Bite force on single as opposed to all maxillary front teeth

The relation of number of teeth to maximal clenching force was tested in 10 healthy female dental students. The maximal force in the interincisal position was tested by spreading the load with individual acrylic splints over a varying number of teeth in the anterior region. In the maxilla, one splint covered teeth 13–23; another covered tooth 11. In the mandible, one splint covered teeth 33–43 in all experiments. The maximal force in the incisal position was measured 10 times, five times with each splint. The maxillary splints were changed in random order. The tactile sensibility of tooth 11 and its antagonists was tested before and immediately after interincisal force measurements. A highly significant difference between maximal forces was seen in comparing biting between a single tooth and multiple teeth. In addition, bite force also showed a significant increase in both single tooth and multiple teeth successive biting trials during the experiments. Tactile sensibility between d 11 and its antagonist was not altered by the maximal bite force trials.     

Dental development of Chinese children with cleft lip and palate.

OBJECTIVE: To compare the dental development and rate of tooth development between children with and without cleft lip and palate. Patients: Age- and gender-matched pairs (231 in all) of southern Chinese children ages 3 to 12 years, with and without cleft lip and palate. METHODS: Dental histories and radiographs were studied. From these, dental development was determined. RESULTS: Of 2946 tooth pairs in the children with cleft lip and palate, 252 (8.6%) were found to be asymmetric, significantly (p < .001) more than the 63 of 3179 (2.0%) tooth pairs observed in the children without cleft lip and palate. The teeth with the highest frequency of asymmetry were the maxillary lateral incisors (38.1%). Differences in dental development on the cleft versus noncleft sides of children with unilateral cleft lip and palate were significant for both maxillary and mandibular teeth (p < .001 and p = .039, respectively). The mean delay in tooth formation of the children with cleft lip and palate was 4.4 months relative to the children without cleft lip and palate. The majority of the teeth in the cleft lip and palate group were delayed by one developmental stage. This happened in 40.0% of the maxillary teeth and 30.1% of the mandibular teeth. The delay in tooth formation increased as the number of missing teeth increased in the children with cleft lip and palate, although not significantly. CONCLUSIONS: This group of southern Chinese children with cleft lip and palate demonstrated a higher prevalence of asymmetric and delayed dental development than did their counterparts who did not have cleft lip and palate.     

Allogeneic bone for secondary alveolar cleft osteoplasty

The purpose of this retrospective clinical study was to determine the efficacy of allogeneic bone for secondary alveolar cleft osteoplasty. Twenty-four patients with unilateral cleft lip and palate treated with allogeneic bone grafts were examined by a surgeon, orthodontist, and prosthodontist 20 to 47 months after surgery. Radiographic and clinical examination of the periodontal status of the teeth adjacent to the cleft and their antimeres were compared for differences with Student's t test and the Wilcoxon test. Radiographs indicated complete bone bridging in 21 patients. Two of the remaining three patients had a 1-mm radiolucent gap in the cleft site. The third patient had a 6-mm-wide radiolucency and recurrence of an oronasal fistula which was regrafted with autogenous bone. No statistically significant differences between the cleft and noncleft tooth antimeres were found for plaque, gingivitis, bleeding, sulcus depth, or level of attachment. A statistically significant difference in the amount of attached gingiva was found between the cleft and noncleft tooth antimeres. Nine patients with missing lateral incisor teeth avoided prosthetic replacement by orthodontic movement of the canine tooth into the grafted edentulous space. In those cases where the maxillary canine was unerupted at the time of the surgery, eruption into the graft occurred. Stability of the maxillary segments was sufficient to allow prosthodontic restoration with a fixed partial denture in those cases where it was indicated.     

