bow increased significantly (P = 0.028). Non-significant changes were observed for the CA for the 2 nasal distances and the 2 other labial distances. No significant changes in 3D nasal asymmetry were detected (P = 0.820). Alveolar bone grafting completes the alveolar ridge but has only little to no clinical effect on the asymmetry of the secondary cleft lip nasal deformity.

Orthodontic Management of a Migrated Maxillary Central Incisor With a Secondary Occlusal Trauma.

INTRODUCTION: Normal or excessive occlusal forces exerted on teeth with a reduced periodontal support might result in a secondary occlusal trauma. This type of injury is diagnosed based on histological changes in the periodontium. Multiple clinical and radiographic indicators are, therefore, required as surrogates to assist the presumptive diagnosis of a (secondary) occlusal trauma. CASE PRESENTATION: In this case report, the diagnosis, management, and the 1-year follow-up of a secondary occlusal trauma of a maxillary central incisor are described. The occlusal relationship was rehabilitated with fixed orthodontic appliances and was further stabilized with both fixed and removable retainers. CONCLUSIONS: A combined periodontal-orthodontic approach for a secondary occlusal trauma allows the rehabilitation of periodontal, occlusal, and esthetic parameters. Twelve months after the end of the active orthodontic treatment, a combination of fixed and removable retainers showed to be effective in retaining the treatment outcome.

The evaluation of the transport medium for extracted premolars prior to cryopreservation: an in vitro study.

Autotransplantation is a versatile technique for the replacement of a missing tooth and cryopreservation can expand its scope. The aim of this in vitro study is to compare the antimicrobial effect of different transport protocols on procured teeth prior to cryopreservation. Streptococcus oralis biofilms were grown on ten sterile premolars, incubated for 48 h and subjected to the following transport procedures: an untreated (contaminated) control group, a group rinsed with phosphate buffered saline (PBS), a group transported in PBS, a group transported in Dulbecco's Modified Eagle's medium (DMEM) supplemented with fetal calf serum (FCS), and a group transported in DMEM supplemented with FCS and antibiotics (AB). The effect of cryopreservation as such, as well as the combination with a transport medium (DMEM + FCS + AB) on the contamination was also tested. The surviving bacteria were harvested, and determined by plate counting. There was no significant reduction in contamination after rinsing the tooth, after transport in PBS or after transport in DMEM with FCS. Significant reductions were observed for transport in DMEM with AB when compared to the control group (p = 0.003). Cryopreservation as such reduced the biofilm significantly (p < 0.001). No cumulative effect could be found when transport in DMEM + FCS + AB was followed by cryopreservation. Within the limitations of this laboratory set-up, DMEM + FCS + AB was the most effective transport medium in S. oralis biofilm elimination. It could not be concluded that rinsing of the tooth gives an additional reduction. Cryopreservation as such decontaminated the teeth more effectively than any tested transport procedure.

Quantifying Soft Tissue Changes in Cleft Lip and Palate Using Nonionizing Three-Dimensional Imaging: A Systematic Review.

PURPOSE: The use of nonionizing 3-dimensional (3D) imaging in cleft lip and palate (CLP) research is well-established; however, general guidelines concerning the assessment of these images are lacking. The aim of the present study was to review the methods for quantification of soft tissue changes on 3D surface images acquired before and after an orthopedic or surgical intervention in CLP patients. MATERIALS AND METHODS: A systematic literature search was performed using the databases MEDLINE (through PubMed), CENTRAL, Web of Science, and EMBASE. The literature search and eligibility assessment were performed by 2 independent reviewers in a nonblinded standardized manner. Only longitudinal studies reporting the assessment of pre- and postoperative 3D surface images and at least 10 CLP patients were considered eligible. RESULTS: Fifteen unique studies (reported from 1996 to 2017) were identified after an eligibility assessment. The assessment of the 3D images was performed with landmark-dependent analyses, mostly supported by superimposition of the pre- and postoperative images. A wide spectrum of superimposition techniques has been reported. The reliability of these assessment methods was often not reported or was insufficiently reported. CONCLUSIONS: Soft tissue changes subsequent to a surgical or an orthopedic intervention can be quantified on 3D surface images using assessment methods that are primarily based on landmark identification, whether or not followed by superimposition. Operator bias is inherently enclosed in landmark-dependent analyses. The reliability of these methods has been insufficiently reported.