Comparison of a new dental trauma splint device (TTS) with three commonly used splinting techniques

Abstract – Splinting is the standard of care for stabilization of replanted or repositioned permanent teeth following trauma. The present experimental study compared four dental trauma splints in 10 volunteers. The evaluated splints included a wire-composite splint (WCS), a button-bracket splint (BS), a resin splint (RS), and a new device (TTS=Titanium Trauma Splint) specifically developed for splinting traumatized teeth. All splints were bonded to the labial surfaces of the maxillary lateral and central incisors. Splints were left in place for 1 week. After splint removal, the next splint was placed after a 1-week rest period. The sequence of splint application was randomized for each individual. The following parameters were assessed: tooth mobility with horizontal and vertical Periotest values (PTV) before and after splint application and splint removal, respectively; probing depths, plaque and bleeding on probing indices before splint application and removal, and chair time needed for splint application and removal. After splint application, horizontal PTV were significantly lower in central incisors for BS compared to TTS ( P =0.04), and for RS compared to TTS ( P =0.005) and to WCS ( P =0.006). Reduction of lateral tooth mobility (=splint effect) expressed by the difference between horizontal pre- and postoperative PTV was significantly greater in RS compared to TTS and WCS ( P <0.05) for central as well as for lateral incisors. However, changes of vertical tooth mobility were not significant across the splinting techniques. Periodontal parameters remained unchanged, reflecting the excellent oral hygiene by the study subjects. The chair time needed for splint application was significantly shorter for TTS ( P <0.01). In conclusion, all tested splints appeared to maintain physiologic vertical and horizontal tooth mobility. However, the latter was critically reduced in RS splints.     

Influence of periodontal ligament simulation and splints on strains developing at the cervical area of a tooth crown

Many in vitro tooth models do not incorporate periodontal ligament (PDL) simulation. This study presents the influence of physiologically loaded occlusal splints on cervical strains in a model incorporating roots and PDL. Four sets (N = 10) of occlusal splints differing in material (hard/soft) and location (upper/lower) were prepared for first maxillary and mandibular anatomic molars. Two strain gauges were bonded to the buccal and lingual aspects of the lower molar. Teeth were embedded in acrylic resin with/without a PDL‐simulating material. Force vs. strain data were acquired during loading and the maximal strains at 500 N were analyzed. When PDL was incorporated into the model without splints, buccal compressive strains were significantly decreased. Usage of a soft splint resulted in compressive strains on both tooth aspects. Usage of a hard splint on the lower tooth resulted in higher compressive strains on the lingual side compared with the buccal side, whereas usage of this splint on the upper tooth resulted in tensile strains on the lingual side. Bending towards the buccal side occurred when the splints were located on the upper tooth. Soft splints reduce buccal bending, but do not reduce cervical strains. Periodontal ligament stimulation materials should therefore be incorporated in models involving teeth.     

Rigidity of commonly used dental trauma splints

Abstract – Background/Aims: The stability of immobilization devices varies from flexible to rigid, depending on the trauma. We evaluated the rigidity of various commonly used splints in vitro Material and Methods: An acrylic resin model was used. The central incisors simulated injured teeth, with increased vertical and horizontal mobility. The lateral incisors and canines stimulated uninjured teeth. Tooth mobility was measured with the Periotest^® device. Vertical and horizontal measurements were made before and after splinting, and the difference between values was defined as the splint effect. We evaluated 4 composite splints, 3 wire‐composite splints, a titanium trauma splint, a titanium ring splint, a bracket splint, and 2 Schuchardt splints Results: For all injured teeth and all splints, there was a significant splint effect for the vertical and horizontal dimensions (P < 0.05). For injured teeth, the composite splints produced the largest changes in vertical tooth mobility; wire‐composite splints 1 and 2, using orthodontic wires, produced the smallest vertical splint effects. For uninjured teeth, the Schuchardt 1 splint and the bracket splint produced the largest splint effects; wire‐composite splints 1 and 2 produced only a slight change in tooth mobility. Composite splints 2 and 3 produced the largest horizontal splint effects for injured teeth, and the 4 composite splints produced the largest horizontal splint effects for uninjured teeth. The most horizontally flexible splints were the titanium trauma splint and wire‐composite splints 1 and 2. Conclusions: According to the current guidelines and within the limits of an in vitro study, it can be stated that flexible or semirigid splints such as the titanium trauma splint and wire‐composite splints 1 and 2 are appropriate for splinting teeth with dislocation injuries and root fractures, whereas rigid splints such as wire‐composite splint 3 and the titanium ring splint can be used to treat alveolar process fractures.     

The effect of splint material and thickness on tooth mobility after extraction and replantation using a human cadaveric model

Although current guidelines for the treatment of traumatic injuries recommend the use of 'flexible' splints, the precise definition of what is considered flexible versus rigid has not been rigorously defined, leaving the clinician with a wide range of options for this critical factor. The purpose of this study was to quantify and compare the effect of eight different splints on tooth mobility after extraction and replantation using a human cadaveric model. Following strict selection criteria including complete root maturation, lack of periodontal disease, normal bone levels, and crown integrity, a maxillary central incisor was atraumatically extracted and splinted with eight different splints. The experimental splints included a 30-pound test monofilament nylon-composite splint and six wire-composite splints made of wires of 0.012' (0.3 mm), 0.016' (0.4 mm), or 0.020' (0.5 mm) diameter stainless steel (SS) or nickel titanium (NT). A direct composite splint represented the most rigid type of splint. These eight splints were applied five times each, and tooth mobility was measured before and after each splint was applied. The average splint effect, defined as the difference between the presplint and the postsplint measurements quantified using the Periotest, was calculated for each splint and compared. No significant differences were found between the nylon-composite and the wire-composite splints. There was significantly less tooth mobility with the direct composite splint compared to all other splints. In conclusion, the results of this study suggest that nylon and SS or NT wires up to 0.016' diameter are significantly more flexible than direct composite splints and thus may be better suited for the splinting and management of traumatized teeth.     

Assessment of the alveolar bone support of patients with unilateral cleft lip and palate: A cone-beam computed tomography study

Objective:To assess the bone support of the teeth adjacent to a cleft using cone-beam computed tomography (CBCT).Materials and Methods:The CBCT scans of 31 patients with unilateral cleft lip and palate (UCLP) were assessed. The data for teeth neighboring the cleft were compared with those of contralateral noncleft teeth. For each tooth analyzed, the distance between the cementoenamel junction (CEJ) and the bone crest (AC) at the buccal side was measured as was the thickness of the buccal bone level at 0, 1, 2, and 4 mm.Results:The bone thicknesses of the central teeth at the cleft region at the crest and 2 mm apically were statistically significantly thinner than that of the central incisor at a noncleft region. The CEJ-AC distance for central teeth at the cleft region was higher than that for central teeth in a noncleft region.Conclusions:Subjects with UCLP showed reduced bone support at teeth neighboring the cleft compared with controls. This may cause some problems during orthodontic treatment.     

Genetic association studies of cleft lip and/or palate with hypodontia outside the cleft region.

OBJECTIVE: The purpose of this study was to determine whether the candidate genes previously studied in subjects with cleft lip, cleft palate, or both are associated with hypodontia outside the region of the cleft. SUBJECTS: One hundred twenty subjects from the Iowa Craniofacial Anomalies Research Center were selected based on the availability of both dental records and genotype information. METHOD: The type of orofacial clefting and type and location of dental anomalies (missing teeth, supernumerary teeth, or peg laterals) were assessed by dental chart review and radiographic examination. Genotype analysis of candidate genes was performed using polymerase chain reaction/single-strand conformation polymorphism analysis. RESULTS: The prevalence of hypodontia in this sample was 47.5%, with 30.0% of subjects having missing teeth outside the cleft. There was a positive association between subjects with cleft lip or cleft lip and palate who had hypodontia outside the cleft region (compared with noncleft controls) and both muscle segment homeo box homolog 1 (MSX1) (p =.029) and transforming growth factor beta 3 (TGFB3) (p =.024). It was not possible in this analysis to determine whether this association was specifically associated with orofacial clefting combined with hypodontia or whether it was due primarily to the clefting phenotype. CONCLUSIONS: In this sample, there was a significantly greater incidence of hypodontia outside the cleft region in subjects with cleft lip and palate, compared with cleft lip only or cleft palate only. Cleft lip and/or palate with hypodontia outside the cleft region was positively associated with both TGFB3 and MSX1, compared with noncleft controls.     