The evaluation of the transport medium for extracted premolars prior to cryopreservation: a systematic literature review.

Prior to cryopreservation, a tooth is transported from a contaminated oral environment to the tooth bank. Our objective was to identify all studies reporting or investigating a transport protocol prior to the cryopreservation of teeth, in terms of decontamination of the subjects. The systematic literature search (1970-2017) was based on MEDLINE via PubMed, Web of Science and the Cochrane Library. The reference lists of the included studies and the Science Citation Index were used for hand searching (snowballing). Only studies reporting the transport conditions of the transplant were included. Language restrictions for English, Dutch or French were applied. The search led to 14 eligible studies. Almost all studies were laboratory studies, so the methodological quality of evidence was low. The majority of the included studies was performed by only five different research groups and the number of subjects varied between 1 and 120 teeth. In general, the teeth were stored in a tissue culture medium supplemented with fetal calf serum and/or different combinations of antibiotics and/or antimycotics. The teeth were transported cooled (4 °C) or at room temperature, for a period of time not exceeding 24 h. Only three studies reported the irrigation of the teeth with phosphate buffered saline prior to the transport. The optimisation of the decontamination during transport was investigated in three studies (from 1971, 1980 and 1982). It was concluded that the literature on this topic is scarce, and the decontamination protocol for teeth, prior to cryopreservation has not been validated recently.

An esthetic evaluation of unilateral canine substitution for a missing maxillary lateral incisor.

OBJECTIVES: The aim of this study is to determine whether variation in size, morphology, and color of a unilateral substituted maxillary canine has influence on the dentogingival attractiveness perceived by dental professionals and laypeople. MATERIALS AND METHODS: A frontal clinical photograph of a patient with unilateral canine substitution was used as standard picture. Five different series were created by modification of following parameters with a raster graphics editor (Photoshop CS 6): (1) width, (2) color, (3) gingival margin height, and (4) crown tip morphology of the substituted canine and (5) the gingival margin height of the neighboring first premolar. For each parameter, the photograph deviating the most from the standard photograph, was combined into a final series. Four groups of examiners (orthodontists, periodontists, dentists, and laypeople) were asked to rank the photographs from most to least attractive. RESULTS: One hundred seventy-four examiners ranked the photographs in order of attractiveness. Overall, a darker canine color (mean rank 4.36 ± 1.03) and a more pronounced canine tip morphology (mean rank 3.47 ± 1.11) were significantly ranked as most unattractive (P < .05). The gingival height of the neighboring premolar was ranked as least unattractive by all groups of examiners (mean rank 1.30 ± 0.74). CONCLUSIONS: Darker canine color and a pronounced tip morphology of a substituted canine are rated as the most unattractive by dental professionals and laypeople. CLINICAL SIGNIFICANCE: The present study showed that the canine color and crown tip morphology are important parameters when considering unilateral canine substitution, both for professionals and laypeople. There is a general preference in favor of canines with a light color and a reduced incisal tip.

Cephalometrics in Stickler syndrome: Objectification of the typical facial appearance.

INTRODUCTION: Stickler syndrome is a connective tissue disorder characterized by orofacial, ocular, skeletal and auditory symptoms. The orofacial phenotype mainly consists of midfacial hypoplasia, micrognathia and cleft palate. Large phenotypic variability is evident though. Few studies have tried to substantiate the typical facial appearance in Stickler syndrome patients. METHODS: Molecularly confirmed Stickler patients were invited to undergo cephalometric analysis based on a lateral radiograph in standardized conditions. Angular and linear measurements were performed according to Steiner's and Sassouni's analysis and compared with age- and gender-matched reference values. RESULTS: Thirteen patients aged 10-62y were included, twelve of whom had type 1 Stickler syndrome (COL2A1 mutation) and one type 2 Stickler syndrome (COL11A1 mutation). The position of maxilla and mandible relative to the cranial base was not significantly different from the reference population (S-N-A: p = 0.73, S-N-B: p = 0.43). The mandibular plane and y-axis showed an elevated angle with the cranial base in most patients, although not significant for the total group (S-N to Go-Me: p = 0.20, S-N to S-Gn: p = 0.18). Dental analysis was normal, except for a higher overjet value (p = 0.006) and a higher angle between occlusal plane and Frankfort plane (p = 0.022). CONCLUSION: Cephalometric analysis was not able to thoroughly prove the abnormal facial appearance in Stickler syndrome. The majority of patients had normal dentofacial proportions. The most frequently observed anomaly in our series is a rather short and posteriorly rotated mandible, but clinical variability is high.

The critical apical diameter to obtain regeneration of the pulp tissue after tooth transplantation, replantation, or regenerative endodontic treatment.

INTRODUCTION: Regeneration of pulp-like tissue in the pulp chamber after tooth transplantation, replantation, or in regenerative endodontic treatment is only possible if the apical foramen is open. According to the literature, the success of regeneration decreases considerably if the foramen is smaller than 1 mm when measured on radiographs. The aim of this study was to study histologically the relation between the width of the apical foramen and regeneration of tissue in the pulp chamber after autotransplantation. METHODS: Fifteen single-rooted mature teeth of 3 adult beagle dogs were used. All experimental teeth were extracted and underwent apicoectomy. The teeth were photographed from the apical side, and the width of the foramen was calculated. The foramen width ranged from 0.24-1.09 mm. All teeth were replanted in infraocclusion. The observation period was 90 days after transplantation. RESULTS: The 10 teeth with the smallest apical diameter, ranging between 0.24 and 0.53 mm, showed vital tissue in at least one third of the pulp chamber. The 6 most successful teeth showing vital tissue in the entire pulp chamber had an apical diameter between 0.32 and 0.65 mm, and 80% of the experimental teeth with a diameter varying between 1.09 and 0.31 mm showed vital tissue in at least one third of the pulp chamber 90 days after transplantation. CONCLUSIONS: The size of the apical foramen seems not to be the all decisive factor for successful revascularization and ingrowth of new tissue after transplantation. The minimum width of the apical foramen has not been determined, but a size smaller than 1 mm does not prevent revascularization and ingrowth of vital tissue. In this animal study an apical foramen of 0.32 mm did not prevent ingrowth of new tissue in two-thirds of the pulp chamber 90 days after transplantation.

Preferences of AP position of the straight Caucasian facial profile.

INTRODUCTION: Several investigators have compared the perception of profile attractiveness between professional and non-professional people, different groups of clinicians, and different ethnic groups. Our aim was to study preferences for facial protrusion in the lateral view for a straight Class I profile and to study the influence of gender, age, sex preference, and profession. MATERIAL AND METHODS: Portrait images of one male and one female model with a Class I occlusal relationship were warped into nine different antero-posterior positions. An internet site was established to reach as many people as possible, and a request was sent by email to participate in a scientific experiment. Finally, 1707 Caucasion assessors could be grouped. RESULTS: The preferred male profile is the straight full ante profile. For a feminine facial profile, the straight average and the straight 2/3 ante profiles were perceived as the most attractive. Surgeons tended to give significantly higher scores to attractive (ante) profiles, which correlated strongly with scores of the orthodontists. CONCLUSION: Whenever possible with combined orthodontic/surgery treatment, straight ante profiles should be aimed for.

Does removal of the original pulp tissue before autotransplantation influence ingrowth of new tissue in the pulp chamber?