Natal teeth: a potential impediment to nasoalveolar molding in infants with cleft lip and palate

The purpose of this article is to describe two cases of bilateral cleft lip and palate with natal/neonatal teeth. Clinical features, prevalence, possible complications, and treatment modalities are discussed. Two patients with cleft lip and palate and natal/neonatal teeth are described. The first patient was a 4-week-old infant with bilateral cleft lip and palate. On initial inspection an odontogenic vestige was noticed on the right lateral border of the premaxillary segment, bordering the cleft. The second patient was a newborn with a vestige on the right side of the premaxilla. At 20 days, another swelling representing a neonatal tooth on the left side was found. Because the teeth interfered with the fabrication and application of the nasoalveolar molding (NAM) appliance, they were removed from both patients. In the first patient, at 1 week after extraction, the NAM device was placed without difficulty. At 8 months, the infant had adapted well to the NAM device and nursed without problems. The second patient did not follow-up for the placement of the NAM device. In patients with cleft lip and palate with natal/neonatal teeth who require NAM, the tooth must be removed to facilitate the fabrication and placement of the device. Natal/neonatal teeth must be extracted with caution because the tooth buds of neighboring teeth may be damaged and remnants of the dental papillae may be left behind. Although general anesthesia is not always indicated for the removal of these teeth, in cases in which the premaxilla is loose, such as the current cases, general anesthesia is warranted.     

Metric results of vestibuloplasty in unilateral cleft patients

Vestibuloplasty was performed on patients with completely closed cleft lip/alveolus or cleft lip/palate, using a mesh of polyglactin for covering the epithelial defect on the alveolar process. The vestibular height in the region of the teeth adjacent to the cleft was measured in 19 cases (average age 7.1 years) immediately before and after surgery as well as 4-10 months later. Although a loss of height of 18% had occurred during the healing period, the original height at the mesial tooth was increased from 6.0 mm to 11.2 mm and at the distal tooth from 3.7 mm to 11.4 mm. This high and freely mobile vestibule of the mouth is considered to be a precondition for undisturbed growth of the orofacial system in cleft patients.     

Effect of muscle relaxation splint therapy on the electromyographic activities of masseter and anterior temporalis muscles

The purpose of this study was to compare the effectiveness of splint therapy on the electromyographic activity of masticatory muscles (anterior temporalis and masseter) before and after the application of a muscle relaxation splint. Electromyography recordings from the masseter and anterior temporalis muscles were analyzed quantitatively during maximal biting in the intercuspal position both before and after treatment without a splint. Fourteen patients whose chief complaint was masticatory muscle pain were selected for the study. After the initial evaluations muscle relaxation splints were applied, and the patients were instructed to use the splints for 6 weeks. Surface electromyographic recordings were taken from each patient before the beginning of clinical therapy and after 6 weeks of wearing the splints. The data obtained were analyzed through paired sample t tests and Wilcoxon's signed rank tests. The results of the study were as follows: (1) the electromyographic activity of the two muscles during maximal biting was not markedly changed after the muscle relaxation splint was used; and (2) the changes observed in electromyographic activity of the involved and noninvolved sides were insignificant as well.     

A split-mouth study on periodontal and microbial parameters in children with complete unilateral cleft lip and palate

BACKGROUND: Complete unilateral cleft lip and palate (UCLP) is a hereditary or multifactorial malformation that can be corrected successfully with a combined orthodontic, surgical and restorative treatment. Such multidisciplinary treatment takes many years and demands a lot of attention to both patients' teeth and periodontium. OBJECTIVES: This split-mouth study aimed to compare the periodontal health as well as the microbial parameters between cleft and non-cleft region. MATERIAL AND METHODS: 75 patients (52 males, 23 females) between 8 and 20 years with a complete unilateral cleft lip and palate (before (n = 30), during (n = 34) and after (n = 11) the active orthodontic treatment) volunteered for this study. Four regions were defined for the split-mouth comparison: teeth neighbouring cleft (site 1), tooth in cleft (site 2), and the corresponding contra-lateral teeth, respectively, in the unaffected quadrants (sites 3 and 4). At all sites the following periodontal parameters were recorded: plaque and gingivitis indices, pocket depth, attachment loss, bleeding on probing, tooth mobility (visual and Periotest), radiographic bone loss and gingival width. In addition, three pooled subgingival plaque samples were taken (around tooth in cleft, teeth facing the cleft, and contra-lateral teeth of the latter). RESULTS: The differences between the teeth neighbouring the cleft and the corresponding contra-lateral opponents were of borderline significance (P 相似文献   

Periodontal disease in patients with cleft palate and patients with unilateral and bilateral clefts of lip, palate, and alveolus