In an attempt to extend the indication area for autotransplantation of vital teeth, two possibilities can be proposed: (i) The enlargement of the apical foramen, with the aim to facilitate revascularization and ingrowth of new tissue. The ingrowth of tissue will eliminate the need for endodontic treatment when mature teeth are transplanted and (ii) the cryopreservation of teeth in case they cannot be transplanted immediately to the receptor site. Teeth with an ideal stage of root formation can be cryopreserved to perform transplantation later. Although pulpcell cultures survive crypreservation in vitro, the pulp tissue cannot survive the cryopreservation procedures when it is kept inside the pulpchamber. Therefore, the pulp tissue has to be removed before cryopreservation. It has been demonstrated that revascularization and ingrowth of new tissue can occur in an empty pulp chamber (1). The aim of this study was to find out if revascularization and ingrowth of new pulp tissue is influenced by removal of the original pulp tissue before autotransplantation. Twenty nine single-rooted teeth from three adult beagle dogs were transplanted after resection of the root tip. One group of teeth (n = 14) had the pulp tissue removed before transplantation. The other group (n = 15) had the original pulp left in situ. The transplanted teeth were histologically analysed 90 days post-transplantation. In the group with the tissue left in situ, 12 teeth (80%) showed a pulp chamber totally filled or at least 1/3 to 2/3 filled with viable tissue. In the group with the pulp tissue removed, 11 teeth (79%) had no or little vital tissue in the pulp chamber. The necrotic masses that develop in the original pulp tissue immediately after transplantation are a possible stimulating factor in the repair process of the pulp. As a conclusion, it can be stated that in case of autotransplantation of teeth, it is advisable to leave the pulp tissue in situ to stimulate the revascularization and ingrowth of new tissue after transplantation.

Influence of cryopreservation on the pulpal tissue of immature third molars in vitro.

The purpose of this study was to evaluate in vitro the viability of isolated and non-isolated pulpal tissue of immature third molars after cryopreservation. This study was divided in three different experiments. Experiment 1: Pulpal tissue isolated from 19 third molars was divided in horizontal segments. Each segment was cultured separately in order to evaluate whether differences in growth capacity within the tissue could be found. Experiment 2: Pulpal tissue isolated from 27 third molars was divided in a mesial and a distal part. One part was cryopreserved before culturing, the other part was cultured immediately. Growth capacity of cryopreserved and non-cryopreserved tissue was evaluated and compared. Experiment 3: 43 third molars were cryopreserved. After thawing, the dimension of the apical foramen was measured and the pulp was isolated and segmented horizontally. The different parts were cultured and growth capacity was evaluated and compared. Results of experiment 1 and 2 showed no significant difference in growth capacity between fibroblasts originating from different pulpal segments of the same tooth without cryopreservation and between fibroblasts originating from cryopreserved and non-cryopreserved isolated pulpal tissue. In experiment 3 it was demonstrated that the dimension of the apical foramen and pulpal viability after cryopreservation are positively correlated. A minimum dimension of 9.42 mm(2) enables the cryoprotective agent to penetrate sufficiently and to protect the pulpal tissue from apex to crown. This study proved that cryopreservation of human pulpal tissue is possible if the cryoprotective agent can reach the entire pulp.

Influence of cryopreservation on human periodontal ligament cells in vitro.

Cryopreservation of teeth before autotransplantation may create new possibilities in dentistry. The purpose of this study was to examine the effect of a standardised cryopreservation procedure on human periodontal ligament (PDL) cell cultures. Human PDL fibroblasts obtained from immature third molars of 11 patients were cultured and divided into two groups. The experimental group was cryopreserved and cultured after thawing. The control group was cultured without cryopreservation. A comparison was made between cryopreserved and control cells. To evaluate possible differences in the characteristics of the fibroblasts, the cells in both groups were tested for viability (membrane integrity), growth capacity and alkaline phosphatase (ALP) expression. The Wilcoxon test for paired comparison between cryopreserved and non-cryopreserved cells was performed for each characteristic. The results showed that membrane integrity of cells was not influenced by cryopreservation. There was no statistically significant difference in growth capacity between cryopreserved and control cells. Non-cryopreserved cells were slightly stronger positive for ALP, but the difference was not statistically significant. From these experiments it can be concluded that the observed parameters are not influenced by cryopreservation.