BACKGROUND: Long-term health of the stomatognathic system, as well as esthetics, is the therapeutic goal in patients with facial clefts. The aim of this study was to analyze the periodontal situation of patients with cleft palate (CP) and cleft lip, palate, and alveolus (CLPA) to elicit the differing degrees and localization of periodontal disease. METHODS: In 30 patients with unilateral cleft lip, palate, and alveolus (UCLPA), 30 patients with cleft palate (CP), and 20 patients with bilateral cleft lip, palate, and alveolus (BCLPA), the gingival situation was identified and classified according to the sulcus bleeding index (SBI). Periodontal attachment loss and pathological loosening of teeth were noted for identification of periodontal lesions. The state of oral hygiene was recorded by the approximal plaque index (API). RESULTS: In general, poor oral hygiene was found in all patients. The SBI showed a high incidence of gingivitis in patients with cleft lip, palate, and alveolus. Patients with cleft palate had a minor extent of sulcus bleeding. Periodontal disease was found to a similar extent to that in the general population in patients with cleft palate, whereas patients with cleft lip, palate, and alveolus had a predisposition to deep periodontal destruction of teeth adjacent to the cleft. The registration of pathological loosening of teeth, a result of attachment loss, corresponded to the degree of periodontal disease shown by the attachment loss. CONCLUSIONS: A critical periodontal situation was found in patients with unilateral and bilateral cleft lip, palate, and alveolus, ultimately leading to tooth loss in the front tooth region. In contrast, patients with cleft palate exhibited periodontal situations similar to that found in the general population with additional damage, which may be attributed to orthodontic treatment.     

Influence of wire extension and type on splint rigidity – evaluation by a dynamic and a static measuring method

Abstract – Objectives: To evaluate the influence of wire dimension and wire length on the splint rigidity of wire‐composite splints in vitro. Materials and Methods: A custom‐made artificial model was used. The central incisors simulated ‘injured’ teeth with increased mobility, and the lateral incisors and canines served as ‘uninjured’ teeth with physiological mobility. To assess horizontal and vertical tooth mobility before and after splinting, the Periotest and Zwick methods were applied. Teeth 13–23 were splinted using wire‐composite splint 1 (WCS1; Dentaflex 0.45 mm) and wire‐composite splint 2 (WCS2; Strengtheners 0.8 × 1.8 mm). Splint length was varied by successively shortening the wire. The influence of wire dimension was tested using t‐test and Wilcoxon–Mann–Whitney test with the Bonferroni‐Holm procedure (α = 0.05). To test the influence of wire length, anova and Kruskal–Wallis tests as well as Tukey range and Wilcoxon test with Bonferroni‐Holm procedure were applied (α = 0.05). Results: Wire dimension significantly influenced splint rigidity (P < 0.05). The wire length significantly influenced the splint rigidity of WCS1 in the horizontal dimension and WCS2 in the horizontal and vertical dimensions (P < 0.05). Splint rigidity was significantly reduced when splinting only ‘injured’ teeth compared with splints including ‘uninjured’ adjacent teeth (P < 0.05). No differences were found between splints including one or two ‘uninjured’ teeth on each side (P > 0.05). Conclusion: WCS1 is flexible compared with the more rigid WCS2. The wire length influences the rigidity. To ensure adequate fixation and reduce the risk of enamel damage during splint removal, the splint should include only one ‘uninjured’ tooth bilaterally.     

Mesiodistal size of deciduous teeth in subjects with unilateral cleft lip and palate

The aim of this study was to investigate whether there was an association between presence of a cleft and reduced size of deciduous tooth on the cleft side. In this investigation, 58 study models of patients with unilateral cleft lip and palate with deciduous dentition were analyzed. The largest mesiodistal dimension of deciduous teeth was measured by a sliding caliper. The size of the same teeth on the side of the cleft and on the non-cleft side was compared. The results of the investigation were statistically analyzed. A difference between the genders was found. In the sample of boys the lateral deciduous incisor and the second deciduous molars on the cleft side were smaller than those on the non-cleft side, while in girls the central and lateral deciduous incisors were smaller on the cleft side than on the non-cleft side. It was concluded that the presence of a unilateral cleft lip and palate was associated with smaller tooth size.     

[牙合]垫对牙齿重度磨耗患者口颌功能影响的临床研究

目的：研究殆垫对牙齿重度磨耗患者口颌功能的影响。方法：用殆垫恢复10例牙齿重度磨耗患者的垂直距离,分别检测治疗前、治疗后1个月、3个月、6个月的咬合平衡性、咬肌及颞肌前束的肌电幅值、颌位及殆的稳定性以及边缘运动的平滑度及对称性的变化。结果：①咬合平衡性、颌位及胎的稳定性以及边缘运动轨迹的平滑度及对称性在治疗后呈逐渐改善趋势,治疗6个月后80％的患者恢复正常;②治疗后各组的息止位肌电幅值均较治疗前显著降低（P〈0．05）,正中颌位紧咬时肌电幅值在治疗后3个月组和6个月组较治疗前显著增加（P〈O．05）。结论：通过6个月的治疗和观察,聆垫对重度磨耗患者的口颌功能的影响呈现持续改善趋势。     

The adult unoperated cleft patient: absence of maxillary teeth outside the cleft area.

OBJECTIVE: The purpose of this study was to investigate the possible absence of teeth in the postcanine region of the upper jaw of the unoperated adult cleft patient. METHOD: The study was performed on 266 dental casts of fully unoperated adult cleft patients. The patients were divided into four groups according to the type of the cleft: unilateral cleft lip and alveolus, unilateral cleft lip and palate, bilateral cleft lip and alveolus, and bilateral cleft lip and palate. RESULTS: No absence of permanent teeth in the canine and postcanine area of the upper jaw could be found. CONCLUSION: The results are in contradiction with the established hypothesis that absence of teeth outside the cleft area of the maxilla is due to an unknown congenital factor. On the contrary, the findings support the hypothesis that surgery for the closure of the hard palate in early childhood is the most important etiological factor for the absence of teeth outside the cleft area in the early operated cleft patient. The superficial position of the tooth germs (at the time of the palatal surgery), especially those of the premolars, supports this hypothesis.     

Root development of permanent lateral incisor in cleft lip and palate children: a radiographic study.

OBJECTIVE: The objective of this study was to compare the root development of lateral incisor on the cleft side with the root development of its contralateral tooth in cleft lip and palate children. SETTING: Cleft lip and palate wing, Meenakshi Ammal Dental College and Hospital, Chennai, South India. MATERIALS AND METHODS: A sample of 96 orthopantamograms of patients with unilateral orbilateral cleft lip and/or cleft palate was selected, regardless of sex and race. MAIN OUTCOME MEASURE: Orthopantamograms were analyzed for root development of lateral incisor on the cleft and non cleft side. Associated anomalies like hypodontia, supernumerary teeth, malformed lateral incisors and root development of canine, if present, were recorded. FINDINGS AND CONCLUSIONS: Root development of permanent lateral incisor was delayed on the cleft side compared to the non cleft side. There was a statistically significant relationship between levels of root development of lateral incisors on the cleft side within the different study groups(P < 0.05). Incidence of hypodontia increased in proportion to cleft severity. Frequency of missing second premolars, supernumerary teeth and malformed lateral incisors increased in cleft lip and palate patients. Root development of canine showed a slight delay on the cleft side when compared to the canine on the noncleft side.     

前方牵引治疗替牙期唇腭裂术后反（牙合）对患者咬合功能的影响

目的 研究前方牵引治疗替牙期唇腭裂术后反（牙合）对患者咬合功能的影响.方法 以15名替牙期单侧完全性唇腭裂术后反（牙合）患者作为研究对象,对其进行前方牵引治疗,并在治疗前后进行咬合功能检查.结果 牙尖交错位（intercuspal position,ICP）习惯咬牙状态（habitual biting）（ICP-HB）时,从最初牙尖接触到最大牙尖交错所需的时间（occlusion time,OT）在治疗前后无明显变化.治疗后咬合接触点增加（P＜0.05）,颞肌前部、咬肌肌电值增加（P＜0.05）,咬合力不对称指数和颞肌前部、咬肌肌电不对称指数无明显变化.牙尖交错位最大力紧咬牙状态（maximal clenching）（ICP-MC）时,治疗后颞肌肌电值增加（P＜0.05）,咬肌肌电值有增加趋势,但无统计学意义.结论 替牙期唇腭裂术后反（牙合）患者在前方牵引治疗后,能在一定程度上改善咬合功能,但仍需要二期系统正畸治疗完善咬合关系的调整.